problem with big muff

[innovine]

I'm trying to build a big muff variant (the toneworks black arts pharaoh) from this schematic:
http://www.bigmuffpage.com/images/schematics/Pharaoh%20Big%20Muff%20Clone%20Schematic.jpg

I've run into a problem though. I can hear the input signal at each side of R19, but the collector of Q3 just sounds like a warbly buzz noise. No trace of the input signal at all, just a constant 'brzrzrzrzrz'. I disconnected C13/R12 in case it was some problem later in the circuit but that didnt change anything. Getting desperate, I took out R17, C12 and C6 but that didn't make a difference either. I can even disconnect the input and it's still the same buzzy noise.

Any suggestions what is causing this, or what I could try to do next?
I'm using a 2n5088 instead of a 2n5089, and my C1 is currently electrolytic, not tantalum as the schematic suggests. Other than that I've the exact components mentioned.

[nocentelli]

Check the pin out, check r20, r21, r17 and r18 are what they are supposed to be, check you have 9v and 0v where they are supposed to be. Removing r17 will definitely stop it working, check it's value is correct then put it back. It will pass signal with c6 disconnected, it will just be less clipped. It should still function after removing c12, but it will be brighter.

[GibsonGM]

If that doesn't help, fill out the data here and repost:  http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

I bet it's something minor.....something in the feedback loop of Q3, or the pinout's wrong, or something is shorting.    Reading the voltages on Q3 will help.

[duck_arse]

what, pray tell, are you using for power, external or battery?

[innovine]

I was using a wall wart (which i use with other pedals with no problem).

I switched to battery, and started soldering the components in stages onto the perfboard. This seems to have fixed whatever it was (bad breadboard? Power supply? I dunno).

Seems to be working better now!

[duck_arse]

which indicates you might be needing to build a powerline filter into anything you want to connect to that supply, or, check the nameplate ratings on the wart.

[innovine]

I switched wall warts and the second one works better but there's a high pitohed squeal in the bhckground. Not enough to hear when playing but as soon as I stop playing its pretty nasty.

What can I do? I've added a 220uF electrolytic between + and gnd but it didn't help. None ofemy other pedals have trouple with either pow'r supply, so does that mean my circuit is overly sensitive to noise?

[duck_arse]

it sounds as if your second supply might be a switch-mode. go here, read, modify. update.

http://www.muzique.com/lab/hum.htm

[nocentelli]

A small resistor (100 ohms) in series with the +9v, THEN the large electrolytic cap to ground is more effective at filtering.

[innovine]

Thanks. The 100ohm resistor did the trick!

I've been playing around with it a bit, and have a few questions for anyone who has a pharaoh or might be able to answer this from the schematic..

1. The overall output seems kinda low, especially when I use the germanium diodes and the low gain switch. I was expecting some voume drop, but this is so low it's less than the bypassed signal even with the Vol cranked. Is it possible to change a component to boost the output a little?

2. I didn't have a 250k pot for the Tone, so I used a 500k. Can someone please let me know what this has done to the frequency response, especially in connection with the Highs knob? Has the whole tone stack become much brighter? The silicon setting is pretty bright even with the tone and highs knobs fully down.. the germanium sounds fine tho. There is certainly a lot of interaction between the two knobs, is this normal or a result of my 500k pot?