Tech: Thoughts on cabs

Speakers and other mods

Along with amp and instrument mods, I've experimented a lot with different speakers over the years. I had more or less settled on a combo of Celestion V30s with G12T75s, until I recently tried some Eminence Red Coat speakers and was very impressed. I'm now using their Governor model in place of the V30s. V30s are 60W speakers and should have been fine with my amp, but I push them hard and they kept blowing up periodically. The Governors are louder (102 dB sensitivity instead of 100dB) and handle 75W. They have better bass and a less harsh upper mid --- basically everything I wished I could change about the V30. I still have V30s in my 1960A, but both of the cabs I use in Rosetta now have 2 Governors and 2 G12Ts. Given how impressed I am with Eminence and how the 97dB G12Ts get drowned out by the Governors, I may swap in some Wizards for the G12Ts. With the Eminences, I've turned the Deep switch off on the amp and get a clearer bass response.

EDIT 3/2011: I did replace the G12Ts with Wizards. Good move! Very loud and very clear.

Beyond speakers, though, you can make other improvements. This video talks about cleaning out your cab with a hose (terrible idea), tightening the screws (good idea), and caulking its seams (decent idea). I skipped the hose section, but have done some of these things, along with others, to my 1960A and B cabs.

The B cab is the one that tours with Rosetta, and it has two Eminence speakers in it that are insanely efficient (i.e. louder at the same wattage: 102 dB @ 1W/1m) --- meaning that since it's driven singly by a 100W amp cranked up, the cab is constantly trying to tear itself apart. As a result it occasionally develops loose screws and weird buzzes, so most of the cab mods I've done have been experiments in trying to improve tightness and clarity under extreme SPLs with low tunings, but have often resulted in greater durability too.

In my experience, the most important thing is getting the center brace set up so that it's stiff, tight, and actually centered. Lots of cabs don't even have these, and the ones that do rarely have them installed properly. On a Marshall, you can take out the two screws that hold the brace to the baffle, then get rid of the tiny staples that hold the T-shape together. Replace them with a combination of strong glue and a wood screw. Spread glue on the baffle-side surface of the T and then screw it back in, tightly. When the glue dries, it should be 99% immovable. You can see the Gorilla Glue foaming in the picture as it dries. If you use it, be careful that it doesn't foam and drip on your speakers. You'll also notice in the picture that in the stock assembly, the brace had wobbled enough that the screw from the back of the cab went in off-center, reducing the strength and effectiveness of the brace. After gluing and tightening the baffle end, the screw from the cab back now goes straight into the middle of the brace.

I'm a non-believer when it comes to speaker cable hype. Still, I don't like all that 18-gauge wiring flapping around inside the cab. It's cheap to improve it, so just replace it with 16-gauge lamp cord or larger. My 1960B has 14-gauge wiring inside (nothing special, just zip cord from the hardware store), and my 1960A has doubled 16-gauge since I had a lot of it laying around. I just used the 2-conductor cable as a single conductor by twisting the ends together, yielding an equivalent 10-gauge connection. I soldered these to the jack plate board and speaker terminals. Keep the lengths short and they won't rattle around inside the cab.

Per the above video, I tried caulking the edge of the baffle after tightening the screws down. This makes no apparent difference above about 250 Hz, as far as I can tell. There are several before and after videos on YouTube that make this point. However, I thought that the low end seemed more present and I felt more attack at the bottom of the speakers' frequency response. Caulking gets criticized and dismissed a lot, but it certainly can't hurt to try it, and hi-fi speakers are almost always sealed in a similar manner.

With the B cab (the one that tours), I went further. Its baffle has worked itself loose enough to buzz on a couple of occasions, just as a result of the volume and beating it gets regularly. Needing a more permanent fix than just continuing to tighten the screws, I removed the baffle entirely and ran a bead of Liquid Nails along the inside cabinet edge where it mounts. I used wider, longer screws on the reinstallation. For good measure I caulked the back of the seam and installed steel L-brackets at spots where the baffle most often loosens. The cab's handles had cracked in a few places from touring wear, so it didn't hurt to replace them with metal ones. You can caulk the handles or gasket them to seal air leaks. I gasketed them so they'd be easy to remove later.

(The B cab also has tape on the inside of the grill cloth [similar to this] in front of the G12Ts, to cut down on high-frequency "beaming" in their very spiky treble range. You can see the tape in this picture.)

Both cabs are now lined with foam. This gets done to bass cabs and hi-fi speakers to help break up standing-wave resonance that can create strange peaks in response. Generally these peaks are "part of the sound" in the upper registers, but in the lower registers of detuned instruments they are objectionable. Foam helps to control that, and with both cabs I liked the additional clarity, especially when using an octave pedal or the 8-string. The difference isn't very noticeable except in percussive riffing or high volume sludge. I didn't find that it took anything away from the tone in the upper registers.


Cabinet marketing voodoo

An awful lot of people say that the Bogner Uberschall 4x12 cabinet is the best they've heard. I've heard them (and thought they were decent) but never seen one opened up. I read that they have damping foam or insulation on the inside, as well as heavy gauge wiring (probably 14 AWG or thereabouts, where Marshalls usually come with 18 AWG stock). Given that Bogner cabs are not made by Bogner, but come from a third-party supplier, consider this:

Bogner 2x12 open back / $789-ish
Avatar 2x12 open back / $389

Bogner Uberschall 4x12 / $1200-ish
Avatar Vintage 4x12 / $529

As far as I can tell, these cabinets are actually made by the same third-party cabinet maker, and loaded with the same speakers. The woodworking and specs are identical in each case. There are two possibilities here to explain the difference in both price and acclaim. One is that the brand name psychology works and is causing people to hear a placebo effect that's not there, and pay more as a result. The other is that Bogner buys these cabs in bulk and then does some extra modification before they're sold, where Avatar doesn't.

I've never seen any of these models open (though I do own some other Avatar cabs and like them very much). If anyone has them, I'd love to know what the insides look like --- it seems that the Bogner cabs have insulation or foam dampening material lining the insides, where I'm pretty sure that the Avatars don't. They may also have heavier gauge wiring (which shouldn't matter that much if it's above 16 AWG). I don't think these "value-added" bonuses are enough to explain the price difference, even if they're all done by hand.

However, based on my experience with modding Marshall cabinets, sealing and dampening can make an audible difference in the clarity of the low end, especially with drop tunings. Let's assume for the sake of argument that the Bogner cabs do have additional touches compared with other brands or models. Hi-fi nuts know the importance of eliminating air-leaks in sealed enclosures: a tiny crack with air escaping does NOT constitute a "port" (that's stupid --- ports are tuned with specific diameters and depths, to produce a certain cabinet Q and frequency rolloff), it simply lowers the cab's efficiency and hurts its transient response. It really can't hurt to eliminate the leaks. Likewise, foam is used in Hi-fi and PA system speakers to help break up standing waves inside a cab. It really won't take away from the "sound" of the wood or the size of the enclosure --- if anything, stuffing a cabinet has the effect of virtually increasing the enclosure size. What it does is help clear up the super-low end, where certain notes on the guitar can cause rattling or unpleasant boomy-ness.

Given that most people playing through Bogner 4x12s are playing metal, the combination of lots of small improvements --- particularly to the low end character --- probably makes enough difference from a Mesa or Marshall cab that they feel they've found something special. That magic is psychologically amplified by the price tag. Still, the reality is that you could buy the Avatar equivalent and add in whatever extra touches the Bogner has --- even buy a Bogner logo on Ebay --- and still have spent several hundred less than you would have otherwise, for an identical cabinet. In this case, it really pays to do it yourself.

Furthermore, it's simple and cheap to do that extra work on any cab. That was my thinking in trying out these different processes on my Marshalls. I'm happy with the results, though it's barely noticeable at all with a regular 6-string. The biggest difference is with the 8-string on the bottom end. Palm-muting sounds more dynamic and percussive, and there's less boom when stopping a note. The biggest improvement you can make is still changing the speakers themselves.

Tech: Home setup

Someone asked in the pedal post what I have on my other board. This is the setup I keep at home -- all the stuff that doesn't get used for Rosetta (except the Marshall head, which comes and goes because I like to play it every day).

The board has a EH LPB2ube, Boss RV-3 Delay/Reverb, MXR GEQ-10, Ernie Ball stereo volume pedal, Boss BF-2 Flanger, and Ibanez WD-7 wah. There are also an Ibanez Thrashmetal and Phaser that I know next to nothing about and are not hooked up.

This 1960A has 3 Vintage 30s and 1 G12H30. I am now using a mix of Eminence (4 Governors) and Celestion (4 G12T75s, possibly to be replaced with Eminence Wizards) in my live cabinets. After break-in, Eminence sound better to my ears at the insane volumes we use live, are more reliable (I was blowing up V30s constantly), and louder at the same wattage.

You can also see the two Valve Juniors, a Randall backup slave head, the Frankencaster, and my Agile 8-string (post forthcoming).

Edit 10/18/09: This post is completely outdated now. The Valve Junior setup is still the same, but that's about it. I have a PODxt/FBV Express MKII > power amp > 1960A setup now for practicing at home, so I can leave the TSL at the practice studio. I sold the Randall and several of the pedals, keeping only the RV-3, LPB2ube, and Volume pedal for the VJs. The MXR EQ is used for 8-string only, mostly at practice. With the POD, it's much easier to record demos cleanly at home. No mic'ing, and I use cabinet impulses in the DAW -- super fast, and means I spend more time practicing and making demos, instead of hooking things up and fiddling with knobs.

You can see the updated setup here.