KMD - Distortion 70's  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Hello,

Looking for a layout for this KMD Distortion pedal.

Any help would be very much appreciated

Thank you
Attachments
hjy4wqqdtmuiezd7z8zc.jpg

User avatar
modman
a d m i n
Information
Posts: 4890
Joined: 19 Jun 2007, 16:57
Has thanked: 4394 times
Been thanked: 2131 times

Post by modman »

It should be the same as the earliest Coron Distortion, which was marketed under a variety of names...J&J, Nashville, Bias and Labo
We do have threads on the later Coron Disortion, but no real thread on this earlier one.... It will be very close to the later Coron Distortion 10
Attachments
Screen Shot 2020-04-23 at 23.39.42.png
Screen Shot 2020-04-23 at 23.40.05.png
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Interesting. Yep looks the exact same.

I Like the way it sounds, would like to possibly rehouse it or maybe re build using the components and make TB. It needs big boost in volume.

Love the text on that "Labo" enclosure btw.
Attachments
IMG_1241.JPG

User avatar
modman
a d m i n
Information
Posts: 4890
Joined: 19 Jun 2007, 16:57
Has thanked: 4394 times
Been thanked: 2131 times

Post by modman »

DjPsychic wrote:Interesting. Yep looks the exact same.

I Like the way it sounds, would like to possibly rehouse it or maybe re build using the components and make TB. It needs big boost in volume.

Love the text on that "Labo" enclosure btw.
WTF, it crossed my mind when I didn't immediately find that picture you posted that you actually owned the pedal, but I learned to to jump into conclusion.
Why didn't you just contribute pictures from the start? And the component side please... I don't think the circuit has been documented yet.

Please don't hack it, it's 80s, but still 40 years old and rare... you will regret this.
Let's first have a look at the circuit as is to see what's wrong with the volume drop.
There is nothing here to salvage for a Tone Bender build...
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

modman wrote:
DjPsychic wrote:Interesting. Yep looks the exact same.

I Like the way it sounds, would like to possibly rehouse it or maybe re build using the components and make TB. It needs big boost in volume.

Love the text on that "Labo" enclosure btw.
WTF, it crossed my mind when I didn't immediately find that picture you posted that you actually owned the pedal, but I learned to to jump into conclusion.
Why didn't you just contribute pictures from the start? And the component side please... I don't think the circuit has been documented yet.

Please don't hack it, it's 80s, but still 40 years old and rare... you will regret this.
Let's first have a look at the circuit as is to see what's wrong with the volume drop.
There is nothing here to salvage for a Tone Bender build...
Actually the picture is from the internet, but it i s the one I bought. I got it off Reverb a while back. I don't want to make a tone bender. I was considering remaking it using the components. But I will consider keeping it as it is, if you think it's that rare.

Looking closer at the solders, chip may have been tampered with.
Attachments
IMG_1246.JPG
IMG_1246.JPG (46.05 KiB) Viewed 11424 times
IMG_1245.JPG
IMG_1245.JPG (34.4 KiB) Viewed 11424 times
IMG_1244.JPG
IMG_1244.JPG (28.2 KiB) Viewed 11424 times
IMG_1243.JPG
IMG_1243.JPG (43.39 KiB) Viewed 11424 times

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

I Like the way it sounds, would like to possibly rehouse it or maybe re build using the components and make TB.
Ah...I see now, I meant "True Bypass", not Tone Bender. My apologies!!

User avatar
soulsonic
Old Solderhand
Information
Posts: 3880
Joined: 27 Jun 2007, 03:38
my favorite amplifier: Traynor YVM-1
Completed builds: too many!
Location: Morgantown, WV
Has thanked: 183 times
Been thanked: 468 times
Contact:

Post by soulsonic »

If you replace the two germanium diodes with silicon ones, like 1N4148, and it will likely be very obviously louder. Replace them with red LEDs and it will be very loud. But this also changes the tone of the distortion, but maybe in a way that you will like.
If you remove the old diodes carefully, you can put them back and make it "original" again if you ever wanted to sell it.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

I'll probably just clone it. @modman convinced me to leave it :thumbsup

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

This should be the schematic.
Tantalium caps' values are missing and I'm not sure about the last 4,7n capacitor value
Attachments
1587740054885_WP_20200424_001.jpg

User avatar
modman
a d m i n
Information
Posts: 4890
Joined: 19 Jun 2007, 16:57
Has thanked: 4394 times
Been thanked: 2131 times

Post by modman »

It seems to match the Coron Distortion 15
Tantalums in that pedal are 10uF, the cap in parallel with the diodes, 10nF
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Intripped wrote:This should be the schematic.
Tantalium caps' values are missing and I'm not sure about the last 4,7n capacitor value
Amazing, thank you!

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

Found 2 errors in my schematic:
The 500k resistor is 510k instead,
and 50k is 51k, like in Coron distortion schematic.

It would be great if DjPsychic could confirm the tant caps' values (the blue ones), and also the 4.7n (?) capacitor: it's the green cap close to the diodes - i can't clearly read the value from the pic - seems to be 472

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Intripped wrote:Found 2 errors in my schematic:
The 500k resistor is 510k instead,
and 50k is 51k, like in Coron distortion schematic.

It would be great if DjPsychic could confirm the tant caps' values (the blue ones), and also the 4.7n (?) capacitor: it's the green cap close to the diodes - i can't clearly read the value from the pic - seems to be 472
The blue tant caps read (as it appears on cap):

10
16


And I believe right leg (looking at printed side) is Positive

The green cap closest to diodes is kind of faded. I THINK it reads:

472k50

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

Ok, so the 2 tant. caps are 10uF 16V.
I think that we can say that the last capacitor (C5) actually is 4.7n
Here's the updated schem - I've added component numbering as in the Coron dist. schematic
Attachments
1587819311910_WP_20200425_004.jpg

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Intripped wrote:Ok, so the 2 tant. caps are 10uF 16V.
I think that we can say that the last capacitor (C5) actually is 4.7n
Here's the updated schem - I've added component numbering as in the Coron dist. schematic
Sorry for delayed response. I finally finished my latest FF build. I have trouble moving on until its in an enclosure and painted/labelled. I'm OCD like that :blackeye

Thanks for drawing that out. I'm going to dive into my first IC build here soon, might start with a "250" style or this. Much appreciated!

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

...made a PCB layout:

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

please excuse me, the previous layout was wrong. i hope nobody has made it.
this is a new correct one:

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

...i'm just having fun with this layout - here is a "modern" version of the circuit, with some filtering on the 9V(so that it can be used with a power supply without issues), and a pull-down resistor at the input to avoid "pop"s if wired in truebypass; i've not put the diode for reverse polarity protection (now that i think of it), but it's easy to add it directly on the power supply jack.
it should fit a 1590B enclosure - there's also the chance to "lay down" the electrolytic and tant. capacitors, so that they don't take too much in height.
Enjoy!

User avatar
Intripped
Cap Cooler
Information
Posts: 670
Joined: 25 Aug 2009, 01:03
Location: Italy
Has thanked: 989 times
Been thanked: 305 times

Post by Intripped »

i'm very sorry, there was another error: DISTORTION POTENTIOMETER WAS WARKING BACKWORDS.
i fixed the two layouts, and now i'm 100% sure they are ok.
you can find below the last revisions of the "vintage" and "modern" version
Attachments
vintage SILK
vintage SILK
vintage BOTTOM
vintage BOTTOM
modern SILK
modern SILK
modern BOTTOM
modern BOTTOM

User avatar
DjPsychic
Breadboard Brother
Information
Posts: 147
Joined: 07 Feb 2020, 21:35
Has thanked: 85 times
Been thanked: 48 times

Post by DjPsychic »

Intripped wrote: 18 May 2020, 23:25 i'm very sorry, there was another error: DISTORTION POTENTIOMETER WAS WARKING BACKWORDS.
i fixed the two layouts, and now i'm 100% sure they are ok.
you can find below the last revisions of the "vintage" and "modern" version
Hey man!

Finally getting a chance to play around with this circuit. The vintage unit has an incredible sound but the amount volume is quite limited.

What components could be altered to provide a bit more volume/headroom?

Post Reply