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292e non-linear behaviour
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge  
Author 292e non-linear behaviour
emp
I just discovered that channel C and D on my 292e shows a strange non-linear behaviour. It's like if the incoming signal "chokes" at certain frequencies and timbres. If i turn the waveform up on a 258v going into it, some seeet spot settings makes it sound as i used to, but other settings makes it just barely audible. Same thing with my DPO as input so i don't think it's the oscillator's fault.. As if the LPG turned into a resonator. And of course i have rehearsals this weekend and playing shows next week. Any ideas what to do?
Kent
Post some audio, pls.
emp
Kent wrote:
Post some audio, pls.

The problem is that it kind of comes and goes. And it seems related to certain presets. Could it be that the 292e actually stores the last incoming velocity as part of a preset? I don't think it should, but maybe it does?
J3RK
Does the 292e use the custom vactrols like some of the other e models, or does it use VTLs?

Some of the e models had custom ones with little plastic boxes around them. If the cover came off you might get some bleed or other odd behavior.

I haven't owned or serviced any e modules, so just a guess on my part. You might take a quick peek at the back though.
solaris
J3RK wrote:
Does the 292e use the custom vactrols like some of the other e models, or does it use VTLs?

Some of the e models had custom ones with little plastic boxes around them. If the cover came off you might get some bleed or other odd behavior.

I haven't owned or serviced any e modules, so just a guess on my part. You might take a quick peek at the back though.


iirc in my 292e there are leds and photocells without any enclosure.
mritenburg
solaris wrote:
J3RK wrote:
Does the 292e use the custom vactrols like some of the other e models, or does it use VTLs?

Some of the e models had custom ones with little plastic boxes around them. If the cover came off you might get some bleed or other odd behavior.

I haven't owned or serviced any e modules, so just a guess on my part. You might take a quick peek at the back though.


iirc in my 292e there are leds and photocells without any enclosure.


The 292e has standard vtl's, the 285e has LED's and photocells.
MechaSeb
mritenburg wrote:
solaris wrote:
J3RK wrote:
Does the 292e use the custom vactrols like some of the other e models, or does it use VTLs?

Some of the e models had custom ones with little plastic boxes around them. If the cover came off you might get some bleed or other odd behavior.

I haven't owned or serviced any e modules, so just a guess on my part. You might take a quick peek at the back though.


iirc in my 292e there are leds and photocells without any enclosure.


The 292e has standard vtl's, the 285e has LED's and photocells.


Depends of the era when the module has been assembled.
227e went out with LEDs & photocells too. It is possible other modules was built this way as well (2009?).
J3RK
Even some original VTLs were somewhat sensitive to external light sources. I've measured change on them while building before just from ambient light. Not huge amounts, but it was measurable. So if these happened to be custom, or open LED+LDR, there could be some non-linear responses especially if other channels were in use at the time. That may not be the case at all here, but it crossed my mind.

I've also had vactrols that just plain didn't have a smooth response curve (from the same batch as ones that did), so it could just be luck of the draw.

If there are trim pots on the back, maybe adjusting the ones for the C/D channels might help too, if you're comfortable doing it. Otherwise, maybe have a tech experienced with e modules take a look.
Drillionaire
The oldest 292e modules I've ever had on my bench (around 2006-7 I believe) had VTLs. There was a firmware update in the past couple years for the 292e that fixed aspects of how the velocity scaling was implemented. I've attached the latest hex file. That might solve the issue.
emp
Drillionaire wrote:
The oldest 292e modules I've ever had on my bench (around 2006-7 I believe) had VTLs. There was a firmware update in the past couple years for the 292e that fixed aspects of how the velocity scaling was implemented. I've attached the latest hex file. That might solve the issue.

Thanks, I had 30.3. It did something at least. I think it was a combination of the velocity and the fact that my custom I/O-module seems to be glitchy.. Anyway, I could get it to behave properly now. Thanks for all replies!
J3RK
Good news!
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