Boss - HM-2 Heavy Metal  [schematic]

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

Re: Boss - HM-2 Heavy Metal

Postby mitchschaft » 23 Nov 2016, 14:22

Just wanted to say R.I.P. to *GodSaveMetal*!!

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Re: Boss - HM-2 Heavy Metal

Postby mister707 » 24 Nov 2016, 15:32

On November 21, in the afternoon, this great friend passed away, Roberto barrios Thays, the great Godsavemetal, now rests his friend.

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https://www.facebook.com/roberto.barriosthays?fref=ts
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Re: Boss - HM-2 Heavy Metal

Postby Dirk_Hendrik » 24 Nov 2016, 18:08

ouch..... :shock:

Rest in peace Roberto. :hug:
Sorry. Plain out of planes.

http://www.dirk-hendrik.com
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Re: Boss - HM-2 Heavy Metal

Postby Fender3D » 24 Nov 2016, 20:45

Yep,
RIP Roberto
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Re: Boss - HM-2 Heavy Metal

Postby kingmafw » 25 Nov 2016, 20:28

Rest in Peace and continue making nice pedals in heaven. You'll probably meet Lemmy Kilmister there [smilie=a_angel.gif] ...
it is mei sizzen net to dwaen

Johannes Harald Kingma - FWS Pedals - Germany
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Re: Boss - HM-2 Heavy Metal

Postby atomicbot » 01 Jan 2017, 04:53

RIP GodSaveMetal. I didn't know him but from what I've read in the thread he was a cool dude. \m/

I'm building the HM-2 based on the vero build on tabboard effects:

http://tagboardeffects.blogspot.no/2014 ... metal.html

I can't seem to find Q2 and Q3 anywhere (a 2SC2240 2SA970, respectively). Would a 2N5088 and 2N5087 work as substitutes for those?
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Re: Boss - HM-2 Heavy Metal

Postby Victor Nery » 17 Jan 2018, 03:23

Greetings,

I was looking into Brian Wampler's "How to modify effect pedals for maximum tone" book and got into a weird stuff (just the info, not the result) about the HM-2 mods.

The frequency he states for the gyrators are tottaly out of the values I've got when I threw them into the amz calculator:

http://www.muzique.com/lab/gyrator.htm

According to the calculator (link above) the stock center frequency would be 86,79Hz for bass control and 958,47Hz/1278,6Hz for treble control.

He suggests inhis mods to change C26, C27 and C30 for 2.2nF, 500pF and 47nF respectively and although the sound is pretty awesome, what he states is too confusing.

Here is what he says about C26 and C27: Stock is around 3kHz and after the mods would be around 7kHz. What I got in the AMZ calculator was 1868,84Hz (C26 - 2.2nF) and 3534,65Hz (C27 - 500pF).

And here is what he says about C30: He says 22nF will give 250Hz, 56nF 100Hz and in the end recomends 47nF but... when I throw in these values in the calculator, the results are tottaly different:

22nF - 152,59Hz
56nF - 95,64Hz
47nF - 104,4Hz

I'd like to understand how he got these results. By the way, here is how my HM-2 sounds after the mods he suggested in his book and some I mods I did on my own (It's an Oliver HM-20, they have the same circuit, though):

https://www.youtube.com/watch?v=zFP2oyoSfok

Thanks in advance.
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Re: Boss - HM-2 Heavy Metal

Postby Manfred » 17 Jan 2018, 09:38

I'd like to understand how he got these results.


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Re: Boss - HM-2 Heavy Metal

Postby Victor Nery » 17 Jan 2018, 12:46

The equation you posted above works exactly as AMZ's. What confuses me are the numbers he mentioned in his book and how he got them. Was that a mistake?
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Re: Boss - HM-2 Heavy Metal

Postby Manfred » 18 Jan 2018, 00:22

Victor Nery wrote:The equation you posted above works exactly as AMZ's. What confuses me are the numbers he mentioned in his book and how he got them. Was that a mistake?

I cannot give you an answer because I do not read the book.
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Re: Boss - HM-2 Heavy Metal

Postby Kukuruzo » 19 Jun 2018, 13:49

Can you please share the book?
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