At 22 x 14 this will fit in a 1590B if you file the sides down a bit, but with it being a two stomp effect you'll probably want to put it in a 1590BB or at least a 125B anyway. But it could be squeezed in a 1590B, Box of Rock style, for someone brave/masochistic enough.
Pre Input and Pre Gain 2 are the connections for the Preamp stomp, Input and Level 2 for the main effect stomp, so each can be switched independently.
I have done this as per the scheme of the original, but a few mod suggestions for those that way inclined from D-Day on FSB:
The only way I could get the gain right was to put the tone section before the second op-amp exactly as a regular TS. It also seems to sound better without the 1M from the base of Q2 (mpsa18) to VB. I decreased the 1.5K from pin 1 to 5 to 1K and preferred it. Lastly it seemed to sound best with .47 coming from the clipping arrangement to ground instead of VB.
To use a regular TS style tone control, you would take the Tone 3 connection straight to Level 3, and you would need to remove the EQ Shift switch and the 100n and 3n3 which connect to EQ Shift 1 and 3. Then pins 5 and 6 of the IC connect to Tone 1 and 3 respectively (you will have to alter the row you use for the Level 3 connection), and Tone 2 connects to ground via a 220n cap and 220R resistor in series (or alter the values based on the frequency response you want). We have enough dead on TS clones though which is why I've left it as per the original, but there's the info for those who like to play. :o)
Info about the original:
The Hematoma is a two channel bass guitar pedal consisting of a Pre-Amp and an Overdrive. Pre-amp and Overdrive can be used independently or combined. Carefully constructed circuitry allows the original bass tone to pass through unaltered. No loss of low end. Pre-amp Features: Pre-gain control for up to 5db boost. Overdrive Features: Gain, Level, Tone and EQ Shift toggle which changes the sweep of the tone control and provides a warmer smoother tone when engaged. True-Bypass Switching.
Awesome, thanks IvIark. Going to add this to my build list.
ReplyDeleteI built one of these a few months ago (I made my own vero for it since Mark didn't post one yet). it's a nice sounding bass OD pedal.
ReplyDeleteBTW, here's a couple of pics of it:
ReplyDeletehttp://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Hematoma/01-Hematoma.jpg
http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/Hematoma/01-Hematoma-02.jpg
Man, I am loving the custom Rick basses you made! WOW
DeleteI wish I had wood working skills like that.
Looks great John, nice job!
ReplyDeleteNice!
ReplyDeleteI have long wanted the pedal itself.
that can be put in place 5484?
instead of 5817 and 5818 will go well?
The 5484 should be ok but you may have the tweak the bias so socketing the 12K or 1K8 resistor may be a good idea.
DeleteThe 5818 will be fine.
I'm looking at this as I want to give it a try, but I don't see any wires for input, and a little confused about the comment from d-day. Are those changes that can be made to the board or are they already made? Also, is the tone section already before the second op-amp? Is there even a second op-amp, cause I ont see one.
ReplyDeleteNo. It is left per original schematic.
DeleteAnd it is a dual opamp, meaning that pins 1-2-3 for another opamp and pins 5-6-7 form another.
+m
Thanks Mirosol. I might give I'll put it on the list and give it a try.
ReplyDeleteNeither of the transistors I got match, I'm using 2N5088 for the buffer and an MPF102 for the FET. Will I be OK?
ReplyDeletenot if you want it to sound like the original.
DeleteI don't mind if it doesn't sound like the original, I just want it to sound good. Lol. I mean will I have any biasing problems, etc.
DeleteBag it and tag it. Thing sounds pretty good, gotta say. Nice low-gain, deep-sounding drive even stock, I may mod it a little later on but not really any complaints with it as it sits. I did fry the pre-gain pot though -_- I wonder if I can use my leftover A500K...
ReplyDeleteBut yeah verified. :)
Excellent, thanks Roberto
DeleteYeah don't use an MPF102... it doesn't bias right. 1.2v on the drain XD but the 5088 for the buffer is acceptable as a substitute.
ReplyDeleteI built this and all appears to be working correctly EXCEPT the pregain. I get nothing from this pot whatsoever.
ReplyDeleteI'm assuming that the pre input and pregain pot 2 go to a simple spst switch, correct? Any ideas as to why I have nothing from that pre gain control?
Fwiw, I used a 2n5457 for Q1, and increased the drain resistor from 12k to 47k to get a bias voltage at drain of about 4.7v.
Hello, first time commenter & builder here!
ReplyDeleteSo I just got this done (had me some troubles on the way...) and it works pretty great! I did substitute some parts, though...
For Q2 I used 2n5088 which seems to work "out of the box". For Q1 I used 2n5485 that I had on hand, and replaced the 12K with a 50K trim pot so I got the drain voltage in the ballpark.
Works nicely with my guitar and 2w Marshall-micro amp. :) Haven't yet tried it with a bass, but will get to it next weekend. :)
Nice one, glad it's working for you and wasn't too painful to build!
DeleteNah, just took a bit of re-learning as it's been a long time since I last soldered anything on a board.
DeleteSecond try went almost without a hitch (first build was scrapped as I messed up with the outboard wiring, and on top of that during testing something shorted and let the magic sound out. *Bop*... :D). Just the usual "I've been staring at this mess for so long, I can't see anything anymore", though not nearly as bad as it was the first time.
Also, forgot to mention. I tested different leds (red, green, yellow) for D2 and didn't notice much difference between them. So I left the red one in since that was the first one I grabbed from the bag.
Little confused about this one...Pre Input and Pre Gain 2 are the connections for the Preamp stomp, Input and Level 2 for the main effect stomp.
ReplyDeleteSo pre input is the input wire and pre gain 2 is the output wire for one 3pdt
and input and level 2 are the input and output for the other 3pdt?
Yes it's confusing, I don't know how anyone has built it based on that crap description :o)
DeleteI'll redo the notes later
I found an error in the circuit vs the original PCB. R13 (1K5, connected to C6, 0.47uF) does not connect to D2, but should connect to pin 2 of IC1. See attached pic.
ReplyDeletehttps://goo.gl/jTNZUH
This was found by detailed analysis of the original PCB on FreeStompBoxes.org