Boss - HM-2 Heavy Metal  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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nofarewell
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Post by nofarewell »

Hi everyone! I'd want to ask since I'm not the best in planning: has ever, anyone reconstructed this pedal in a way 'madbean' did it with Dr. Boogey? I'd need a version which can be done differently, where on the other side of the PCB I can insert the pots. If someone ever did it, please post it to me, if not and it's easy, do it for me please :) It would be a great amount of help to me, and would be much appreciated.

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GodSaveMetal
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Post by GodSaveMetal »

nofarewell wrote:Hi everyone! I'd want to ask since I'm not the best in planning: has ever, anyone reconstructed this pedal in a way 'madbean' did it with Dr. Boogey? I'd need a version which can be done differently, where on the other side of the PCB I can insert the pots. If someone ever did it, please post it to me, if not and it's easy, do it for me please :) It would be a great amount of help to me, and would be much appreciated.

Ahhh you wana true by pass??? no matter The famous of this pedal is what it is!!!! electronic send return with booster!!!!
Taste It; is great IT!!!!!

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nofarewell
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Post by nofarewell »

To be honest I'd want a ptp version. I would spend my whole life making pcbs but I'd prefer if I could do it in a ptp way. Size doesn't matter. :)
GodSaveMetal wrote:
nofarewell wrote:Hi everyone! I'd want to ask since I'm not the best in planning: has ever, anyone reconstructed this pedal in a way 'madbean' did it with Dr. Boogey? I'd need a version which can be done differently, where on the other side of the PCB I can insert the pots. If someone ever did it, please post it to me, if not and it's easy, do it for me please :) It would be a great amount of help to me, and would be much appreciated.

Ahhh you wana true by pass??? no matter The famous of this pedal is what it is!!!! electronic send return with booster!!!!
Taste It; is great IT!!!!!

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GodSaveMetal
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Post by GodSaveMetal »

nofarewell wrote:To be honest I'd want a ptp version. I would spend my whole life making pcbs but I'd prefer if I could do it in a ptp way. Size doesn't matter. :)
GodSaveMetal wrote:
nofarewell wrote:Hi everyone! I'd want to ask since I'm not the best in planning: has ever, anyone reconstructed this pedal in a way 'madbean' did it with Dr. Boogey? I'd need a version which can be done differently, where on the other side of the PCB I can insert the pots. If someone ever did it, please post it to me, if not and it's easy, do it for me please :) It would be a great amount of help to me, and would be much appreciated.

Ahhh you wana true by pass??? no matter The famous of this pedal is what it is!!!! electronic send return with booster!!!!
Taste It; is great IT!!!!!

Well take your time make your own PCB!!!!!!!!!!!

I wana´see it 8)

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Freppo
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Post by Freppo »

I've been wanting to build the HM-2 for a long time..
So I though i'd give it a try at making my own layout, so here it is. :)

I've exchanged the IC's and transistor to modern more common ones.
I had to make two separate boards because of the size.
But they both fit comfortably inside a 1590BB.

Image
Image
Image

Built and verified by me. Sounds good, definitly has the HM-2 tone!
Might just have a tad less gain then the original, but I can't say for sure since I don't own one.
I will borrow one from a friend and compare when I get the time.
Attachments
hm-2ny.gif
HM2eq.gif
HM2mainv1.gif
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Freppo
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Post by Freppo »

Oh, and btw..

I did get some oscillation when the gain was maxed.
But increasing the value of C5 cured that, so try socketing C5 just in case.

I also changed the pot values from the schematic to values I think works much better.
But feel free to experiment :)

cheers
/ Fredrik
Check out my building blog at http://www.parasitstudio.se

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Freppo
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Post by Freppo »

Another update...

I borrowed an original from a friend today to compare.
My layout/clone has way less gain and sounds a bit bassier aswell.. :(

Probably because of the transistors, so I will try out a bunch of different ones to see if I get closer to how it should sound.
Check out my building blog at http://www.parasitstudio.se

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Post by Slabbefusk »

Hello people,

I finished making my first clone of this recently. Made a big PCB since a friend of mine wanted to have it rackmounted. Thing is that it doesn't have nearly the distortion I though it would have. I'm not sure but could it be a poor choice of GE-diodes? I just took ones I had at hand which were AA119.

I'm going to try increasing the available gain in the first OP-amp stage to see if I get more volume and grind out of it.

Also, what transistors have you guys used when building? I used a BF 245 as in the schematic but couldn't find the other two so I picked a 2N5550 for the NPN and a 2N5401 for the PNP.

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Slabbefusk
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Post by Slabbefusk »

I put a BC547B and BC557B in there instead and now it sounds like it should! :D

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GodSaveMetal
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Post by GodSaveMetal »

Slabbefusk wrote:I put a BC547B and BC557B in there instead and now it sounds like it should! :D
whatbtransistor you replace man??

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candletears7
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Post by candletears7 »

Excellent work mate. :D
There's another thread here on FSB where a guy made a rackmount version with different transistors and like you he got much lower gain. He used the correct ones and got tonnes of gain back.

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Freppo
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Post by Freppo »

candletears7 wrote:Excellent work mate. :D
There's another thread here on FSB where a guy made a rackmount version with different transistors and like you he got much lower gain. He used the correct ones and got tonnes of gain back.
Cheers! Yes, I tried BC547B and BC557B for transistors (for Q2/Q3) and I get almost the same amount of gain as the original, but it's still lacking the same "bite" as the original and it's not as loud either.. :?
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Post by soulsonic »

This is not expensive. In fact, I think they cost more than this new in the 80's: https://www.ebay.com/itm/Boss-HM-2-Heav ... 33873eecc5
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

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Slabbefusk
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Post by Slabbefusk »

GodSaveMetal wrote:
Slabbefusk wrote:I put a BC547B and BC557B in there instead and now it sounds like it should! :D
whatbtransistor you replace man??
I replaced the 2SC2240 with the BC547B and the 2SA970 with a BC557B.

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Post by Slabbefusk »

At first I put a 2N5551 instead of the 2SC224 and a 2N5401 instead of 2SA970. I don't know why i picked those replacements in the first place, I guess I trusted google too much. Now there is a BC547 where the 2SC2240 is originally and a BC557 instead of the 2SA970. Is there no editing function on this forum? :?

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Post by GodSaveMetal »

Slabbefusk wrote:At first I put a 2N5551 instead of the 2SC224 and a 2N5401 instead of 2SA970. I don't know why i picked those replacements in the first place, I guess I trusted google too much. Now there is a BC547 where the 2SC2240 is originally and a BC557 instead of the 2SA970. Is there no editing function on this forum? :?
Please note hte 2SA970 is a PNP E-C-B and the BC557 is a PNP E-B-C watch the pinout!!!! :hmmm:
Also the 2SC2240 is a NPN E-C-B and the BC547 is a NPN E-B-C watch the pinout!!!!!!!!!!! :?

Please read all my recomendations and changes!!!!!!!!!! :twisted:

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Post by macsniper »

Hi,

I tried to build one using your layout. Doesn't work yet, I have some strange issues with the voltage divider (Voltage drops to 1.7V, not to 4.5V, but I'm not sure thats the problem why I don't get any sound). Anyway, I noticed a mistake in your layout: In the schematic, C3 is between 4.5V and ground. In your layout, C3 is between +9V and ground. Not sure if that makes any difference though...

cheers

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motormenace
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Post by motormenace »

Is there a layout that adds a mid knob?

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Post by darmstat »

I don't lnow if this will help you but this is what i did for mine.

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Freppo
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Post by Freppo »

macsniper wrote:Hi,

I tried to build one using your layout. Doesn't work yet, I have some strange issues with the voltage divider (Voltage drops to 1.7V, not to 4.5V, but I'm not sure thats the problem why I don't get any sound). Anyway, I noticed a mistake in your layout: In the schematic, C3 is between 4.5V and ground. In your layout, C3 is between +9V and ground. Not sure if that makes any difference though...

cheers
Hi!
Thanks for spotting the error, correcting it actually helped with reducing the oscillation I had problems with earlier. :D :thumbsup
The fix was very easy, just move the positive leg of C3 down to row F. I will update and post the changed layout soon.
Now it's working 100% for me. Strange that you get 1.7v at the voltage divider.. I hope you find the problem.

Cheers!
/ Fredrik
Check out my building blog at http://www.parasitstudio.se

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