ESR Graphic Fuzz  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...

Re: ESR Graphic Fuzz

Postby petey twofinger » 29 Jul 2015, 06:59

so if one woud use active pick ups , would this in fact negate the filter effect knob , or change the effect ?

dont mind me i am slow
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Re: ESR Graphic Fuzz

Postby EBRAddict » 20 Aug 2015, 17:40

petey twofinger wrote:so if one woud use active pick ups , would this in fact negate the filter effect knob , or change the effect ?

dont mind me i am slow


I'm not sure what the output impedance of active pickups looks like but I would say yes. I have a bass roll-off on my guitar and when engaged it rendered the effect useless.
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Re: ESR Graphic Fuzz

Postby allesz » 01 Dec 2015, 16:20

Finally I made this one :horsey:

Tried the first schemo, without input and output caps, but it did not work.
Then tried the later schematic with the regular power rail, and it worked at first try; the soud is very similar to the YT videos.

It's a funny pedal, but I think I won't box it right now, the feedback is nice, but makes the use of the thing quite limited. I like it also because, like, the hot cake (a totally different animal, I reckon), it overdrives the IC without diodes.

I did some experiments with the 0,1 uF and 200R output network: it seem to have a big influence on the feedback, and I thin it can help tuning it.
I really still don't understand how it works: if the 1M pot was a fixed resistor I would say it's just an inverting IC amp with ultre high gain.... but since the pot is just a variable resistor I really can't explain how it works. Strange beast.
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Re: ESR Graphic Fuzz

Postby zosotone » 10 Apr 2016, 17:35

Can I use the TL071? I have built the vero from tabbycat and I have no sound.

Image

Some oscillation but nothing more. The 9v and ground are the common true?
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Re: ESR Graphic Fuzz

Postby roseblood11 » 10 Apr 2016, 19:55

Missing trace cut under R5 - you have connect the level pot to +9V.
Not very healthy for the folowing pedal and for C6...

Never use a layout before you've compared it to the schematic!
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Re: ESR Graphic Fuzz

Postby zosotone » 11 Apr 2016, 18:09

Well, I thought the layout was verified, in theory works well. So, the cut under R5 it's wrong?
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Re: ESR Graphic Fuzz

Postby Nocentelli » 11 Apr 2016, 18:40

The vero IS supposed to be verified, I think roseblood is suggesting that IF you missed that hard-to-spot cut under R5, this would send 9v DC direct to the output.
mmolteratx wrote:absolutely zero commercial use allowed. If I find anyone selling these, I'll fly to your house and kick you in the nads. And you may or may not find yourself in trouble.
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Re: ESR Graphic Fuzz

Postby zosotone » 23 Apr 2016, 22:30

Finally, I've done the vero from Tone Report Weekly Issue 118 http://www.magazine.tonereport.com/tone ... 1457730164

Page 40-48

Image

I've added a volume pot after the level. Sounds amazing, full and organic but the filter pot only works well backward for my taste. How can I set the filter at minimum? maybe with a low value resistor between wires filter 2 and 3?
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Re: ESR Graphic Fuzz

Postby tabbycat » 24 Apr 2016, 13:33

zosotone wrote:Well, I thought the layout was verified, in theory works well. So, the cut under R5 it's wrong?


hi zosotone, the original (larger) layout i did for this is earlier in this thread ( viewtopic.php?f=19&t=22197&start=60#p247467 ). that one i built and works great. 1-1 with the main demo on yt.

i revisited it a while later and realised if i jiggled a couple of components around it could be a few rows smaller for those who like compact layouts. as the r5 cut then moved to under the resistor (though still just visible through the colour) i added an additional written note to the layout just in case anyone missed it.

i haven't built the second layout (though it is fundamentally the first just compacted, which i have built) but members at gfx have and reported good results.

it also might be worth swapping lm741 just in case you have a faulty one. i read somewhere that there are different types of lm741, some which will work and some which don't. have just had a quick google but can't find that forum post quickly,
but i remember that issue coming up somewhere. perhaps it's in the suffix. some are marked lm741tc and some lm741ua or something alone those lines.

sorry to hear you haven't been able to get a good result. as i say, i built the first layout and got excellent results. the subsequent compacting of the layout was pretty minimal, just shuffling things left or right to tidy up but maintining the basic topography.
"be a good animal, true to your instincts" (d.h. lawrence).
"there is no excellent beauty that hath not some strangeness in the proportion" (francis bacon).
"ni dieu ni maître" (anarchist slogan).
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Re: ESR Graphic Fuzz

Postby peepsthecat » 07 Aug 2016, 17:21

3 years later... I wanted to try an op amp on eyelet board, back to the Graphic Fuzz. It sounds better to me than the 1st vero layout I posted- more responsive and tamable with the guitar volume/filter. Must be the mojo parts. Either ua741 or lm741 work fine as long as they are Texas Instruments.
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Re: ESR Graphic Fuzz

Postby traktop » 08 Dec 2017, 09:38

So the tabbycat working layout is the one posted above by zosotone, (dated on 25-42015), right?
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