hissy Jen wah

[Guitarist]

I've got a '67 Italian wah and suspect that some of the old carbon-somp resistors are causing some mid-sweep noise. Which ones should I target? Those feeding voltage to the Q's?

[Jazz P Bass]

Schematics

Any chance that you could post the schematic?

[Guitarist]

Sure, here are a couple.

Info att. #1 from RG and Travis Brown. #2 from LA Holt.

Also some more background info I had typed up for someone else:
'took out the new pot again, because I took apart the old 100K one and saw that the wiper was floating up in the air; also the carbon disk was a little warped in the center. So I used a bit of crazy glue behind it. Cleaned everything up carefully with an iso-bath and some contact spray, kindly retensioned the gold coloured "kinks" and reassembled the pot. I added a bit of Burt's Bees to grease (thinking this may be where the hiss is originating, a toodry path) the wiper a bit (and added a black ground wire - one was missing altogether) from input to the main grounds).

Its board's components are not fully original- most may be. However, the new parts sound amazing and appear to be the standard mod values, though I'm no expert on this. Red Fasel inductor seems a bit beat up, possibly fine-tuned coil resistance.
Arco Caps, carbon comp resistors, 2n5232a and SIP5172 transistors,

[Bloodbath]

Honestly, I would replace the electrolytic caps before any resistors on an older pedal. They tend to leak over time and go bad.

[Guitarist]

Thanks BB,

I actually did replace the 4.7UF cap because it was long gone. Being aged it made the pedal act more like a volume pedal.
I'll try to change out Rc1 and Rc2 (22K, 1K). Maybe lower them a bit to lower the gain?
This beast does up the signal level a fair heave, so that could be toned down somehow. It actually clips stuff further downstream, mainly a Digitech 1101.
see att. wave form. Off/On

[Guitarist]

Colorsound - jumpered emitters?

I'm loving the sound of a Colorsound wah. Apparently they ground/jumper the emitters of the transistors. Is this what makes them sound so good?

[raymond]

Hissing wah

I noted also quite substantial hissing in my old Vox wah. The actual reason was that the first transistor was hissing and replacing it with a low gain equivalent cured the problem. I also noted that dying battery increased the hissing.

[Guitarist]

Hey Ray,

What kind of transistor would you recommend, perhaps a J201?

thx, G

[Bloodbath]

Hey Ray,

What kind of transistor would you recommend, perhaps a J201?

thx, G

No, A J201 is a FET. You want something like a BC107 a Bipolar transistor. Transistors have different pin configurations so find the datasheet for your replacement transistor and match the pins to the datasheet of the stock one.

[raymond]

Transistor used in wah

Sorry for my delayed reply and thank you Bloodbath for your input not to use a fet. And also check the pinout of your current transistor and align the new one according to the old one.

In a standard wah npn transistors are used and in vintage (Italian) wahs these used to be ex. BC109B, although the hissy transistor in my wah was BC318B. I have used ex. MPSA06 which has a medium or low gain (hfe) with good results, but 2N5210 or 2N5089 could be good canditates.

[Bloodbath]

It's a good idea to use transistor sockets or SIL Sockets so you can try different ones and it also eliminates the chance of you destroying one from overheating it when you solder it in.

I've used some BC109C's with good results. I usually throw a low hfe one in Q1 and a high hfe (~200-300)one in Q2.