How to make the TSL-100 good at almost everything
(but especially sludge/doom)
Update 8/19/2011:
This post should be considered grossly outdated. This work was done years ago. While this amp is still on the road and being used every week, you would be better served by looking at the current mods in this post.
This post should be considered grossly outdated. This work was done years ago. While this amp is still on the road and being used every week, you would be better served by looking at the current mods in this post.
If you are in the Philadelphia region and interested in having these or similar mods done inexpensively, please see Atomium Amplification.
This post is Google bait, so that someone else won't have to do all the searching I did in researching these mods. All of them require some experience soldering components on PCBs. They are presented in the order I did them.
Schematics here, with links throughout. Before doing these mods, please be sure you know about the voltage hazard inside the amp from the supply caps. The TSL (at least my 2005-made model) has bleeder resistors, so you can leave the amp unplugged for an hour and the caps will discharge themselves --- but ALWAYS CHECK WITH A VOLTMETER before diving in. A quick web search should yield whatever info you need here.
1. Get rid of the fizz
Perceived sonic change: large and immediately obvious
These amps have a reputation for being "fizzy" or "buzzy" in the lead channel. You can easily and cheaply get rid of this without making the amp sound dull.
Use two silver mica capacitors to create a 12dB/octave low pass filter at around 7.5kHz, in the preamp. This not only kills fizz in the preamp, it saves some headroom in the power amp and the power tubes break up more smoothly when they saturate. The treble you do keep is more pleasing.
Put a 390pf cap across R1 on the main circuit board (the one the tube sockets are on, this DOES affect ALL channels), and a 47pf cap across the lead channel volume pot -- VR2 on the lead channel panel PCB (ONLY affects lead channel). Note that the pots used have 4 terminals; one of these is part of the pot case, for grouding/shielding. Counting from the side toward the gain pot, use terminals 1 and 3. There should be only one pin (pin 2) between the two pins connected to the cap, and one pin on the side toward the treble pot. You will have to remove the chassis, tubes, aluminum top plate, and panel PCBs to do this mod --- that includes all the knobs and pot washers. You will want to put pieces of tape on each of the wires you disconnect, labeling what they connect to.
If you want to do the same thing to the crunch channel, just add another 47pf cap to the outer terminals of the volume pot (VR2) on that channel's panel PCB. I tried this and didn't like it, so I removed it -- the crunch channel's voicing seems ok to me.
EDIT 3/30/09: I have since changed the VR2 cap to a 68pf, to remove even more fizz and increase smoothness. I left the 390pf cap alone, since I know now that it affects all channels ever so slightly. So now the filter on the OD channel starts at a lower frequency, and maintains a 6dB/octave slope up until 7.5 kHz, where it steepens to 12dB/octave.
2. Change the tubes
Perceived sonic change: medium
This is inevitably a taste issue. If you want more raunch and a warmer sound, JJ tubes do nicely. This is what I use --- ECC83s preamp tubes, and E34L power tubes. Eurotubes offers a full re-tube kit for the TSL with a variety of options. I used the high-gain preamp tubes (I love gain). I have tried JJ's KT77 power tubes and found them to be muddy/farty and fizzy compared to JJ's E34L tubes when playing downtuned or sludgier material. There are applications where they are appropriate for adding roundness to the sound, but the bass is too loose for full-on gutteral roar. JJ's straight EL34 is a good option for a more traditional Marshall sound, more like the stock Svetlanas but better. The E34L type seems to improve both low-end extension (without mud) and headroom -- great for more rumble without fartiness.
EDIT 1/12/09: For E34Ls to sound best, they need to be biased on the high side, at about 90mV per side, or higher if you don't mind decreased life. 90mV per side is Marshall's spec for the amp, but most agree that this is high, and anything in the 80-90mV range is ok. I found that below 90, the E34Ls sounded a little fizzy and cold at lower volumes. There is good info on how to bias the TSL/DSL here.
EDIT 4/4/09: The high-biasing advice above really only applies if you replace the OT (see #7 below!). If you don't, most settings between 80-90mV per side will sound similar.
EDIT 6/15/09: On the other hand, since the MMOT handles more power cleanly, you can bias lower and get actual usable headroom --- with the same nice warmth at a higher volume level. Biasing low, to 70-80mV per side or so, gets you noticeably more volume before things start to break up --- by "noticeably" I mean that it feels like the speaker cabinet is going to fall apart. For Rosetta's European tour, I converted the voltage and ran the amp at ~80mV per side, and turned it a notch louder to compensate for a less efficient speaker cab.
3. Clean up the rectifier
Perceived sonic change: none
D3 through D10 (8 adjacent 1N4007 diodes) form the rectifier portion of the power supply. These are crappy, cheap diodes. Recently, using ultra-fast (low recovery time) diodes in guitar amp supplies has gotten really popular, with people saying they sound "less harsh" and "more tube-like." These claims may be spurious -- since ultra-fast diodes have nothing remotely like the occasionally desirable voltage sag in tube rectifiers -- but you can clean up hash and switching noise, and improve reliability, by replacing the diodes with faster ones.
There are two options: FREDs (Fast Recovery Epitaxial Diodes) or UF4007s. FREDs are the parts that are getting all the attention. They are huge, look like two-legged transistors, and have the lowest possible recovery time (40ns) at extremely high voltages and currents. They also cost $5-7 a piece, and you need 8 of them. The other option is just the ultra-fast version of the stock diodes -- UF4007s instead of 1N4007s. They cost about 25 cents a piece, with 75ns recovery time.
I went all-out with the FREDs, to see what it would do. They eliminated the supply switching noise, and as far as I could tell, they did not change the tone.
To change the rectifier, replace D3 through D10 (8 diodes) on the main circuit board, but be absolutely sure to observe polarity -- connecting a diode backwards will pretty much blow up your amp. If using FREDs, cover any exposed metal with electrical tape so they don't accidentally short. But it's not really worth it.
4. Add a choke
Cost: $35
Perceived sonic change: medium
A choke is an inductor that helps to filter ripple out of the power supply. Inductors in series act as a lowpass filter -- like in a crossover network -- so one that is large enough to filter out everything down to DC can smooth out the 60Hz ripple after the rectifier (it doesn't matter if you didn't understand that). They were often used in older amps back when large-value supply capacitors weren't as readily available. Now, large caps are easy to come by and cheaper than filter chokes, so they are used by themselves. However, with high inductance, chokes also seem to be able to store a certain amount of current, making that available to the power tubes in high-demand situations. I installed a Mercury Magnetics MC10H choke, and found that the amp became more responsive in high gain situations with a lot of low end in the sound --- palm-muting, octave pedal stoner riffs, etc. It had more attack in the bass and seemingly some more volume.
To install a choke, desolder R71 on the main circuit board. Mount the choke to the chassis next to the power transformer and run the wires through a small hole in the aluminum top plate. Solder them where R71 used to be.
EDIT 10/23/09: I notice that Mercury now has a 25H choke from the Axiom line. I'd be interested to hear people's experiences with that... might be even better for this application than the 10H.
5. Misc. cap value changes
Cost: less than $1
Perceived sonic change: medium
Comparing the TSL with its earlier cousin, the DSL, some find the DSL to have a slightly darker, bassier sound, though the amps are nearly identical. One reason for this may be the coupling cap C16 on the main circuit board. In the TSL, it's a 2.2nF ceramic, in the DSL, it's 4.7nF. I replaced C16 with a 4.7nF Orange Drop cap (nicer than ceramic anyway). The 4.7nF value rolls off frequencies below about 35Hz, which should be pretty insignificant unless you're playing an 8-string or hybrid guitar/bass. The TSL's normal 2.2nF rolls off frequencies below about 72Hz, which shouldn't be terribly noticeable with a 6-string tuned standard. But when you get below that, it certainly does make a difference. The preceding triode (V1B) is not run full-range anyway, so the coupling cap is adding to an existing lowcut.
I eventually found that the 4.7nF cap wasn't great with downtuning -- it didn't add anything I like, and made the amp muddier at high gain. 2.2nF sounds tighter to my ears, so I switched back.
EDIT 4/4/09: I recently noticed another (much more important) component value difference between the DSL and TSL -- C18 on the main circuit board is designed to bleed treble frequencies to ground coming off the V1AA triode. Since this triode is not used by the clean channel, this area is crucial to distortion voicing. In the DSL, the cap is a 470pf cap, but in the TSL, it's only 100pf. This means that more treble passes through to the next stage in the TSL than in the DSL. I have replaced the 100pf ceramic cap C18 with a silver mica 470pf cap, and this is a bigger and better change than the coupling cap swap. The tonality change between stages makes breakup in the later preamp triodes smoother and more mid-centric, but without altering the clean channel. I think this is probably a key source of the perceived difference between DSL and TSL.
Another cap to change is C9 (a 470pf ceramic cap) on the Lead channel circuit board -- this cap bleeds treble past the gain pot on the lead channel. It has no effect when the gain is maxed out (so I didn't notice it while playing with Rosetta), but makes the tone brighter when you turn down the gain. I happen to think it makes the channel sound "quacky". You can reduce the value to 100pf to move the corner frequency higher, or just clip it entirely. I clipped it and find the sound to be much more predictable at different gain points.
6. Fix undersized cap
Cost: less than $1
Perceived sonic change: none
C46, a 22pf/500V ceramic cap on the main circuit board, has been known to fail in the TSL. If it shorts, it can destroy all the power tubes and the output transformer. There is absolutely no reason a 16-cent part should be allowed to cause $300 worth of damage. I replaced this cap with another of the same value, but rated for 3150V.
7. Replace output transformer
Cost: $250
Perceived sonic change: substantial, but not necessarily better
The stock output transformer on the TSL is a Dagnall general purpose model, part #C3070, TXOP 00001. Mercury Magnetics makes a drop-in replacement -- the MAR100-OM -- that is bigger, more reliable, and is supposed to sound better. It's pricey. This mod requires no soldering and no drilling, just reconnecting the 7 wires to the right spade terminals on the new transformer. Mercury includes a diagram.
The new OT has wider bandwidth (read: deeper and higher), so it perceptibly improves clarity and attack. The lead channel seems fizzier at low volumes, but maybe a touch smoother at really high volumes. The "improvement" becomes more audible as you turn up the amp, which is to say, the breakup of the power section comes in more slowly, and there's more consistency from low to high volume. You may or may not consider this a good thing. There is quite a bit more bass available in the tone network, no doubt due to the extended low-end response of the MM. However, this can make the tone sound "tubby" at higher volumes with very low tunings.
I now realize that while this transformer is undoubtedly more reliable and cleaner than the stock model, it may be a little too polished (i.e. linear), lacking some of the "gravel" in the old one. The added bass also makes it initially sound less "tight" with high gain detuning. It's hard to say whether I became attached to the "imperfections" in the old OT, or had gotten so used to compensating for them that it's hard to make the MM work for me. The MM model may be suited to a more traditional style of playing, where the Dagnall seems to be (accidentally?) tighter and smoother for more extreme gain and tuning. I would say the Dagnall has a more (gasp!) "vintage" sound, since old Marshalls often had ill-suited and undersized transformers off the shelf, and the MM is more modern. It may all be a matter of taste, and $265 is a lot to spend on something that subjective.
EDIT 4/2/09: I switched back and forth between the Dagnall and MMOT a couple of times, and found that even though the saturation of the Dagnall was occasionally pleasing, it was no substitute for the greater volume and bass response of the MMOT. The MM transformer opens up a lot of possibilities.
The real issue is that it was one of the later mods I did, so the earlier component and settings choices had been made unconsciously to accommodate or to flatter the Dagnall's limitations -- after I tweaked some of my existing mods (pulled even more treble out of the lead channel, most importantly) and started over from scratch with all the controls at 5, I found I could get what I was looking for. I can now hear a much bigger difference between different bias settings, and the tone network's behavior actually makes sense. I now have to pull the bass back a lot --- but doing so gets back a good deal of the "tightness" I missed from the old setup, and reveals some lower frequencies (below the center frequency of the bass control) that were never there at all before.
However, make no mistake: the MMOT will not get rid of the "fizz" in the amp, contrary to some other opinions I've seen, and will probably make it even more noticeable. There are advantages to it, but less fizz isn't one of them. To put it succinctly: if you think the amp is fizzy, and you hate that you have to turn it up too loud to get a good sound, don't get the MMOT. If you are modding out the fizz (or you like it as-is) and you wish the amp was louder and had more "oomph," then by all means go for it.
EDIT 4/6/09: On further reflection, I think that the undersizing of the Dagnall is mostly responsible for the "tonal qualities" I was hearing --- it is highly likely that its core was saturating when I pushed the amp hard. I say this because with the Dagnall in the amp, I would hit a wall at about 6 on the lead channel's volume knob, beyond which the amp would not get louder --- but would start to sound dramatically different, losing bass response and tightness. With the MMOT, that wall was removed. I had assumed before that I was hitting power tube distortion, but if that were the case, the limit onset would have changed with different bias settings (it didn't) and would not have changed with a new OT (it did).
Furthermore, the Dagnall OT would get very warm while playing loud, while the MMOT remains the same temperature as the surrounding chassis, even at extreme volume. I can only assume the extra heat from the Dagnall was output power that was lost due to inefficiency, core saturation, or both. This would also explain why there are so many stories of the Dagnall OT blowing up when people try to run the TSL on the clean channel with all the knobs at 10 (Plexi-style). The amp is in fact capable of much more volume and bass response than its stock transformer allows, at least from a perceptual (standing in front of the amp) standpoint.
This added power could be good or bad depending on your needs -- if the amp only sounds good at enormously high power levels which you could never use, then it's not an upgrade. For my purposes though, it's a great thing, although I never expected I would think an amp was "too loud" (yikes!). Eventually I may be able to eliminate my Marshall 3210 slave head and drive both of my 280W 4x12s into speaker breakup with only this amp. I couldn't do that before.
Digression: I have heard that Mesa apparently uses deliberately undersized OTs in their Rectifier heads (but NOT in their other models) to get an effect similar to what I describe above. Maybe that's more integral to the "Mesa tone" of "pleasing compression" than their much-vaunted tube rectifiers...? But then again, "cheap, small output transformers" doesn't make for good marketing copy, so who knows?
At this point, I wouldn't trade this amp for one 5 times as expensive. You can hear it on every track on Wake/Lift except (Temet Nosce), using all three channels. At the time of that recording, the amp had mods #1-4 above, with the 390pf/47pf version of #1. The other mods hadn't been done yet. I used some EQ on the Wake/Lift guitar tracks, mostly to compensate for the microphone's non-linearities, but also to get a sound closer to what I imagined in my head. The amp is closer to that sound now, by itself. It is a very good-sounding amp now, one of the best I've ever played through, as far as the qualities I prize most: smoothness, bass transient power that maintains tightness, bell-like cleans, enormous gain, and of course sheer volume. I doubt that --- short of a custom design --- I could find anything else that would be as satisfying, in stock form.
As far as comparisons, I suppose it has a Bogner-ish and/or hot-rodded JCM800 kind of character, but deeper and with a more Fender-y clean channel. It is very much a Marshall, though, maybe more than in its original form. The gain on the lead channel is outrageous but stays focused at high volumes (I have the gain at ten, volume at the edge of power tube & speaker breakup). Crunch is nicely versatile. The VPR circuit actually sounds decent now, too, and whether it's on or not, the amp sounds steadily better as you turn it up. I would characterize the sound as the "next logical step" if Marshall had continued producing amps with the philosophy and quality of the JCM800s, but with modern levels of gain.
Some thoughts:
+ The most effective mods are not necessarily the most expensive. I've tried to be as objective as possible here, balancing what I've heard (NOT properly/scientifically ABX tested, obviously) with what I know about electrical engineering and amp design.
+ No mod will improve an amp for everyone. Different tastes have different requirements. I don't see these changes as "fixing" the amp; instead it's more about keeping the things I liked and refining the things I didn't. Since so much of the tweaking of this amp involves controlling the treble: before you get out the soldering iron, put an EQ in the effects loop and see what you like and don't like in the voicing. Try an EQ in front of the amp, too.
+ Mercury Magnetics has quite a hype machine, but for the most part their products live up to it, and they are helpful to talk to. I would buy from them again.
+ As a taste issue, I also swapped the reverb tank on the amp. The stock one is very good, just not as dense as I'd like. EDIT 8/28/09: I had Accutronics make me a custom Type-9 reverb tank and it's even better than the one I had swapped in before. Nice and rich --- the part number is 9BB3C1D.
EDIT 8/17/09:
"Tightness" vs. "looseness" -- while a lot of this has to do with what kind of cab you're using, I've found that the modded TSL is WAY tighter sounding than any Mesa. Even A/B'ed against a VHT (Sig:X) or Engl (Fireball), it holds its own. You can boost the input, roll back the gain, and get amazingly percussive tones without fizz. It's crunchy but VERY controlled. It's the closest thing I've ever gotten to a Meshuggah tone without a POD (on a Marshall! How weird is that?). My 8-string sounds incredible (even on the low E-flat string!), with the tone controls all at 12 o'clock and the lead channel gain at 4, and a 6-8 dB boost in front of the amp (a little "frown curve" EQ helps too).
This is all quite opposite of what I originally intended the mods to do --- give me a thicker, smoother saturation for enormously high-gain sludge riffing. It really speaks to the true versatility of the basic design (as opposed to its initially compromised realization) as well as the retention of a lot of buried "Marshall tone" that only came out after modification.
This post is Google bait, so that someone else won't have to do all the searching I did in researching these mods. All of them require some experience soldering components on PCBs. They are presented in the order I did them.
Schematics here, with links throughout. Before doing these mods, please be sure you know about the voltage hazard inside the amp from the supply caps. The TSL (at least my 2005-made model) has bleeder resistors, so you can leave the amp unplugged for an hour and the caps will discharge themselves --- but ALWAYS CHECK WITH A VOLTMETER before diving in. A quick web search should yield whatever info you need here.
1. Get rid of the fizz
Perceived sonic change: large and immediately obvious
These amps have a reputation for being "fizzy" or "buzzy" in the lead channel. You can easily and cheaply get rid of this without making the amp sound dull.
Use two silver mica capacitors to create a 12dB/octave low pass filter at around 7.5kHz, in the preamp. This not only kills fizz in the preamp, it saves some headroom in the power amp and the power tubes break up more smoothly when they saturate. The treble you do keep is more pleasing.
Put a 390pf cap across R1 on the main circuit board (the one the tube sockets are on, this DOES affect ALL channels), and a 47pf cap across the lead channel volume pot -- VR2 on the lead channel panel PCB (ONLY affects lead channel). Note that the pots used have 4 terminals; one of these is part of the pot case, for grouding/shielding. Counting from the side toward the gain pot, use terminals 1 and 3. There should be only one pin (pin 2) between the two pins connected to the cap, and one pin on the side toward the treble pot. You will have to remove the chassis, tubes, aluminum top plate, and panel PCBs to do this mod --- that includes all the knobs and pot washers. You will want to put pieces of tape on each of the wires you disconnect, labeling what they connect to.
If you want to do the same thing to the crunch channel, just add another 47pf cap to the outer terminals of the volume pot (VR2) on that channel's panel PCB. I tried this and didn't like it, so I removed it -- the crunch channel's voicing seems ok to me.
EDIT 3/30/09: I have since changed the VR2 cap to a 68pf, to remove even more fizz and increase smoothness. I left the 390pf cap alone, since I know now that it affects all channels ever so slightly. So now the filter on the OD channel starts at a lower frequency, and maintains a 6dB/octave slope up until 7.5 kHz, where it steepens to 12dB/octave.
2. Change the tubes
Perceived sonic change: medium
This is inevitably a taste issue. If you want more raunch and a warmer sound, JJ tubes do nicely. This is what I use --- ECC83s preamp tubes, and E34L power tubes. Eurotubes offers a full re-tube kit for the TSL with a variety of options. I used the high-gain preamp tubes (I love gain). I have tried JJ's KT77 power tubes and found them to be muddy/farty and fizzy compared to JJ's E34L tubes when playing downtuned or sludgier material. There are applications where they are appropriate for adding roundness to the sound, but the bass is too loose for full-on gutteral roar. JJ's straight EL34 is a good option for a more traditional Marshall sound, more like the stock Svetlanas but better. The E34L type seems to improve both low-end extension (without mud) and headroom -- great for more rumble without fartiness.
EDIT 1/12/09: For E34Ls to sound best, they need to be biased on the high side, at about 90mV per side, or higher if you don't mind decreased life. 90mV per side is Marshall's spec for the amp, but most agree that this is high, and anything in the 80-90mV range is ok. I found that below 90, the E34Ls sounded a little fizzy and cold at lower volumes. There is good info on how to bias the TSL/DSL here.
EDIT 4/4/09: The high-biasing advice above really only applies if you replace the OT (see #7 below!). If you don't, most settings between 80-90mV per side will sound similar.
EDIT 6/15/09: On the other hand, since the MMOT handles more power cleanly, you can bias lower and get actual usable headroom --- with the same nice warmth at a higher volume level. Biasing low, to 70-80mV per side or so, gets you noticeably more volume before things start to break up --- by "noticeably" I mean that it feels like the speaker cabinet is going to fall apart. For Rosetta's European tour, I converted the voltage and ran the amp at ~80mV per side, and turned it a notch louder to compensate for a less efficient speaker cab.
3. Clean up the rectifier
Perceived sonic change: none
D3 through D10 (8 adjacent 1N4007 diodes) form the rectifier portion of the power supply. These are crappy, cheap diodes. Recently, using ultra-fast (low recovery time) diodes in guitar amp supplies has gotten really popular, with people saying they sound "less harsh" and "more tube-like." These claims may be spurious -- since ultra-fast diodes have nothing remotely like the occasionally desirable voltage sag in tube rectifiers -- but you can clean up hash and switching noise, and improve reliability, by replacing the diodes with faster ones.
There are two options: FREDs (Fast Recovery Epitaxial Diodes) or UF4007s. FREDs are the parts that are getting all the attention. They are huge, look like two-legged transistors, and have the lowest possible recovery time (40ns) at extremely high voltages and currents. They also cost $5-7 a piece, and you need 8 of them. The other option is just the ultra-fast version of the stock diodes -- UF4007s instead of 1N4007s. They cost about 25 cents a piece, with 75ns recovery time.
I went all-out with the FREDs, to see what it would do. They eliminated the supply switching noise, and as far as I could tell, they did not change the tone.
To change the rectifier, replace D3 through D10 (8 diodes) on the main circuit board, but be absolutely sure to observe polarity -- connecting a diode backwards will pretty much blow up your amp. If using FREDs, cover any exposed metal with electrical tape so they don't accidentally short. But it's not really worth it.
4. Add a choke
Cost: $35
Perceived sonic change: medium
A choke is an inductor that helps to filter ripple out of the power supply. Inductors in series act as a lowpass filter -- like in a crossover network -- so one that is large enough to filter out everything down to DC can smooth out the 60Hz ripple after the rectifier (it doesn't matter if you didn't understand that). They were often used in older amps back when large-value supply capacitors weren't as readily available. Now, large caps are easy to come by and cheaper than filter chokes, so they are used by themselves. However, with high inductance, chokes also seem to be able to store a certain amount of current, making that available to the power tubes in high-demand situations. I installed a Mercury Magnetics MC10H choke, and found that the amp became more responsive in high gain situations with a lot of low end in the sound --- palm-muting, octave pedal stoner riffs, etc. It had more attack in the bass and seemingly some more volume.
To install a choke, desolder R71 on the main circuit board. Mount the choke to the chassis next to the power transformer and run the wires through a small hole in the aluminum top plate. Solder them where R71 used to be.
EDIT 10/23/09: I notice that Mercury now has a 25H choke from the Axiom line. I'd be interested to hear people's experiences with that... might be even better for this application than the 10H.
5. Misc. cap value changes
Cost: less than $1
Perceived sonic change: medium
Comparing the TSL with its earlier cousin, the DSL, some find the DSL to have a slightly darker, bassier sound, though the amps are nearly identical. One reason for this may be the coupling cap C16 on the main circuit board. In the TSL, it's a 2.2nF ceramic, in the DSL, it's 4.7nF. I replaced C16 with a 4.7nF Orange Drop cap (nicer than ceramic anyway). The 4.7nF value rolls off frequencies below about 35Hz, which should be pretty insignificant unless you're playing an 8-string or hybrid guitar/bass. The TSL's normal 2.2nF rolls off frequencies below about 72Hz, which shouldn't be terribly noticeable with a 6-string tuned standard. But when you get below that, it certainly does make a difference. The preceding triode (V1B) is not run full-range anyway, so the coupling cap is adding to an existing lowcut.
I eventually found that the 4.7nF cap wasn't great with downtuning -- it didn't add anything I like, and made the amp muddier at high gain. 2.2nF sounds tighter to my ears, so I switched back.
EDIT 4/4/09: I recently noticed another (much more important) component value difference between the DSL and TSL -- C18 on the main circuit board is designed to bleed treble frequencies to ground coming off the V1AA triode. Since this triode is not used by the clean channel, this area is crucial to distortion voicing. In the DSL, the cap is a 470pf cap, but in the TSL, it's only 100pf. This means that more treble passes through to the next stage in the TSL than in the DSL. I have replaced the 100pf ceramic cap C18 with a silver mica 470pf cap, and this is a bigger and better change than the coupling cap swap. The tonality change between stages makes breakup in the later preamp triodes smoother and more mid-centric, but without altering the clean channel. I think this is probably a key source of the perceived difference between DSL and TSL.
Another cap to change is C9 (a 470pf ceramic cap) on the Lead channel circuit board -- this cap bleeds treble past the gain pot on the lead channel. It has no effect when the gain is maxed out (so I didn't notice it while playing with Rosetta), but makes the tone brighter when you turn down the gain. I happen to think it makes the channel sound "quacky". You can reduce the value to 100pf to move the corner frequency higher, or just clip it entirely. I clipped it and find the sound to be much more predictable at different gain points.
6. Fix undersized cap
Cost: less than $1
Perceived sonic change: none
C46, a 22pf/500V ceramic cap on the main circuit board, has been known to fail in the TSL. If it shorts, it can destroy all the power tubes and the output transformer. There is absolutely no reason a 16-cent part should be allowed to cause $300 worth of damage. I replaced this cap with another of the same value, but rated for 3150V.
7. Replace output transformer
Cost: $250
Perceived sonic change: substantial, but not necessarily better
The stock output transformer on the TSL is a Dagnall general purpose model, part #C3070, TXOP 00001. Mercury Magnetics makes a drop-in replacement -- the MAR100-OM -- that is bigger, more reliable, and is supposed to sound better. It's pricey. This mod requires no soldering and no drilling, just reconnecting the 7 wires to the right spade terminals on the new transformer. Mercury includes a diagram.
The new OT has wider bandwidth (read: deeper and higher), so it perceptibly improves clarity and attack. The lead channel seems fizzier at low volumes, but maybe a touch smoother at really high volumes. The "improvement" becomes more audible as you turn up the amp, which is to say, the breakup of the power section comes in more slowly, and there's more consistency from low to high volume. You may or may not consider this a good thing. There is quite a bit more bass available in the tone network, no doubt due to the extended low-end response of the MM. However, this can make the tone sound "tubby" at higher volumes with very low tunings.
I now realize that while this transformer is undoubtedly more reliable and cleaner than the stock model, it may be a little too polished (i.e. linear), lacking some of the "gravel" in the old one. The added bass also makes it initially sound less "tight" with high gain detuning. It's hard to say whether I became attached to the "imperfections" in the old OT, or had gotten so used to compensating for them that it's hard to make the MM work for me. The MM model may be suited to a more traditional style of playing, where the Dagnall seems to be (accidentally?) tighter and smoother for more extreme gain and tuning. I would say the Dagnall has a more (gasp!) "vintage" sound, since old Marshalls often had ill-suited and undersized transformers off the shelf, and the MM is more modern. It may all be a matter of taste, and $265 is a lot to spend on something that subjective.
EDIT 4/2/09: I switched back and forth between the Dagnall and MMOT a couple of times, and found that even though the saturation of the Dagnall was occasionally pleasing, it was no substitute for the greater volume and bass response of the MMOT. The MM transformer opens up a lot of possibilities.
The real issue is that it was one of the later mods I did, so the earlier component and settings choices had been made unconsciously to accommodate or to flatter the Dagnall's limitations -- after I tweaked some of my existing mods (pulled even more treble out of the lead channel, most importantly) and started over from scratch with all the controls at 5, I found I could get what I was looking for. I can now hear a much bigger difference between different bias settings, and the tone network's behavior actually makes sense. I now have to pull the bass back a lot --- but doing so gets back a good deal of the "tightness" I missed from the old setup, and reveals some lower frequencies (below the center frequency of the bass control) that were never there at all before.
However, make no mistake: the MMOT will not get rid of the "fizz" in the amp, contrary to some other opinions I've seen, and will probably make it even more noticeable. There are advantages to it, but less fizz isn't one of them. To put it succinctly: if you think the amp is fizzy, and you hate that you have to turn it up too loud to get a good sound, don't get the MMOT. If you are modding out the fizz (or you like it as-is) and you wish the amp was louder and had more "oomph," then by all means go for it.
EDIT 4/6/09: On further reflection, I think that the undersizing of the Dagnall is mostly responsible for the "tonal qualities" I was hearing --- it is highly likely that its core was saturating when I pushed the amp hard. I say this because with the Dagnall in the amp, I would hit a wall at about 6 on the lead channel's volume knob, beyond which the amp would not get louder --- but would start to sound dramatically different, losing bass response and tightness. With the MMOT, that wall was removed. I had assumed before that I was hitting power tube distortion, but if that were the case, the limit onset would have changed with different bias settings (it didn't) and would not have changed with a new OT (it did).
Furthermore, the Dagnall OT would get very warm while playing loud, while the MMOT remains the same temperature as the surrounding chassis, even at extreme volume. I can only assume the extra heat from the Dagnall was output power that was lost due to inefficiency, core saturation, or both. This would also explain why there are so many stories of the Dagnall OT blowing up when people try to run the TSL on the clean channel with all the knobs at 10 (Plexi-style). The amp is in fact capable of much more volume and bass response than its stock transformer allows, at least from a perceptual (standing in front of the amp) standpoint.
This added power could be good or bad depending on your needs -- if the amp only sounds good at enormously high power levels which you could never use, then it's not an upgrade. For my purposes though, it's a great thing, although I never expected I would think an amp was "too loud" (yikes!). Eventually I may be able to eliminate my Marshall 3210 slave head and drive both of my 280W 4x12s into speaker breakup with only this amp. I couldn't do that before.
Digression: I have heard that Mesa apparently uses deliberately undersized OTs in their Rectifier heads (but NOT in their other models) to get an effect similar to what I describe above. Maybe that's more integral to the "Mesa tone" of "pleasing compression" than their much-vaunted tube rectifiers...? But then again, "cheap, small output transformers" doesn't make for good marketing copy, so who knows?
---
As far as comparisons, I suppose it has a Bogner-ish and/or hot-rodded JCM800 kind of character, but deeper and with a more Fender-y clean channel. It is very much a Marshall, though, maybe more than in its original form. The gain on the lead channel is outrageous but stays focused at high volumes (I have the gain at ten, volume at the edge of power tube & speaker breakup). Crunch is nicely versatile. The VPR circuit actually sounds decent now, too, and whether it's on or not, the amp sounds steadily better as you turn it up. I would characterize the sound as the "next logical step" if Marshall had continued producing amps with the philosophy and quality of the JCM800s, but with modern levels of gain.
Some thoughts:
+ The most effective mods are not necessarily the most expensive. I've tried to be as objective as possible here, balancing what I've heard (NOT properly/scientifically ABX tested, obviously) with what I know about electrical engineering and amp design.
+ No mod will improve an amp for everyone. Different tastes have different requirements. I don't see these changes as "fixing" the amp; instead it's more about keeping the things I liked and refining the things I didn't. Since so much of the tweaking of this amp involves controlling the treble: before you get out the soldering iron, put an EQ in the effects loop and see what you like and don't like in the voicing. Try an EQ in front of the amp, too.
+ Mercury Magnetics has quite a hype machine, but for the most part their products live up to it, and they are helpful to talk to. I would buy from them again.
+ As a taste issue, I also swapped the reverb tank on the amp. The stock one is very good, just not as dense as I'd like. EDIT 8/28/09: I had Accutronics make me a custom Type-9 reverb tank and it's even better than the one I had swapped in before. Nice and rich --- the part number is 9BB3C1D.
EDIT 8/17/09:
"Tightness" vs. "looseness" -- while a lot of this has to do with what kind of cab you're using, I've found that the modded TSL is WAY tighter sounding than any Mesa. Even A/B'ed against a VHT (Sig:X) or Engl (Fireball), it holds its own. You can boost the input, roll back the gain, and get amazingly percussive tones without fizz. It's crunchy but VERY controlled. It's the closest thing I've ever gotten to a Meshuggah tone without a POD (on a Marshall! How weird is that?). My 8-string sounds incredible (even on the low E-flat string!), with the tone controls all at 12 o'clock and the lead channel gain at 4, and a 6-8 dB boost in front of the amp (a little "frown curve" EQ helps too).
This is all quite opposite of what I originally intended the mods to do --- give me a thicker, smoother saturation for enormously high-gain sludge riffing. It really speaks to the true versatility of the basic design (as opposed to its initially compromised realization) as well as the retention of a lot of buried "Marshall tone" that only came out after modification.
56 comments:
you're such a smarty pants!
One of my favorite courses in college was an electronics class that involved building the likes of low pass filters. So, messing with amps sounds like a lot of fun.
INtersting thanks for sharing. Do you know if this would work with a DSL 100? I am wanting to get rid of the fizz in the Lead 1 Channel.
Do you have any pics of the 390pf cap across R1 on the main circuit board (the one the tube sockets are on), to indicate how it is connected?
Thanks
No, I don't have a picture of that cap. It's simple to add though: you just solder one lead of the cap to each lead of the resistor R1. You can do it on the top or bottom of the circuit board, whichever you like. Polarity doesn't matter. The cap lets high frequencies flow through it, but forces low frequencies through the resistor.
I am certain that these mods will work on a DSL 100. Components may have different numbers or be located in different places, though. I believe R1 on the main circuit board of the DSL is exactly the same, but VR2 on the front panel PCB may not be the volume pot. Put the 47pf cap on the volume pot (as pictured in this post), regardless of what its name/number is.
Thanks for the info. That explains it. I may try this.
Cheers
Hey. Could you please tell me the dimensions of the pot size? It would be much appreciated as I'm currently fixing a Valvestate mk2 (and the pots look similar - they had the same plastic shaft, and the two solider points for mechanical stress) in another city and lost my dimensions. I'm trying to find some to order.
Cheers,
Daniel
Daniel,
I haven't measured the pots, but as far as I know they are metric-sized, with NON-knurled shafts (smooth with a flat surface to mate to a knob). and a narrow bushing. I have no idea who makes them or where to get them, but your best bet is to call Marshall. They are generally pretty helpful about this stuff.
I got lost putting mine back together, do you have a chart for making the connections between boards, e.g. con 6 main to con 2 lead
I don't, but these guys do:
Marshall amp forum TSL connections
Hey great post!!!! I will try these 4 sure.
I have a tsl 602 that comes with really crapy wolverine speakers. I swapped them with 2 g12-75 and placed a .47pf cap across R109 as suggested on Harmony central. The cap mod and the speaker swap really upgraded the amp from wanting to throw it away and now liking it. I will now try your mods and hope for even better results!! Thanx again
The 47pf cap mod on VR2 (Crunch/Clean volume pot) or VR4 (Lead1/Lead2 volume pot)affects both channels if placed across the outer pins of either VR4 or VR2. It all depends on exactly where you place the cap. For it to only affect the lead channel you must place the cap between the wiper and ground on VR4 pot. The R1 mod only affects the lead channel. I don't believe you even need the 47pf mod if you want to place it across the wipers of the pot. I think whoever designed this mod wanted to affect both channels by placing the cap across the outer terminals.
Tony,
You're absolutely correct, in the case of the DSL (Dual Super Lead) --- which I gather you're referring to by the reference to the shared Crunch/Clean and Lead1/Lead2 pots. I am not as familiar with the schematics for that amp.
However, in the case of the TSL (Triple Super Lead), the channels and their volumes are entirely independent and the 47pf cap across the outer terminals only affects the channel in question. I've confirmed this on the TSL by connecting the cap to a switch and flipping it while playing. There is a perceptible difference on the modded channel and not on the others.
As to the R1 mod, are you sure that on the TSL it only affects the lead? Is R1 in the same location in the DSL? From what I can tell on the TSL schematic, R1 is on a triode used by all three channels.
Sorry, I was referring to the DSL only. Even so you are correct and I was mistaken, R1 affects all channels. I made a hasty study of a very complicated schematic (DSL). The signal passes through V3 triode at all times. It appears from a quick glance that the TSL is the same for the R1 mod. It also appears that the 47pf mod on the TSL would only affect the channel in question just as you stated. Thanks for correcting me.
Do you have a product number for those diodes? Were they Vishay HEXFREDs?
I don't have the product number for what I ordered --- I got it from Digikey, which doesn't email your invoice. It's possible they were HEXFREDs... they didn't look like diodes, but more like larger discrete transistors with only two terminals. Each had a screw-mount hole in the body for attachment to a heat sink.
Hi, I have a TSL 601 and I need to make the effects loop work in series. Do you know how to do it? I imagine you can copy the way the TSL 100 does it but I'm intimidated! Any guidance you can give me is a plus
OK, I've been studying the schematics for hours and I think I have to short R106 to make the fx loop act in series on the TSL 60. Can someone who knows what the hell they are doing please take a look and make sure I'm not doing anything to blow the amp? Look at the top right of location E2 to find R106. The schematic is here: http://www.drtube.com/schematics/marshall/tl60-60-02.pdf
Thanks so much to anyone who responds
Disclaimer: I'm no expert on the TSL 60, since it is significantly different from the TSL 100.
However, I think you mean "clip" R106 (as in, removing it from the circuit), as opposed to short. Shorting it would simply increase the dry signal gain going into V3A, and probably do other undesirable things.
Removing it from the circuit would probably mean that there would be no sound unless the FX loop were connected, which is I think what you want. But the amp simply wouldn't make sound without a signal source feeding the FX return, and you would have to adjust the output level of the attached FX to get as much signal to V3A as you had before.
An extensive Google search is your friend here. You also might want to study the TSL 100 schematics, since you know its FX loop becomes series when the mix knob is rotated all the way to 10. I can't be much help here because I use the TSL100 FX sends to drive slave power amps in a live setting, and all my effects are in front of the amp.
Thank you for the amazing article!! I´m about to do these mods to my 2004 tsl100 and i was just wondering when installing the choke, does the polarity matters of those two wires? As i´ve understood all the other components like the silver mica, orange drop and ceramic capacitors are non-polar?
Second question: You changed the value of the C18 from 100pf to 470pf to be similar with DSL. If i put a 390pf silver mica capacitor there instead of 470pf (i could´t find that value from local electronic shop) how would it act compared with the original 100pf? Better or worse?
There's no need to observe polarity with the choke or with film, silver mica, or ceramic capacitors. Only electrolytic capacitors, diodes, and semiconductors require proper polarity, and they are usually well-marked.
C18 bleeds off treble after V1AA. It starts a roll-off of 6dB per octave at some particular frequency (not sure what that frequency is). In any case, increasing the cap value will move the onset of that roll-off DOWN in frequency. Every time you double the value, it moves the onset down by an octave. So on that particular gain stage, the DSL is getting rid of treble more than two octaves down from where the TSL does --- a pretty big difference! I think this has something to do with why people think the DSL sounds "warmer" than the TSL.
So higher values get rid of "more treble", but by increasing the frequency range of what's being thrown away, not throwing away more of it. A 390pf would be in between the TSL and DSL values, and I'm sure it would sound just fine. You can always change it later if you want, but remember that the volume pot cap I mentioned will have a more dramatic effect.
I finished yesterday my modifications and i´m more than satisfied with the results!! I didn´t change OT but did the chapters 1 (390pf/47pf), 2, 4 and 5 (replaced C18 with 390pf and C9 snipped away). I´m running the amp with JJ tubes.
Now the amp sounds totally different and way better than before. Now i´ts warm and natural sounding without being muddy at all! All that awful buzz and harsness of the lead distortion channel is gone! After mods it has a lot more "good" bottom end and still got great note articulation. I´t breaks up nicely and has a really kick ass rock tone!! I´m not such a fan of high gain tones and were little concerned about the article referring to your taste to play with gain maxxed out, but these modifications seems to work very well also with lower gain settings! It´s loud, punchy and ROCK! Thanks again for the great instructions!
Now it beats easily my Mesa DR and non modded DSL100(which sounded better before). =)
The bridge is also waiting to die blew my second only to tech spec it and find it's rated to 140 forward the 200 reverse was bad but 140 dude the pt puts out 220. Hopefully the nte5314 will fit and cover it to 240. And thanks for the con list hookup; life saver.
Hi
My tsl is very fizzy and buzzy on the crunch and lead channels so I would like to do the some of the mods you talked about. I have a limited amount of experience in electronics but believe I can do it with a little help if you'd be so kind. I'll put the 390pf cap across R1. I don't have my amp apart but does whats already in R1 stay there and I'm just adding the 390pf cap also, or am I replacing the existing component with a 390pf cap? Adding the 47pf caps seems straight forward enough. Since I'm not changing the tubes, transformer, adding a choke and such, would you recommend I go for the 68pf caps or the 47pf caps. I really hate the fizz but don't want the amp cold and dead sounding either. I'd also like to change C18 on the main with a 470pf cap like you've done. Could you please provide a link to that part as well like you'd done with the other caps? I'd really appreciate it. I want to make sure I get the correct parts. Did you notice a considerably warmer sound after the C18 mod? Thanks for the help and great page. Jeremy
R1 is a resistor, which needs to stay exactly where it is. You add the cap from one end of the resistor to the other, "piggy-backed" with it so they're parallel.
The link for the 470pf mica cap is here.
After the C18 mod, it's hard to say. This simply brings that part of the circuit in line with the DSL model values. The DSL is known to be a slightly darker amp, and IMO C18 is likely the reason. I think other things I did probably had more effect.
Very interesting post indeed - good job. I was wondering if some of these mods can be applied to my TSL 602? A friend of mine who deals with electronics can help me with them but I'm not sure If they're going to have a sonic impact on my amp. The infamous R109 mod worked fine on my TSL. Can u please give me a heads up on the matter??
Tony B.
Tony,
Most of them will work fine with a TSL 60/601/602, but you will need to determine the correct component names from the schematic. I don't know the TSL 60 all that well.
TSL 60 schematics etc.
So for example, when I refer to R1, it's R74 on the TSL 60. R109 that you bypassed is R31 on the TSL 100. It's interesting --- that mod actually gives a mid/treble boost on the triode that I have intentionally cut treble on, with the 390pf cap across R1. If you like your clean channel now, stay away from the 390pf cap mod, or reduce its value. The 47/68/100pf cap across the lead channel volume pot will kill fizz without altering your clean channel.
Thank you for your immediate response. Well after I retubed my TSL 602 (JJ tubes)and did the R109 mod the presence knob started functioning properly and the amp became more versatile since the eq section has now wider range. But I have some issues that makes me think about selling this amp.
1) The Crunch channel is way better than the lead channel, sounds more tube-like (like JCM 800) but does not have so much gain. I haven't tried a TS9 as a boost though. I have a DS-1 keeley but I don't like it as boost.
2) The Lead channel sounds plastic, has no tightness at all. No tube feeling at all :(
How can I find a correspodence between your mods for the TSL100 and the TSL60? Can an expert do that by comparing their schematics between the amps?
Tony B.
Tony,
I have a feeling that you won't necessarily be happy with boosting your crunch channel either. The topology/voicing of the crunch and lead channels is very similar, the lead channel just has a lot more gain. Things will naturally get pretty sponge-y with the gain that high. That said, you can probably improve the lead channel quite a bit by doing some of these mods. I think the cap across the lead channel volume pot is the most important one. You don't need to study the schematic for this one, just solder the cap across the outer legs of the lead volume pot.
Beyond that, you can improve tightness and "umph" by adding a choke. If you want more low end in the lead channel, try the coupling cap change (it's C50 in the 60, not C16)... but that won't improve "tightness", it might actually make things looser. The biggest positive change, though, would probably come from adding the MercMag OT.
You don't need to be an expert to figure out components. Make a printout of the TSL 100 and TSL 60 main board schematics, and look at what's around the different preamp tubes. If there's something in particular you can't find, email me and I can help you track it down.
TSL 100 mainboard
TSL 60 mainboard
Once again thanx for your concern. I really apreciate it.
1) I really like to use a tubescreamer, especially the keeley modded one. Since from what I've hearn not only adds boost, but also can change a bit the voicing.
2) Right now my amp doesn't work:( At first it blew a fuse. After replacing it worked fine, but only for 2-3 days. Then I heard a humming noise and it is dead since then. The tubes are ok, something that makes me believe that probably is a faulty transformer which needs replacing. If it's the OT i'll consider MercMag if available in my country. (Greece)
3) Since i'm going the amp to a tech for fixing it, I'm considering doing some of the mods you proposed, besides changing the OT, the other mods are cheap.
4) The biggest change in this amp are the speakers. Wolverine are really muddy sounding.
I'm considering finding a 2x12 cab with V30's which is a keeper especially when considering buying and another amp head
Thanx once again,
Tony B.
Hello,
Great information. I just bought a TSL602. I've looked at both schematics, but couldn't find the TSL602 equivalent to C9 that you removed on your TSL100. Any ideas?
Thanks, Chris
Chris-
Looking at the schematic, I'm not sure myself. What you need to do is figure out which VR on the schematic is the lead channel gain pot. The easiest way to do this is open up the amp and see what's printed on the board next to that pot. Find that pot on the sheet and see if there's a cap going from the input to the output (not to the ground leg). That should be the equivalent to C9. Keep in mind that the TSL60 is a pretty different circuit and there may not be an analogous component.
Thanks--exactly what I was thinking. I'll label the components (VRx) on the schematic after I have it apart and can take a look.
What speakers does your TSL100 have in the cabinet? I didn't notice too much buzz out of mine until I replaced one of the Wolverine's with an Eminence Swamp Thang speaker that I had lying around. Now the amp has quite a bit more high end and buzz. I am wondering if Marshall didn't specify the Wolverine speaker to eliminate/minimize some of the high end that the circuit produces. Any thoughts? With that said, I think that the new speakers (I'll have to replace the other one) along with the mods will have some very serious potential to improve this amp.
I really like the Vintage 30 with the TSLs, particularly after mods. That said, they don't seem very reliable (I was blowing them up semi-regularly), though I never blew up any of the G12T-75s that I was using them with.
Currently I use a combo of two Eminence Governors and two G12T-75s in each of my cabs. It takes a punishment and sounds very nice at really high volumes.
Hi, great post,
I posted earlier about the r109 on my tsl 602 but i removed it to try your mods since it added more highs, wth the g12t75 i had the deep switch engaged but the bottom is muddy, I also have vintage 30s but i like the 75 better,they sound tighter, i imagine wth the mods it will sound much better, my question would be, are all the cap numbers the same on the 602?? Since you stated that the R1 on the 100 had a different value???
Outstanding posts - thanks so much Tony. As to the TSL60s, I did the following mods from your TSL100 info:
*TSL60 - TSL100
*Clip C49 - Clip C9
*Replace D9~D29-Replace D3~D10
*Replace C26 & C27-Replace C46
*R74 add 390pf mica cap- same as R1
*VR10 add 68pf mica cap-same as VR2
*Replace C50 w/Orange drop 4.7nf cap - same as C16
I could never identify the C18 equivilent on the TSL60 - any ideas?? I looked long and hard, but I just couldn't find it :(
Also, it's important to note that the TSL60 actually has TWO "undersized" 22pf/500V ceramic cap: C26 AND C27 - the TSL100 has only one whimpy cap: C46. C27 died in my TSL602 and this is what began my quest that ended with the finding of this awesome blog!
Replaced my stock 12s with a Vintage 30 and a G12 Century Vintage. WOW
OPPS - I mean thanks M. Weed!
And I do mean thanks!!!
BTW - the equiv. to the TSL100's C9 is C49 on the TSL60s.
Clip and remove :)
Ok great thanks for the tsl 60 help!!
Is C18, C48 on 602???
Thanks for posting this great info. Do you know the mod for the fx loop at all? Cheers
Tnx Mr Weed. I did most of the mods and they work perfect! But since you know what you're doing I have aquestion: The volume on my TSL122 fades away but comes back direct. It's like a pumping effect. I can hear a type of popping sound when it goes back to normal state. This repeats, but not permanently. I have new tubes and bias set to 80mV. Any suggestion what it could be?
I don't want to speculate on what the volume pumping could be without the amp in front of me, but I know that others have had this problem. If I were you I'd do a search at the Music Electronics Forum and see what it turns up. There are lots of good techs on that forum that deal with JCM2000s all the time, and someone has probably run into that problem before.
Right on the money about making the TSL good for anything. I'm a seasoned blues guy who prefers the Marshall side of the blues. Did all mods cept the 390 across R-1.
Now the amp talks back to me without fizz...Kinda Schenker meets Lukather, and real nice Clapton + A Bros Fillmore tones. Back end of the amp really sounds like it finally started working!!!
Changing out the 100pf cap, added the cap cross the vol control and adding an original choke from a blond Bassman REALLY made the gain channel come alive. Most important though is the cap across the vol control as I didn't do the crunch channel and while better, it still has some fizz. These are GREAT Mods, not simple, but they retain the Marshall tone and really kill the fizz without giving anything up. Amp is cleaner, and meaner, and you're right the useless VPR actually works better.
Thanks for posting and carefully explaining the process. The amp sounds beautiful!!!
This is a geat site indeed. Firstly, I have a TSL100 with the latest version Main board (Issue 20) and whilst this fixed the problems of outut tubes perishing due to the PCB becoming conductive with heat, I still found Channels 2 & 3 to be really harsh.
Harsh compared to what, my JMP100 superlead and my vintage modern heads. Here's the thing, my buddy in the band uses a DSL100 AND IT SOUNDS THE BOMB! no question it whips the TSL for classic rock tones.....and yet the 2 are almost identical. I think I've found the magic bullet and I'm suprised nobody else has suggested this. The answer lies in the cathode circuit of V2 PIN 3 - The DSL doesn't have a 10nF cathode bypass cap switched in for channels 2 & 3.......but the TSL does!!This my friends is the answer - I snipped out the fet (TR2) as it was easier than desoldering the 10n cap. If you aren't sure and you want to try it first, lift THE CATHODE of D1 which connects to TR2 gate - if you measure this with a DC voltmeter you will see that for ch 2 and 3 +12volts is present to switch on the fet and create a path to ground for the 10nF cap. Lifting the diode prevents this. This the MAIN difference between the 2 aside from the seperate EQs as that 10n adds loads more high frequency gain and you just don't need it. Best of Luck,b
That's a good catch on the DSL/TSL schematics. As I've said, I'm not that familiar with the differences because I don't own a DSL and don't know many people who use them. This looks effective for toning down the buzz above 6kHz, which is right about the range that my volume pot caps address. The only thing to remember is that it will affect both the crunch and the lead channels equally. So for the people who like the sound of the crunch channel as-is, or want a different rolloff characteristic between crunch/lead, they'd be better off adding caps to the volume pots.
A great support site. Unfortunately I have a TSL 601. This amp has an parallel fx loop which makes my TC G major fx unit almost unusable. I want it to be modded as serial but my tech did not find it possible. Do you have any idea on achieving this? Many thanks in advance.
@Gurkan
If the amp has op amps for amplifiers after the effects loops then you could just use the left input and connect the two inputs up internally. You could even make a lead up for this so you can take it out and it will be back to normal.
As for what is coming out of the amp (effects send), it's most likely the preamp is mono, so you probably just be able to use one output.
Cheers,
Daniel
I don't know anyone who has satisfactorily modded the TSL 60/601/02 effects loop to be serial. It's possible but there are far too many tradeoffs. I've never done it because no one has ever thought it would be worth it to risk their amp and drop a ton of money on this particular system.
@Daniel --- the send stage uses a mono opamp, and the return stage uses a switching opamp with one half dedicated to each channel.
So I have to use what I have. I like and use all the three channels of TSL601. My problem is that(especially
the lead channel) I want to boost the lead channel a few desibels during solos. Since it is a saturated channel, even a clean booster in front only saturates the sound more. But I only need a level up instead of more gain. I know that bypassing the fx loop with a cable increases volume like a volume boost but with G major it won't be of any use. I understand this place is dedicated for mods instead of chatting about rigs. Thanks for your time and answers. Cheers.
@M. Weed -- When you say switching op amp, I assume you mean dual - two op amps in one package?
Daniel
@Daniel
No, the chip has two differential inputs, like a dual opamp, but only one output. There is a switching pin that if a voltage is applied to it, it switches the output to either the A or B input. Check the schematic at IC3 (reverb) and IC6 (FX loop).
hey man thanx for the mod info!!...i have a tsl 602 60 watt combo and the lead channel does not switch..
clean and overdrive switch fine...any ideas what it could be?
i thought the relays might be bad so i switched them but doesnt solve my issue...help??
Mr weed. I dig your mod work. I am looking to make my amp Brighter not darker. Any suggestions? Maybe put a small cap on c18? Im not sure if there is a way to put a potentiometer on the amp to make adjustments.
Thank
Tbone
I have a TSL601 combo and did three cap-mods: Apart from the R109-mod (installing .47uF cap acrosss R109, which does not seem to fit for the TSL100), I did only mod the R1- and the VR2-mods(47pF-cap for VR2 is fine, R1 resistor is R74 in the TSL60 circuit).
I also replaced the crappy Wolverine speaker with a Celestion Century Vintage. This was the very first significant improvement for a much clearer and defined sound.
Another thing is a complete tube replacement. A good start is to replace all preamp tubes with JJECC83s (I use the TAD-versions with a Highgrade in V1). The Mullard EL34 Reissues or SED Winged 'C' EL34 are a great choices for the power amp tubes. I also tried JJ EL34 (not bad, but no highlight), JJKT77 (way too bright) and EH 6CA7 (a little stiff).
The very simple cap-mods really helped a lot to get rid of the fizz. The sound is now very classical Marshall-sound, but with more gain-possibilities. The cap-mods are real winners! Now, the amp sounds great at very low bedroom level up to cranked volume.
I have no idea if the sound is closer to DSL and I don't care. Right now, the TSL601 is a class of its own and a real keeper.
Thanks a lot for sharing your knowledge and experience. Kind regards from Germany, Heiko
Hey there,
I'd just like to say thank you so much for the research and work thats gone into this blog.
I've got a TSL60 head and got a friend of mine to do these mods:
*TSL60 - TSL100
*Clip C49 - Clip C9
*R74 add 390pf mica cap- same as R1
*VR10 add 68pf mica cap-same as VR2
*MMOT upgrade.
*Full tube replacement JJecc83 high gains (preamp) and JJkt77's
the amp just plays better in every department. the biggest difference is the control and tightness at high volumes, followed by a massive increase in the presence of low mids.
The presence knob is a lot more usable, and the gain controls on both crunch/lead channels are so much more functional now...
previously the gain controls would work to about 12oclock and any further it just got more mushy and was completely worthless.
Now I can dial in massive amounts of gain and it stays nice and tight... I used to use a keeley modded ts7 tubescreamer in front of it to try and tighten things up (used to have the gain on the amp @ 12oclock and the screamer gain dimed), I don't need to anymore.
The amp is the center piece of my setup and sounds great and I get complimented on my sound at every show I play now.
I play mostly punk-hardcore and 80's thrash, lots of midrange and gain. I play a Greco 71-74 EG Les Paul copy and a Gibby SG into a stereo chorus into a Sovtek Mig60 (4x10 sovtek cab) (high channel) and the TSL60 (2x12 marshall cab gt75s) and everything sounds freaking brutal.
Thanks to everyone who has participated in this blog from one super stoked Kiwi from New Zealand.
Cheers
Has anyone noticed that there are the wrong value screen resistors in these amps...200k instead of 5.6k. Also the bias can go AWOL, as they put in Negative Temp Co resistors....all in all contributes to one of the worst amps anyone put on the market.
http://www.lynx.bc.ca/~jc/TSL122.html
TSL60 Translations
I tried most of these mods on a TSL 602 and the ones that I felt were the most beneficial were:
.47ph on Volume of lead channel (didn't like what it did to the gain structure when added to the crunch channel)
22n Cap on C63.
Higher Voltage Caps on c26/26
220ph cap across R74
.05pf cap with a toggle to R109( tried different values but this one seemed to produce the best balance of dynamics without a huge volume change between settings) I would call this a tight (stock) or loose(mod) switch. The clean channel sparkles more with the cap working and the gain channels have the touch sensitivity that I always thought this amp lacked. The stock setting works great for rhythm.
R72 changed to 220k.
Vintage 30's in place of crap stock speakers ( this has the most immediate effect on the Volume problems people report with the amp. The wolverines have a low sensitivity rating and unless you can push them with 100 watts, sound like there is a blanket on the amp.
I recently played a JCM900, SL5, DSL40, and Jubilee. I now like my TSL better than all but the Jubilee. That is a really nice sounding amp, but not a versatile as This modded tsl602.
NOW- If anyone can tell me how to change the fx loop from parallel to serial, this would be perfect. there is a Modder in the Czek republic, 4rocker mods, that offer the service but he hasn't been willing to give up the secret. He did tell me it is only two resistors. Please let me know if you have had any luck with the FX loop mod.
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