Carlsbro - Fuzz Box 1966(?)  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
Post Reply
User avatar
nightraven
Breadboard Brother
Information
Posts: 149
Joined: 21 Jul 2009, 18:38
Location: UK
Has thanked: 17 times
Been thanked: 97 times

Post by nightraven »

This forum's kinda slow, huh?
Did you run out of vintage pedals to reverse,clone etc?

I scored this off eBay a few months ago. The previous owner said he bought it in 1966, which I thought was rather early, so I opened it up yesterday to see if the date codes on the pots disputed that. It seems to be an interesting part of the UK fuzz box story. Cosmetically it obviously harks back to the FZ-1. I haven't got one of those pedals to compare but the scale and size is probably spot on the same. Kinda the opposite of how Harry Gurst and co. were presenting a FZ-1 clone as something brand new, this thing actually appears to be a different circuit...

(credit to Effectsdataboob for finding the schematic)
Attachments
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 guts
Carlsbro - Fuzz Box 1966 schematic
Carlsbro - Fuzz Box 1966 schematic
https://fuzzboxes.org | authoritative and clickbait-free resource for 1960s fuzz pedals

User avatar
Dirk_Hendrik
Old Solderhand
Information
Posts: 4189
Joined: 03 Jul 2007, 08:44
Location: Old Amsterdam
Has thanked: 232 times
Been thanked: 886 times
Contact:

Post by Dirk_Hendrik »

nightraven wrote:This forum's kinda slow, huh?
Did you run out of vintage pedals to reverse,clone etc?
... nope. The question is, where have YOU been!? haven't seen a lifesign for years. Good to see ye live and kicking! :thumbsup
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

User avatar
nightraven
Breadboard Brother
Information
Posts: 149
Joined: 21 Jul 2009, 18:38
Location: UK
Has thanked: 17 times
Been thanked: 97 times

Post by nightraven »

Dirk_Hendrik wrote:
nightraven wrote:This forum's kinda slow, huh?
Did you run out of vintage pedals to reverse,clone etc?
... nope. The question is, where have YOU been!? haven't seen a lifesign for years. Good to see ye live and kicking! :thumbsup
Hi D_H! How are things? How's the cat?
I've been here, I've been there, I've been in between...
Been meaning to actually send you an e-mail. Are you still tinkering about with effects yourself? I don't go near swirly pedals anymore, when I'm on the guitar I only really enjoy naughty 60s fuzz, but I do keep going back to this 00's reissue Deluxe Memory Man. It's one of those magic ones that only reaches about 300ms of delay time, rather than the advertised 450ms or whatever. The sound is really nice, but I have some ideas for modifications that would make it much more musical, and if you were able to cram one into one of those TGP sized enclosure then I'll bet you can sort this out.
https://fuzzboxes.org | authoritative and clickbait-free resource for 1960s fuzz pedals

User avatar
BMS1971
Solder Soldier
Information
Posts: 175
Joined: 31 May 2020, 14:18
Has thanked: 56 times
Been thanked: 42 times

Post by BMS1971 »

I made it, great tone, even with Hfe 40/50 cleans great with volume of guitar

User avatar
TWSpedals
Breadboard Brother
Information
Posts: 53
Joined: 30 Dec 2020, 23:48
Has thanked: 18 times
Been thanked: 51 times

Post by TWSpedals »

BMS1971 wrote: 23 Oct 2021, 10:47 I made it, great tone, even with Hfe 40/50 cleans great with volume of guitar
What voltages did you have on the transistors?

I've redrawn the schematic so it's easier for others to read.

Can't imagine the output volume is much with that poor output impedance and the max headroom being not being too much above the ground rail
Attachments
Redrawn Carlsbro Fuzz Schematic
Redrawn Carlsbro Fuzz Schematic
Have a nice day!

User avatar
VIgeoff
Information
Posts: 7
Joined: 26 Nov 2021, 04:05
Has thanked: 12 times
Been thanked: 6 times

Post by VIgeoff »

Hi guys ... first post :)

I admit to being a newly, I've made about five pedals in ten years. Usually on tag-strip, usually pnp fuzz.

I decided to go way over my depth and try a replica of a Carlsbro Fuzz-Tone on phenolic board with eyelets and OC71 transistors in a wedge enclosure. Working from a few photos off the Web and the factory schematic.

All along the build I kept thinking "This will be a nightmare to troubleshoot". And here I am! I just fired it up and getting a totally clean signal about unity gain.

So before I dive in to troubleshooting I wanted to ask what's probably a very obvious question. The factory schematic (as posted above by nightraven) shows 9V negative to earth and positive applied to the circuit. Being PNP I assumed this was just an error. Am I correct in that assumption?

User avatar
VIgeoff
Information
Posts: 7
Joined: 26 Nov 2021, 04:05
Has thanked: 12 times
Been thanked: 6 times

Post by VIgeoff »

20211126_154828.jpg
20211126_154150.jpg
Pulled it out of the enclosure and it works. So answered my own question about negative voltage. I'm guessing it's a bad solder joint somewhere (earth wire dropped off when I was removing it from the enclosure, might be it? ). Also busted my brand new tropical fish output cap in half, delicate little things.
20211126_154150.jpg
It has an absolute ton of output volume and a fair few different sounds lurking in there. Can be a bit like a wild nasally version of a three-knob Tone Bender, or spitty/trumpet Maestro sound with guitar volume back right off. Much more variety to it than I expected.

A very worthwhile build :) ... if I can tidy it up and get it back in the enclosure.
Attachments
20211126_154147.jpg

User avatar
nightraven
Breadboard Brother
Information
Posts: 149
Joined: 21 Jul 2009, 18:38
Location: UK
Has thanked: 17 times
Been thanked: 97 times

Post by nightraven »

I'm glad to see interest in this obscure early fuzzbox!

It's interesting that VIgeoff's has lots of output volume, because my old one doesn't get much further past unity. It's definitely one of the quieter models from the time.

Here are the voltage readings that I took just now from the old original. I hope I've got the terminals of the transistors all the right way around (but trust that it will still make sense if not!)

The transistors are pretty temperature sensitive, so I tried to do these readings pretty quickly to try to keep them as balanced as possible.

Q1
b: 0.45v; c: 1.09v; e: 0.43v

Q2
b: 1.23v; c: 3.87v; e: 1.09v

Q3
b: 0.55v; c: 0.02v; e: 0v

Battery: 9.52v (9.33v in-circuit)
https://fuzzboxes.org | authoritative and clickbait-free resource for 1960s fuzz pedals

User avatar
VIgeoff
Information
Posts: 7
Joined: 26 Nov 2021, 04:05
Has thanked: 12 times
Been thanked: 6 times

Post by VIgeoff »

Nightraven a big thank you for posting those photos. I relied heavily on those to try and copy the layout.

I used a 250k Volume pot rather than the original arrangement of a 25k pot followed by a 220k resistor in series. I think that might account for the extra output, I have the option to dial out that extra 220k completely. It's actually so loud I'm worried it damaging something if I accidentally step on it mid-song with the volume anywhere near cranked. If I decide to use it in a band setting I'll have to reconfigure it to something like a 100k pot followed by a 150k resistor. It also gets pretty hissy with the volume up too far so that extra volume is probably useless anyway.

Here's my voltages. They seem to ballpark match yours other than Q3 base and collector are switched around. I'll post my map of transistor pinouts below.
My OC71 hfe readings were q1-43 q2-49 and q3-48. I ran them through my cheap transistor checker and took photos of the parameters/readings on the screen but I actually have no idea what they mean :) or if they show leakages.

Voltages
Battery 9.18
Q1 collector 1.14
Q1 emitter 0.47
Q1 base 0.53
Q2 collector 3.45
Q2 emitter 1.14
Q2 base 1.28
Q3 collector 0.51 to 0.72 (varies with Attack pot rotation)
Q3 base 0.02
Q3 emitter 0.0 (direct to earth)
Screenshot_20211121-123049_UPB Editor.jpg
The finished pedal. Not perfect but I do like it. Controls were going to be front mounted but I stuffed up my measurements when drilling the holes so they got moved to the top and I have an engraved Fuzz-Tone sign coming in the post to cover up my goober :slap:
20211127_105308.jpg
20211127_105333.jpg
20211127_105347.jpg

User avatar
nightraven
Breadboard Brother
Information
Posts: 149
Joined: 21 Jul 2009, 18:38
Location: UK
Has thanked: 17 times
Been thanked: 97 times

Post by nightraven »

Your build is ace! That blue hammertone sure looks close to the original too. My only suggestion would be to replace that horrible white washer 8)
https://fuzzboxes.org | authoritative and clickbait-free resource for 1960s fuzz pedals

User avatar
BMS1971
Solder Soldier
Information
Posts: 175
Joined: 31 May 2020, 14:18
Has thanked: 56 times
Been thanked: 42 times

Post by BMS1971 »

I made a PCB for it. Will arrive next week

Ben

User avatar
VIgeoff
Information
Posts: 7
Joined: 26 Nov 2021, 04:05
Has thanked: 12 times
Been thanked: 6 times

Post by VIgeoff »

PCB seems a bit more sensible :thumbsup What transistors are you using?

I'm taking back my comment about the 250k Volume pot. The hiss turned out to be a grounding issue. This is my first experience with insulated jacks and the noise went away if I touched the stompswitch or the battery switch so I ran a little jumper wire from behind the battery switch to earth on the jack to ground the enclosure and it's gone. Need to sort it out properly though. And there's a nice square wave sound a bit like an organ if I back the guitar volume down waaaaay low and make up the volume at the output. So 250k stays for now.

User avatar
Manfred
Tube Twister
Information
Posts: 1936
Joined: 04 Apr 2009, 23:42
Has thanked: 1668 times
Been thanked: 1344 times

Post by Manfred »

For enthusiasts of PTP wiring.
Board size 3 by 2.2 inches.
carlsbro_fuzz-2knob_board_view1.jpg
carlsbro_fuzz-2knob_board_view2.jpg
carlsbro_fuzz-2knob_drilling_template.pdf
(60.95 KiB) Downloaded 151 times
LochMaster4.0 - file:
Carlsbro_2-knob_FuzzBoard.zip
(75.99 KiB) Downloaded 137 times

User avatar
BMS1971
Solder Soldier
Information
Posts: 175
Joined: 31 May 2020, 14:18
Has thanked: 56 times
Been thanked: 42 times

Post by BMS1971 »

VIgeoff wrote: 28 Nov 2021, 05:32 PCB seems a bit more sensible :thumbsup What transistors are you using?
MP41A all the way
Ben

User avatar
BMS1971
Solder Soldier
Information
Posts: 175
Joined: 31 May 2020, 14:18
Has thanked: 56 times
Been thanked: 42 times

Post by BMS1971 »

Strange stuff, only the schematic of this page works:
http://tagboardeffects.blogspot.com/201 ... zzbox.html
IF you change the 47UF by 47nf...
And 1/2 of the schematics have negative ground 1/2 positive ground.... So is there an actual right schematic out there?
Cheer
Ben

User avatar
VIgeoff
Information
Posts: 7
Joined: 26 Nov 2021, 04:05
Has thanked: 12 times
Been thanked: 6 times

Post by VIgeoff »

I used the factory schematic that Nightraven posted at the top of this thread and also compared it to the photos of original pedals (by colour code) while I was figuring out the original layout. I'm certain it's 100% accurate except for the way the battery polarity is drawn, that's backwards and should be 9V+ to earth. Your MP41A transistors are PNP like the original OC71 so definitely need their juice from the negative side of the battery.

The schematic TWSpedals posted above looks 100% as does the layout by Manfred.

User avatar
BMS1971
Solder Soldier
Information
Posts: 175
Joined: 31 May 2020, 14:18
Has thanked: 56 times
Been thanked: 42 times

Post by BMS1971 »

yes after correcting the polarity problem it works fine. Next I will try the bias adjustment and MP21A transistors

Post Reply