Why I don't do mods to old amps

Machine Gun Amps Why I don't do mods to old amps.

There's nothing that bothers me more than a nice vintage amp that has been modded by a hacker. I've seen way too many very nice and extremely valuable amps that were hacked to pieces mercilessly by people that think they know more than the people that designed the amps. I am under no impression that I'm as famous as the amps I work on.

I don't do mods other than to make the amp more stable, safe, or to make it sound different without modifying the circuit (ie different tubes). I do mod silverface Fenders back to blackface quite often. This may be considered a misguided mod by some people, but I consider it no more misguided than the things the propellerhead engineers at "Fender" did in the CBS era (not a dig on all engineers by any stretch). The blackface circuit sounds better.

I'm going to go through some mods that people ask for and reasons why I think that they are misguided. Most of these examples will be in the context of a Fender or Marshall because these are the amps that I get asked about to mod more than others.

"I want a master volume installed on my amp"
This mod is requested far too often. People don't understand what a master volume does, but they ask for it anyway. Amps that have a master volume to get distortion do so through preamp clipping. This means that there was some sort of previous thought involved in shaping the preamp gain and response to make it sound good with a master volume. I get people asking me to add a master volume to a blackface Fender because they want it to sound like it does cranked up, but at a lower volume. Guess what folks? IT AIN'T HAPPENING. And I can't seem to convince people of this. That nice distortion you get from your Super Reverb is due to preamp, power amp, and speaker clipping, and other issues that happen only when the amp is up loud all at the same time. Since the master volume removes the latter two factors from the equation (the master volume is installed right before the power section on most amps), how can you expect to get that tone at lower volumes? Fender preamps don't clip all that nicely anyway (brownface and later). Here's another example: I've had a few people that own Deluxe Reverbs that say they love the sound of it cranked, and want me to install a master volume on it to get it at lower volumes. The preamps of the Deluxe Reverb and Twin Reverb look VERY similar. Do they sound the same cranked up? No! So why assume that adding a master volume is going to capture that sound? Here's another one: Fender installed master volumes on later model silverface amps. Does it make it sound like a Marshall? No! Let's get off the master volume ignorance! You can get closer with a speaker load simulator (such as the THD Hot Plate, or Marshall Power Brake), but that still neglects the speakers. Speakers do contribute to the distortion characteristic.

Now, after all this, I'm sure people are still going to ask me to install a master volume on their amp. My answer is still "no". The reason why techs still do it is because misguided people still believe that it will solve all their problems. There are a few isolated circumstances where it will do something useful, but I'm not going to go there right now.

"Make my Fender sound more like a Marshall"
Uhhh, no. Why do you have a Fender if you really want a Marshall tone? The subset of this one is "Make my Fender have a footswitchable boost that makes it sound like a Marshall". That ain't happening. There are a lot of "techs" out there that claim to have done just this, yet I don't see them making a ton of cash because an amp like this sure would be useful! And it's not going to happen within a Super Reverb chassis! Marshall tone has a lot to do with the whole package. This includes the circuit, tubes, speakers, cabinet, transformers... It goes on and on. Changing one aspect of the amp to make it more Marshall like isn't going to make it sound like a Marshall. Changing all of these things to make it sound like a Marshall is an exercise in stupidity. Think about what you will have when you are done. Parts and labor that are more expensive than an entry level used Marshall, and a hack-butchered amp you have after the mods is now worth nothing! A Fender is a Fender. If you want a Marshall, go sell your Fender and buy one.

"Install EL34's in my Fender to make it sound more like a Marshall"
This mentality follows the master volume mentality fairly closely. EL34's do not make a Marshall. The first Marshalls came with 6L6's! Marshalls from a few years ago came with Sovtek 5881's! Do they still sound like Marshalls? Yes they do! So what makes anyone think that EL34's in a Fender will make it sound more like a Marshall?

Another consideration: The EL34's draw more than 50% more filament current than a 6L6GC. A 6L6 equipped Fender will usually handle this fine, but I wouldn't guarantee that it would every time. Installing these in a Deluxe Reverb or Princeton Reverb is an almost instant death sentence. Don't do it!

EL34's will change the tone, and some people may like what they do. However, I won't do it, so let's not talk about it.

"Install 6V6 tubes in my Fender 6L6 amp"
This is an often asked for mod that I won't do in any case. The current delivery in a 6L6 amp is too high for the 6V6's to handle. If you look at plate voltages in a Twin Reverb vs. a Deluxe Reverb, you will find that the Deluxe Reverb is higher in many cases. So is the Princeton Reverb. These amps don't deliver the current that the bigger amps do, so the tubes don't get worked as hard as the plate voltage may suggest. If you install 6V6's in a Twin Reverb or Super Reverb, you are actually unburdening the amp slightly (6V6's draw less current than a 6L6), so there is even more current available to deliver. This means that plate voltage will increase even more. The outcome? Your 6V6's will be toast. They are not able to do what you are asking of them in a bigger amp. They may work for a little while, but they won't last forever. Often they will short dramatically and take other expensive parts with them. I don't care what any other tech has written in any book about it. It's a stupid thing to do and expect any longevity out of it. I won't do it and please don't ask me to.

"Install more preamp tubes in my Marshall ______ to give it more gain"
This is an 80's relic mod attitude. The modded Marshall days are over, get over it! Many techs have made their name modding old Marshall amps to give them more gain. That's all well and good. But these days, there are a million amps that are made new that give that same tone as the old modders were going after. Even Marshall makes amps that are designed to emulate the old modded amps! It would be more worthwhile to sell the amp you have while it's still worth something and get one of these high gain amps. Examples of high gain amps that sound pretty good and are hella cheap are Metaltronix, Peavey Ultra, Peavey 5150, Carvin, Lee Jackson, Marshall JCM900, and countless others. I wonder why these amps are so cheap now? All of these do the modded Marshall thing better than modded Marshalls do themselves in my opionion.

"Install an effects loop in my vintage Fender"
I will never understand the reason for an effects loop in an old Fender. They are clean amps. If you need an effects loop, then you are using the wrong effects or you think you need a loop but you don't. Run effects through the input of the amp, plain and simple. There are noted techs out there that install loops in vintage amps and it pisses me off. If you really need it, then you are missing the point of a vintage amp anyway. I'm sure there are circumstances where a loop is warranted, but I'm not doing it. There are some companies now that have loops that plug into a tube socket. I don't have any experience with them, but this is a great idea if they work good. I think Magic Parts sells a kit that does this. I will absolutely not install an effects loop in any vintage amp.

"Randy Smith (of Boogie) and Jim Marshall started out modifying Fenders, don't you think you are as good?"
No, I don't. They started modding amps back in the days when you couldn't go down to the store and buy the sound you wanted. So these guys come in and set a new standard by modifying Fender circuits. In Mesa's case, modifying them very heavily. Can I do this? Yes. Am I going to do it? No. Go down to the store and buy an amp that sounds like what you want. There's no use in hacking up an old amp that thousands of people would want just the way it is. Leo Fender made these circuits sound as good as they ever could have been, all I want to do is preserve that. I'm not going to change the world by making a few mods to some amps. It's too bad that there are a million techs in this country that think they are the next Randy Smith. There are a million hacked up Fenders sitting on a junk pile now to show how successful they've been.

To the main page. To contents. Email me. Flame me!

All content of this web site © Machine Gun Amps.
All company and product names are presumed trademarks of their respective companies.

Last updated 7/12/01