More crunch?

[J M Fahey]

Hi Chuck, *killer* mod.
A real "Dr Jekyll-Mr Hyde" switch, and as simple as can be.
I love simple and elegant solutions , and this is certainly one of them.

[petemoore]

It's the speaker/output tubes/power supply sound we're hearing that makes me build these tube amps.
Voicing the preamp and using lower gain V1 is recommended to try [12a_7, anything except an 12ax7], distortion from the preamp is semi-futile [when I play too low for the ''speaker/tubes sound''], something else makes the distortion for that.
Lower effeciency speaker, but I don't mess with that either, I like 'em effecient so have little experience and envision a difficult time finding a 'queit' speaker that breaks up/has same basic tone as my 'standards' {GB's Blue, TT's} speakers.
Along with the sweet tone of the tube/speaker relationship @volume, you'll notice a more strict relationship between volume and tone changes than say a bigger cleaner [higher wattage] tube output/speakers to handle it, relying on distortion provided by preamp or pedal. Pretty much directly relates volume and distortion, especially plugging the pickup to the amp input.
However, trying out 6k6 output tubes would be most interesting in the ''drops volume without changing tone'' dept. [a misnomer].
If I was having 6k6's here, I'd be trying that out.

[Sweetfinger]

You could just put a clean boost pedal in front of the amp. The Duncan pickup booster is cheap and works well for this application.

[daz]

To expand upon that idea in a way that would make it more controllable volume wise, he could use a clean boost in front and add a simple master volume at the PI. this way he could hit the preamp hard enough to get anywhere from a ton of drive to just a bit from the pre and get it at any volume. Now of course thats not going to sound the same as the 6V6's cranking, but if he wants grind at lower volume this will give it to him at most any volume. plus he can turn the master up to a point just where the 6V6's are partially distorting then adjust the clean boost to add just the right amount and get a blend of pre and power amp grind and in that way also find different colors he may like too. It's like total adjustability with a simple one pot mod and a clean boost pedal. I' have used that in the past on many amps with some very good success. And a clean boost i find can actually be a better sounding way to OD preamp tubes than cascading them.

[sean k]

I just came up with this. To stack the channels you just plug into the "mic" channel and throw the switch. It allows you to have a stock amp or stack the channels and it's just simple as hell. This one places the tonestack later in the preamp (good). The only rub is that you can't use multiple inputs on the amp when the mod is switched in. Well, you probably could, but the results may be less than satisfying. However, if you do it this way you can still "jumper the channels" or use an A/B pedal for either channel with the mod switched off. So it's just like the stock amp until you throw the switch which could be located in the "low gain" hole of the "mic" channel so no extra holes need to be drilled.

Chuck

I was looking at this and liked it but was a little worried at the 33k to ground as I contemplted its use for an amp I'm building. Eventually I figured you could use a DPDT switch and use the other half to switch out the ground connection in the Hi input and run it across a pot or trimmer. So basically the junction of the 33k ( the joins of the two 68k's to ground) gets lifted when the switch is thrown and a fixed or adjustable resistance goes accross the outer lugs so normally it's all grounded as usual and switch thrown. A drawings better eh?

[Chuck H]

A drawings better eh?

Yes... But I get it. And it's a good idea. The only rub is that the load is the bias resistor. If you switch it out your going to leave the grid of that stage floating for a moment. I don't think it would hurt the tube but it will almost certainly make a loud "POP" when the switch is flipped. The onlt way to avoid the POP would be to hang another load resistor ahead of the switch... And now it's getting complicated with the DPDT and the extra circuit changes. My point to this was that it's really simple.

Chuck

[sean k]

Yeah Chuck, the original is simple and efficient but as always I'm using i for something I'm doing so I've added things to make it a little more to my taste and I'm glad you bought up the pop. A 2.2M from the bottom tubes cap, centre lug on right side of switch,accross to the bottom lug of the other side of the switch should take care of that... or do you mean the new cap that goes to the top tubes grid... won't that then have the 1M to ground on the input to shift the charge.

[Chuck H]

AAAhh. I got ya now. Good idea. I thought you meant to switch the load to a dedicated circuit apart from the two 68k's. That would certainly POP. But your idea simply parallels them with a pot. In your drawing the normal 1M input load resistor keeps bias on the tube so the act of switching won't float the grid of that triode. Should work great. If it does pop it probably won't be so bad as to be annoying.

Chuck

[AcePepper]

My fave mod for the 5E3 is:
-12AX7 preamp tube
-Split cathodes on input/1st tube. Make the "bright" side 2.7k/.68 (yes, like a Marshall) the "normal" side 1.5k/10uf (sorta like a Fender.)
-.02 coupling caps in the preamp, down from .1
Makes it behave w/humbuckers, still acts like a 5E3, fairly crunchy when cranked and any little p.o.s. o/d pedal sends it straight to VanHalen/ZZ Top-land.
Hope ya dig it.
Ace!8-)>
Ace Pepper Custom Amps