freestompboxes.org

Schematic from DOD

That's certainly prettier than mine.
Where'd you get it from?

Oh, here's an update based on the PDF:

I requested it from DOD and a few minutes later it was in my email.

EddieTavares wrote:It looks like a modified infamous boss hm-2:

http://1.bp.blogspot.com/-k5ZZPH95Fxg/T ... 2BHM-2.gif

that's the same I thought aboutwhen I looked at the schematic!!! wouldn't it be all SMD it'll be quite easy to mod these to more HM2-vibes!

I have the HM-2 and Boneshaker. There are some similarities to the HM-2, but they sound very different to my ears.

If you block it out,

The Boneshaker is SHO -> Opamp gain stage with Depth -> Si diodes to ground -> gyrator eq (or just SHO -> DOD 250 -> eq)

The HM-2 is two transistor gain stages -> TS style soft clipper -> GE diodes in line -> SI diodes to ground -> gyrator eq

While the gyrators are similar, the clipping section is quite different. The HM-2 is a hodgepodge of clipping stages, and IMHO suffers from it. Plus the GE diodes in that configuration are fairly uncommon in dirt boxes. I think removing some of the diodes in the HM-2 might actually improve it. I've jumped the GE diodes and preferred it.

For the Boneshaker, it might be interesting to put a 5k gain knob in place of the 820k resistor. That would complete the SHO circuit. Stock, the BS always has some distortion, even at the lowest gain setting. I imagine it would act as a saturation control. Then add a switch to bypass the DOD 250 section. A SHO into a semi-parametric eq would be very useful.

Khas Evets wrote:The HM-2 is two transistor gain stages -> TS style soft clipper -> GE diodes in line -> SI diodes to ground -> gyrator eq

While the gyrators are similar, the clipping section is quite different. The HM-2 is a hodgepodge of clipping stages, and IMHO suffers from it. Plus the GE diodes in that configuration are fairly uncommon in dirt boxes. I think removing some of the diodes in the HM-2 might actually improve it. I've jumped the GE diodes and preferred it.

FYI, those are coring diodes. IIRC, they function as a crude noise gate.

Gila_Crisis

Years ago a friend gave me one hm-2. Honestly I have never used that out of my house, some days ago I got it to apply some mods to make it sound more "Boneshakerish" and it sounds much better now. I just increase the feed back resistor r15 to 330k to reach the gain that I've heard in the videos.

In the eq section I don't want to add more pots but find some values that sound better in my rig, so I decided to keep the two tone control and maybe I set internally the mid control cutting some db's at 500 to 800 hz.

Khas Evets

Off course they are not the same, hm-2 imho is a peace of ***** but both have almost the same building blocks, the boost and drive sections cam be easily applied in the HM-2, there is no space in the enclosure to add 5 more pots but I'm setting internally the frequencies and band width to something more usable with my guitar and amp.

FYI, those are coring diodes. IIRC, they function as a crude noise gate.

They do function as a noise gate, but they also introduce crossover distortion, which is the part I don't care for.