More crunch?

[chuckb]

Hey guys,
Can anyone here tell me how to get more crunch out of my 5e3? Do I decrease the value of the cathode resistor and increase the value of the plate resister in the preamp stage? I'm pretty new to this,and this is my first PTP build.I just want to get more crunch by using my guitar volume going from clean to dirty.

Chuck.

[Chuck H]

Are you saying the distortion you have isn't "crunchy" enough in nature? Or are you saying you want more overdrive/distortion? Or both?

Chuck

[chuckb]

Hey chuck ,thanks for the reply.I want more overdrive/distortion. Can't seem to get it to break up enough without having everything almost cranked.I would like to get some good overdrive without having to dime it.I hope this makes sense?

Chuck.

[Chuck H]

Hey chuck ,thanks for the reply.I want more overdrive/distortion. Can't seem to get it to break up enough without having everything almost cranked.

That's because the power tubes don't start to overdrive enough prior to that.

I would like to get some good overdrive without having to dime it.I hope this makes sense?

I think I understand. But what is the goal??? Do you want the amp to make more distortion at a lower volume? At this point it's worth noting that once your amp is starting to clip (overdrive/distort) the volume won't increase appreciably as you turn it up. It will just become more distorted. So if your getting some crunch at, say, five on the volume control, the distortion at eight or even ten will be much greater but the volume should not increase noticably.

Most of the 5E3's overdrive is in the phase inverter and power tubes. To get more distortion at a lower volume you would need an attenuator. But this will reduce your clean tone volume when turning down your guitar's volume knob. A stacked gainstage and a master volume would also give you more distortion at a lower volume. But it won't sound at all like a 5E3, and without "channel switching" you will still be limited on clean headroom by using a master volume too.

This is just the nature of the equipement.

Chuck

[chuckb]

Hey Chuck, Thanks for the input to my questions. I will leave my amp as it is now because I don't want to sacrifice the tone of the 5e3. I love that sound of overdriven tubes. I once used alot of overdrive/distortion pedals in the past, but once I heard the sound of a naturally overdriven amp I was hooked. IMHO, there is no pedal that can give that can give you that pure tone. My friend says I'm spoiled now because I have that tone in my head and that no pedal can replicate that. I believe that to be very true. Thanks again.

Chuck.

[Chuck H]

You could still build an atennuator for quieter practicing. I outlined an affordable one here:

http://music-electronics-forum.com/t16468/

If your using a 12ay7 in V1 you can swap that for a 12ax7 for more gain. If you stll want more overdrive it requires mods that would change your amp to something other than a 5E3. Aclean boost pedal in front of the amp can also add more dirt and won't sound like a stomp box.

Chuck

[MWJB]

You could try splitting the cathodes at V1 give one channel 1K to 1.2K, the cleaner channel 1.5K, each resistor will need a bypass cap. I'd put the lower value on the Normal/Mic channel as the Bright/Inst channel naturally has better fidelity. You'll still most likely need to turn the Normal channel way up.

A channel switcher/ABY box is a better way to go from dirty to clean.

You are happy that the amp is workig as intended in the first place?

[chuckb]

Hey Chuck,yes, I would like more overdrive,can you suggest a mod. I already have a 12ax7 in V1 now.

Chuck.

[HTH]

Hey Chuck,yes, I would like more overdrive,can you suggest a mod. I already have a 12ax7 in V1 now.

Chuck.

220k plate resistors on the first gain stage will give you more gain.

Alternatively (or additionally depending on how much more gain you want), you'd get much more gain by cascading the two channels...



This is just a starting point, you'd want to split the cathodes on the first tube (1k5/10uF on each is a good place to start)

[chuckb]

Thanks HTH for the info. I'll give your advice a go and see what kind of results I get. I'll let you know how it works out.

Chuck.

[Chuck H]

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

[ThermionicScott]

In addition to bumping up those plate resistors, you could try "mis-biasing" the second gain stage so that it will clip sooner. Merlin's book has some good info on this. (One example is a Soldano gain stage that uses a 39k cathode resistor instead of the usual 1.5k)

- Scott

[Bruce / Mission Amps]

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

Have you tried this yet? I have not.
Since the two triodes share the same cathode biasing resistor, and they will now be 180 degrees out of phase with each other, I wonder what the consequences will be....? You might get better results if you split the two cathodes and let them have their own biasing resistor and bypass cap.

ChuckB

Most good 12AY7 triodes in this circuit will make about 2.5vac to +3vac output... yes some stock tubes are hotter.
The next stage (and only other gain stage, the 12AX7 volume pot recovery amp), will output around 22-24vac before distorting the PI.
But even with a cleanish max volume level output, it is still usually more then enough over drive, saturate and or clip the cathode biased power tubes.

If you want just a little more preamp gain.... remove the 22K B+ dropping resistor from the B+ rail (between the last to filter caps) and use a 5K@1w to 10K@1w resistor instead.
Then use a 130K to 150K plate load resistor on the bright channel but reduce the coupling cap down to .047uF.

[Chuck H]

Have you tried this yet? I have not.
Since the two triodes share the same cathode biasing resistor, and they will now be 180 degrees out of phase with each other, I wonder what the consequences will be....? You might get better results if you split the two cathodes and let them have their own biasing resistor and bypass cap.

Bruce, I haven't tried this. Hence the "I just came up with this". But it should work. And I did seperate the V1 cathode circuits in the diagram. There is no volume control for the stacked channel. instead it's attenuated by the parallel 68k input/grid resistors on the instrument channel for a load of 34k. If you look at the diagram you'll see that it's a REAL simple mod, and not very refined as there would probably be some wierdness if you switched in the mod and tried to run both inout jacks simultaneously or on an A/B pedal. So in that respect it's not really useable as a factory mod type thing. But you can use the amp as stock with the mod switched out. With the mod in your options would be to plug into the instrument channel and use it as normal OR plug into the mic channel for a boosted input signal to the instrument channel. Still, it's so simple that I thought someone may find it useful.

I don't own a 5E3 so I'd love it if you (or someone else with a 5E3) tried it and report on how it goes. Maybe refine it?

Chuck

[Bruce / Mission Amps]

Bruce, I haven't tried this. Hence the "I just came up with this". But it should work. And I did seperate the V1 cathode circuits in the diagram. There is no volume control for the stacked channel. instead it's attenuated by the parallel 68k input/grid resistors on the instrument channel for a load of 34k. If you look at the diagram you'll see that it's a REAL simple mod, and not very refined as there would probably be some wierdness if you switched in the mod and tried to run both inout jacks simultaneously or on an A/B pedal. So in that respect it's not really useable as a factory mod type thing. But you can use the amp as stock with the mod switched out. With the mod in your options would be to plug into the instrument channel and use it as normal OR plug into the mic channel for a boosted input signal to the instrument channel. Still, it's so simple that I thought someone may find it useful.

I don't own a 5E3 so I'd love it if you (or someone else with a 5E3) tried it and report on how it goes. Maybe refine it?

Chuck

oops... sorry Chuck, I didn't notice the split Ks in the artwork.
I was fighting the onset of a blinding migraine headache this morning and was killing time waiting for the numbing drugs to take effect!
I have couple 5E3 amps I'm building over the holiday week and I might give it a go if it doesn't take too long to implement and reverse.