Final build diagram with all changes

drpastorbob · Post by **drpastorbob** » Sat Jul 12, 2008 10:09 pm

Attached you will find the D'Lite diagram where I have noted all the changes I made based on suggestions and what I read on the post to get to the sound I have. The recent changes I made based on suggestions from Scott such as my having two resistors backwards on V2, etc. have not made the amp any less balanced for single coils vs humbuckers, both work great. If anything, correcting my error on the resistors (which changed the V2 plate voltages) may have made the amp sound less "complex" - go figure. Maybe voltage imbalances on the preamp tubes are good? I know this goes against the 200V plate voltage philosophy/lore/magic, etc. I'll try to post some new clips sometime soon.

Bob

skyboltone · Post by **skyboltone** » Sun Jul 13, 2008 2:50 am

Thanks Bob

bluesfendermanblues · Post by **bluesfendermanblues** » Sun Jul 13, 2008 7:34 am

drpastorbob wrote:having two resistors backwards on V2, etc. have not made the amp any less balanced for single coils vs humbuckers, both work great. If anything, correcting my error on the resistors (which changed the V2 plate voltages) may have made the amp sound less "complex" - go figure.

Bob

could the complex sound be due to more assymetrical clipping with the V2 resistor backwards/swopped around ??? Please enlighten me on this one?

Guitarman18 · Post by **Guitarman18** » Sun Jul 13, 2008 9:47 am

You might be on to something, with the resistors in backwards!.

phsyconoodler · Post by **phsyconoodler** » Sun Jul 13, 2008 4:14 pm

One of the biggest changes is the removal of the local feedback circuit on V1.This can make the clean channel much more responsive.It gets real chewy at higher volumes and is far more touch sensitive.But...it lowers the clean headroom and jazzy tones are less satisfying.I suggest a switch to put it back in when desired.

Structo · Post by **Structo** » Sun Jul 13, 2008 9:04 pm

Bob did you keep the 500 ohm choke resistor?
I changed mine to 330R per Scotts advice.

Also did you keep the same screen and grid resitors on the power tubes?

Did you keep the jumper on the bass pot?

Thanks

drpastorbob · Post by **drpastorbob** » Sun Jul 13, 2008 9:43 pm

phsyconoodler wrote:One of the biggest changes is the removal of the local feedback circuit on V1.This can make the clean channel much more responsive.It gets real chewy at higher volumes and is far more touch sensitive.But...it lowers the clean headroom and jazzy tones are less satisfying.I suggest a switch to put it back in when desired.

Thanks for the information about that. Maybe I haven't played loud enough yet to notice, although I have had the amp up pretty loud and tried it both ways and could not tell much difference. I tried it again just the other day. If I have room on the back panel I'll take your suggestion and put in the switch. The way I got to having it removed was that I initially wired it up wrong and found it was not connected at all (don't ask how that's possible) but sounded fine. I believe I noticed on a post from Larsmuller that in his diagram he also has it removed.

drpastorbob · Post by **drpastorbob** » Sun Jul 13, 2008 9:45 pm

Structo wrote:Bob did you keep the 500 ohm choke resistor?
I changed mine to 330R per Scotts advice.

Also did you keep the same screen and grid resitors on the power tubes?

Did you keep the jumper on the bass pot?

Thanks

I checked and I do have the 500 ohm choke and all the power tube resistors just as shown in the diagram I posted. The bass pot is also wired just as shown.

drpastorbob · Post by **drpastorbob** » Sun Jul 13, 2008 9:47 pm

bluesfendermanblues wrote:
drpastorbob wrote:having two resistors backwards on V2, etc. have not made the amp any less balanced for single coils vs humbuckers, both work great. If anything, correcting my error on the resistors (which changed the V2 plate voltages) may have made the amp sound less "complex" - go figure.

Bob
could the complex sound be due to more assymetrical clipping with the V2 resistor backwards/swopped around ??? Please enlighten me on this one?

This is more of an observation/question on my part about having a big imbalance in the V2 plate voltages. Someone who knows more about this should chime in. I would also like to know!

dimitris · Post by **dimitris** » Sun Jul 13, 2008 10:16 pm

DrPastorbob i see in the layout that you posted that you have more volt at the side of the pi with the bigger resistor.I thought that the opposite should happen for best tone.

dogears · Post by **dogears** » Mon Jul 14, 2008 12:12 am

Agree with Dimitris. Swap PI tubes until you get one with at least 5V more on the first triode.

Also, make sure your presence pot is not grounded to the buss bar on that 3rd lug. Only the resistor and 1uf cap get grounded. Not the pot!!

I'd also suggest swapping the 500ohm "choke" resistor for a 330ohm or so.... You may greatly prefer it. I did.

drpastorbob · Post by **drpastorbob** » Sat Jul 19, 2008 5:38 pm

dogears wrote:Agree with Dimitris. Swap PI tubes until you get one with at least 5V more on the first triode.

Also, make sure your presence pot is not grounded to the buss bar on that 3rd lug. Only the resistor and 1uf cap get grounded. Not the pot!!

I'd also suggest swapping the 500ohm "choke" resistor for a 330ohm or so.... You may greatly prefer it. I did.

So, I swapped PI tubes and found a long-plate Mullard that had a 7V difference and used the trim pot to get the difference to 5V as suggested. The PI voltages are now 279V/284V (120K-ohm resistor/110k-Ohm). I also put the V1 feedback in/out on a locking switch on the back panel so I can switch it in and out, should I desire to do so. I also went back to the 150k-ohm slope resistor; just my preference. I checked the presence pot and it is just as you suggested Scott, no 3rd-lug connection.

I did not change the choke resitor value from its current 500 ohms because I assume that I will have to change all the other resistors downstream again to get all the voltages right. If you could elaborate on what is significant about going to 330 ohm, that would help.

One big change coming up is that I just bought a 1981 Celestion G12-65 on ebay. It came yesterday, but I have not yet tried it out. I'm assuming this will make a big change in the overall tone. I'll try to make some new clips to compare against the Eminence Legend 1218 I have been using so far.

Everyone, thanks again for all the help and suggestions. Much appreciated!

Bob

dogears · Post by **dogears** » Sat Jul 19, 2008 7:20 pm

Bob, the first triode of V3 is the 110K and then the feedback side is 120K. Is this how yours is? You should have more voltage on the 110K side. Which is the side that has the .02 cap.

Also, you go to the 330ohm resistor with little or no effect on downstream voltages. No need to adjust any.

drpastorbob · Post by **drpastorbob** » Sat Jul 19, 2008 9:36 pm

dogears wrote:Bob, the first triode of V3 is the 110K and then the feedback side is 120K. Is this how yours is? You should have more voltage on the 110K side. Which is the side that has the .02 cap.

Also, you go to the 330ohm resistor with little or no effect on downstream voltages. No need to adjust any.

Scott,

The relative magnitudes of the voltages is now reversed from what I had before. The higher voltage is on the 110K side with the .02 cap. I don't have a 330-ohm choke resistor and will have to order one, but its good to know it has little effect on the downstream voltages. You still didn't tell me what the effect of the change from 500 ohms to 330 ohms is.

Bob

dogears · Post by **dogears** » Sat Jul 19, 2008 9:39 pm

The amps articulation will improve a lot with the 330ohm. 500ohm is really smooshy and darker.

drpastorbob wrote:
dogears wrote:Bob, the first triode of V3 is the 110K and then the feedback side is 120K. Is this how yours is? You should have more voltage on the 110K side. Which is the side that has the .02 cap.

Also, you go to the 330ohm resistor with little or no effect on downstream voltages. No need to adjust any.
Scott,

The relative magnitudes of the voltages is now reversed from what I had before. The higher voltage is on the 110K side with the .02 cap. I don't have a 330-ohm choke resistor and will have to order one, but its good to know it has little effect on the downstream voltages. You still didn't tell me what the effect of the change from 500 ohms to 330 ohms is.

Bob

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Final build diagram with all changes

Final build diagram with all changes

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