Bluesmaster PI-DLite= Bloom & Harmonics?

[Buschman]

Maybe I read too much but every time I see a tweak on here it makes me want to heat up the soldering iron & buy resistors. I have a homebrew DLite running 6l6s. I think it sounds pretty good but would enjoy more harmonics. Will the Bluesmaster PI get me there. I am a rock player mainly but would not want a grainer sound.
Dogears had a clip with lots of harmonic bloom. That's what I need.

[heisthl]

Try less filtering on the first stage(40 - 60 uF). Next try a smaller RF MOD (coil substitution) resistor(250 - 390). Next try balancing the PI with a 10k trimmer( go for about 6 volts difference on a matched 12AX7 with 120k and 110k plare resisotrs). Next, As a last resort, try the Bluesmaster PI.

[markmalin]

Just to chime in here, I think heisthl has some great advice. Take it in steps.

I'm no expert, and am new to this amp design, but after building my D'Lite 22 (6V6's) I tried some of the common mod's. I found that changes to the tone stack (including the treble and brite caps), rewiring the Presence control and changing the feedback resistor had the most prfound effect on the tone. After that, just playing it and learning how to use the amp is becoming a big help as well.

Mark

[Buschman]

Thanks Heisthl,
I put the 250 ohm RF Mod in. I am running a dual 50 mf at 500v first stage. I could lift one of these. Will it make the bass a bit flabby? I do not have a trimmer but I did install the 120k & 110k resistors. Where are you looking for 6 volts. There is lots of talk about PI tweaking but I am not following it so well. I do not have a scope. Every 12ax7 I put there reads different. I have left one in there that reads 318 on pin 6 & 305 on pin 1. Some of the tubes I tried reversed this. I thought it would be better to have the higher voltage on 6. This is how the voltage chart read anyway. Any clarification would help. The amp is sounding strong. Thanks!

[Buschman]

What feedback resistor did you end up with?

BTW Mark, I am a BMW nut as well.

[heisthl]

I used to use a scope or AC meter to do it but now I just do it by ear and adjust the PI where I think it sounds best and it always seems to be around 6 volts difference, meaning P6 is 6 volts higher than P1. On some amps it makes a pretty dramatic improvement. Enough to make a believer out of me on incorporating a trimmer in a build. Evidently HAD thought so too.
If you have a choice use a long plate tube in the PI position. I do try and use "matched" tubes but that is not really important.
Let me know how you like less filtering(50 uF).

[markmalin]

What feedback resistor did you end up with?

BTW Mark, I am a BMW nut as well.

I used a 4.7k, I think. It was per the "D'Lite Tweaked" schematic.

Yes, bimmers are my other obsession

Mark.

[phalanges]

"Try less filtering on the first stage(40 - 60 uF)"
Sorry to be dense, but is this the 22uf cap on the PS board closest to the fet resistor and connected to the 2k2 3w dropping resistor?

[heisthl]

"Try less filtering on the first stage(40 - 60 uF)"
Sorry to be dense, but is this the 22uf cap on the PS board closest to the fet resistor and connected to the 2k2 3w dropping resistor?

Density is my middle name
I meant the main B+ stage (the first place that has DC).

[phalanges]

Thanks, I'm really enjoying this learning process.
John.