D'lite-ish 6V6 tone tweak questions.

[martin manning]

I was hoping for a schematic rather than a layout, but I believe it's the usual arrangement with the clean volume between V1a and V1b, the OD entrance trimmer in front of V2a, the OD Drive in front of V2b, ratio/level pot at the OD output, and master at the PI input.

The way I look at the ODS controls is the clean volume and the OD drive determine the level of distortion for the clean and OD sections, but the clean volume has a significant effect on the OD distortion. The OD has its entrance trimmer, which in my view sets the minimum OD distortion level.

The ratio/level pot at the OD output is used to balance the clean and OD volumes, and the master is used to set the overall volume. You have an attenuator after each preamp stage, so there is a lot of flexibility there.

[deiseldave]

I was hoping for a schematic rather than a layout, but I believe it's the usual arrangement with the clean volume between V1a and V1b, the OD entrance trimmer in front of V2a, the OD Drive in front of V2b, ratio/level pot at the OD output, and master at the PI input.

The way I look at the ODS controls is the clean volume and the OD drive determine the level of distortion for the clean and OD sections, but the clean volume has a significant effect on the OD distortion. The OD has its entrance trimmer, which in my view sets the minimum OD distortion level.

The ratio/level pot at the OD output is used to balance the clean and OD volumes, and the master is used to set the overall volume. You have an attenuator after each preamp stage, so there is a lot of flexibility there.

Thanks Martin. That's what I would think (lots of flexibility). However, when I turn up the input enough for PAB to make cleans dirty up, clean side is way louder than OD side, even with OD Level maxed out.

[martin manning]

I believe most people are using PAB as a boost in clean or OD, not for adding distortion to the clean. It will make the OD more distorted, though, and increase the overall volume.

[deiseldave]

I believe most people are using PAB as a boost in clean or OD, not for adding distortion to the clean. It will make the OD more distorted, though, and increase the overall volume.

That's the way I want to use PAB. I just mentioned PAB, because it is the only way I can get some dirt out of the clean channel. I can dime the volume on the clean channel, and it is still clean.
Any ideas how I can get clean side to break up a little better, without screwing everything else up?

[martin manning]

What voltage do you have on your V1 plates? Most people like something around 180-190. If you are near 200, definitely consider lowering it by increasing the dropping resistor feeding the preamp (18k?).

[deiseldave]

Thanks Martin. Depending on tubes used. My V1 voltages have varied between Pin 1: 190V-194V Pin 6: 196V-201V.

[martin manning]

I'd try reducing the preamp voltages, maybe 15V, and see if you like that better. I'm still not sure that PAB is intended to dirty up the clean as much as to provide a volume boost to whichever channel is in use.

[deiseldave]

I'd try reducing the preamp voltages, maybe 15V, and see if you like that better. I'm still not sure that PAB is intended to dirty up the clean as much as to provide a volume boost to whichever channel is in use.

Thanks Martin. I'll give it a shot, and let you know how it works out.

[ToneMerc]

I'd try reducing the preamp voltages, maybe 15V, and see if you like that better. I'm still not sure that PAB is intended to dirty up the clean as much as to provide a volume boost to whichever channel is in use.

I agree wholeheartedly.

TM

[ToneMerc]

I believe most people are using PAB as a boost in clean or OD, not for adding distortion to the clean. It will make the OD more distorted, though, and increase the overall volume.

That's the way I want to use PAB. I just mentioned PAB, because it is the only way I can get some dirt out of the clean channel. I can dime the volume on the clean channel, and it is still clean.
Any ideas how I can get clean side to break up a little better, without screwing everything else up?

I look at these amps as a single channel affair with a switchable gain stage and the D'lite is just a gelded version of the original. If you had the FET function you could make it switchable so you could at least goose the front end of V1. The ODS topology is not really a clean dirty amp and the clean stages feed the OD function and thus is full of compromises from the very beginning.

You can always push the front end with a pedal.

TM

[deiseldave]

I believe most people are using PAB as a boost in clean or OD, not for adding distortion to the clean. It will make the OD more distorted, though, and increase the overall volume.

That's the way I want to use PAB. I just mentioned PAB, because it is the only way I can get some dirt out of the clean channel. I can dime the volume on the clean channel, and it is still clean.
Any ideas how I can get clean side to break up a little better, without screwing everything else up?

I look at these amps as a single channel affair with a switchable gain stage and the D'lite is just a gelded version of the original. If you had the FET function you could make it switchable so you could at least goose the front end of V1. The ODS topology is not really a clean dirty amp and the clean stages feed the OD function and thus is full of compromises from the very beginning.

You can always push the front end with a pedal.

TM

Thanks TM. I have to work today. But plan on lowering the preamp voltages this evening. I've gotta think a happy medium can be achieved.

[M Fowler]

I think this is the schematic for that layout.

[deiseldave]

I changed the 18K B+4 dropping resistor to 22K. Attached before and after readings. That dropped B+ 4 and 5 down about 15V, and the V1 & V2 plates about 10V. Not a lot of audible difference. Clean channel still no dirt, and when volume maxed, becomes louder than OD channel with level maxed.
I then replaced the 2.2K for B+5 with 10K This brought V1 Plates down to about 175/180V. Still not much audible difference.
Then, I thought about the problem: V1 volume turned up passed 3-4 oclock still doesn't have enough dirt, yet becomes louder than OD with level maxed out. So it seemed to me, that I would only want to lower V1's voltages, right? So, I maintain as much headroom as possible on V2. Am I thinking right? I mean, any dirt I get from clean channel would have to come from V1, right?
Anyway, I went ahead and went back to 18K for the B+4, and kept in the 10K at B+5. All voltages (except B+5 & V1) returned to first scan values, and V1 plates (1/6) became 183V/190V. Not much audible difference, again. But, seems a little more cooperative.
I think I'll try moving some tubes around tomorrow, with the lower B+5 voltage. Maybe I'll get lucky.
Any other ideas?

[Duble]

So it seemed to me, that I would only want to lower V1's voltages, right? So, I maintain as much headroom as possible on V2. Am I thinking right?

Yes you are correct. Make V1 B+ the last in your Power Supply, so you're only effecting V1 B+. The OD's B+ is best around 200v.

[10thTx]

Clean channel still no dirt, and when volume maxed, becomes louder than OD channel with level maxed.

Am I understanding you correctly? The clean channel maxed is louder then the clean channel maxed into the OD channel maxed?

IF that is the case, then I would check every value of every resistor and potentiometer in the OD channel.

The four gain stages of the preamp should be louder then the two gain stages of the clean amp unless something in the OD channel is attenuating the volume too much?

The OD channel should increase the volume of the clean channel not lower it.

With respect, 10thtx