Here is a sound sample from a cheap clone. Can you recognize the original dirt circuit ? Please ?

eh là bas ma

eh là bas ma

Well-known member
Hello,

Here is a sound sample i made, max gain at 0:55 :

https://soundcloud.com/ehlabas-ma-chaussure%2Fsd100samplewav

This is one of my first stompboxes ever. A cheap clone bought second hand on internet, years ago.

The circuit has been sold under various brand names : Xpression SD-100, Boston SD-100, Odak SD-100, WSL SD-100, Harley Benton SD-100...

I always liked its sound, but never could find the real original circuit. That's too bad because the clone is probably made of cheap parts and some settings are unusable because of some loud background white noises introduced in the signal. Happens when High or Sustain are set anywhere in 2nd half of rotation, also when Dist is set on high values. There's a big "shhhhh" between each note, it's so annoying... It gets better with a noise gate, but not totally fixed, unfortunately.

I thought i'd try my luck on this forum, just in case...

I already tried to find out what it is 2 years ago, but no luck. Here is the previous thread i started about it, you'll find some pcb pictures reply #9 :

How to reduce background noises on a smd-built distorsion clone ?

How to reduce background noises on a smd-built distorsion clone ?
www.diystompboxes.com

Can someone recognize this specific distorsion ? Or at least something very very similar ?

No ? Please close your eyes, empty your mind, listen to the sample from 0:55' once again... i am begging you !

3 ICs, 14 transistors , 9 diodes, around 60 resistors and 30 capacitors. What could it be ?

I can provide better pictures if needed.

Every observations, comments, wild guesses and straight answers are welcome.

Thank you for your help.
 
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Not able to listen at the moment, but I have to say that my first instinct is something in the Rockman world— the mention of the VCA in the thread you linked makes me think of something functionally similar to the Rockman Ultimatum (or any of the other Rockman distortion circuits, which features a compression circuit as part of its core sound. Likewise, the name SD-100 makes me think of SD&R and the X-100. Add to that the fact that it was sold under a brand name of “Boston,” which I can’t find any history of making other pedals the way the other brands it was badged as did, makes me feel that they were really leaning into this having some sort of Rockman-ish dna. Maybe not an actual Rockman circuit, but a more cost effective stab at one?
 
eh là bas ma said:
Can someone recognize this specific distorsion ? Or at least something very very similar ?
Click to expand...

Bricksnbeatles said:
Not able to listen at the moment, but I have to say that my first instinct is something in the Rockman world— the mention of the VCA in the thread you linked makes me think of something functionally similar to the Rockman Ultimatum (or any of the other Rockman distortion circuits, which features a compression circuit as part of its core sound. Likewise, the name SD-100 makes me think of SD&R and the X-100. Add to that the fact that it was sold under a brand name of “Boston,” which I can’t find any history of making other pedals the way the other brands it was badged as did, makes me feel that they were really leaning into this having some sort of Rockman-ish dna. Maybe not an actual Rockman circuit, but a more cost effective stab at one?
Click to expand...
My experience with the Rockman X100, a few of their other headphone units, Acoustic Pedal and Ultimatum taught me that genuine Rockman gear does not use VCA topology and relies mostly upon opamps and precious few carefully selected JFETs. And as all genuine Rockman gear was manufactured under the "SR&D Rockman" brand, the use of "Boston" in any other pedals brands (IMO) is as reaching as the "Mockman" circuit in its attempt to mimic a genuine Rockman.

The compression feature in most Rockman (non-rack-mount) gear is comprised of a carefully selected & biased JFET applied into the negative feedback loop of an opamp that is situated early in stage of the circuit's signal path.

TBH and further illustrate my opinion, with the auto-compression schemes used in internet technology, audio circuits in PCs, laptops, tablets & phones and the slew of audio codecs so applied to audio files therein transferred, tends to throw off any accurate reproduction of dirt circuit recordings - especially those with any sort of compression.

And I think the attached audio file bears no resemblance to the Rockman X100, their other headphone amp series, or the Ultimatum. The compression used in Rockman gear seems tuned to solely for coping with & reducing attack transients, while the compression I detect in the audio sample seems to be tuned more toward sustain. So, I suspect no real resemblance to Rockman topology.

Unfortunately, I have nothing with regard to what sort of circuit topology the Expression SD-100 pedal uses. An accurate circuit trace could render the best results. Maybe Harley Benton or one of the other vendors of that pedal might be willing to share the schematic. And FWIW, in my quick searches while writing this, I found the SD-100 readily available from different places on the net for around 50 zorkmids. It's distributed as the "SD-100 Soft Distortion" under at least a dozen different brands.
 
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Thanks for your replies !

I checked again, since the Boston brand name caught your attention.

It's "Boston engineering" and their circuit is called DS-100. It looks almost exactly like mine, but listening to a demo it is different. Much less gain for example, and no Sustain control.

I could find a reference in effectdatabase website, and it looks like my brand, Beta Aivin, also made a DS-100. So they're not the same circuit.


The circuit under investigation is this one, with a slightly different name : https://www.effectsdatabase.com/model/betaaivin/100/sd100#pictures

Please forgive me for this wrong reference, Boston Engineering didn't do any SD-100 like i mentioned in my first post.

Sorry if i've put you on the wrong track with this brand name. However, I've read other reports online complaining about the SD-100 noise from the compressor (in french) :

fr.audiofanzine.com

Distorsion guitare Harley Benton SD-100 Soft Distortion

Distorsion guitare de la marque Harley Benton
fr.audiofanzine.com fr.audiofanzine.com

So i guess we can be 99% sure it's a compressor in there, and not a faulty noise gate on my unit.

A compressor inside a distorsion circuit ? For the Sustain control ? That should narrow it down. I've never noticed any distorsion with a built-in compressor like that before.

Are there many similar circuits out there ?

These brands like Harley Benton and such, they always replicate some commercially succesful stompboxes, right ? The review mentions a price around 30 euros, mine cost me 20 euros second-hand, i doubt it's an original design for this price ?.
 
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Robert said:
This isn't going to be your circuit but is the first thing that came to mind when I saw your thread.

Coincidentally, this one also has some form of compressor built in.
Click to expand...
Thanks ! So there are a few other similar circuits.

Maybe i should try to build some other circuit, some distorsion with built-in compressor available in the diy world, instead of looking for the SD-100 original circuit forever.

According to what i could find, this one sounds very interesting too, but hasn't been traced yet.

I won't be able to build it.

Too bad, i like this brand. On pictures from the freestompbox website i can count 16 transistors in there... It would have been a new record for me.

Guyatone - PS-011 Distortion/Sustainer Schematic

Hi, is there anyone out there who owns a Guyatone PS-011 Distortion/Sustainer, and would be willing to post a photo of the wiring inside, with PCB? Maybe even schematics, but I won’t get my hopes up. I’m working on repairing one that was in terrible
www.freestompboxes.org www.freestompboxes.org

They say the PS-011 was designed to compete with Boss DF-2 super feedbacker. Is there a compressor in PPCB Backfeeder ?
 
Nah, it's nothing like the DF-2. I'll get around to tracing it eventually...

If I can get my hands on one of those Soft Distortions I'll trace that one as well. Can't do much from photos with all of the SMD capacitors though.
 
"It is a modded Boss ODB-3. First amplifier stage has been modded with a variable gain cell and acts as a compressor, second stage is a LED overdrive with adjustable gain. afterwards is the standard Boss ODB-3 Bass/Treble tone control."
 
Robert said:
Nah, it's nothing like the DF-2. I'll get around to tracing it eventually...

If I can get my hands on one of those Soft Distortions I'll trace that one as well. Can't do much from photos with all of the SMD capacitors though.
Click to expand...

I'll uncork my last bottle of champagne to celebrate these wonderful news !

A new PPCB pcb based on a guyatone circuit ? SD-100 mysteries finally unveiled ? Hurrah ! Glory to Robert !

I would gladly send you mine, but the shipping fee from france would cost more than the stompbox itself i'm afraid... Unfortunately i can't trace it myself, all i have is my good old DMM to help me. Last time i tried to trace a circuit, some diy Morning Glory pcb without instructions, i made several mistakes. I'm sure i would get it half wrong.

SD-100 really is a good distortion. Since the day i bought it, i built dozens of various classic distortion circuits. I still enjoy playing with this one, I often say to myself : " Holy smoke, this distortion's sound is impressive, perfect to blow some steam".

mdc said:
"It is a modded Boss ODB-3. First amplifier stage has been modded with a variable gain cell and acts as a compressor, second stage is a LED overdrive with adjustable gain. afterwards is the standard Boss ODB-3 Bass/Treble tone control."
Click to expand...
Thanks !

SD-100 is a modded ODB-3 ? LED overdrive ? Meaning LED clippers ? I can't see any led on the SD-100 pcb :

How to reduce background noises on a smd-built distorsion clone ?

How to reduce background noises on a smd-built distorsion clone ?
www.diystompboxes.com

Can you please give a link to your source ?
 
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Robert said:
if you happen to see one for sale somewhere let me know
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I've been looking and i'm quite surprised to see it became a rare thing these days.

All i could find is this add on the french craig's list :


I guess you won't buy from europe.

Just in case, he wrote "negotiable price", most people here speak at least a little english, so i guess you could try to contact the seller and negotiate the price (20 or 25 euros) and the shipping method. Sending 1kg shipment to the usa costs 32.85 euros, 500g is 29.55 euros...

I'll keep an eye open for more convenient adds, and i'll give a sign if i can see something .
 
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mdc said:
It's a 12yo thread, the image links are gone.
Click to expand...
Nice catch !

If it's true, no wonder it sounds so good and quite different from all the other distortions i've tried. I guess Analogguru is a reliable source...

Thanks for this info, it makes this effect even more interesting.

Would it mean that it's not a clone, it's their own ODB-3 guitar variant ?
 
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