Built a Deluxe Memory Man! A couple issues and questions por favor.

[guitylerham]

Hey guys,
I'm in the middle of building my analog multi-effect pedalboard. One of the circuits it is going to have is the DMM. I managed to find a corrected copy of the layout online here with the help of some really cool people! I found some MN3005's through UT Source and after waiting FOREVER to compile all the other parts, I finally put it together and after reversing the power supply polarity, it worked!! I tuned the trimpots by ear (surprisingly not that difficult though I may not have them set to ideal). It sounds great... except for a horrendous intermittent, crackling, windy, popping noise. It'll play fine for minutes at a time and then all of a sudden the noise will get more and more intense. I recorded some audio of it. Any ideas? I'm thinking it might be a capacitor issue but I'm a learning noob. Fyi, I measured the wall wart I'm temporarily using and it's putting out 29vdc instead of the 24v that it says on the label! I assume the regulator takes care of that at the expense of some extra heat. Should I make a voltage reducer (LM317T perhaps?) or is this overpower ok?

Last question is about the bypass switch. Below is a picture of part of the layout that I have. The diagram shows an SPDT switch. Currently I have a 3pdt wired just like you would a positive ground circuit. I used the labeled "INPUT" and only the "ECHO OUT." I'm not going to be using the "DIRECT" Out so I left it empty. My question is regarding the points 4,5, and 7. Right now those aren't used, do you think I need to incorporate these somehow into the switching design? Right now the effect bypasses just fine but I'm wondering if this may be contributing to my noise from above.


Audio clip of me playing guitar when the noise started. It worked for several minutes when I first turned it on. It is a Tele through the DMM into a Vox Ac15cc1 through a Zoom H2.
https://sites.google.com/site/guityler123/clips/noise.mp3

I cannot wait to finish this pedalboard. It's become an obsession/distraction from the things I should really be doing but I've got an idea in my head and I won't stop until I realize it! I'm telling you guys, you're gonna be so excited!

[bean]

Your switch wiring is okay except you should not be grounding the fx input to +9v. Ground is still 0v even in the DMM, which uses a center pin positive 24v supply. If you want to do true bypass then what you have drawn is fine (except for the +9v thing). The DMM is not actually wired TB so usually you would only need an SPDT to switch between the output from the first gain stage and the echo output.

Don't worry about the over voltage in your wall-wart, that's normal. The rating (24v) indicates the minimum power it will supply under load, so usually it comes out a few volts over without any load. The regulator takes care of grinding it down to the normal -15v needed to power the circuit. My EHX wall wart reads about 29v, IIRC.

The best way to track down the source of your noise is to use an audio probe. You need to check in the inputs and outputs of the different ICs to see where the noise starts. Try starting around the BBDs to see if the noise is coming from there (or somewhere in the first half of the circuit)...so using your probe check pin7 (input) and then pins 3 and 4 (outputs) of each BBD. From there it's just a process of tracking the noise to its source.

[lopsided]

except you should not be grounding the fx input to +9v. Ground is still 0v even in the DMM, which uses a center pin positive 24v supply.

I have asked this question elsewhere ( http://www.diystompboxes.com/smfforum/index.php?topic=91935.msg785726#msg785726 ) and from the answers I got and from what I saw in mine, DeluxeMM (the original +-2002 reissue ) is a positive ground circuit.
Then again mine goes on 24V so I am not sure if this applies to guitylerham's project too, maybe the new ones go 9 volts.

[guitylerham]

Your switch wiring is okay except you should not be grounding the fx input to +9v. Ground is still 0v even in the DMM, which uses a center pin positive 24v supply. If you want to do true bypass then what you have drawn is fine (except for the +9v thing). The DMM is not actually wired TB so usually you would only need an SPDT to switch between the output from the first gain stage and the echo output.

Don't worry about the over voltage in your wall-wart, that's normal. The rating (24v) indicates the minimum power it will supply under load, so usually it comes out a few volts over without any load. The regulator takes care of grinding it down to the normal -15v needed to power the circuit. My EHX wall wart reads about 29v, IIRC.

The best way to track down the source of your noise is to use an audio probe. You need to check in the inputs and outputs of the different ICs to see where the noise starts. Try starting around the BBDs to see if the noise is coming from there (or somewhere in the first half of the circuit)...so using your probe check pin7 (input) and then pins 3 and 4 (outputs) of each BBD. From there it's just a process of tracking the noise to its source.

Hmm, my wallwart is center pin positive, and I have that center pin from the dc jack going to the main ground that surrounds the circuit. I'm still cementing the internals of a the bypass switch in my head but I'm a bit foggy. Using this new picture, do I simply move the wire from the sleeve of output jack to another 9v- point?

[guitylerham]

I just got back from work and looked at the early morning post I left when I woke up! I think what you meant was to just remove the wire going from my input sleeve to ground. Sorry for not getting the obvious. I'll make up an audio probe and get back to you guys (I'm gonna do some reading on audio probes too). Thanks for chiming in!

[guitylerham]

Hold on, I have confused myself. The second drawing I added this morning is WRONG. I accidentally mislabeled the input/output jacks. Here is the corrected drawing below.


So now that the jacks are correct... I'm confused. I have the input grounded through the 3pdt switch but I cannot grasp all the common points during the two stages of the switch! I don't have the switch turned 90 degrees do I?