Help! - Doepfer MS-404 playing always the same pitch

[Antonino]

Hi guys, I just bought a second hand MS-404, but I have a problem.

I tried it with several MIDI controllers, but I always seem to have a big issue: basically the notes don't change pitch In other words, if I play different keys on the keyboard I always seem to get a G, even if I can actually hear some slight differences in the harmonics. All the rest (LFOs, filter, etc.) is working fine.

The guy who sold me the module is honest and I do believe him when he said it was functional. He told me that he was using it fine with Pro Tools MIDI.

What can have happened? could it be a MIDI problem? is there any chance that I can solve this problem in any way without sending it to repair? thanks!

[th0mas]

The MS-404 has CV out. Plug in a cable to the CV output and see if the voltage changes in response to different MIDI notes. If it's not changing then my guess would be it's the internal MIDI->CV converter that's pooched (if you know for certain your MIDI interface is working, say, by making sure the same method works with your microkorg).

It could also maybe be that the connection from the MIDI-CV converter to the VCO is damaged, so only gate is reaching the synth? I don't know if that would result in the VCO playing anything audible though (my guess would be it'd be attempting to play at 0V -> close to 0 Hz.

[Antonino]

The MS-404 has CV out. Plug in a cable to the CV output and see if the voltage changes in response to different MIDI notes. If it's not changing then my guess would be it's the internal MIDI->CV converter that's pooched (if you know for certain your MIDI interface is working, say, by making sure the same method works with your microkorg).

It could also maybe be that the connection from the MIDI-CV converter to the VCO is damaged, so only gate is reaching the synth? I don't know if that would result in the VCO playing anything audible though (my guess would be it'd be attempting to play at 0V -> close to 0 Hz.

Thanks for the answer! I'll try this out for sure.. but how can I know if the voltage changes? It's my first true analog synth so I'm not really very handy with CV

[Antonino]

Some quick recordings of the problem (lowest note at the beginning and then a 5 octave chromatic scale):
SAW
SQUARE
NOISE
NO INPUT

[RD9]

Weird. It sounds like there's at least some change in pitch in the square example though.

Does frequency modulation work at least? What happens if you hold down a key (ASDR:0-0-12-0) while the frequency oscillates very slowly let's say at level-10 and freq-10 (switch up). Does the unit at least respond in the expected way?

[th0mas]

Thanks for the answer! I'll try this out for sure.. but how can I know if the voltage changes? It's my first true analog synth so I'm not really very handy with CV

Sorry, I didn't explain too well.. plug a cable into the "CV out", then with a voltmeter, go to the other end of the cable and hold the leads to each side of the cable's connector (one on the tip, one on the ring) and then measure the voltage.. It should go up as you play higher notes.

[Antonino]

Weird. It sounds like there's at least some change in pitch in the square example though.

Does frequency modulation work at least? What happens if you hold down a key (ASDR:0-0-12-0) while the frequency oscillates very slowly let's say at level-10 and freq-10 (switch up). Does the unit at least respond in the expected way?

It somehow works but in a weird way and the result is different from note to note.. This is the result:
C1 (lowest key)
C2
C3
C4
C5
C6 (highest key)

[Antonino]

Thanks for the answer! I'll try this out for sure.. but how can I know if the voltage changes? It's my first true analog synth so I'm not really very handy with CV

Sorry, I didn't explain too well.. plug a cable into the "CV out", then with a voltmeter, go to the other end of the cable and hold the leads to each side of the cable's connector (one on the tip, one on the ring) and then measure the voltage.. It should go up as you play higher notes.

OK I get it now.. I'll definitively try that!

[RD9]

Weird. It sounds like there's at least some change in pitch in the square example though.

Does frequency modulation work at least? What happens if you hold down a key (ASDR:0-0-12-0) while the frequency oscillates very slowly let's say at level-10 and freq-10 (switch up). Does the unit at least respond in the expected way?

It somehow works but in a weird way and the result is different from note to note.. This is the result:
C1 (lowest key)
C2
C3
C4
C5
C6 (highest key)

Hm... That doesn't sound right. Maybe the problem is beyond MIDI/note control. I don't know anything about electronics, but maybe it's a short?

Here's a pic of my settings and an audio sample if you care to compare:

http://soundcloud.com/9dr9dr/ms-404-fm

[Antonino]

Midi-CV works perfectly, so the problem must be something that has to do with the analog circuit, it isn't MIDI related for sure. Unless some miracle happens I think I'll have to send it to repair somewhere to make it work

...

Here's a pic of my settings and an audio sample if you care to compare:

http://soundcloud.com/9dr9dr/ms-404-fm

Very useful as a comparison, thanks again.

[Antonino]

F*CKING YESSSSS

I was desperate: or send it to pricey assistance or sell it low price as broken unit. So I opened the box and used the "touch and try" method.. I said " why not give it a go at this point"?

I touched random parts here and there and then the "magic condenser" near to the Audio Out.. et voila' the doepfer started to sing again!!!! Hope it lasts for a bit now, but in any case I know who the bastard is at least

Thanks again to Th0mas and RD9.. I would really offer you a beer in this moment.. your help was essential to focus better the problem

Now at last I can play some notes other than G.. I was getting sick listening to those weird noises..!

cheers

Antonio John

[th0mas]

F*CKING YESSSSS

I was desperate: or send it to pricey assistance or sell it low price as broken unit. So I opened the box and used the "touch and try" method.. I said " why not give it a go at this point"?

I touched random parts here and there and then the "magic condenser" near to the Audio Out.. et voila' the doepfer started to sing again!!!! Hope it lasts for a bit now, but in any case I know who the bastard is at least

Thanks again to Th0mas and RD9.. I would really offer you a beer in this moment.. your help was essential to focus better the problem

Now at last I can play some notes other than G.. I was getting sick listening to those weird noises..!

cheers

Antonio John

glad its working! Not 100% on your method but... hey, it works now right on

[RD9]

Wow that's awesome. Congrats. There are lots of great bars where I am in Brooklyn if you ever come to nyc.
What the heck is a magic condenser? Is that anything like a Magic Hat?

[moremagic]

I touched random parts here and there and then the "magic condenser" near to the Audio Out.. et voila' the doepfer started to sing again!!!!...

Now at last I can play some notes other than G.. I was getting sick listening to those weird noises..!

I'm wondering if I should start touching random parts of the singer to see if she'll sing in a key other than G!

[Rhoda]

the notes don't change pitch In other words, if I play different keys on the keyboard I always seem to get a G

Here's someone with the same problem.

I touched random parts here and there and then the "magic condenser" near to the Audio Out.. et voila' the doepfer started to sing again!!!!

Would anybody know what's the "magic condenser"? Thank you in advance.