Something sounds off with my recent Pauper build

[jessemhopkins]

I built a dual drive for a friend with the Informant on the right and pauper on the left with an order toggle and added clipping toggles on the Informant side. Informant sounds great, Pauper sounds... ok. It has an aggressive high end character that I can't quite put my finger on and really only sounds good when cranked. It also does not have as much gain as my stock (non-high gain model) King of Tone and doesn't have much dirt at all until about 65-70% through the sweep. Anyone have any thoughts? I used metal film resistors, WIMA film caps, Nichicon fine gold electrolytics, NJM4580 IC and proper MA856 diodes that tested well. Even in the open clipping mode I notice the weird splatty high end thing so I don't think that's to do with the diodes. It's not terrible, but noticeably different than my KOT. Would love to hear some component recommendations.

 

[jessemhopkins]

Realizing I should have posted this in troubleshooting, but I’d still love some input if anyone has any ideas or experience with this circuit. Thanks!

 

[music6000]

Check & see if the Pauper Gain pot isn't Cracked or Faulty. Remove the Gain pot nut & while playing a Chord, wiggle Up & Down & turn the pot shaft.

 

[jessemhopkins]

Check & see if the Pauper Gain pot isn't Cracked or Faulty. Remove the Gain pot nut & while playing a Chord, wiggle Up & Down & turn the pot shaft.

Pots seem fine, I even desoldered the gain pot to get an accurate reading and it’s well within range. Any other thoughts?

 

[music6000]

Look for any misplaced solder ( Dry joint, Bridging ) on the back of the Pauper PCB, I presume you have insulation between the Tone Pots & PCB's.
Also try another Op Amp, NJM JRC4558D, TL072, LM833N, LF353N, OPA2134PA.

I'm not sure what effect the Informant Buffered Bypass is having on the Pauper being True Bypass at the moment!
I would have gone with True Bypass.

 

[jessemhopkins]

None of those issues are present, but I would also presume them to cause much worse problems. I believe it to be either down to component choice or incorrect values in the build doc, though I have not studied either schematic so I can't be certain.

Basically, it's not catastrophic, it's just... not quite right.

 

[jessemhopkins]

Oh, and it's the same regardless of what order the effects are in so the buffer does not appear to be a factor.

 

[music6000]

Can you confirm what value capacitor's you have in C2 & C15 ?

 

[jessemhopkins]

C15 is definitely 1uf, I went with MLCC bc the build doc said 1 of the three 1uf caps was to be ceramic and so I assumed that's where it would go. But it's also only in the circuit with the "Lift" dip switch engaged, correct?

C2, I assume I followed the build doc and it is 100pf, but I don't have it in front of me to confirm.

 

[Robert]

The components listed in the build docs should be correct, this board hasn't seen any revisions and it's been built successfully quite a few times.

You can look past C15 if flipping the Lift switch makes no difference.

Does the Turbo switch make any difference?

Just out of curiosity, have you tried another opamp, like maybe a TL072 or JRC4558?

 

[jessemhopkins]

The components listed in the build docs should be correct, this board hasn't seen any revisions and it's been built successfully quite a few times.

You can look past C15 if flipping the Lift switch makes no difference.

Does the Turbo switch make any difference?

Just out of curiosity, have you tried another opamp, like maybe a TL072 or JRC4558?

Yes, Turbo switch adds gain and brings it a little closer to the range of my normal gain KoT, distortion-wise. I think the lack of distortion may have to do with the MA856 diodes I used being a little lower in voltage drop (they all meter out at almost exactly 700 vs the ones in my KoT being more in the 800 range) but the harshness in the top end is the bit I'd mostly like to tackle. I'll try a different op-amp and see what that does for me.

 

[zgrav]

Seems like the gain drop and the harshness could tie in to your diode selection.

 

[jessemhopkins]

Seems like the gain drop and the harshness could tie in to your diode selection.

The gain drop, yes, but the harshness is present even in boost mode (no diodes).

 

[zgrav]

Do you still hear the harshness when the diodes are in the circuit? And is the harshness you are describing in the boosted clean signal even when you dial down the signal level? Do you think it sounds better cranked just because you are overdriving other components at that point?

 

[jessemhopkins]

Do you still hear the harshness when the diodes are in the circuit? And is the harshness you are describing in the boosted clean signal even when you dial down the signal level? Do you think it sounds better cranked just because you are overdriving other components at that point?

Yes, it's present in all 3 modes. It has kind of a paper-thin, torn speaker quality to it, or like channel strip distortion. It's definitely more present at lower gain settings, but in boost mood it's pretty noticeable across the sweep. dialing back the presence trimmer and tone knob help some.

I suppose it's worth noting that I've not used a Prince of Tone before, only a King of Tone. So my comparison may be flawed from the start, as I believe the circuits are slightly different. But I'm not sure what sonic differences exist between those two pedals, if any, so if what I'm describing is to be expected then maybe I should just move on with my life .

 

[zgrav]

I guess there are two issues --- whether there is a problem in the circuit design or a problem with a part being used. Given that the circuit is functional but persistently harsh, I would probably take the suggestion from Music6000 to substitute the op amp in search of a smoother choice.

 

[phi1]

Did you ever confirm C2 is 100pF? Usually I see that value as ceramic, not a box type. If you used a higher cap there on accident, I can see that cutting down the gain amount from that op amp.

 

[jessemhopkins]

Great suggestions, I'll try a few different opamps and verify c2 value when I get home. Thanks!

 

[music6000]

I guess there are two issues --- whether there is a problem in the circuit design or a problem with a part being used. Given that the circuit is functional but persistently harsh, I would probably take the suggestion from Music6000 to substitute the op amp in search of a smoother choice.

The reason I suggested trying another Op Amp is there are a lot of Suspect ones coming from China and they look like the real deal!
Confirming that the available Wima C2 is 100pf as I queried earlier would also help rule out a accidental higher Value.

 

[zgrav]

Good point that some op amps might not be what they seem, but I think there is variation among smoothness of op amps too. At least based on an internet search earlier, it looks like the Prince of Tone pedal actually sockets the op amp and notes that some owners might want to try different ones. And that's not even accounting for the "woo" factor. : ^ )