DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: Gus on December 15, 2012, 01:57:33 PM

Title: another three transistor fuzz
Post by: Gus on December 15, 2012, 01:57:33 PM
(http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=48418&g2_serialNumber=1)

As always tune to taste.   I do think the cap values are good starting points.

Simple guitar cable sim at the left side. 
Three controls 1K gain, 100K audio output and 5K bias(set up as a rheostat 0 to 5k, gated to compress)

The 1meg at the thin thick it to help reduce the pop when switched and YES you could make it a blend pot with no switch.
Title: Re: another three transistor fuzz
Post by: pinkjimiphoton on December 15, 2012, 08:07:02 PM
looks nice, gus!! i see that filter you were talking about too.
one day...when i get a chance... one more for the build collection!! ;)
thanks bro!
:icon_mrgreen:
Title: Re: another three transistor fuzz
Post by: Derringer on December 16, 2012, 11:03:17 AM
how do you like having the thin/thick circuit after the first gain stage as opposed to before it like in the hot silicon?
Title: Re: another three transistor fuzz
Post by: Toney on December 16, 2012, 08:32:49 PM

Thanks yet again Gus!
Bit busy at the moment, but I would like to spend some time with the breadboard in the near future and audition it.
Title: Re: another three transistor fuzz
Post by: Gus on December 23, 2012, 10:50:58 AM
Quote from: Derringer on December 16, 2012, 11:03:17 AM
how do you like having the thin/thick circuit after the first gain stage as opposed to before it like in the hot silicon?


It is another place you can adjust the circuit.  It depends if you want to cut more lows before the first gain stage or do you want to adjust it after the first stage.  You can use two switched caps sections one before the first stage and the 2nd as drawn in the sim(this is a good experiment to do). 

The sims and circuits I post are set to a IMO good setting starting point.  As always you can adjust RCs and bias to taste.

Toney and pinkjimiphoton thanks for posting.  I set the output a little hotter 1.8K and 8.2K (note they add to 10K).

If I was to add a Tone control I would use a 10K and omit C3 and connect the tone volume to Q3's collector.

Here is something to try IF you still want the low pass before the output with C3 omitted place a cap in parallel with R6  (look up inverting opamp circuits, a FF is kind of like a limited open loop gain inverting opamp circuit) search for the the JH F1 this has a cap across the feedback bias resistor
Title: Re: another three transistor fuzz
Post by: AnalogPackrat on December 23, 2012, 04:15:39 PM
Nice one, Gus.  I hope I have some time after the new year to breadboard this and some of your other fuzzes.  Thanks for all the cool stuff you post here.
Title: Re: another three transistor fuzz
Post by: pinkjimiphoton on December 23, 2012, 06:00:31 PM
+1 on that, gus!!

working on a vintage bass brassmaster for a friend, and his polyphase pedal too. got both working; both need parts tho!! ;)

so that's gonna keep me tied up for a little bit.
Title: Re: another three transistor fuzz
Post by: Scruffie on December 24, 2012, 12:23:08 PM
Quote from: pinkjimiphoton on December 23, 2012, 06:00:31 PM
+1 on that, gus!!

working on a vintage bass brassmaster for a friend, and his polyphase pedal too. got both working; both need parts tho!! ;)

so that's gonna keep me tied up for a little bit.
Wait, is that a vintage Polyphase? Got gut shots?
Title: Re: another three transistor fuzz
Post by: pinkjimiphoton on December 24, 2012, 02:03:24 PM
yes indeed, a 1976 polyphase.
looks like someone tried to sub a dual opamp for the 1458...probably why it's not working.
i can get you gut shots, but not GOOD ones, unfortunately. no macro function on my phone.
i wonder if i could scan it on my scanner?

but yah, while i got it, i'll take pics as best i can, any questions? measurements?
Title: Re: another three transistor fuzz
Post by: Scruffie on December 24, 2012, 02:12:54 PM
Quote from: pinkjimiphoton on December 24, 2012, 02:03:24 PM
yes indeed, a 1976 polyphase.
looks like someone tried to sub a dual opamp for the 1458...probably why it's not working.
i can get you gut shots, but not GOOD ones, unfortunately. no macro function on my phone.
i wonder if i could scan it on my scanner?

but yah, while i got it, i'll take pics as best i can, any questions? measurements?
Well 1458 is dual but yeah, maybe they used a chip no good for the LFO/Envelope.

I need shots under the pots basically, trying to get a true schematic done as the ones out there don't match up or have flaws and the only shot I could find obscured sections (cause of the pots so half the board was pretty much covered) so I couldn't finish tracing it and verifying the values.

If you could that'd be grand  :)
Title: Re: another three transistor fuzz
Post by: pinkjimiphoton on December 24, 2012, 02:26:04 PM
i'll do the best i can bro, and see what i can do. the problem really is gonna be getting high enough resolution to be worth it. but..bear with me, i'll get on it!