My ASM1 is working! - but still some problems!

[Magnus Danielson]

>>>>> "w" == wbajus  <wbajus at bhv.ipnet.de> writes:

 w> My ASM1 is working! - but still some problems!
 w> Hi ASM1 Owners!

Congratulations!

 w> Finally I have finished the assembling of my ASM1 and am glad to join
 w> the ASM1 Comunity :-)

Wellcome!

 w> The modules worked from the first time I powered the ASM1 on. I only
 w> burned a
 w> resistor due to a misconnected tantal-cap.
 w> But I have still some problems with it. Maybe some of you have made
 w> similar
 w> experiences or have an idea what´s going wrong:

 w> 1. The Oscillators seem to modulate each other even when not connected
 w> more than
 w> the onboard lines. I can hear that when I just listen to one OSC and
 w> change the tune
 w> of the other. At low frequencies this is very clear.

Hmm... haven't noticed this (doesn't say it's there).
Spontaniously this sounds like the current drawn by one VCO (due to
tuning) will affect the overall voltage on the board. I know that
there is one unfortunate dependency between supply voltage and tuning
such that this could be possible. This weakness can cause grave
detunings. I will try to describe it properly some day.

Please use a DVM to check the supply voltage as you tune VCOs
diffrently. The low frequency stuff also point this way, since the
current source will draw more then, but personally I think that this
should not be unless you have a very weak powersupply...

 w> 2. The OSCs drift when I change the value of a voltage control on
 w> another module e.
 w> G. when I turn down the Cutoff-frequency of the Filter the OSC tunes
 w> down more than
 w> a semitone. I think there should be something wrong with the current
 w> supply of these
 w> controls but I can´t imagine what. I just connected them all parallel.
 w> Or is the fault in
 w> the OSC-Module itself?

This sounds like the same problem.

 w> 3. The VCA produces a plopp-sound at the start of an Envelope, but only
 w> when
 w> connected to the VCF. Some kind of feedback perhaps?

I think I have heard comments about this before on the list. I recall
something about "basic properties of those devices" but never got an
explanation good enougth for me to understand... Juergen?

 w> (I am running my ASM1 by a PAIA MIDI2CV8, it´s supplied by an
 w> Elektor-Formant-like power supply)

 w> That is most I have recognized yet. Apart from this I am quite happy
 w> with it and
 w> optimistic to solve these problems.

Have Fun!

 w> Happy X-mas, Heiko

Happy X-mas to you to, and all the others at Synth-DIY of course!

Cheers,
Magnus