Pinnacle problem

iqvalue · January 22, 2010, 04:07:02 PM

I built wampler pinnacle using this schematic:
<Schematic link removed due to manufacturer request 1-24-10>
But I have one problem...
When the tone knob is turned to the right it sounds normal, graphicaly like this:

But when tone knob is in the middle or left positions (more bass) it behaves like this:

So when i hit a string, it takes about a second to reach normal volume.

Any ideas how to fix this?

Thanks

caspercody · January 22, 2010, 04:22:08 PM

Check your wiring, or bad pot?

I have made this pedal using that schematic, and have had no problems.

iqvalue · January 22, 2010, 04:25:16 PM

i suppose everything is ok before the tone pot, so its probably something in that contour circuit. what jfets did you used?

caspercody · January 22, 2010, 04:29:23 PM

All are J201. The contour pot is a reverse taper. Not sure if it would have this effect you are having. I did remove the boost switch, ad the resistors. I do not have any need for the boost, and when I did turn on the boost had a lot more noise.

I used the pcb layout for the BSIAB from GGG. Added my own for the contour, and re arranged the components for the last stage on a fetzer valve pcb.

iqvalue · January 22, 2010, 04:57:50 PM

I used J201s for 2nd stage, others are 2n5457.

Now I plugged it on another 9V supply and it works ok, but on battery and another adapter it produces that effect :S

Now I think it pulls some supply voltage to ground so it works with stronger power supplys.

Edit: Is it possible that problems are caused because i connected +9V directly, without diode?

caspercody · January 22, 2010, 06:09:46 PM

Probably not. The diode is there to protect from if you connected battery backwards. I have always used my on a 9 volt battery. never tried on any other power source.

earthtonesaudio · January 22, 2010, 09:51:13 PM

Measure drain voltages on the last two JFETs. They should be not too far from 1/2 supply voltage. I bet one or both of them is biased badly.

iqvalue · January 23, 2010, 08:42:01 AM

is used 15k resistors as on schematic

maybe i should use J201 instead 2n5457 for last two transistors, I'll try to replace them with J201s

caspercody · January 23, 2010, 12:27:55 PM

Make a audio probe, and check output from each stage. I do not think the different Jfets are the issue.

earthtonesaudio · January 23, 2010, 01:35:41 PM

Just to clarify, I'm not suggesting the substitution of a different JFET is the problem, but simply the fact that they are JFETs.

wampcat1 · January 24, 2010, 11:18:25 AM

where did you find this schematic?

iqvalue · January 24, 2010, 11:59:17 AM

google

iqvalue · January 25, 2010, 09:25:47 AM

I changed last jfet and biased it and it works fine now

caspercody · January 25, 2010, 09:55:48 AM

Glad to hear you got it working. What do you think of the sound? Close to the Pinnacle?

Wonder if you had a bad Jfet? Or if the pin out was different on the Jfet you had? What Jfets did you end up using?

Paul Marossy · January 25, 2010, 11:32:02 AM

The Pinnacle schematic is not supposed to be floating around on the internet. I wonder if someone reversed it?

iqvalue · January 25, 2010, 12:04:23 PM

1st stage - 2x 2n5457
2nd stage - 2x J201
3rd stage - 2n5457
4th stage - J201

works excelent now!

pinout is the same for both of them, I bought them from banzai

wampcat1 · January 25, 2010, 01:12:09 PM

Quote from: Paul Marossy on January 25, 2010, 11:32:02 AM
The Pinnacle schematic is not supposed to be floating around on the internet. I wonder if someone reversed it?

I'm guessing so... the bad thing is that it (the posted schem) was totally incorrect, so hopefully I won't have a ton of people floating around saying the pedal sounds terrible! (well, at least because of an incorrect assumed design

)
bw

Paul Marossy · January 25, 2010, 01:26:39 PM

Quote from: wampcat1 on January 25, 2010, 01:12:09 PM
Quote from: Paul Marossy on January 25, 2010, 11:32:02 AM
The Pinnacle schematic is not supposed to be floating around on the internet. I wonder if someone reversed it?

I'm guessing so... the bad thing is that it (the posted schem) was totally incorrect, so hopefully I won't have a ton of people floating around saying the pedal sounds terrible! (well, at least because of an incorrect assumed design )
bw

I see. Well, they'll just have to use a schematic like that at their own risk then, won't they?! Besides, once they hear the real thing, they'll know that the Real McCoy isn't jacked up.

iqvalue · January 25, 2010, 06:45:07 PM

problem with mine was in bad transistor, by replacing it, drain voltage increased to 4V from 0,8V. I also changed bias little bit and now its 4,5V

comparing to youtube videos its pretty much like original pinnacle, in a few days i'll be able to compare them face to face.

wampcat1 · January 25, 2010, 07:29:40 PM

Quote from: iqvalue on January 25, 2010, 06:45:07 PM
problem with mine was in bad transistor, by replacing it, drain voltage increased to 4V from 0,8V. I also changed bias little bit and now its 4,5V

comparing to youtube videos its pretty much like original pinnacle, in a few days i'll be able to compare them face to face.

which version? We've changed the circuit quite a bit over the years...

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Pinnacle problem