Dunwich released a small run of DIY PCBs a few years ago of a modified HM2. There is a few changes from a stock HM2 most noticable the on/off switches for both soft clipping and hard clipping diodes. You may want to experiment with the cap values at one of the gyrators for a more effective separate Mid control. AMZ and Griffin Effects have very useful bandpass filter/gyrator calculators.
Built this up this evening and it sounds like an HM-2. Everything works except for the overall volume level - it isn't anywhere near as screaming loud as every other HM-2 variation I've built. I'm going to look over my work tomorrow and see if there is anything I missed.
ReplyDeleteColl!
DeleteThanks for giving it a try!
For your earlier HM2 builds, did you build it stock or did sub any of the component values?
I socketed all the semiconductors and tried out a bunch of different parts - but it did not seem to have much effect on the overall gain & volume. I was wondering if the original schematic was online anywhere? I couldn't seem to find it.
ReplyDeleteAnd as far as previous builds go - I have done both stock and builds with part subs. Testing out an HM-2 circuit for me has always been putting all four knobs at max and seeing what pitch the feedback whine is.
DeleteNo, the build doc and schematic is not online as far as I know. A friend sent me a PDF file for it but I'm a bit hesistant to upload it here without Mr Dunwich permission...
DeleteBut I can send the file to your email, if that is ok with you?
I would like that very much - you can email it to stellokronix@gmail.com
ReplyDeleteI finished this off last night and it works perfectly, I'd say tag it!
ReplyDeleteThis is a great sounding hm-2, now back to see why my left hand path version doesn't sound as it should.
Thanks! It is now tagged.
DeleteSo...what's wrong with your Left Hand Path?. No sound? Noise? Lack of output?
It just seems like the tone knobs don't behave like they should, I need to check and make sure I've got the eq pots are wired correctly. I've looked over the board a couple of times and all the components, links and cuts are in the right place.
ReplyDeleteDoes all the tone controls act wierd or just a few of them?
DeleteFrom memory it's both mid controls but it could be all of them, its hard to get a usable sound out of it. It's got too much high end. Need to open it up and check it out as im sure I did something wrong somewhere.
DeleteJust had time to check it out and exactly as I thought. I had a couple of the eq pot 1&3 lugs wired up wrong. Now this thing kills!
DeleteHey - I am going to have a go at this one....Is there 2 SPST Switchs? Are they both on/on or on/off?
ReplyDeleteSPST is always on/off. You can also use SPDT on/on.
Deletehello sir may i have the schematic for this layout? if possible, I will be very happy, and this is my email hsjshrbjysbmsjn@gmail.com thank you
ReplyDeleteHello. Is any possibility to get the schematic for this HM2 layout, please
ReplyDeleteand thank you.
My mail is allkon844@gmail.com