Monday, 5 May 2014

Boss HM-3 Hyper Metal

Another one for the metal heads.  The 2SK184 JFETs can still be obtained from some sellers on eBay, but it's just a buffer at the end of the day so you can use others with the same pinout like 2SK117, 2SK170, 2SK30, BF244A etc.  The transistors used in the gyrators though don't seem to be readily available and I couldn't even find a specific datasheet so I've used a CBE pinout so you can use a modern NPN transistor like the 2N3904 or 2N5088 etc.

There was a DIP8 version of the M5218L made by Mitsubishi, but they may be hard to source now, so any common dual opamp can be used in there such as JRC4558, TL072, NE5532, LM358 etc.

Info about the original:

Despite its compact size, this effect can put out a richand truly powerful distortion sound which can sustain for very long durations.

Two specially designed Color Mix controls provide for wide ranging tone control.

Whether for solos or for backing, it makes possible a well balanced new age metal sound.







21 comments:

  1. I´ve built this and it works! But then I turn the Distortion up fully, theres some squeeling....any suggestions to fix it? Its a great distortion, worth building.

    Regards Mortua

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    1. ...I used SK30A, OP275 and 2N5088 as substitutes.

      /Mortua

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    2. That's excellent, thanks for verifying. Have you boxed it yet? I always get squeals out of distortion, fuzz and even overdrive pedals sometimes when I test them at higher gain settings before boxing up. The shielding provided by the box usually cures any problem like that. And try to keep separation between the input and output wires.

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    3. Well, I have boxed it now...even replaced all wiring to shielded wire, the squeals remains. The squeals comes then I turn the Distortion up to around 3/4...should I try another value on the pot or do you have an another idea?

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    4. You could try upping the values of 47p to 120p and 100p to 220p. That should take most of the oscillation.
      +m

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    5. I made those changes but the values wasent enogh. I ended up replacing both with 1nf and now it works excellent!
      If thrash/deathmetal is your thing, BUILD IT! =)

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    6. 1n feels like a bit too much as it's bound to cut some top end. I'd suggest using sockets to find the smallest values that stop the oscillation.

      Good to hear you got it running!
      +m

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  3. I have rebuilt this cause I wasent realy happy with the values on those caps. I built it same transistors and IC as my first build and get the same problem with oscilation.
    So I replaced the 5088 with 3904 and used tl072 instead of op275. I changed the 47pf cap to 100 and the 100 to 220 as suggested and now it works perfectly!
    So if anyone builds this I suggest to use TL072 and 2n3904 and change the values to 100 and 220pf.

    Cheers Mortua

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  5. Is it possible to fit in the same holes two electrolytic capacitors in parallel (1uf and 0.47uf) instead of the 1.5uf? I 'm having trouble finding those 1.5uf's.... Am i going to have any problems with the circuit? (New in DIYing.....)

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    1. Yes you'll just have to bend them to the sides slightly (depending on the size of the caps) so you can physically fit them in the space. Both caps will of course keep the orientation required in the layout in terms of the negative and positive leads

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    2. Thank you IvIark!! I was afraid of having smokes and fire out of this pedal...ha ha...
      but if you say so I'll go for it.... Keep up the good work....Cheers from Greece!!

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    1. Finally built this and it's a... Noisy Fuzzy Beast!
      I used 1N4148 diodes,2N3904 for Q2 to Q4, 2SK30 (opposite orientation!)
      for Q1,TL072's and the tip Mark advised me above...
      The only problem is high pitched squeals at higher gain settings
      and squealing when I pull the cable out of the guitar when the effect is on...
      (I get the same cable problem whith my OCD ver3 clone)...Probably something's
      wrong with my wiring...

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  7. somebody have the schematic, because is my first circuit in this board, i dont know where i put the wires..

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  8. sorry I see it, thanks for designe

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  9. Hi
    First I have to say sorry for my bad english.
    I have build the HM3 but I have a problem. If output from guitar is high it sounds ok but if the tone becomes quiter it begins to crackle and then suddenly the tone dies. The distortion trimmer also doesnt work at all - just full distortion.
    Has somebody an idea where to search the problem?
    Thanks
    Kai

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  10. hi
    i am looking for HM3 schematic but using M5218L ic please anyone can help me?

    thanks in advance

    GElias
    E: goncalves.ge9@gmail.com

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