HBE Hematoma Bass Overdrive/Preamp (guts)  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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D-Day
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Post by D-Day »

hematoma.jpg
A friend brought one of these in to the studio that I frequent and it sounded great. He let me borrow it to show you guys. From reading around the web I find out that it's YATS but the thing sounds great and it's relatively well put together so I figure there's no harm in getting it naked. It was gooped but I cracked that fairly easily and with no harm done! The only thing in question is C7. I mean I assume that's a cap. I suppose I could cross reference a TS schem and get a working value but I'm not terribly interested in building one of these (it's the only TS derivative I can think of that I've really enjoyed and even then only for bass which I don't really play) so it's no big whoop to me. I'll leave it torn apart on the desk for awhile in case anybody needs further info. Below are gut shots, BOM and wiring guide.

Labeled board:
hematoma-board-labeled.jpg
Labeled toggle:
hematoma-toggle.jpg
hematoma-toggle.jpg (53.57 KiB) Viewed 3331 times
Numbered footswitch:
fswitch.jpg
fswitch.jpg (33.32 KiB) Viewed 3331 times
Parts side:
hematoma-parts.jpg
Solder side:
hematoma-copper.jpg
A couple of misc gutshots:
hematoma-guts.jpg
hematoma-guts1.jpg
BOM

IC1 - 4558

Q1 - 2N5484
Q2 - MPSA18

D1 - silicon
D2 - silicon
D3 - LED
D4 - 1N4001

C1 - 1n
C2 - 4u7
C3 - 100u
C4 - 47u
C5 - 47n
C6 - .47u
C7 - ?
C8 - 50p
C9 - 4u7
C10 - .47u

R1 - 47K
R2 - 10M
R3 - 1K8
R4 - 100K
R5 - 1K
R6 - 10K
R7 - 12K
R8 - 1M
R9 - 10K
R10 - 10K
R11 - 10K
R12 - 47K
R13 - 1K5
R14 - 1M
R15 - 1K
R16 - 10K
R17 - 10K
R18 - 1K5
R19 - 1K
R20 - 1K
R21 - 1K
R22 - 1M

CONNECTIONS

PRE
1 - GND
2 - BP 2
3 - board

GAIN
1 - board
2 - board

TONE
1 - LEVEL 3
2 - TOGGLE 2
3 - board

LEVEL
1 - GND
2 - OUT
3 - TONE 1

BO FOOTSWITCH
1 - LED
2 - board
3 - LEVEL 2
4 - GND
5 - BP 6
6 - OUTPUT JACK TIP
8 - bypass
9 - bypass

BP FOOTSWITCH
1 - CIRCUIT IN
2 - PRE 2
3 - LED
4 - INPUT JACK TIP
5 - BO 5
6 - GND
7 - bypass
8 - bypass

Never degooped or took part in an RE before so let me know if I've done something wrong or have not been thorough enough.

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bubstance
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Post by bubstance »

Could you remove the pots and post the values?

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D-Day
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Post by D-Day »

Oh duh! I wrote that down and forgot to include it. Thanks for reminding me.

PRE = B100K
LEVEL = B100K
GAIN = B500K
TONE = B10K

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bubstance
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Post by bubstance »

Blammo.

As always, report any errors, blah blah blah, herp derp herp.
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Hematoma.png
Hematoma.png (7.63 KiB) Viewed 3216 times

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D-Day
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Post by D-Day »

Nice one! My girl leaves town tomorrow and I'll give it a good look then. And jeez the youtube videos for this thing paint it in a pretty bad light. People who have wielded overdrives with bass before should be able to get something real sweet out of this.

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Post by bubstance »

Yeah, I noticed the same thing about the YouTube videos.

On a different note, a test value for the "?" capacitor could be around 1µF.

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pedalgrinder
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Post by pedalgrinder »

this is my thoughts hey bubstance great trace good one!!! if you added a charachter pot same as the tubezone. I found with bass it's excellent as it tightness the flabbyness of the distortion up. It would only take say a 1uf cap and a pot of the 2 distortion diodes and you can control how to tight so to speak the distortion is on the lower bass notes when used on a bass. Try you will see what i mean. Cheers
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D-Day
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Post by D-Day »

Sorry for the long interval guys. I have a very old dog who is just coming apart at the seams these days. If it's between my dog and YATS I'll make the same choice every time.

Okay, C7 is (or might as well be) 1uf. 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. The whole thing works as you've drawn it Bub, but it sounds just like the original with these changes.

I have to give this thing back soon so if there's any info anybody'd like please let me know asap.

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Post by daemons »

Hello,

I know this is an old thread, but I was looking into building this pedal.
I prefer having the part references and not only the values, so while I was checking the schematic I believe I found an error :

R13 - 1k5 connects on one side to C6 (0.47uF, in turn connected to VB), just like the schematic. :thumbsup
But the other side of R13, by tracing the PCB should connect to pin 2 of IC1, and not to junction R12/R11/D2/D3. :!:
R13 and R12 are not connected together in any way. You can verify this looking at the copper side image.

So that might be why D-Day needed to make changes to make it work correctly.

This also means the stripboard version posted on tagboardeffects is incorrect.

Btw, thank you D-Day for the photos and values. Great job! :) :thumbsup

Dae.
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Schematic error
Schematic error
Hematoma_err.png (4.9 KiB) Viewed 2486 times

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daemons
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Post by daemons »

Well I've been waiting for close to 2 weeks for an answer from bubstance with no response, so here is my redrawn and corrected schematic for the Hematoma with part references. I made the correction for R13, as well as added the pinout for both footswitch so hopefully it makes it clearer for everyone. I also added the LEDs, as they were on the original PCB. Let me know if I missed anything, or if you have any questions.
Updated HBE Hematoma schematic
Updated HBE Hematoma schematic
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Daemons

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Post by Silver Blues »

I built one of these using the Tagboard vero layout and it works just fine for me. It does have a very dark sound to it (expected, I was informed this was the natural case) and I made a few mods to the tone control and whatnot and it sounds good. :hmmm:

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Post by D-Day »

daemons found an error!

5 - should be BP 5

Can a mod please edit?
D-Day wrote: BO FOOTSWITCH
1 - LED
2 - board
3 - LEVEL 2
4 - GND
5 - BP 6
6 - OUTPUT JACK TIP
8 - bypass
9 - bypass

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D-Day
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Post by D-Day »

daemons wrote:Well I've been waiting for close to 2 weeks for an answer from bubstance with no response, so here is my redrawn and corrected schematic for the Hematoma with part references. I made the correction for R13, as well as added the pinout for both footswitch so hopefully it makes it clearer for everyone. I also added the LEDs, as they were on the original PCB. Let me know if I missed anything, or if you have any questions.
Hematoma.png
@bubstance, if you want your nickname removed from it, let me know and I'll change it.

Daemons
Thank you daemons!!!

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Post by Manfred »

I made a PCB-clone from the first version for my private use:
I don't know if the dimensions matches the original size, because a created it form shots.
It is not verified in practice, but verified by the SprintLayout6 trace function.
HematomaLayout.JPG
HBE_HematomaComponentSide.pdf
(23.67 KiB) Downloaded 51 times
HBE_HematomaSolderSide.pdf
(5.72 KiB) Downloaded 49 times
HBE_HematomaSolderSideMirrored.pdf
(5.76 KiB) Downloaded 48 times
SprintLayout6:
HBE_hematoma.zip
(25.57 KiB) Downloaded 51 times

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