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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dai h.
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Post by dai h. »

hey, don't let one person's subjective opinion put you off (or anyone else for that matter) from liking it. :wink:

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juni
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Post by juni »

dai h. wrote:hey, don't let one person's subjective opinion put you off (or anyone else for that matter) from liking it. :wink:
Of course i wont! No worries 8)

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Lovekraft
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Post by Lovekraft »

soulsonic wrote:SWEDISH CHAINSAW TONE FOR LIFE!!!!!!!
Funny thing, my buddy in Sweden wants me to find a bunch of these for him, I guess it's the Swedish Death Metal pedal of choice! It does sound pretty cool in the Godflesh video. I used to listen to Entombed as well, still break out some Carcass occasionally!

Ethan

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yahoo!
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Post by yahoo! »

i'll post my hm2 here. wait for the pics

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Tomby
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Post by Tomby »

Hi all!

First post here. Really interesting forum.
I'm not an electronics expert, so I would like to ask you some questions.

-A friend of mine had a HM-3 stompbox which didn't work, so I took it a few years ago and actually used it for parts to repare other audio gear.

So I'm currently thinking about using the box either for
-a repared HM-3, but I remember the sound didn't convince me when it worked fine.
-another dist, if possible using mainly the original parts.
-a HM-2 stompbox since i love swedish DM sound, but I looked at the drawings and except the names HM-2/HM-3, these stompboxes don't seem quite close from each other.


What do you think about that. Any mod suggestions? Any comments on HM-2 HM-3 schems?
(I found these on this forum:
HM-2: http://nicosonic.free.fr/schems/BossHM2.pdf
HM-3: http://nicosonic.free.fr/schems/BossHM3.pdf )

Thanx!

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Tomby
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Post by Tomby »

So....
sorry for being off topic speaking about HM-3 but..... I just repared it and it sounds very interesting in fact :thumbsup
I'd really like to compare it to the HM-2.

I think I'll try some mods on it but keep the original basis. I dont see the "typical HM parallel diod" in HM-3 so Icould test it in the same place as HM-2.
I find the bypass really bad. Is there a way to improve it without going true-bypass which I don't really need since I'll mostly use this pedal for studio recording. I did a mod on an SD-1 and by changing a resistor it was suppose to have a better bypass.

Anyway, as a studio experimentation stompbox, any mod suggestion to have different sounds would be appreciated.

Thank you!

-(I may create a new topic for HM-3 if you think it would be better, but since I found almost no info on it I tought it would be more interesting to post there)

-Off topic too: I found nothing here about Guyatone Metal Monster. This stompbox doesn't fully satisfy me, so if some of you are interested to create a topic about it or know where to find information.... PM me

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nooneknows
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Post by nooneknows »

Little OT: I've played a behringer HM300 and I'm quite sure it's a plain copy of the HM-2, if anyone is interested in....

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AFF
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Post by AFF »

Thanks for the part swap info Bside.

Can anybody or would anyone be willing to decifer the hm-2 circuit?

I have a copy of it so let me know if you need it. I honestly cannot read schems that well anymore and I hate to ask.
C30 makes me think that it is part of a tone control and that I can comprehend but looking at the schematic I start seeing the lines moving and things start looking like weird shit ... even stare at the clouds and make figures ... yeah that what happens now.

Anyways I appreciate any help!
Oh by the way I bought another hm-2 from my local pawn shop ... it is a MIJ and it works perfect and I only paid 20 bucks plus 1.60 for tax!!! So I am going to mod my MIT HM-2.
Long live swedish death metal buzzsaw TONE!!!
Thanks
AFF

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AFF
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Post by AFF »

AFF wrote:Thanks for the part swap info Bside.

Can anybody or would anyone be willing to decifer the hm-2 circuit?

I have a copy of it so let me know if you need it. I honestly cannot read schems that well anymore and I hate to ask.
C30 makes me think that it is part of a tone control and that I can comprehend but looking at the schematic I start seeing the lines moving and things start looking like weird shit ... even stare at the clouds and make figures ... yeah that what happens now.

Anyways I appreciate any help!
Oh by the way I bought another hm-2 from my local pawn shop ... it is a MIJ and it works perfect and I only paid 20 bucks plus 1.60 for tax!!! So I am going to mod my MIT HM-2.
Long live swedish death metal buzzsaw TONE!!!
Thanks
AFF
I think I should have also added that I was looking for soomeone who would be willing to list things like... C?? and R?? affect the freq for the highs and C?? and R?? control the lows .... R?? controls the amount of distortion you seem to hear .... does that make sense? If you think you would be willing to do this then send me a message and we can work something out for your hard work!
Thanks
AFF

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Ubelkeit
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Post by Ubelkeit »

First of all, hello!!

I'm into Swedish death metal for years but it was 2 weeks ago when I decided to play in a band with some friends (2 at this moment!!! :oops: ). I heard about this pedal to achieve that great sound, but I'm a big fan of DIY and this brought me to freestompboxes.org!!!
I found in the net a lot of schematics and photos of the pedal, but I can't find the pcb layout (I'm not skilled for electronics at all!!!!!!) and it's better for me to see more or less where the components are placed, because I draw with pcb wizard and the results aren't good enough and I can't decipher anything!!
I would like to know if somebody could send me a PCB layout of Boss HM-2 and wiring process.

Thank you and sorry for my english!!!!!!!

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Ubelkeit
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Post by Ubelkeit »

Hello!!

I'm looking for the pcb layout of Boss HM-2...! Yes, I know that another post of the same pedal is open, but I've found some photos and schematics (I'm not skilled in electronics) and it's really hard for me to understand those things.
I've found in another post the whole inside of Boss CS-3 and that's what I want!!!!!!!!

Thank you very much!!!!!!

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Post by RnFR »

please don't start another topic for a pedal when one already exists. all of this is stated in the forum rules. please read before posting.

thank you.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

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Post by MoonWatcher »

soulsonic wrote:Charon was absolutely right-on! All the knobs all the way up absolutely NAILS the old Entombed sound! The frequencies of the Hi control are exactly the perfect Swedish Chainsaw mid peak!!! I feel like a fool for not getting one of these years ago.

These crazy on-the-edge guitar sounds are what sets that kind of music apart... whether it's the Chainsaw tone of Entombed or the crushing squall of Godflesh, the HM-2 has been a key ingredient to many underground metal bands, and it's a tradition that will live on and hopefully be re-discovered by new generations.
Wow - I've been searching high and low for this info FOR YEARS. Left Hand Path and Clandestine are two of the heaviest guitar tone albums that I've ever heard. The strange mids and how to get them just right has haunted me since I first heard those records. Carnage's Malignant Epitaph gets the same thing going. It sounds like a combination of a notch and a peak, and the crossover distortion diodes probably have something to do with it, as well.

...I'm also a huge Godflesh fan, and Slateman is probably my favorite of all. Justin just seemed to wrangle a bit more harmonics out along with all of the typical cacophony that was going on. I was chasing the tone on that song so hard that I had to get the same JCM800 that he used. The tones on the Jesu records aren't bad, but they're just a bit different.

Best runner up tone was Carcass. Everything prior to Exhume to Consume was a bit too jagged (or just poorly produced), but Bill refined it just enough make it work. It's cool that they're back together again, at least for now.

Standard tuning dropped to B with a combination of tube amp distortion and the right stompers always seemed to be the magical combination, but I never could nail the tones on those first two Entombed albums.

I've got to get me some HM-2's. I'm glad that I stopped to read this thread!

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Post by soulsonic »

I'm very happy to see another fan of this music here! :D
I've been getting some very cool results lately with the combination of a Rat set to low gain boosting the HM-2. The Rat tightens the sound up in a good way and adds a nice edge. This sounds best when the Hi control isn't boosted like crazy - when it's set lower and slightly more scooped. The edge from the Rat keeps it from sounding dull.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

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Post by MoonWatcher »

You know - I think I'm just going to cut to the chase on this one. I have FX59 that I tried to tweak into an HM-2, but the pcb is really ragged. And I could kick myself, as I had a pair of FX56, but they are long gone...

...It's that active bandpass circuit at the end that has got to be the critical part, IMO. I think I'm going to build a SDMEQ box (Swedish Death Metal EQ) that provides the peaks at 87 Hz, 958 Hz, and 1279 Hz, just like the tail end of the HM-2 and throw in three separate pots, like the Boss and DOD boxes should have had in the first place. That way, I can put the EQ after my other dirt boxes and see what combo really marries well. It would be fun to mess with the stock Q's as well, although 3.5 to 4 is probably optimal.

Probably Rat->SMEDQ->Boost would be what I think would work, as well. Slammming a LM308N slewing mess into that EQ would just have to sound like Sinners Bleed, methinks.

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Post by RnFR »

MoonWatcher wrote: ...It's that active bandpass circuit at the end that has got to be the critical part, IMO. I think I'm going to build a SDMEQ box (Swedish Death Metal EQ) that provides the peaks at 87 Hz, 958 Hz, and 1279 Hz, just like the tail end of the HM-2

that's a cool idea. i would be sure to put a buffer in before the EQ though, as you might get some unforeseen impedance issues on the effect previous.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

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Post by Curby »

I havent found a pcb for this unit, so I'm working on my onw, but if someone have a PCB it would be nice :)
Or i am blind and found nothing on the internet :(

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Post by MoonWatcher »

I just got a nice road rashed HM-2 yesterday in a trade. The funniest part is that someone scratched "Joe Perry" on the treadle plate. Yeah, that's the guitarist I think of when I hear the HM-2.

Now I get bet my Sinner's Bleed and When Life Has Ceased jones satisfied, even through a Blackheart Little Giant...

Yeah - this one needs to stay stock, for the most part. Probably a trimpot in the battery compartment to allow for separate mixing of the T & B. I'm very tempted to replace the electros and tants with metal film for the 1uF (and smaller) and nonpolarized E's for the few 10uF caps, but kinda wondering if I'll end up neutering the thing.

And a switch to bypass the crossover diodes, as well. Funny that no one has mentioned to also short out the 10K preceding it. Come to think of it, R30 s/b reduced to 1.5K to 2.2K, IMO. So probably a switch that does all that would work best.

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Post by wgtp »

IIRC the 2 "in-line" GE diodes produce "crossover" distortion which is also produced by class AB tube power amps when driven hard. These include just about anything putting out more than 15 watts with dual or quad output tubes . Marshalls, Fenders, Boogie, Soldano, etc. It distorts the smallest signals instead of the largest, adding a low level grit that may be hard to hear with everything else going on with this pedal. Using Silicon diodes produces a more pronounced effect. You may or may not like it.

It appears the idea behind this pedal is for the first set of 3 diodes in the feedback loop to approximate the asymmetrical distortion of a pre-amp with the GE diodes and the Silicon diodes to ground approximating the symmetrical power amp distortion. Messing with the cap values in the tone controls should allow for additional tweaking of the tone.

They also have a noise gate effect as stated above. ;)

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Post by f2netxxx »

i read this topic, but didnt found anything for what to change to use it with bass guitar.

can anyone tell me what to change in this schematic:
http://nicosonic.free.fr/schems/BossHM2.pdf

thanks!

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