Crowther Audio - Hot Cake Overdrive

JHS · Post by **JHS** » 30 Jul 2007, 10:08

Acc. to some Japanese DIY-guys switching on the 1977 HC looks like this...

https://s206.photobucket.com/albums/bb4 ... C-1977.gif

@modman
The image shall I used stores pic only for 3 month, that's the reason why the link is dead. I rework the item and then I'll post a pic to photobucket.com. As far as I remember it was the class-A biasing subject for the IC...

JHS

JHS · Post by **JHS** » 30 Jul 2007, 12:03

If you use the 1977 schem from analogguru's site and build the HC with a TL071 drop the 220k from pin 2 to VREF. This R produce a slight basscut to remove the woof from the 741 and is not needed for the 071 due to the tighter bass response. On the units equipped with the 071 I-cap is 10n and O-cap is 56n.

For the class-A mode look here ...

https://s206.photobucket.com/albums/bb4 ... A-mode.gif

JHS

Post by **modman** » 03 Aug 2007, 11:05

It don't seem to be able getting signal beyound the opamp using Torchy layout. I was thinking - according to the schematic the signal chain is input cap -> R5 -> pin 3 of the opamp.
The layout is I supposed, looking at the copperside through the board. So pin 1 should be in the RIGHT corner??? must be missing something

Using a TL071CP and a 8.6V zener.

bajaman · Post by **bajaman** » 03 Aug 2007, 12:42

Pin 1 is the top left corner looking from the parts placement side - Torchy's layout looks okay to me - briggs built it okay from torchy's layout - make sure you have cut the tracks where the X marks are and check you have not got any copper shorts across the tracks, and check your op amp is in the correct way around
cheers
bajaman

JHS · Post by **JHS** » 03 Aug 2007, 15:06

Today I built a protoptype of the '77HC with 741 opamp.

There is, due to the 741, a bit more noise compared to the std. 071-version but to me it sounds more musical. The sound is nearly identical with the 2006 cake but the '77 is more up front and has a bit more punsh, similar to the 071-trannie version.

JHS

bajaman · Post by **bajaman** » 03 Aug 2007, 20:49

Hi JHS
I agree - the 741, although noisier, lacks that glassy top end that the bifet devices seem to have.
To my ears the 741 sounds more Marshall - smooth, and the 071 sounds more Fender - edgy

A friend of mine recently brought me his reissue DOD Distortion + pedal. He complained that it did not sound very good, and he had the original schematic that showed a 741 device instead of the dual op amp (only 1 half used) that was in his reissue.
I changed the op amp for him (plus a couple of minor resistor changes) and he could not believe his ears

He has since modified at least 10 of these pedals back to original specs, and has sold them to his friends etc.
It may be noisy but the old 741 (with it's very poor slew rate and low unity gain bandwidth) sure sounds good overdriven

cheers
bajaman

Post by **modman** » 05 Aug 2007, 14:27

bajaman wrote:Pin 1 is the top left corner looking from the parts placement side - Torchy's layout looks okay to me

Exactly, but in the stripboard layout we are looking at the opamp through the board, legs pointing towards us. If I would number the IC on Torchy's layout I would go

8 1
7 2
6 3
5 4

1 is top left if you look from the component side of the board. For me the layout puts the signal to 6. Or am I really missing some essential veroboard convention here.

Torchy · Post by **Torchy** » 05 Aug 2007, 18:42

All the veroboard layouts Ive done (and all those Ive seen) are looking down on the component side of the board. I dont see the logic of drawing it looking up through the tracks.

Post by **modman** » 05 Aug 2007, 21:51

Thanks Torchy, for putting me out of my misery.
Done quite a lot of pcb layout transfer where this is the case. The logic would be that while mounting components your working mostly on the copper side soldering.
Anyway in designs without IC it really doesn't matter

thanks for clarifying.

bajaman · Post by **bajaman** » 21 Aug 2007, 11:46

I have always been curious to know where Paul found this idea for a distortion pedal - according to Brad Coate's MELMUSIC in Melbourne Australia , it is described as the illegitimate offspring of the famed Gronk Box or Herbert Box as it is known in some circles - perhaps one of our English forum members may be able to shed some light on this - so far I have been unable to find any other reference to this Gronk or Herbert Box.
When Split Enz first visited Great Britain, Paul Crowther was their drummer, and it was there that he came up with the idea supposedly.
Tim Finn and company were friendly with Roxy music and in particular Phil Manzanera at this time - he was credited on a Manzanera album, singing backup vocals etc.
Holden sound industries, here in New Zealand used a similar bypass switching arrangement for the distortion channel on one of their amplifiers
around the same time the Hot Cake first appeared in the late 70's.
apparently the design came from a Carlsboro Amplifier that their designer brought back from a holiday visiting relations in England - only heresay though.
Also Analogguru mentioned a German pedal? that had a similar frequency dependant feedback system tone control like the Hot Cake uses.
Any information to clarify this mystery would be appreciated.
cheers
bajaman

greenskull · Post by **greenskull** » 23 Aug 2007, 06:17

I'll be breadboarding this up hopefully tomorrow to play around with. My goal is to use Torchy's vero layout in the end, but muck about with different opamps and maybe in/out caps. I won't forget about the 220k when experimenting with the 741!!
I'll be dropping back in with the results and probably will have a few questions along the way.

analogguru · Post by **analogguru** » 23 Aug 2007, 06:22

Also Analogguru mentioned a German pedal? that had a similar frequency dependant feedback system tone control like the Hot Cake uses.

Have a look at the Hawk Booster and - very similar - the Univox UEQ-375 Impersonator...

Never heard something about the Gronk Box or Herbert Box....must be something from the other side of the world.

analogguru

Torchy · Post by **Torchy** » 23 Aug 2007, 09:41

Rory Gallagher used the Hawk Booster ... Ive heard of the Gronk Box but thought it was an urban myth. Never seen one, and noone I know (in my age bracket ahem) has either.

Post by **modman** » 23 Aug 2007, 10:03

Had the TL071 in and that screamed like a pig at full gain. Changed to lower drive pot 20K lin with that opamp. Was going to, and did try the 741 and won't be going back. killed that pig immediately. I remembered Bajaman's comments.

Had to bend the opamp's legs the other way around - made a mistake interpreting Torchy's layout, because it did have the copper traces and components on the same side... but that's just my vero incompetence. Taking out the TL071 the poor fellow already got dismembered.

The overdrive is solid, but like it more at lower gain setting for more ruttle and attack dynamics in the sound.

kagaxdx · Post by **kagaxdx** » 23 Aug 2007, 12:36

Yes I think it's so good on LOW drive settings... one of the most I've liked for these purpose. low-gain

It's very musical and dinamic IMO

bajaman · Post by **bajaman** » 23 Aug 2007, 21:39

Yes I think it's so good on LOW drive settings... one of the most I've liked for these purpose. low-gain It's very musical and dinamic IMO

That is how most local guitarists use it - at high gain settings the top end response (sizzle) completely disappears and it becomes a very muddy sounding device

bajaman

greenskull · Post by **greenskull** » 23 Aug 2007, 21:46

Modman, sorry to hear the 741 didn't work in Torchy's vero layout. Might have to do an exact '77 parts build for that?

I'm a big Rory Gallagher fan, but didn't know about the Hawk Booster. ... thought he used a Rangemaster. I don't have a Vox amp to play through, but I wonder how it would sound through a Silver face Fender Vibrolux? Maybe something I'll look into after tackling the Hotcake.

bajaman · Post by **bajaman** » 23 Aug 2007, 21:55

Have a look at the Hawk Booster and - very similar - the Univox UEQ-375 Impersonator

I would if I could find them - any chance of a link or post perhaps

Cheers
bajaman

analogguru · Post by **analogguru** » 24 Aug 2007, 08:33

Have a look at the Hawk Booster and - very similar - the Univox UEQ-375 Impersonator
I would if I could find them - any chance of a link or post perhaps

I will have a look what I can do....

In the meantime, here:
https://www.diystompboxes.com/smfforum/ ... ic=60553.0
I read:

aron wrote on Aug 24, at 01:17:16 AM:

The last time I used a Hotcake it was at a jam session through a Fender amp. I was using a Les Paul and it sounded much, much better than a famous Fuzz Face for me. Again, my touch and the sound I like was more suited to the Hotcake than the Fuzz Face.

Now I am totally confused... Why this sh*tty two-transistor-square-wave-fuzz-toy should sound better than a Hotcake.... and this with a Les Paul and a Fender?
Which sound people expect from a Fuzz...., Overdrive....., Distortion ?
Should a Hotcake sound like a Fuzz-Face ?.... and a Klon like a Wholly Mammoth ?
And should a Burger taste like chocolate ?

analogguru

Post by **modman** » 31 Aug 2007, 19:50

Remember Aron's just a keyboard player go easy on him.

If you're into classic sounds, nothing sound better than a good les paul into a good fender amp. weapon of choice for the bluesplayers that wanted to get that screaming sound from the humbuckers pushing the preamp harder than single coils.

whatever.

build, buy, choose with your ears and nothing else.

Want to lend it out to some friends to test without them knowing what it is. See if they like like it against their tube screamers, xotics, and fulldrives...

Crowther Audio - Hot Cake Overdrive [traced]