Crowther Audio - Hot Cake Overdrive

the3secondrule · Post by **the3secondrule** » 31 Jul 2010, 05:45

The does any kind soul have Torchy's Hotcake vero layout, and want to forward it to me? the links earlier in the thread are no longer active.

I have a zip file with a whole bunch of Torchy's Layouts, but the Hotcake isn't in there.

I have two newer hotcakes, but I'd like to build one to the '77 spec, and try a few mods for bass, as well.

would much appreciate it, the Hotcake is one of my favourite overdrives, and contrary to what a lot of other people say, I love it with drive at full. usually run one with drive at noon, and the other on full... sounds great running into my Jansen Bassman 50

chris_d · Post by **chris_d** » 31 Jul 2010, 06:02

I don't think i have the Torchy one anymore.

But here is the vero for the '77 version that i used when i made mine: http://www.aronnelson.com/gallery/main. ... 1.gif.html

It is a good layout and an easy build.

That is definitely a one of my favorite pedals into a Vox-ish amp.

the3secondrule · Post by **the3secondrule** » 31 Jul 2010, 06:16

Awesome, thanks!

looking forward to comparing the '77 with my recent ones

culturejam · Post by **culturejam** » 15 Dec 2010, 02:36

soulsonic wrote:Okay, here is the files for my Mojo Hotcake with the metal can 741. The .zip file contains the PCB artwork, layout, and schematic of my version of the circuit. The circuit is tweaked a little bit to taste and it's sort of a blending of the '77 and current versions.
Download the package here:
members/soulsonic/Layouts/MojoHotcake.zip

It looks as if there is no direct coupling cap on this schematic. Is that kosher?

I just knocked out a PCB layout from soulsonic's schematic and now have etched a board. But I *just now* noticed that I don't think there is an output cap. Can somebody take a look at the schematic in the quote above and straighten me out here?

Thanks.

WhiteKeyHole · Post by **WhiteKeyHole** » 15 Dec 2010, 02:54

Take notice of the second 56nF capacitor on the board that is not present in the schematic.

culturejam · Post by **culturejam** » 15 Dec 2010, 02:57

WhiteKeyHole wrote:Take notice of the second 56nF capacitor on the board that is not present in the schematic.

Well shit.

That's what I get for following the schematic. I wonder why they don't match?

I'll just run a cap either between Presence and Volume pot or something like that. It'll make it look more "boutique" like that anyway.

WhiteKeyHole · Post by **WhiteKeyHole** » 15 Dec 2010, 03:03

But there is a capacitor between the Presence and Volume potentiometers ...

culturejam · Post by **culturejam** » 15 Dec 2010, 04:56

WhiteKeyHole wrote:But there is a capacitor between the Presence and Volume potentiometers ...

On the schematic that soulsonic posted? I'm looking at it, and I just don't see it. But you can show me if you like, and I'll admit that you're right.

As I see it on the schematic by Martin, lug 2 of presence connects directly to lug 3 of volume.

I'm talking about the layout I did. It doesn't have the output cap because it's not on soulsonic's schematic, which I used for my layout. He's got two 56n caps on the layout, but only one on the schematic. His schematic and layout do NOT match as far as I can see.

You see what I'm saying? Or am I somehow not seeing a cap between presence and volume:

Compare that to this similar schematic drawn by our dear AG:

WhiteKeyHole · Post by **WhiteKeyHole** » 15 Dec 2010, 06:59

Ah, I see. I thought you were referring to soulsonic's layout, didn't realize you'd done one of your own. My apologies.

culturejam · Post by **culturejam** » 15 Dec 2010, 13:29

WhiteKeyHole wrote:Ah, I see. I thought you were referring to soulsonic's layout, didn't realize you'd done one of your own. My apologies.

No problem at all. I just want to make sure I'm not going crazy!

culturejam · Post by **culturejam** » 23 Dec 2010, 02:33

The layout I posted is now verified. edit - project files moved this thread

I've got some possible issues with the one I built. I'd love any input anybody has on this one.

For Gain, I have an A50K pot. For most of the pot sweep (about the first 75%), it's basically clean. Then it abruptly gets very dirty and also a LOT louder. I thought maybe it was a taper issue, so I tried B50K, but that made it much worse. So I'm back to A50K. Is this typical of the Hotcake?

Also, the presence control is only somewhat noticeable. I can definitely hear a difference from one end to the other, but it's on the more subtle side. Is this also normal?

I'm building this for someone else, so I'd like to get it wrapped up ASAP, as I'm already late in deliver.

Thanks guys.

bajaman · Post by **bajaman** » 23 Dec 2010, 02:44

gain should be 50k reverse log

there should be a VERY noticeable difference with the presence control - something is not wired right

cheers
bajaman

culturejam · Post by **culturejam** » 23 Dec 2010, 03:59

bajaman wrote:gain should be 50k reverse log

Isn't that just a log pot with the sweep reversed? If so, I don't see how it would help. If not, I guess I better try that.

bajaman wrote:there should be a VERY noticeable difference with the presence control - something is not wired right
cheers

Well, the schematic and board are consistent, according to Eagle. So there must be something awry with the schematic...or perhaps the pot is bad.

Thanks, Steve.

bajaman · Post by **bajaman** » 23 Dec 2010, 09:00

a log pot with the sweep reversed?

NO - I used to think that, but it has a completely different law and is perfect as a gain control in this application.
Reverse log potentiometers are quite often used in tube tremolo circuits for their more even speed variation versus rotation of the shaft.
cheers
bajaman

culturejam · Post by **culturejam** » 23 Dec 2010, 15:08

Right then, I'll get the C50K pot.

Also, now I see a cap value that I got waaaaay wrong, and another that is somewhat less off. I bet those changes will straighten out the Presence control.

Thanks again, baja!

Post by **modman** » 02 Jan 2011, 00:13

culturejam wrote:Right then, I'll get the C50K pot.

I've built this more than once using A100K with a 100K resistor across and it works, but the gain pot will be so sensitive, it's worth getting the C-taper. It's a sound I really love, but only useful in some middle gain setting. Full gain sounds horrible, but I think Soulsonic's built proposes some value changes that broaden te scope of this little gem.

But looking at your Flapback schematic, there are a number of differnences with
http://analogguru.an.ohost.de/193/schem ... e-2003.gif
Notably 82n and 22n capacitors are missing...didn't even check any further then...

culturejam · Post by **culturejam** » 02 Jan 2011, 23:57

modman wrote:But looking at your Flapback schematic, there are a number of differnences with
http://analogguru.an.ohost.de/193/schem ... e-2003.gif
Notably 82n and 22n capacitors are missing...didn't even check any further then...

I based mine off Martin's version, but I changed a cap value here and there (nothing major).

New project/layout is here:
viewtopic.php?f=13&t=11809

JOHNO · Post by **JOHNO** » 04 Jan 2011, 09:46

Bread boarded this circuit this evening and it sounds really nice, though I haven't really had a chance to crank it yet. Mine is kind of a hybrid at the moment. I used the voltage divider from the 77 model that AG drew up for us but I ended up dropping the last 12n cap and 10k resistor and used a 50k log for the presence control from the later model HC instead. Seems to work just fine. For the gain pot I used a 50k log wired backwards and that works really well too, although it does work backwards. I used an RCA 741 and I ran the 220k resistor from the voltage divider to pin 2 of the Ic. I think removing the 220k makes the circuit slightly brighter, but I'm not really sure, its a very subtle difference if there is one at all. Thanks to all the who put this project together.
Johno

culturejam · Post by **culturejam** » 06 Jan 2011, 22:36

Just got the C50K today. It's still super-sensitive to the point of being no better than A50K.

But I find, actually, that B10K (of all things) gives a very usable pot sweep ranging from clean to dirty. And looking at it, I can't see why linear wouldn't be the best option for a simple variable resistor.

What whatever.

Post by **CodeMonk** » 06 May 2011, 15:57

Sorry for reviving an old thread but....
I have an AC30 and I have heard that the hotcake is THE OD to have for the AC30.
Got all the files for building one, but....sources for the metal can 741?
Searched mouser with no luck...thanks.

Crowther Audio - Hot Cake Overdrive [traced]