Crowther Audio - Hot Cake Overdrive

sadrew · Post by **sadrew** » 16 Jan 2009, 08:48

THANKS!

jumper · Post by **jumper** » 16 Jan 2009, 11:25

Thank

Tubemania · Post by **Tubemania** » 21 Mar 2009, 20:13

Many Many Tank........

dualmono · Post by **dualmono** » 30 Mar 2009, 22:33

Hey there,

long time lurker, first time poster, and excited to be part of the community.

I built the Hotcake based on Torchys vero layout and I'd like to know whether it is based on the 77' or the 03' version.
The reason for building it was, I was lucky enough to play a Pete Cornish P-2 Distortion unit and recognize that none of my distortion devices was reacting as lively to dynamic nuances of my playstyle or adjustement of my guitars volume pot.
Anyway, looking through the DIY boards, I got the impression, that the Hotcake would be an excellent choice when it comes to clearing up the device via the guitars volume pot.

I've one or two questions though. On full drive setting, I got the squeal which I avoided by changing R6 from 220R to 1K (lost full gain this way, but thats not the devices strength anyway, I have been told). Is there another way of avoiding squeal instead of swapping R6?

What is the function of the relay switch in the 03 version? Any influence on the devices distortion characteristic, or just a 'soft switch' to have a buffer, which is alway turned on, instead of true bypass?

Since I had no 470pF ceramic cap i used a foil 500pF. Does this have a negative influence on the sound?
How important is the material and the value of C4?

The reason I'm asking this, is that I think there is something wonky with the way the distortion of the unit starts off.
Picking a string softly with raising force, I have the impression that the distortion doesn't 'appear' very homogenic. There is a point when the first audible distortion appears which is very sudden. This is also apparent when the strings vibration lessens.
Do I make any sense? Trying to jump the language barrier here... ;(
Does this sound like a behaviour you know, and if so, is there a way around it? Which component should I take a closer look at, to try and get rid of this?

Any ideas are greatly appreciated.
Cheers,
dualmono

floris · Post by **floris** » 31 Mar 2009, 22:40

Since I had no 470pF ceramic cap i used a foil 500pF. Does this have a negative influence on the sound?
How important is the material and the value of C4?

A think a foil will sound good. Audio-wise, people say there is a small nuance difference but I guess I don't have "golden ears". I'll go with foil instead of ceramic in the audio path anytime.

Picking a string softly with raising force, I have the impression that the distortion doesn't 'appear' very homogenic. There is a point when the first audible distortion appears which is very sudden. This is also apparent when the strings vibration lessens.

Hmm, doesn't sound like a good overdrive should. Guess there is something wrong. Perhaps you can post photos and measure and post voltages.

dualmono · Post by **dualmono** » 01 Apr 2009, 00:40

Thanks for your reply.

Could you please advise which points to measure for voltage?
I'll glady post images, but since this is just a first shot at building it, there is not much to see (except funny soldering work

). No casing, no knobs etc.
Once I am satisfied with the sound, I'm going to recreate it in my layout application.

As soon as the thing is breaking up and i play really hard, it sounds fantastic, it is just the transition from 'clean' to crunch which bothers me a little; haven't heard something like this before.

Maybe I will make a little recording of the phenomenon and upload it somewhere (nothing fancy, just the guitar directly into the console via the Hotcake, to reproduce the sound I'm trying to desrcibe). Could you recommend a good place to upload sound examples to?

floris · Post by **floris** » 01 Apr 2009, 11:52

For instance measure and post the voltages of:
- Power supply
- Opamp IC pins

Waimana · Post by **Waimana** » 02 Apr 2009, 08:59

Hi Looking for some advice on a version of this I have built according to Torchy's layout

Changes:
Used UA741 IC with 220k resistor from Vref to pin 2
Used a 50KA pot for drive control, reverse-wired instead of 50KRA
Used 100n cap for C6 instead of 82n...no 82n available
Used Zener 1n4738A rated 8.2v instead of 8.6v
Wired for true-bypass with 3PDPT i.e. no buffers or relay

Voltages are:
V+ into board - 9.14v
V+ at ZD1 Kathode - 8.06v
Vref - 4.4v

IC
1 - 0.13v
2 - 4.42v
3 - 4v
4 - 0
5 - 0.13v
6 - 4.42v
7 - 8.06v
8 - 0

Problem I have is the distortion decays really abruptly after about a second or so with no smooth transition to clean, particularly on the bass notes

Have tried another UA741 and also tried taking the diode out and running it at 9.1v, same problem. Compared to my Blues Driver, the abrupt decay is quite noticeable.

Is this the nature of the Hotcake beast or can it be tweaked i.e. resistor or cap changes?

Any advice would be greatly appreciated, Cheers, Andrew

floris · Post by **floris** » 02 Apr 2009, 10:22

I never build nor heard the Hot Cake Overdrive but "Waimana" and "dualmono" are both posting about the abruptness of the distortion/overdrive in attack and decay of the sound.
Does anybody have experience with that in this pedal? Seems too much of a coincidence that both have the same circuit error or something...

Greg · Post by **Greg** » 02 Apr 2009, 10:46

I have a genuine Hotcake and one that I've built..
I don't really hear anything unusual in the note decay.

It does sound different to most other OD/Distortions.. remember this is opamp distortion with no clipping diodes to limit the circuit and compress the signal, and it has a bit of a Fuzz character..
It's also a pedal that can sound great with the right amp and pretty ordinary with an amp that it's not suited to... for some reason it seems to love EL84 tubes.

Ben N · Post by **Ben N** » 02 Apr 2009, 15:55

Greg_G wrote: It's also a pedal that can sound great with the right amp and pretty ordinary with an amp that it's not suited to... for some reason it seems to love EL84 tubes.

Yup, my reference point for this pedal is the sound Neil Finn gets with his goldtop and an AC30, and I'm pretty sure it is the combination that makes it.

Post by **mdd59** » 02 Apr 2009, 16:50

I have a 2004 version and mine does have a bit of a "gatey" quality to the decay. It doesn't appear to be a smooth transition from clean to dirt and back again. It is especially noticed in lower gain settings. May be dependent upon the parts quality used, I'm not sure.

madmac · Post by **madmac** » 02 Apr 2009, 23:43

I have also noticed this strange note decay in my build. It sounds good otherwise but I must say copared to my kot and eternity it sounds fairly average.

I built the 2003 version. Haven't bothered fault finding as I thought this may have been how the original sounds. It does seem to not have much sustain compared to other builds.

fuzzheimer · Post by **fuzzheimer** » 03 Apr 2009, 14:19

I seem to recall a review of the Hotcake by Ken Fisher in an old Vintage Guitar Magazine. I think he said the crackle in the decay wouldn't be noticed when running into an amp set for verge of distortion. Also mentioned Crowther was working on a fix. This was probably back in the early 90's.

Louishr · Post by **Louishr** » 13 May 2009, 01:09

the links to torchy's vero layout aren't working for me

is this happening to anyone else?

floris · Post by **floris** » 14 May 2009, 08:21

Louishr wrote:the links to torchy's vero layout aren't working for me is this happening to anyone else?

https://www.freestompboxes.org/viewtopic.php?f=28&t=4337

sadrew · Post by **sadrew** » 28 May 2009, 10:24

how can i have less gain? mine sounds more like a fuzz than an overdrive

What resistors should i change to reduce the gain of the opamp?

Or maybe putting some clipping diodes?

floris · Post by **floris** » 28 May 2009, 13:34

The gain is mainly set by the ratio of the feedback resistor, between opamp output (pin6) and the opamp minus input (pin2), and the resistor between opamp minus input (pin2) and ground. Google for "non inverting amplifier":
http://en.wikipedia.org/wiki/Operationa ... _amplifier
So:
Make the 100k feedback resistor smaller (R7 in the schematic of analogguru if I'm not mistaken).
Or make P1 drive pot larger.

Greg · Post by **Greg** » 28 May 2009, 13:58

If you're Hotcake doesn't clean up when you turn the gain knob back, there's something wrong with it.
It should be able to do a relatively clean boost with the gain right back, and good Overdrive sounds up to about mid point on the gain.. From there it will start to morph into pretty heavy tones bordering on Fuzz with the gain right up.

sadrew · Post by **sadrew** » 29 May 2009, 10:14

it cleans up very well with the gain pot at min... but i don't want that fuzzy sound when the gain is max.

thanks floris for the input, i'll try to change the resistors

Crowther Audio - Hot Cake Overdrive [traced]