MF-104Z trimpots

Hiwatt Bob · Post by **Hiwatt Bob** » Tue Sep 29, 2009 10:45 pm

does anyone know what the trimpots inside control?

anyone tried messing with them?

Bryan B · Post by **Bryan B** » Tue Sep 29, 2009 11:29 pm

This would be nice to know, good question!

Bryan T · Post by **Bryan T** » Tue Sep 29, 2009 11:36 pm

If it is like other analog delay pedals, I wouldn't touch them . . .

Hiwatt Bob · Post by **Hiwatt Bob** » Wed Sep 30, 2009 12:24 am

Bryan T wrote:If it is like other analog delay pedals, I wouldn't touch them . . .

for me it's the complete opposite.

i went ahead and fooled around with them (carefully). i still don't know what they all do technically, usually it's easy to tell on the other pedal trimpots i've messed with.

anyhow, i was able to get the pedal to self-oscillate on it's own (feedback set to 10) by tweaking a couple of the trimpots individually. one annoying thing about the moog is that at stock settings you need to trigger the unit with a note to get it to self-oscillate. now all i have to do is set it to 10 and it will start playing by itself.

anyhow--if you're looking at the pedal with the back plate off--the northern-most trimpot along the left edge of the circuitboard. mine was set to 7-8:00 (which is maxed out on the trimpot). i backed it off to half-way, or 3:00 in this case. doesn't seem to have an effect on anything else, and it'll always be easy to remember that setting it back to stock just means diming the trimpot again.

if there's a moog tech or any other expert, i'd love to hear a more technical description/explanation of what the pots do--and from other users if they've found cool settings.

CTRLSHFT · Post by **CTRLSHFT** » Wed Sep 30, 2009 1:01 am

Hiwatt Bob wrote:
Bryan T wrote:If it is like other analog delay pedals, I wouldn't touch them . . .
for me it's the complete opposite.

i went ahead and fooled around with them (carefully). i still don't know what they all do technically, usually it's easy to tell on the other pedal trimpots i've messed with.

anyhow, i was able to get the pedal to self-oscillate on it's own (feedback set to 10) by tweaking a couple of the trimpots individually. one annoying thing about the moog is that at stock settings you need to trigger the unit with a note to get it to self-oscillate. now all i have to do is set it to 10 and it will start playing by itself.

anyhow--if you're looking at the pedal with the back plate off--the northern-most trimpot along the left edge of the circuitboard. mine was set to 7-8:00 (which is maxed out on the trimpot). i backed it off to half-way, or 3:00 in this case. doesn't seem to have an effect on anything else, and it'll always be easy to remember that setting it back to stock just means diming the trimpot again.

if there's a moog tech or any other expert, i'd love to hear a more technical description/explanation of what the pots do--and from other users if they've found cool settings.

i'd suspect the feedback pot is probably the only one where alterations to the settings will produce any usable changes. i used to have a diamond memory lane which included a section in it's manual which deliberately mentioned how you could adjust a pot setting to make the feedback more sensitive (which presumably is what happens when you move that pot on the 104z back).

it'd be cool to see if you're able to change any settings on any pots to adjust the time control, (maybe get faster delays?) although i suspect this might have negative effects on normal operation for that control (abnormally shortened delay lengths, perhaps.) please let us know if you find anything in this vein though, it'd be cool to know about!

EricK · Post by **EricK** » Wed Sep 30, 2009 1:07 am

Okay,
My delay was repaired because it used to not always self-oscillate. WHen it woudl function, it did so just after the 8, where its supposed to. Now it works fine but acts like a totally different pedal. It starts self oscillating in between 6 and 6.5, which is sort of annoying because I want 6 echoes and not necessarily self oscillation. I wondered if one of those trimpots would affect where it will begin the self oscillation process, cause Id like to reset it back to the 8.

Though, Im nowhere near wualified to screw around inside there, but I think that turning a trimpot won't start any fires. Im going to keep my hands out of there for now though.

I am pretty sure that doing so would void the warranty.

Eric

Hiwatt Bob · Post by **Hiwatt Bob** » Wed Sep 30, 2009 9:24 am

i'm not concerned about the warranty, it's only a year right? and i got mine second hand--so i'm 99.9% sure it wouldn't be covered.

basically, mine is now set up so that at a hair past 8 (or 9:00) i get a ton of regeneration and it's at a careful balance so that if i hit it with a hard enough signal, it will continue infinitely (albeit substantially degraded at that point). in between 8-10, it acts like it did before, where it will self oscillate, but you need to trigger it. at 10, it will start self-oscillating after about a second or two.

Vitja B · Post by **Vitja B** » Sun Oct 25, 2009 5:56 pm

Yes! the Time pot????????
If I could set it to shorter time I could get a real flanger out!!!
I will mess around tomorrow with that!
I will se what I can do.

stiiiiiiive · Post by **stiiiiiiive** » Fri Jun 01, 2012 4:42 am

Vitja B wrote:Yes! the Time pot????????
If I could set it to shorter time I could get a real flanger out!!!
I will mess around tomorrow with that!
I will se what I can do.

Any news from the past, Vitja?

Vitja · Post by **Vitja** » Fri Jun 01, 2012 6:44 am

Upsss.. I forgot to try it.
I don't think this is possible.
It would be great since I use max delay time around 300-400 ms on short setting.
But flange need a really short delay time 5-20 ms...
Chorus would be possible... but I hate chorus

I would love to know all the possible adjustments on trim pots for all the foogers.
I tried something with Ringmod. While ago I adjust one pot and got less noise. I would love to adjust the threshold of RM.
I hate the fact that I can't play guitar softly when or when note fades... it just dies when the volume is under threshold.

I also turned the feedback trimpot on delay to not self oscillate, for that I insert cable to feedback loop and when I want to self oscilate, I just hit the rocker switch.

stiiiiiiive · Post by **stiiiiiiive** » Fri Jun 01, 2012 7:41 am

Ah too bad for flange...

Thanks

stiiiiiiive · Post by **stiiiiiiive** » Fri Jun 01, 2012 7:51 am

I've just remember I wrote to Moog once to know what trimmer adjusts what.

Disclaimer: the Moog tech who answered me recommended "not to adjusting any of them, as they require special equipment here at the factory". You are taking your risks.

Here are some answers then:

- VR1: Controls the strength of feedback in relation to the position of the pot. The factory spec is for the feedback to be at "the verge of infinite" (i.e., endlessly repeating with minimal distortion) when the feedback pot is set to 8.
- VR2: Adjusts the symmetry of clipping distortion in the op-amps
- VR3: Adjusts the +15 voltage in the power section
- VR4: Calibrates the compressor/expander to maximize the signal-to-noise ratio

BTW my mail was about the lowpass filter roll-off. It turns that there is not trimmer to adjust its roll-off. The setting is built in the circuitry.

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