Boss - DM-2 Delay  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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Scruffie
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Post by Scruffie »

It can be done pretty well by ear?

Adjust the bias trimmer first untill delay passes and you hear the least distortion on delays.
It'll be a small range for the best sound so tweak carefully.

Then adjust the clock trimmer untill whine is introduced then back off untill it dissapears.
(This adjusts max delay time)

Then use the cancel trimmer to see if you can get any more noise out of the signal, you can try going back and forth between this and the clock trimmer to get the best balance of delay and noise.

Done!

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dthurstan
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Post by dthurstan »

Zokk wrote:Hi
why don't you go with software stuff like that:
http://www.sillanumsoft.org/

there are also many simple softs which can produce basic waveforms which can do their job quite well.

Cheers
Z.
+1

I calibrated mine with this software, a homemade audio probe & Laurie's notes. It's pretty straight forward. I only had a bit of trouble scaling & divisions, but I figured it out in the end.

I was hoping to cal by BF-2 with it but it doesn't go up to 40kHz so that was out.

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apollomusicservice
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Post by apollomusicservice »

procedure for calibration BOSS DM-2
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adjustment boss dm2.jpg

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candletears7
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Post by candletears7 »

My DM-2 has died and has that delightful burnt out smell. I believe I may have accidentally fed it a higher voltage than it can take, however the zener (that I replaced last time someone else plugged the wrong adaptor into it) hasn't blown as far as I can see.

I'll replace that zener just in case, but if the voltage has gone further through the circuit, can someone post any voltages I should expect to see on the IC's?

Thanks for any help.

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candletears7
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Post by candletears7 »

Nevermind, it was the Zener. Replaced and up and firing as per usual.

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ksenanekro
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Post by ksenanekro »

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BOSS DM-2.jpg

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box
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Post by box »

Hi,
Please check pin out of MN3005.
Thanks,
box
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MN3005.JPG
MN3005.JPG (12.93 KiB) Viewed 2671 times

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lolbou
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Post by lolbou »

+1! Is the layout tested and verified? Did you make any BBD conversion?
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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ksenanekro
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Post by ksenanekro »

yes box...you're right man... guys over guitarfxlayouts point that too...i made a mistake cause i was reading at the same time datasheets of mn3005 and 3007...
i'll update the layout in the next days, or i'll just draw a daughterboard.

and lolbou no.it's not verified yet...and i don't think i'll spent 20 euros for that chip in the near future!!!
sorry but i don't understand what bbd conversion is...???!!!

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box
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Post by box »

ksenanekro wrote:yes box...you're right man... guys over guitarfxlayouts point that too...i made a mistake cause i was reading at the same time datasheets of mn3005 and 3007...
i'll update the layout in the next days, or i'll just draw a daughterboard.

and lolbou no.it's not verified yet...and i don't think i'll spent 20 euros for that chip in the near future!!!
sorry but i don't understand what bbd conversion is...???!!!
Hi,
BBD conversion- its BBD adaptor a daughterboard.
Rgds,box

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lolbou
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Post by lolbou »

box wrote:BBD conversion- its BBD adaptor a daughterboard.
Yes, or maybe the layout (and circuit) is already modified to accomodate some cheaper and easier to find BBD chip...
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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ksenanekro
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Post by ksenanekro »

no lolbou...i drew it from the schematic above.it was just my mistake.in the next days i'll post a now one maybe or a daughter board .
have you guys ever seen how expensive this ic is???
$35....omg... :shock:

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astrobass
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Post by astrobass »

You can also use the MN3205 or the V3205, which is a functional equivalent produced by CoolAudio. The DM-2 only runs on 9V anyways.

The DM-2 came with both, depending on which year it was produced.

There are those who argue that the MN3005 DM-2s sounded better, that the delay is darker and less noisy, but I suspect that's cork sniffing and owes more to a mix of incidental component variation, poor sampling techniques/bias, etc. And in any case I don't know how it'd apply to a V3205, but the V3205 is quite a bit cheaper on ebay.

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ksenanekro
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Post by ksenanekro »

hi guys!

very happy that the site is back...
here is the updated layout!thank you guys for your open eyes!
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boss dm-2.png

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ksenanekro
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Post by ksenanekro »

astrobass wrote:You can also use the MN3205 or the V3205, which is a functional equivalent produced by CoolAudio. The DM-2 only runs on 9V anyways.

The DM-2 came with both, depending on which year it was produced.

There are those who argue that the MN3005 DM-2s sounded better, that the delay is darker and less noisy, but I suspect that's cork sniffing and owes more to a mix of incidental component variation, poor sampling techniques/bias, etc. And in any case I don't know how it'd apply to a V3205, but the V3205 is quite a bit cheaper on ebay.
that's good to know man!
thanks!
i'll have that in mind!

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