Author Topic: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues  (Read 511 times)

Rodgre

DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« on: September 02, 2020, 09:53:26 AM »
Hi all.

I built up the very rare Foxx Select-a-Fuzz clone last night using the DeadEndFX board and some 2N3569 transistors I bought from a US seller on ebay. The pedal works but sounds terrible. The circuit is pretty straightforward: signal goes in through a rotary switch selecting various input caps for different tones feeding a BJT transistor-based fuzz. The tone that I'm getting in pretty much any input cap setting is muddy, weak and bland. The circuit does not have a "drive" or "sustain" control. There is a very mild and pretty much ineffective "mellow/bright" control.

My basic issues are first off that it's very dark and muddy in all tone settings. There isn't quite enough drive/sustain to the fuzz and the "mellow/bright" control barely affects anything. I'm wondering if there are better cap values that would tailor the tone more to my tastes and I'm wondering if I'm having transistor bias issues.

Has anyone else built this? Any thoughts?

Build Document: https://drive.google.com/open?id=11I8tdRm2zsEqto9nQSaTEGKwolNtMiq1

Demo video: https://www.youtube.com/watch?v=ChpAV4QzGBk

Thank you!

Roger

11-90-an

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #1 on: September 02, 2020, 10:24:28 AM »
hello...

there are given proper voltage readings in the build doc, try referencing from there...
flip flop flip flop flip

Rodgre

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #2 on: September 02, 2020, 10:36:22 AM »
Good eye. Good point. Thanks for noticing that!

Roger

duck_arse

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #3 on: September 02, 2020, 10:41:23 AM »
.... but tell us what readings you get, obvs. also - rotary switch is a warning flag.
Now battery powered. Remove plug when not in use, please.

digi2t

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Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #4 on: September 03, 2020, 06:34:43 AM »
Whatever components I used on the breadboard went straight into the build, so no camera trickery there.

Voltages. Yes. Voltages.

Oh yeah, and I did notice that it's fairly sensitive to the transistors used. I tried the bog standards like 2222, 3904, 5088, et al. and none really blew my skirt up. I think not using transistors with too high a gain (less than 200) is key. YMMV
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Rodgre

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #5 on: September 03, 2020, 10:38:59 AM »
Thanks! I'm wondering if my transistors are kind of part of the problem to begin with. I ordered 2N3569s off eBay, which is always a crap shoot. I tried 5088s too, and they pretty much sounded the same as the 3569s. I will experiment a bit more this afternoon and check voltages.

BTW, I messaged you the other day via the DeadEndFX site. Is there a better way to get a hold of you?

Thanks!!
Roger

digi2t

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Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #6 on: September 04, 2020, 07:02:00 AM »
Thanks! I'm wondering if my transistors are kind of part of the problem to begin with. I ordered 2N3569s off eBay, which is always a crap shoot. I tried 5088s too, and they pretty much sounded the same as the 3569s. I will experiment a bit more this afternoon and check voltages.

BTW, I messaged you the other day via the DeadEndFX site. Is there a better way to get a hold of you?

Thanks!!
Roger

PM sent.

Email was received, just scrambling for time of late.
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willienillie

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #7 on: September 04, 2020, 07:15:27 AM »

Gus

Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #8 on: September 04, 2020, 08:03:51 AM »
Whatever components I used on the breadboard went straight into the build, so no camera trickery there.

Voltages. Yes. Voltages.

Oh yeah, and I did notice that it's fairly sensitive to the transistors used. I tried the bog standards like 2222, 3904, 5088, et al. and none really blew my skirt up. I think not using transistors with too high a gain (less than 200) is key. YMMV
I looked at the build doc in the link.

Have you tried adjusting R1 the 100k first transistor collector value with the 2n2222 etc transistors at the first FF like stage to adjust the collector voltages?

Looking at the last stage, adjusting R10 the 12k might be the easier way to adjust the collector voltage for different transistors.

I normally don't like changing the output collector resistor in a FF like or an output off a collector out gain stage without feedback
however
the first stage of the FF like section is buffered by the 2nd transistor and higher Beta transistor will load it less
The output stage has collector to base feedback R11 this lowers the output resistance
« Last Edit: September 04, 2020, 08:15:56 AM by Gus »

digi2t

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Re: DEFX Dial "F" for Fuzz/Foxx Select-a-Fuzz clone issues
« Reply #9 on: September 04, 2020, 01:52:28 PM »
Demo video: https://www.youtube.com/watch?v=ChpAV4QzGBk

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