Thursday, 2 February 2012

Crowther Hotcake

Another great sounding overdrive


Quite a few people have had issues with the circuit oscillating with presence and gain maxed. This has been known to happen more easily with some pickups, while there hasn't been an issue with others. Usable cure has been to put a buffer in front of the circuit to isolate the circuit from the pickups and to give higher input impedance. I drew this layout to add a buffer from tubescreamer to the circuit input. IT IS EXPERIMENTAL AND CURRENTLY TOTALLY UNVERIFIED. So please do not build it, unless you know what you're doing. I've been it over a few times and couldn't see anything wrong with it. However, if you build it (or notice something wrong) let me know if it works...


Please note! With the transistor buffered version, there have been reported cases with the squeeling still there. If you experience this behavior, try replacing the 1M resistor from VRef to 1µ/10K with another 10K resistor. This should fix the issue. If it does, please let me know and i'll fix the layout accordingly... (P.S. 1M -> 10K works for the original layout too. It just changes the signal impedance maybe a bit too much to be viable fix.)

145 comments:

  1. Hi IvIark! I've just built the hotcake and it works very well! nice pedal, with a lot of dinamics. it's also very transparent and quiet. thanks a lot!

    ago

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  2. That's excellent, glad you like it and thanks for verifying.

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  3. Hey I've built this but there were two things that I didn't have exactly, I put a 560pf instead of the 470pf and 68k instead of the 82k (I dont have that one).

    It's very very noisy and the gain doesn't work at all. I have the proper reverse log pot for it.

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    Replies
    1. Oh yeah and the 56n, I put a 47n (the closes I had).

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    2. I know this one is ok, so can you post me pics again just to have a double check. You say the gain pot doesn't work, are you sure the pot itself is ok?

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  4. I had a closer look and I did find a 470p and then I noticed something was off. There was something touching that wasn't supposed. Now it sounds fine!

    By the way, the 82k resistor. Does it affect the gain? I guess because I put a lower value, when I turn the gain all the way up, it's a little too much and almost turns into a fuzz pedal hah!

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    1. Cool! The 82K forms a bias voltage divider with the 100K to ground below the opamp. If you've used a 68K instead of 82K then it will put the bias at a higher voltage and so yes I would expect it to affect the range.

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  5. I see, the only two resistor values that I have close to 82k is 68k and 100k. The 100k is sounding better but I think I need to make it a proper 82k though.

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  6. I soldered two resistors in series to form a 80k resistor, that's as close as I can go. It still sounds a little off. You can hear a "fuzz-like" sound going on but it isn't very pleasant. I watched a few videos on youtube to hear how it's supposed to sound. The pedal is pretty low gain until the last quarter of the drive knob. Like I said, I'm using all the right components (except the one 56n which is 47n in my case).

    It doesn't sound anywhere close to what it's supposed to.

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    Replies
    1. Sounds exactly like a Hotcake to me! :o) Read this:
      http://freestompboxes.org/viewtopic.php?f=10&t=15720

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    2. No I'm saying that mine doesn't sound anywhere near the original one. It's weird! I'll check that link, thanks!

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    3. Hey Mark, what kind of caps are used? (obvious noob...)

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    4. I've got quite a big stash of caps and when I'm doing my layouts I tend to use a representation of the caps I intend to use in the build. The maroon ones that you see in a lot of my layouts are Panasonic ECQ, but for 1 row spans I tend to use box caps with one of the legs bent back to make it suitable for a 2.5mm gap. Box caps are great for this, but not really suitable for anything over a 3 row span because they usually come with short legs, so if you're looking at getting some I'd suggest a set of the green mylar caps you see from a number of eBay sellers like here:

      http://stores.ebay.co.uk/Sky-Electronic-Mart/Polyester-Capacitors-/_i.html?_fsub=2815595012&_sid=967416192&_trksid=p4634.c0.m322

      or maybe look at the mylar value pack from Futurlec:

      http://www.futurlec.com/ValuePacks.shtml

      because both of these have long enough legs to make any of my layouts.

      For values below 1nF get some ceramics and for values over 1uF get electrolyics or tantalum radial. Check out eBay for some real bargains on these, especially from some Chinese sellers.

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  7. Hi IvIark, Ive just made this, can this be wired now as buffered?
    Thanks mate.

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    Replies
    1. Sorry mate, do you mean you want to make it buffered bypass rather than using a 3PDT?

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    2. Yeah that's right, thanks

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  8. Hey mate, is it basically sending gain 3 to ground via DPDT to turn the effect off to make it buffered bypass?

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    Replies
    1. Not really, all that would do is simulate the minimum setting of the gain pot. You would need to do true bypass switch wiring, but instead of shorting across two of the poles to create the true bypass link, you'd take those pole to the input and output of a buffer, similar to the way Bjorn did with the Ruby Red Booster here:

      http://tagboardeffects.blogspot.com/2012/02/mad-professor-ruby-red-booster.html

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    2. Oh ok, I might leave it for this one then . I thought this had a buffer of sorts already. Thanks for the education though, appreciate it.

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  9. Would you happen to know where I could find out how to add the Blueberry mod? I been looking on the internet, but no dice. And thanks for the great layouts. You do incredible work, man.

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    Replies
    1. Sorry I don't know what it is. I'll ask around though and see if anyone knows

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  10. I built the pedal and it worked fine until I found out the reverse pot was faulty. Now I have a new functioning pot and the pedal sounds nice, however when bypassed there's a high-pitch oscillation going on and the tone and gain knobs change the pitch of the oscillation. When I move the input wire, the osc signal gets either louder or quieter, sometimes even changes the pitch. This did not happen before.

    Do you know what's going on?

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    Replies
    1. How did you wire the switch? You can get bleed through sometimes with dirt pedals, but this is usually avoided if you use a switching method which grounds the board input during bypass.

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    2. I always use this for everything: http://www.muzique.com/tech/wiring.gif

      I've never gotten this OSC happening on any other pedal. Strange..

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    3. The problem with that type of true bypass is that the circuit is just hanging in bypass and noise from it can still pass through the ground connections. I used to use that exact same method for everything too but eventually had a similar problem which was cured by altering the wiring so the effect input is grounded which effectively mutes the circuit. Try this method here:

      http://tagboardeffects.blogspot.co.uk/2012/02/offboard-wiring.html

      Admittedly it is strange that you weren't experiencing the problem before but are now, but at least if you use that method it will eliminate one potential source of the problem. Failing that make sure your ground soldering is all ok, check for continuity between all points of ground including jacks and switch, and pay special attention around Gain 1 and 2 which is the thing you've just changed and so another potential cause.

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  11. Cheers for that!

    There's one thing that I'm wondering about. The little veroboard on that image represents the circuit, right? Otherwise this would be weird hah!

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    1. Yes it just represents the circuit board. I only put it in because with the input, output, 9V and ground wires going to it, it shows all the relevant wires

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    2. Okay cool, I'm trying this soon and I'll report back if it solved the issue. Thanks!

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  12. I have just made me a little tonemonster using your beautiful layout.
    Thanks for making it more simple for non scientist like me!
    I even added a little led.....
    It will not be the last one i'm building with your layouts!

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    Replies
    1. Excellent, glad you're finding the layouts useful

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    2. But i would like yhe Bluesberry mod as well. I think it's gainig the upper mids too much though. A little harsh sounding.

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    3. If i could just spell right....

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    4. And i use a JRC4558. Is this okay?

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    5. Not with this layout. The TL071 is a single opamp, JRC4558 is dual and so the pin layout is different.

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    6. That was not so good.....

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    7. You could try an LM741 if you've got any?

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    8. I am a little slow these days. The 4558 was in another project of yours. I will try another opamp. Thanks for your patience : )

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  13. "Volume 2 to Output"

    Does that mean it goes to what would be the output lug of the 3pdt?

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    1. To the "board output" lug of the 3PDT. The output lug of the switch will then go to the output socket.

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  14. Is this unit buffered, and how do i i wire it to go with the buffer.( I'm getting a little addicted to this little bastard)

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  15. No there is no buffer in this. If you want to experiment with adding one then make up a buffer board and put it before the Hotcake.

    Input > Buffer > Hotcake > Output

    http://tagboardeffects.blogspot.com/search/label/Buffer

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  16. I built this and I'm getting oscillation on the gain control. The pitch changes as you move it up and down and the gain doesn't ever really clean up - it's dirty fully counter clockwise and and gets dirtier as you turn it up.
    There are no bridges I can see. I don't think it's a cold solder joint - hard to tell as I'm using lead free solder - but I've a good iron and it's set right for lead free solder..

    I put the gain and volume ground connections on the strip next to ground. This is okay isn't it? Isn't that whole row ground? If not, where should I connect those?

    I tend to use madbeanpedals.com wiring - http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf - as I almost always include a battery just to have in case, although I almost always have my pedals plugged into a power supply unless I'm testing them. It would be cool if you could include the battery wiring on your wiring diagram. What wiring do you prefer and is there a conflict with the madbean wiring and this circuit? I don't see how there could be..

    Thanks for the site! I've built the Timmy and it's awesome and there are plenty more I'm going to build that are on this site.

    Any help would be appreciated

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  17. Replies
    1. Have you tried knifing the strip gaps? Are all the cuts where they should be? As there are a few successful reports, i don't believe that the fault is in the layout. Any part substitutions?
      +m

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    2. Yes it's very difficult sometimes to diagnose a problem without having the pedal in front of us. What I will say is that 100% of the time that someone has had a problem with a verified build and I have found out since that it was sorted, the problem was either a misplaced component (or cut), unwanted bridge, an incorrect value component or a faulty component and they're all things that the builder needs to check for. If you send a front and back pic I'll look for anything misplaced but you're going to have to check for the component problems and maybe using a multimeter to accurately check for unwanted continuity of a microscopic bridge.

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    3. Thanks for the reply guys! Will take a knife to the strip gaps and test for continuity with the meter. Tried taking a pic with my phone but it didn't turn out so well. Will try and take appropriate pics and get them to you.

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    4. Finally got around to fixing this..the problem was I had one leg of resistor that I missed when soldering. Doh!
      Soldered it, plugged it in and it fired up with no other issues..

      Have to say the tone is a little on the fizzy and brittle side for my tastes.

      Built it because I'd read some people say it's the best OD for a Vox AC30.
      I recently got a Valvetech Hayseed 30 and wasn't able to get a sound I was real thrilled about.

      Oh well..

      In the meantime I've built a Klon buffer using a TL 072. Best buffer I've used yet!

      On to the next build.

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    5. Yes a few people have described this as fizzy, I think it's one of those pedals that works great with some guitar/amp setups but not so well with others. Still there's plenty of alternatives to try here

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    6. This comment has been removed by the author.

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  18. Thanks for the layout! Sounds great!

    I would like to have the normal / bluesberry switch mounted on the enclosure. Do somebody know what does it change? I can not find anything about this mod on the internet.

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  19. Noob question - as long as the values are the same, how much does it matter whether you pick say ceramic caps over Philips or Panasonic caps?

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    1. Some people can't hear any audible difference in the different cap types, some say they can. I do think there can be subtle differences between some of the cap types but I've never done any measured testing where I have thought one sounded great and another sounded bad. As a rule I'd avoid cheapy ceramics because they can be microphonic, and I definitely think they have a weird decay in some circuits, although that may be an advantage in some noise makers or fuzzes. Ignoring the more exotic types I tend to favour polyester where possible (I have them in reasonable sizes up to 2.2uf) and I like multilayer ceramics for the sub 1nF values. I also like using tantalum instead of the more conventional aluminium electrolytics, but that's really because they are smaller and will last much longer. I'd recommend breadboarding something simple and doing a few tests for yourself to see what you think.

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    2. Yup. I'd say the same thing. Plain ceramic discs tend to give out unwanted noise. Mylar, monolithic/multilayer ceramics, plastic box polyester, panasonic and other metallized polyester. Those are all good. And i can't hear any difference between monolithic and plastic box... :)

      And yes. Radial tantalums cost about 5-10 times what aluminum electrolytics, but they are better :)
      +m

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    3. Look for good deals on eBay and you can pick them up for similar prices, that's where all my tantalums came from! :o)

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  20. anyone using a 741 instead of a tl071?

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  21. I'm building another one of these. Can i use a 1N34A diode instead? I don't know anything at all about what is doing what in these projects, so thats why these dumb questions come up....

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    1. I don't think that'll work. You could try it, but my bet would be that it needs to be zener, and close to 8V2 value...

      Haven't built this so i can't say for sure...
      +m

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    2. The zener is used to drop the supply voltage to 8.2V. If you don't have one it would be easier to put a 1N4001 in series with the supply which should drop the voltage by about 0.7V and so from 9V get you down to a very similar level.

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  22. I can say now that i tried, it was very fuzzy. When i turned up the volume it got fuzzy too...
    I'll go buy me some zeners.

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    Replies
    1. I'm guessing that the design is pretty pedant about getting exactly that 8.2V..
      +m

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  23. But hey guys,
    thank you for informing me a little about things... ; )

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  24. What difference will it do if i use a 22k presence pot instead of the 50k, as some layouts say?
    And by the way, i finished it and it sounds great...

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  25. According to crowther audio's site, the hot cake is a buffered pedal. Sabrotone has a layout for a buffered mojocake. The buffer is really nice

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    Replies
    1. They may well have changed the circuit again to add a buffer, but the original 1977 and also 2003 versions this is based on definitely didn't have one. It's always worth experimenting though if it's a circuit you like.

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  26. Hi, can I use 1N4738A Zener Diode?

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    Replies
    1. However, I bought 1N5237B, which is 1/2W 8.2V Zener Diode.
      Does it works?? THANKS A LOT!!

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    2. Yup. That'll work just fine.
      +m

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  27. Hey Guys!

    This will be my second build on vero, but i have a question about the polarised eletrolytics: Do i have to use the polarised electrolytics to make this and any other layout in the future work, or could i just use unpolarised tantalums like them here -->

    http://www.musikding.de/Passive-Bauteile/Kondensatoren/Tantal/Tantal-10uF::1045.html

    i dont really care about the 40 cent difference since i heard that the electrolytics tend to break after some time.

    Thanks for your help and this beautiful page,

    Raphael

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    Replies
    1. Hi and welcome Raphael!

      Those tantalums are polarized. The longer leg is the + side, and those are usually marked with + sign too. Tantalums are way better than aluminum electrolytics - however - you really can't get those in larger values and most of the circuits require 47µ or 100µ for power supply ripple filters. There's not really an option for those. You could get some aluminum non-polar caps - but they have same degrading-by-time-issue as the polarized ones.

      I'd suggest you check out the shop most of us use: Tayda Electronics

      You can get tantalums up to 33µF from there. For good prices too.

      While you're shopping there, i would still suggest that you get these:
      47µF aluminum electrolytic
      100µF aluminum electrolytic

      Getting 100 of each will set you back 6 usd and those will last you a long time :)
      +m

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    2. Oh. If you like them on facebook, you can grab 15% off codes from them. That usually covers the postage fees.
      +m

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    3. Discount code: 933666, ends 23rd Jan. If you're quick...

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  28. Oh thanks for this shop, thats alot cheaper than the one where i used to buy parts :)

    Do you know how much they charge for shipping to Europe, i couldnt find it on their page ;)

    Raphael

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  29. Anyone had an issue with their build where it emits a high-pitched squeal when the gain is at the last 5% of the sweep? I'm using a TL071CP.

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    Replies
    1. Judging from the schem of the 2003 Hotcake, perhaps I should increase R6 to something slightly more than 220 Ohms to to stop the oscillation when the gain knob is maxed out? Tried swapping the IC but the problem remains.

      http://4.bp.blogspot.com/-pgDMzXAv3Pw/TxxcF2JgeNI/AAAAAAAAAqg/zYABLMqgeXA/s1600/Crowther_Hotcake-2003.gif

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  30. I just built one of these today. IMO, it sounds ALOT better with an LM741 than the TL071. I also installed the bluesberry mod in mine but it doesn't do much of anything so i'm leaving it out.

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    1. completed with a few clipping filter changes to make it work better with a bass. it sounds awesome now.

      pic:

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Hotcake/Hotcake-01.jpg

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    2. I just finished boxing one of these for a friend, I'm not giving it to him until later today so I may just swap the opamp on your recommendation. Do you have the details of the Bluesberry mod? I had a half-hearted attempt to try and find some info but got side tracked watching pedal demos on Youtube (as usual). It's a great sounding pedal, so much so that I've got the parts together for one for myself.

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    3. what do you have to do for the bluesberry mod? Does somebody know how to get rid of the strange decay in the background?

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  31. Hi Chaps
    I built one this evening and am gettin osccilation at high gain settings but i havent put in a 8v2 zener yet. Any suggestions as to curing this?
    Thanks
    Dave

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    Replies
    1. You should probably put it in there as that tames the voltage going to the IC from 9V down to 8.2V.
      +m

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    2. Got my 8v2 zeners today and put it in, still oscillating. Shame because it actually sounds great when it i play.
      Thanks
      Dave

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  32. Hi!
    I just built this with a 50k lin for gain instead of 50k rev. I get no gain. When i bypass the pot with a direct connection from gain 3 to ground I get full blown gain as it supposed to be I guess.
    Is there anyone who can chip in and tell me how i can solve this with out the 50k rev as it's hard to find for decent money in a local store? I will order some from a webstore, just not right now. I think I'll wait till I get more components that i have to order.
    So can this be used with out the 50k rev except from bypassing the pot. Or is there something else on my board that is acting weird maybe?
    /L

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    Replies
    1. Maybe the pot is broken. I get strange values when measure it...
      /L

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    2. It turned out to be the a broken pot. Didn't have any other 50k lin so i soldered a 100k lin with a 100K resistor between the outer plugs of the pot. It now works. One problem though. It oscillates when cranked at max gain. Any ideas? All the soldering on the board looks fine to me.
      I'm aware that it's hard to guess what might be wrong when you can't see the board. It's like trying to help your dad with his computer over the phone when his computer suddenly gets a blue screen :) But maybe some of you have an idea what might be the problem?
      /L

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  33. Hi!
    I built this and it sounds fine, but i'm also getting osccilation at high gain settings. Funny thing, when I tried the circuit unboxed though my breadboard it sounded fine. Any ideas?

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  34. Hello,
    i built this today but no sound out. Maybe, in the first try, i mounted the IC wrong: which is the right way? Canthis breaked the IC?
    Thanks

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    Replies
    1. Ok, I found the right way on the picture, but still not sound...hummmm

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  35. I am starting to think that there might be something fishy going on with the layout. I am getting the exact same oscillation that other people are reporting. I have done everything I can think of to debug it, the only thing that has knocked the oscillation out so far has been switching the IC to a 741. The only problem with it then is it starts to behave in a not so linearly fashion. When the gain is maxed the sound is super dark and wooly (in a bad way). At lower gain settings it sounds decent. I suspect there are some resistor values that need to change if one wants to use a 741. I tried checking the schem but I am getting confused about where the switching system ends and the actual effect begins.

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    Replies
    1. Hi, one alternative I came up with which seems to have worked is to run the pedal after a buffer, or you could build a buffer and attach it before this circuit.
      Thanks
      Dave

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    2. Just a week ago, i built two of these boards and both work fine...
      +m

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    3. +1. if you're having issues with it, then there's a build error. this layout follows the schematic exactly.

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  36. Could using the TL071CP be the cause? I have checked my build a bunch and everything since ok. I also have the problem resolved when putting a buffered pedal in front. It appears to be an input impedance thing. Some of my guitars sound ok through the HC until I roll my volume down a little, then it will osc. until I roll it down a little more. Another guitar I have just oscillates no matter what. I have a guitar that seems to work with no problems until I select the pickups in series mode, then I get the osc. Is there something you could recommend changing out so I can avoid building a buffer into the circuit?

    ReplyDelete
    Replies
    1. Well the TL071 has a very high input impedance with it having a FET input stage so maybe that isn't matching well with your particular set up. Trying other single ICs with a BJT input stage like the 741 may find a better match.

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    2. I think the original (1st release) Hot Cakes used a LM741 if that's any help. Mine worked fine with a TL071 but it did get a little wooly at the highest gain setting. Maybe that's the nature of this particular beast.

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    3. Yeah, I popped a 741 for a bit and it tamed the osc. a bit. It also darkened the pedal to the point where it seems some other components might need to be changed to brighten it back up.
      all I seem to be able to get my hands on are TL071CP's. Is there a way I can change the input impedance of the circuit? Maybe changing the value of the 10k resistor that goes to the + input of the chip?

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  37. Ditto on the osc issue. Did a grounded input wiring, everything is right. Even built a 2nd one just to be sure... any ideas guys? I really need this thing to work right now in the studio... argh.

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  38. alright, the version with the TL071 has a buffer, but it's built onto the circuit board on the switch. can one of you guys transfer the schem into a vero layout to add on to what's here?

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  39. Outstanding layout and great sounding pedal! Works like a charm. Thanks Ivlark!

    Does anyone have info on the XLF (bass guitar version) mod switch?

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  40. Heyho, i have Oscillation with both ICs (TL071 and LM741). I checked out the cuts and soldering and everything seems to be right. I can't find any solution.. :(

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    Replies
    1. Hi Marcel
      Quite a few of us have had this problem, as far as I'm aware, if you put the pedal after a buffered bypass pedal like any boss/behringer pedal, OR you could build a buffer like the klon buffer for example, that should cure it.
      Thanks
      Dave

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    2. Hey dave,

      Thanks for the hint. I already checked out the same here, but I don't know if I'm happy with that. I wanted to build the pedal for a friend. okay, if he would have a buffered bypass it would be no problem, but if not he'll have a problem. Another disadvantage is the tone lose (okay it might be voodoo) with that cloned buffer. Hasanybody checked out tthe other two very layouts in the Internet?

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    3. If a buffer sorts it, you could build one of the boards from here and place it between the switch and hot cake board's input. You would still have true bypass and that would cure the oscillation.
      +m

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    4. weird. mine has zero oscillations and sounds great all the way up to super saturated distortion which makes me think that those that have oscillation issues have a wiring layout problem.

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    5. I've built a couple of these with different outcomes, first one was fine - no oscillations or whistling, second one had whistling and noise when the presence and gain were maxed out. To solve it I built up a klon buffer and put it in between the 3pdt and the Hot Cake input, you still get true bypass as the buffer is only active when the effect is engaged. It sounds sweet too so don't worry about it affecting the tone. I you're concerned about the buffer you could always add a 3PDT toggle to switch the buffer on and off, DPDT if you don't want an LED.

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    6. Thats what I'm going to do with mine when I eventually get around to boxing it up, glad it sounds good. From the amount of people with this problem, I really don't think it is a wiring issue.
      Thanks
      Dave

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    7. There's been reports of successful builds without the buffer. My boards worked fine on some pickups, while Presence/Gain maxed led to oscillation on others. That's why i was confident about my builds at first. This could be the reason why John's builds work flawlessly - bass pups.

      I wonder if basic TS input buffer would cure it. TS buffer is famous for high input impedance and low colouring of the the tone. I could draw and add a modded layout with that.
      +m

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    8. I kind of thought this could be something to do with part tolerances which is why it's affecting some people but not others. Seeing as it only kicked in at the extremes of presence and gain it could be that some builds have that magic combo that work perfectly. If it's right on a knife edge that would explain why some pickups are fine and other seem to push the board into oscillation. I might see if I can borrow the one that works and measure some of the parts and compare it to the one I kept with the buffer. I think the modded layout's a great idea miro, seems like the buffer really helps if people are having issues and doesn't seem to impact to tone.

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    9. I *think* this behaviour happens because of pickup loading. Meaning that the input impedance is too low for some pickups to get the signal correctly on the circuit. My reasoning should be valid due to reports of some pups working better than others and the fact that it seems to be cured with a buffer in front of it.

      I drew the mods already, but i'm ~400km away from my desk and the poor choice of OS (and DIYLC bug with that OS) on my laptop makes it impossible to export the project to png. So I'm waiting for a friend to get off from work to get it exported :P

      Let's see if the TS buffer cures it for good. I drew it 1:1 with the original screamer buffer, so it may let a bit more low frequencies in. I think we'll need a guinea pig to build it first.. Any takers? Madferret?
      +m

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    10. I'd happily build it, I've been wanting a more elegant solution than boxing it up with a separate buffer.
      Thanks
      Dave

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    11. There you go Dave. Let me know if it works.. Or if you notice something wrong..
      +m

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    12. Hi Miro, Built it today and I think there is something wrong, I'm getting motorboat noise which usually means that something isnt grounded that should be. I'll check over my build again later but just thought I'd give you a heads up.
      Thanks
      Dave

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    13. Ok so the layout is fine per se, I found a micro bridge on my build (thats what happens when you try to squeeze a build in before graduation). However, interestingly this buffer hasn't solved my oscillation problem at least, on the neck and middle position of my jazzmaster it is ok although a bit noisy at some settings, but when I change to the bridge it oscillates again. Wonder if we should try another buffer, maybe the klon or cornish?
      Thanks
      Dave

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    14. That's weird... Is it just noisy, or does it oscillate exactly like the previous board? With that much gain it is bound to have some levels of noise when maxed.
      +m

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    15. Hi Miro, tried to reply last night but the damn ipad kept deleting my answer when I hit publish. Anyway.... when I'm using the neck or middle positions I'm getting a high pitched background noise, it sounds like it is on the verge of oscillation, when I go to the bridge pickup it oscillates just like before.
      Thanks
      Dave

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    16. Buffer didn't solve my oscilattion as well.. :/ Did anybody of you tried it with the grounded Input Bypass

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  41. I'll try the Buffer on Monday then :) Thanks for the interest about that issue! Have a nice weekend guys!

    Regards
    Marcel

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  42. i built one of these with a basic TS buffer in front, similar to the one above, using a 5088, solved all problems, but not with Miro's layout, i just slapped a separate little board in there. can anyone verify this one yet? the 1uf buffer cap should be smaller, i used 100n and omitted the extra diode.

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  43. Hi IvIark, I built the first one yesterday and the one with a TS buffer today. Both versions are oscillating like crazy! A huge hum that fluctuates with the guitars pickup when I am not playing. When I do play I can still hear the guitar and the hum quietens. I have checked for continuity all over the board. I used a 10u cap where you specified 100u. Does this matter?

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  44. Just finished this. I made a few cock-ups, mainly because of me being sloppy in the layout stage. I should have put the IC socket in place straight after the jumpers. Otherwise, it was an easy build. No oscillations from me either. It'd be interesting to know which component is causing this for some people. I'm going to give the tremulator a go next.

    Any chance of a small stone phaser clone?

    Many Thanks.

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  45. finally finished building this tonight. My first pedal build. Spent an entire day finding out I had a "10u" tantalum Capacitor where the "10k" one should have been. Sounds great. But I do get a crazy high pitched tone in the last 5% of the gain knob as described above. The presence also adds to this at the highest setting. Wondering if this is because the original hotcake isn't true bypass.

    Also does anyone know if this is based on the 2003 hotcake, the originall 1977 version, or both?

    If you know any of the answers to these questions please email me at nealzetek@gmail.com

    cheers and good luck.

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  46. Hello, I've just built my second one of these and I'm having some issues. Sadly, the first one has been taken off my hands so I can't set the measurements to check where I've gone wrong. Basically, I'm getting noise as an output. My IC readings are:
    0.14 0
    4.46 8.14
    4.04 4.46
    0 0.09

    I've tried knifing gaps and have been over the components again to check I've not missed anything or had a bad cut. I've attached front and back pics. Any help would be appreciated.

    https://dl.dropboxusercontent.com/u/7620516/hotcake%201.jpg
    https://dl.dropboxusercontent.com/u/7620516/hotcake%202.jpg

    Sam

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  47. Would JHS Little Black Buffer works good before the hotcake? Thank

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  48. is the second layout verified to cure oscillation? or verified at all?

    thanks

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    Replies
    1. Verified, but doesn't cure the oscillation.
      +m

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    2. hmm... any ideas as to what it could be?

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  49. Hi Ivlark! I've bought all the parts for this build and they have all just arrived. I have never built any pedals before but decided to start with this one because I hear they go great with Vox amps. Anyways, I cannot tell the polarities ( or which way) the capacitors are supposed to be positioned from your veroboard layout. Does it matter? Or can you please explain, because I don't want to blow up my build. Thanks.

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    Replies
    1. If you look closely each of the electrolytic caps has a shaded side, that's the negative leg

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    2. One more thing: Where's the effect output on the board? Sorry, I'm new at this. All I have is a DPDT, will it work or do I need a 3PDT. Thanks

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  50. Mine sounds really good. It was oscillating at gain maxed when playing through the center mic of a stratocaster. But when I put a DS-1 (which has a buffer, even in bypass) between the guitar and the hotcake, the oscillations dissapeared.
    It is a bit noisy and dark, and with my setup, unlike John K said, it sounded better with TL071 than the LM741... So, as always, it's a matter of trying!
    Thanks!

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  51. I built this and it sounds really good, however, my 'presence' knob just acts like a volume knob. With the presence knob all the way down there is no volume and as I turn it the volume goes up but there is no difference in tonality. What could be the problem? Thank you

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  52. Tried both versions out and got oscillation, ts buffer version oscillated by it self, but with buffered pedal(Dano fish n chips) got no oscillation. Added JHS little black buffer to original version and still oscillated (much less, only al max gain).

    But ... I tested with LM308, as LM071 is still on it's way. Are different opamps prone to oscillate more easily ?

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    Replies
    1. BTW... I also added mojocake values

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    2. LM741 is on it's way .. sorry about that :)

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  53. First off all, thanks for all the layouts, I already built a couple of pedal from this site!
    But I've got a problem with this one.
    It's not the oscillating, I get a volume DROP from this pedal. To be more specific the singnal at the input (pin 3) of the OP-Amp is much louder than the Output (pin 6) of it.
    Might i just be a faulty IC?

    Thanks!

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  54. hi there guys! i've build mirosol's version with the input buffer yesterday. it passes signal, but i have an issue with the gain pot and i think that there is a problem. it gives gain only when it's full total CW! at any other set, it's the same mild overdrive like if it was always at zero full CCW..anyway i was checking the schem from here

    http://revolutiondeux.blogspot.gr/2012/01/crowther-audio-hotcake-overdrive.html

    and i believe that grounding lug2 with lug1 is wrong. unfortunately i'm not at my lab right now, and i can't check my build. i don't have a 50k rev log, so i "made" one by soldering 100k resistor on lug1 and lug3 of a 100k pot. i know that this could cause the problem, but i'm pretty sure it doesn't. cause even with that fixed pot, i would have some control of the sweep. now i have none.

    other than that, i'm using a squier jaguar and a fender deluxe reverb and had no oscillation problems as other people have with presence full CW and gain full CW(as i can't get anything else from it...!)
    strange this comes when i roll back guitars volume. even with a small decrease a high pitch annoying sound appears.
    that was all. tomorrow i hope i can find some time and go check my build.
    any input would be creat

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  55. I am going to attempt this as my first pedal build. Am I assuming that the Red Squares with the Red Dots are places where I should cut the conductor strip on the back side of the Veroboard?

    Thanks!

    ReplyDelete
    Replies
    1. Yes.....BUT. The layouts are drawn from the bare component side...as if you have x-ray vision. So mark the cuts on the bare side exactly as you see them here, then flip over to the copper side and make the cut.

      Example...the top right cut on 9V rail is 4 holes in from the right. Use a sharpie and count 4 holes in from the right on the bare side and mark with your sharpie. Flip the board over and you'll see the mark is now on the left side. Cut here.

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  56. Thanks for this incredible resource! Can't wait to finish this build.

    Has anyone had issues with switch pop? Would there be any reason not to add a row to the board for a pulldown resistor from input to ground? Would 1M be suitable? Thanks again!

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  57. This might be a long shot on the oscillation issue but I recall when I had one of these that the circuit board was totally covered in glue(?) sandwiched with some card.

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  58. Just got this built, and while there is some oscillation, I'm quite happy with the gain down a bit. Mine starts around 3 o clock, so I'm not missing out on much. The effect seems quite dark without the presence topped off, so thats where I keep it.

    I taste tested a few different opamps in mine. HA17741, which may or may not be a 741 variant, google wasn't really sure, but it seems very close on the spec sheet if not the same. the HA17741 was a bit harsh, not terrible though. CA3140EZ was dull, underwhelming. TL071 was really smooth, one might say creamy, very rich sounding. Finally the AD711KNZ which sat somewhere between the HA17741 and the TL071, quite nice. I think people may like it as a middle ground, but the sound of the TL071 was the winner for me (for now).

    The circuit was very easy to build. I ended up using a 1N4738 zener diode from tayda and it seems to have worked nicely. Boxed it up in a viola pink 125b also from tayda. http://imgur.com/a/tTRS2

    ReplyDelete
  59. hello i built this overdrive, sounds good for indy rock (thurston mmore uses to have it with sonic youth) BUT even at 0, the gain put is a little bit drive, i can't have " a clean booster" like the original, do you can help me ?

    ReplyDelete