ODS Done - Clip with Strat and Clip with Hamer at Full Bore

[Tonegeek]

Hi All,

I tried a 10K trimmer and I can hear a region in the range where there seems to be more gain. I could not hear a change in the harmonics (aka sweet spot) so I set it for about a 5V difference between the two voltages. Since there is additional resistance now to both plates (common voltage into the wiper and the balanced voltages out to each plate through the same resitors as before), the overall plate voltages are lower: 282V, 287V. Should I have only used the Trimmer pot on one side so as not to reduce the overall voltages to the plates? I was at 293V and 292V before.

Bob

Sounds like you wired it correctly and your voltages look good too. FWIW my PI plate voltages are 270, 273 but I use a long plate tube which may explain the extra voltage drop.

[dogears]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

[ic-racer]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

What do you think about #94? Mid cap looks bigger than the .01 on #124 and slope looks like it has a green band (150k?)

[bluesfendermanblues]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

If

slope 150k / 0.01 uF
slope 100k / 0.05 uf

what's the correct slope resistor with a 0.02 mid cap ? - 120k

I'm using 150k with the 0.02 mid cap at the moment and its sounds ok, but as always, willing to experiment

[drpastorbob]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

I am about to take it out of the head cab again and make the change to 100K. What should I expect to hear?

BTW I have decided instead of a midboost to use the switch on the back to be able to toggle the treble cap between 331pF and 470pF. The 470 adds some noticeable midboost, but not an overwhelming amount.

Bob

[dogears]

Bob, if you have the .002uf in series, try 390pf. That gives you a net 330pf.

The 100k slope will have a nice low mid than the 150k slope when used with the .05uf mid cap. The 150k slope flatten the curve and has a little less gain. Should be pretty noticeable.

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

I am about to take it out of the head cab again and make the change to 100K. What should I expect to hear?

BTW I have decided instead of a midboost to use the switch on the back to be able to toggle the treble cap between 331pF and 470pF. The 470 adds some noticeable midboost, but not an overwhelming amount.

Bob

[ayan]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

That is not in agreement with the couple of classic preamp amps I've had my paws on, as well as pictures from a couple of amps of that era. Furthermore, I think Gregor's amp has a .047uF midrange cap, and it seems to have a 150K slope resistor. It all depeneds on what one is after... If a little more chime and upper mids, the 150K slope may be the ticket. For what it's worth, I prefer the 150K slope resistor myself for the classic preamp.

Gil

[Tonegeek]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

+1 on the 100k, .05 = warmer

[drpastorbob]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

That is not in agreement with the couple of classic preamp amps I've had my paws on, as well as pictures from a couple of amps of that era. Furthermore, I think Gregor's amp has a .047uF midrange cap, and it seems to have a 150K slope resistor. It all depeneds on what one is after... If a little more chime and upper mids, the 150K slope may be the ticket. For what it's worth, I prefer the 150K slope resistor myself for the classic preamp.

Gil

Thanks guys for the additional info. I got sidetracked and have not yet made the change, but I now know what to listen for (I think). Yesterday morning while my ears were fresh I did get out the tele and the strat to check and make sure I had not lost the versatility since making the resistor correction and adding the 10K trimmer to the PI circuit as Scott had suggested. The amp still sounds great with all guitars. It will be interesting to hear the 100K vs 150K. If Gil is correct, I will stick with the 150K since I want to use both humbuckers and single coils.

I'll let you know later today.

Bob

[dogears]

I know there are a couple of 150K/.05uf amps. There is also a pic of a 150K/.02uf amp. I don't think that using the 100K and .05uf will make the amp worse on handling both singles and hums. I find the 150K and .05uf lacking when using the bridge pup. I think it boils down to whether you predominantly solo on the bridge or neck.

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

That is not in agreement with the couple of classic preamp amps I've had my paws on, as well as pictures from a couple of amps of that era. Furthermore, I think Gregor's amp has a .047uF midrange cap, and it seems to have a 150K slope resistor. It all depeneds on what one is after... If a little more chime and upper mids, the 150K slope may be the ticket. For what it's worth, I prefer the 150K slope resistor myself for the classic preamp.

Gil

Thanks guys for the additional info. I got sidetracked and have not yet made the change, but I now know what to listen for (I think). Yesterday morning while my ears were fresh I did get out the tele and the strat to check and make sure I had not lost the versatility since making the resistor correction and adding the 10K trimmer to the PI circuit as Scott had suggested. The amp still sounds great with all guitars. It will be interesting to hear the 100K vs 150K. If Gil is correct, I will stick with the 150K since I want to use both humbuckers and single coils.

I'll let you know later today.

Bob

[drpastorbob]

Bob, try lowering the slope resistor to 100K. The .05uf midcap and 150K slope do not go together, IMHO. The 150K slope was paired with the .01uf midcap. Dumble used the 100K slope with the .05uf mids. Sounds much nicer. Try it!

Scott,

I tried the 100k slope resistor. It works fine also. I can't tell a noticeable difference between the 100k and the 150k. I guess that's why they call you "dogears". Thanks for all the suggestions.

Bob

[angelodp]

Scott, I actually stumbled onto the .001 470pf combo when first doing my mid-boost and liked it. Then I thought I should try the more traditional combo of 330 .002 suggested by Moss. That later combo has me re-thinking the mid-boost as the 330 .002 seems muddy and not as musical.
you reckon I should switch back. I know i should do some sound clips, I am a bit intimidated by all the great players.

best ange
A few observations.

1) Your V2 cathode leads may be crossed. Check the size of V2a and V2b cathode resistors. Yoru voltages lead me to believe they are backwards.

2) Add a trimmer between PI plates. Your PI tube is so imbalanced you have more voltage on the feedback side. Your first triode should be higher than the second. Maybe swap tubes.... Shoot for about 5-6 volts more on the first half. Noticeable improvement in bass feel IMO.

3) The treble cap size has no effect on midboost. Just the cap size which is traditionally .002 and not .02 as you wrote. Try either .002/390pf or .001/470pf. You may prefer the .001/470pf as it gives you less extreme boost.

With the changes in place, try increasing the od trim to 30K or so....

Let me know. I think you'll dig them.[/quote]

[angelodp]

Scott, I actually stumbled onto the .001 470pf combo ( had those values on hand ) when first doing my mid-boost and liked it. Then I thought I should try the more traditional combo of 330 .002 suggested by Moss. That later combo has me re-thinking the mid-boost as the 330 .002 seems muddy and not as musical.
you reckon I should switch back. I know i should do some sound clips, I am a bit intimidated by all the great players.

best ange
A few observations.

1) Your V2 cathode leads may be crossed. Check the size of V2a and V2b cathode resistors. Yoru voltages lead me to believe they are backwards.

2) Add a trimmer between PI plates. Your PI tube is so imbalanced you have more voltage on the feedback side. Your first triode should be higher than the second. Maybe swap tubes.... Shoot for about 5-6 volts more on the first half. Noticeable improvement in bass feel IMO.

3) The treble cap size has no effect on midboost. Just the cap size which is traditionally .002 and not .02 as you wrote. Try either .002/390pf or .001/470pf. You may prefer the .001/470pf as it gives you less extreme boost.

With the changes in place, try increasing the od trim to 30K or so....

Let me know. I think you'll dig them.[/quote]