Weener Wah Help

[pryde]

OK, I am troubleshooting a Weener wah for a friend. This is his first build and the result not so hot.

The build is an old GCB-95, fabbed pcb, Whipple inductor, all stock values on BOM except 47k in R2, and 1.1k in R15 and R16. A 3.3uf and parallel 1uf cap was used for C2. He added external freq and peak pots as well. The sweep pot is the STOCK 100k that came with the pedal (not an ICAR).

The issue: There is some wah but it is weak sounding, i.e. not much range with very little expression. I have a stock crybaby that sounds way better so I know this thing aint right. The freq pot does work. i dont hear any difference on the peak control.

So far I have checked all component values, re-flowed a few suspect joints with no improvement in the tone. Here are some voltage readings I am currently getting:


Q1: E 0, B .67, C 4.12

Q2: E 3.25, B 2.69, C 8.17

Q3: D 8.53, G 1.35, S 0



Any ideas? Thanks in advance for the help

[JakeFuzz]

Try disconnecting the frequency pot and see if that helps.

[pryde]

OK. Disconnected the freq pot and it still does not sound good as in pretty subtle sweep and just not musical at all really.

I did learn that he first put the electrolytics in backward, then reversed them later  . Is it possible the caps got cooked somehow being in backward or something? Do the transistor voltages listed above jive?

Thanks again for the help.

BTW Jakefuzz, your demo of the weener wah is just sick. This one is NOT even close to that tone.

[pryde]

OK. Just an update for those interested. I got rid of the freq pot, removed C6, changed C1 to 15n, changed C5 to 10n. BINGO. Sounding super chickie-wickie now 

I like the idea of a freq pot but it seams like this option has not worked for many here? Anyway, I will likely build up one of these someday for myself, very nice wah for sure.

[JakeFuzz]

Awesome! Glad to hear it is working. What did you have in C5 to begin with? Not 3.3nF I hope. If so that was definitely the culprit, that is the furthest end of the freq sweep to the treble end of things. Mine gets very weak when I get down to that value too. I left 100n as the input cap. Nice and warm!

[pryde]

C5 had the stock value in it, I believe 3n9 was it. Bumping up to 10n seamed to be key here.

I am going to give my friend a few extra cap values to experiment with as I socketed C1 and C5 for him. Right now on my rig 15n and 10n are sounding great.

[jball85]

I havent built the weener wah yet, but on my thoroughly jacked with vox, the transistors had a lot of impact on the sweep intensity, low gain bc109 as suggested by everyone in various forums would not work/sound good for my wah

[timbo_93631]

Alot of times BC109's have a "sizzle" sort of sound from my experience.  2N2924's and 2N2925's are great, the latter being the same as the 5117 numbered transistors in a Thomas organ wah.  I just tried OC 141 in Q1 of my Junk-O-Wah and am digging the NPN Germanium goodness, but it is louder than with 2n2925 there, gotta lower R2 or raise R4 to get things balanced again.