ESR Graphic Fuzz  [schematic]

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

ESR Graphic Fuzz

Postby peepsthecat » 17 Apr 2013, 03:48

Greetings. I did some R&D, traced this beast, and slapped together a vero layout. It works like the clips.
Lm741 and TL061 work the best in terms of taming the whine. UA741 works okay, though the squeal is always present. I suppose one could add a series resistor to the frequency pot. This is my 1st layout using the DIY software- I typically work from a hand-scribbled notebook...
Cheers,
Peeps
You do not have the required permissions to view the files attached to this post.

For this message the author peepsthecat has received thanks: 10
agoldoor (17 Apr 2013, 06:54), allesz (02 Dec 2014, 18:06), flatcrabs (17 Apr 2013, 21:40), induction (19 Apr 2013, 21:52), IvIark (17 Apr 2013, 20:16), Nocentelli (17 Apr 2013, 18:53), Paul B (07 Dec 2015, 10:47), tabbycat (03 Dec 2014, 20:50), the3secondrule (21 Apr 2013, 07:29), tp801 (19 Apr 2013, 21:14)
peepsthecat
 
Posts: 8
Joined: 24 Dec 2012, 17:39
Has thanked: 3 times
Have thanks: 12 times

Re: ESR graphic fuzz traced & layout

Postby agoldoor » 17 Apr 2013, 06:55

Wow, that's so interesting... weird timing. I know mirosol and IvIark were pulling their hair out over this one... In the meantime I had been looking at it separately. Thanks for finally getting something working!
agoldoor
Breadboard Brother
 
Posts: 112
Joined: 26 May 2011, 05:37
Has thanked: 41 times
Have thanks: 21 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 17 Apr 2013, 19:07

Thanks for this. I have a couple of questions - Did you research and tracing involve an original unit, or is the information from the DIYSB thread? Secondly, I tried breadboarding it from the schem at DIYSB but had no luck getting any sound at all. On the layout, where it says "ground", should this be connected to the normal ground connections (i.e. Input+output sleeve, power supply negative and battery negative), OR the battery negative ONLY. I understood from the DIYSB thread that the "ground" for this circuit needs to be isolated from all other ground connections, since it is actually at a different reference voltage, meaning it cannot be daisychained with other pedals to a common power supply. However, I may be be totally confused - Hopefully you can help.
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout  [schematic]

Postby Intripped » 17 Apr 2013, 21:15

this should be the schematic - I've done the R.E. again, starting from the pics you can find on the net
the schem is coherent with the veroboard layout posted by peepsthecat
You do not have the required permissions to view the files attached to this post.

For this message the author Intripped has received thanks: 6
allesz (18 Apr 2013, 11:09), flatcrabs (17 Apr 2013, 21:40), induction (19 Apr 2013, 21:52), Nocentelli (17 Apr 2013, 21:50), peepsthecat (27 Jul 2016, 15:39), tp801 (19 Apr 2013, 21:14)
Intripped
Cap Cooler
 
Posts: 458
Joined: 25 Aug 2009, 02:03
Has thanked: 557 times
Have thanks: 210 times

Re: ESR graphic fuzz traced & layout

Postby peepsthecat » 17 Apr 2013, 23:21

Nocentelli wrote:Thanks for this. I have a couple of questions - Did you research and tracing involve an original unit, or is the information from the DIYSB thread?


I traced the original circuit by comparing every picture of the board I could find- component and solder sides. I used no schematic, though I read somewhere the 9V- went directly to the board. It was the last wire to figure out, then it worked like the sound in available clips. The degree of squeal can be controlled by choice of op amp or a little series resistance with the Filter pot (which I labeled "freq" in the layout). Other omissions: Vol is 10k log, Filter is 1M lin, and output is from Vol 2.
Now, can we improve this circuit?

This layout was verified at tagboard effects by JaviCAP.

Cheers,
Peeps

For this message the author peepsthecat has received thanks:
Nocentelli (17 Apr 2013, 23:28)
peepsthecat
 
Posts: 8
Joined: 24 Dec 2012, 17:39
Has thanked: 3 times
Have thanks: 12 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 17 Apr 2013, 23:50

Many thanks to peeps and intripped for the advice, i've got it on the breadboard and i'm getting some fuzzy sounds but only at a very narrow window on the frequency/filter pot: Either side of that, it cuts out totally. It's late, i'm using headphones so it's hard to tell, but i'm pretty sure there's no sign of the extreme filtering effect, huge slabs of heavy fuzz, or oscillation as evidenced on this awesome video http://www.youtube.com/watch?v=h3VEA6ivC1M

I'll check all my connections, maybe swap the chip, and try again over the next few days. I'm pretty sure I understand the circuit, but I just want to check I have this right: On intripped's schem, all the ground symbol points should be connected together and can presumably also be connected to the guitar cable shield, the pedal chassis, and therefore the negative of the AC power supply of any other pedals in the chain; As long as this one circuit uses a battery connected at +9v and -9v on the schem (and is therefore separated from power supply of the other pedals), it should all work, right?
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 18 Apr 2013, 00:14

Simple/stupid mistake (pinout error), works now! Oscillation aplenty, tweaking begins tomorrow.
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby allesz » 18 Apr 2013, 11:08

:applause:

So is the schematic verified?
I don't like (or can :oops: ) work with ic, but this one it's very inspiring. Sadly I did not understand the schemo posted on diysb.... great work intripped., it goes on my to do list (very short recently).

btw... It seems that the filter is nothing but a feedback control, and so I understand the effect of it; but I don't understand the fuzz effect: is it just the chip being overdrived? On the video posted above I see no relationship between the clipped sound and the position of the feedback knob (guitar volume maybe?); If so it would be possible to build a very simple overdrive-disto-fuzz with very few components :hmmm: Not that I want to dismiss the fun factor of the filter control, only tring to understand the thing better.

btw n. 2... does jhon l. basicaudio posts here?
allesz
Cap Cooler
 
Posts: 525
Joined: 15 Jun 2009, 17:29
Location: Italy
Has thanked: 46 times
Have thanks: 120 times

Re: ESR graphic fuzz traced & layout

Postby John Lyons » 18 Apr 2013, 13:37

The Schematic has been verified for a year or more.
Granted the Schematic I posted was missing a ground and a 10k resistor. :oops: :lol:
User avatar
John Lyons
Solder Soldier
 
Posts: 188
Joined: 18 Aug 2007, 04:09
Location: West Virginia
Has thanked: 5 times
Have thanks: 26 times

Re: ESR graphic fuzz traced & layout

Postby allesz » 18 Apr 2013, 14:27

John Lyons wrote:The Schematic has been verified for a year or more.


Late to the party?

I just got to get me some single ic (only 4558 and tl072 on hand) and start breadboarding me too :horsey:
allesz
Cap Cooler
 
Posts: 525
Joined: 15 Jun 2009, 17:29
Location: Italy
Has thanked: 46 times
Have thanks: 120 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 18 Apr 2013, 16:38

allesz wrote:On the video posted above I see no relationship between the clipped sound and the position of the feedback knob (guitar volume maybe?); If so it would be possible to build a very simple overdrive-disto-fuzz with very few


The filter knob really is just that - It visciously filters the fuzz sound (HPF?), and at the extreme maximum setting, it cuts the signal all together. The difference in fuzzy-ness levels in the video must be from adjusting the guitar's volume control.
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby allesz » 18 Apr 2013, 17:27

Thank you for the info... the feedback is funny, but it would be useful to control the distortion too: maybe an input pot?
I called John Lyons because it seems he has done a little bit of work and experimenting on the circui,t so maybe he could give some hints about it. It's a basic circuit so maybe I will find out by myself... since I have only double ic chips I could try to use only one, and maybe use the second one for something else (clipping, buffer, boost,mondo gain?).
allesz
Cap Cooler
 
Posts: 525
Joined: 15 Jun 2009, 17:29
Location: Italy
Has thanked: 46 times
Have thanks: 120 times

Re: ESR graphic fuzz traced & layout

Postby John Lyons » 19 Apr 2013, 00:05

When you use a buffer before the circuit it will help with bringing back some high end
and stabilizing the circuit a bit. The oscillation is the fun part of the circuit.
There are a lot of big fuzz sounding circuits but this one has some weirdness
which is neat.
User avatar
John Lyons
Solder Soldier
 
Posts: 188
Joined: 18 Aug 2007, 04:09
Location: West Virginia
Has thanked: 5 times
Have thanks: 26 times

Re: ESR graphic fuzz traced & layout

Postby peepsthecat » 19 Apr 2013, 20:55

Weirdness. Yes, that's the fun. For me the graphic fuzz takes a back seat to Escobedo's Bronx Cheer, which can get properly weird with a twist of a guitar knob or even a slight circuit tweak. I'm curious to see if anyone tweaks the graphic fuzz...
peepsthecat
 
Posts: 8
Joined: 24 Dec 2012, 17:39
Has thanked: 3 times
Have thanks: 12 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 20 Apr 2013, 10:54

Any idea how Jimmy Behan (http://www.jimmybehanfx.net/custom/eart ... aphic-fuzz) has got this to work on a standard shared DC adaptor power supply? I looks to me (a total amateur with virtually no knowledge of electronic theory, and very little experience of using opamps) like the original graphic fuzz circuit has a voltage divider (10k/10k) that produces a dual supply of positive and negative 4.5volts from the battery relative to "vref" which is tied to the sleeve ground.

Could one change it to a standard divider with battery/power supply negative tied to ground, 10k/10k to battery/PS positive, and feed the 4.5v centre vref to the original ground points? I have an idea that the opamp's inverting input and output would not need a cap in series with the vref, but the non-inverting input would now need a cap. I also suspect that one would need to add input and output caps and maybe keep the volume pot connection to ground, but I hasten to repeat I have very little understanding of how this circuit works so please correct my misconceptions if you can.
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 20 Apr 2013, 11:13

Correction - I think you would need a cap from the output 10k to the new verf, as this part looks to be how the filter pot works as a high pass filter that goes all the way up to total cut-off :scratch:
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby John Lyons » 20 Apr 2013, 17:07

^ That seems like a way to do it. I think all the info about Jimmy's is there at DIystomp.
(Well at least very close to what he did at least)
User avatar
John Lyons
Solder Soldier
 
Posts: 188
Joined: 18 Aug 2007, 04:09
Location: West Virginia
Has thanked: 5 times
Have thanks: 26 times

Re: ESR graphic fuzz traced & layout

Postby Nocentelli » 20 Apr 2013, 17:42

Thanks John, but I've read that thread a number of times, and didn't pick up any info about how to wire it for standard power, just the references to the resistor + cap (680k + 47p) in parallel with the filter pot to delay the onset of the oscillation. I'll go back and read through it again.
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.
User avatar
Nocentelli
Tube Twister
 
Posts: 2061
Joined: 09 Apr 2009, 08:06
Location: Leeds, UK
Has thanked: 824 times
Have thanks: 825 times

Re: ESR graphic fuzz traced & layout

Postby John Lyons » 20 Apr 2013, 21:03

Most of the talk is about the filter knob but check Paul's (PRR)
first post which is very close to your scheme, and my question as the initial post.
User avatar
John Lyons
Solder Soldier
 
Posts: 188
Joined: 18 Aug 2007, 04:09
Location: West Virginia
Has thanked: 5 times
Have thanks: 26 times

Re: ESR graphic fuzz traced & layout

Postby Intripped » 20 Apr 2013, 21:21

i've studied a bit the pic of Jimmy's graphic fuzz
the only thing i cannot understand is the jumper indicated by the arrow: it connects pin2 of the IC to....??? the only components in the row (yes, seems to me a veroboard) are the vertical 220 Ohm(?) resistor, and the 100n(?) cap connected to pin6.

if so, the schematic could be like the one attached
You do not have the required permissions to view the files attached to this post.
Intripped
Cap Cooler
 
Posts: 458
Joined: 25 Aug 2009, 02:03
Has thanked: 557 times
Have thanks: 210 times

Next

Return to Vintage Stompbox Corner ( ... - 1975)

Who is online

Users browsing this forum: No registered users and 3 guests