Deluxe Memory Man build help

omarvolta · April 23, 2008, 05:34:58 PM

hello there, I put together a DMM about a month ago and to my surprise it's working pretty good. The only thing that's bothering me is a very high pitch sound when the Delay pot is at about 1 o'clock and it lowers as the delays get longer. what could be the reason for that? where should I start looking??

theehman · April 23, 2008, 05:37:25 PM

Not sure which version you built but usually there's a Balance trimpot on the outputs of the delay IC. You adjust this for the lowest noise on the highest delay setting. Sometimes you just can't get rid of the noise completely but proper setting helps immensely.

omarvolta · April 23, 2008, 05:54:28 PM

I built the one with two MN3005. I've tried messing with all of the trimmer for a while now and managed to get a great sounding delay. The balance pot I've noticed it doesn't do much or maybe it's not working at all or it's too small in value(5k). Thank you for you reply theehman.

theehman · April 23, 2008, 05:58:49 PM

You should hear the noise louder at either extreme of the Balance trimpot's rotation and much quieter in the center. According to the original schematic, 5K is correct. It's connected to pins 3 and 4 of the MN3005 with the wiper providing the output?

omarvolta · April 23, 2008, 06:03:40 PM

"It's connected to pins 3 and 4 of the MN3005 with the wiper providing the output?"
Yes sir.

theehman · April 23, 2008, 06:06:42 PM

Quote from: omarvolta on April 23, 2008, 06:03:40 PM
"It's connected to pins 3 and 4 of the MN3005 with the wiper providing the output?"
Yes sir.

Try a different trimpot. Any value should show some change.

omarvolta · April 23, 2008, 06:10:21 PM

That I'll do and report back as soon as I'm done. Thank you very much!

omarvolta · April 23, 2008, 08:02:58 PM

ok, so I put a 10k in there and now the noise is present from 3 o'clock and on. does it make any sense?? should I go higher??

theehman · April 23, 2008, 08:08:47 PM

No, just put a different 5K in there and try it.

omarvolta · April 23, 2008, 08:13:34 PM

ok, the 5k I took out is fine though(measured it and it's fine), but I'll try a diferent one anyways. Thanks a ton.

omarvolta · August 20, 2008, 07:35:41 PM

I'm back.... yup, after building the Echobase I liked the waveshape control a lot so I wondered if this could be done to the DMM. Also, I've looked for information on a momentary switch to make the feedback pot go into oscilation but haven't found any yet. Any info is greatly appreciated. Below the waveshape for the Echobase and the DMM LFO. Also the circuit around the Feedback pot of the DMM.

beatnik · August 21, 2008, 05:02:01 AM

Hi omar,

do you have a layout for the DMM?

or at least a verified schematic. i have the factory one but i've read somewhere that it contains errors.

omarvolta · August 22, 2008, 02:35:48 PM

Well, got the momentary switch working to switch between two pots(one of them for oscillations). Also put a pot for modulation rate. No luck with the waveshape yet.... is it even possible??

Quote from: beatnik on August 21, 2008, 05:02:01 AM
Hi omar,

do you have a layout for the DMM?

or at least a verified schematic. i have the factory one but i've read somewhere that it contains errors.

Yeah man, want it?

mat · August 23, 2008, 01:15:57 PM

Quote from: omarvolta on August 22, 2008, 02:35:48 PM
Well, got the momentary switch working to switch between two pots(one of them for oscillations). Also put a pot for modulation rate. No luck with the waveshape yet.... is it even possible??

Quote from: beatnik on August 21, 2008, 05:02:01 AM
Hi omar,

do you have a layout for the DMM?

or at least a verified schematic. i have the factory one but i've read somewhere that it contains errors.

Yeah man, want it?

If possible, I would also like to see the layout/schem.

Matti T.
mtiilama[at]pp.htv.fi

beatnik · August 23, 2008, 01:49:55 PM

Quote from: omarvolta on August 22, 2008, 02:35:48 PM
Well, got the momentary switch working to switch between two pots(one of them for oscillations). Also put a pot for modulation rate. No luck with the waveshape yet.... is it even possible??

Quote from: beatnik on August 21, 2008, 05:02:01 AM
Hi omar,

do you have a layout for the DMM?

or at least a verified schematic. i have the factory one but i've read somewhere that it contains errors.

Yeah man, want it?

That would be great!!!!

My email is sadrew_1000[at]hotmail.com

I will stop all of my "in progress" builds and try this one.

I just love it !

sean k · August 24, 2008, 04:35:01 AM

Yes indeed, a link to a DMM schematic that works would be great. I've got all the parts to build one but always go back to digi delays because it's too much like hard working out the schemo I've got which seems to have obvious mistakes all over the place. That said as I play with delays and loopers I'm starting to get it all sorted but, yes indeedy, a real live working and verified schematic looking like the snippets you have above would be something to cherish. As for making the LFO go into oscillation, oops sorry, the feedback pot go into oscillation. Wouldn't you want to lift some resistance in the feedback path so the signal doesn't drop each time it goes around while also switching in a resistance between the pins that set the frequency of delay so you get something ofshorter duration. Also a switched in bandpass filter might be an idea to control the limits of the oscillation. Sorry I don't have the easy answer and am just surmising what I'd try and do if I wanted what you wanted... guessing what I'd like to happen if I pushed that momentary switch.

I've just been to make a cup of tea and thats actually quite a big ask with my limited knowledge.
Firstly I suppose you either want to self oscillating to go on until you hit the mom again or it's a timed thing that you can change. As for the timed thing I know that electronic drums in the early days were ringing oscillators and they had a way of doing snare and cymbals sounds using white noise from avalanched transistors and then timing them up using inductors accross a collectors resistor to V+. Theoretically, and I'm really just guessing but I'd say you could time up this little pulse generator to control the switches in a 4066 and have this little lot do what you ask.

So I reckon upping the size of some of the caps and the inductor should give a longer pulse which, now I think about it, could be used with fets as switches as you'll be able to follow the curve, as it were, as opposed to switching in and out. I hope theres an easier way to do what you ask because this is just me guessing.

Dimitree · August 24, 2008, 01:34:00 PM

I'd like to see a correct schematic too..

Dimitree@hotmail.it
thanks!

Auke Haarsma · August 24, 2008, 02:57:29 PM

I'd appreciate the schematic (and possible) layout a lot as well!
aukehaarsma at gmail dot com

Much appreciated.

Michael Allen · August 24, 2008, 04:41:10 PM

why not just upload it somewhere and post a link?

omarvolta · August 24, 2008, 05:16:41 PM

Quote from: Michael Allen on August 24, 2008, 04:41:10 PM
why not just upload it somewhere and post a link?

Because it's not my work, I can't go and just post it anywhere though I've sent it to a couple of people but no more. I have no permission or any way to ask for permission to post them. I know you'll find them if you search like I did.

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Deluxe Memory Man build help