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WIGGLING 'LITE' IN GUEST MODE

Dot Com Q112/Q113 Mysterious Ouput Header
MUFF WIGGLER Forum Index -> 5U Format Modules  
Author Dot Com Q112/Q113 Mysterious Ouput Header
Rex Coil 7
Anyone know what this is for, or how I would go about testing it? If it's tough to read, it's a 2 pin output header that says "Jack 1/4 Inverted Out".



It's not marked A/C or D/C. What I'd like to know is if I can use it to invert VCO waveform outputs.

How would I go about testing it without a scope? At my disposal, currently I have a Q106 operating and one Q109 up and running. I suppose I could also use a 9v battery as a DC test source going ~IN~ to the mixer as well.

This feature could be useful (very!) if it is sends inverted audio. I just don't know how to test it to find out if it A/C coupled.

Think of how COOL it would be to have either an additional inverted summed out jack , or even a toggle switch to swap between inverted and non-inverted summed out.

Thank you!
ranix
the only way to safely identify an unknown signal without a schematic or a scope without risking damage is to reverse engineer the board. You could try to follow the pcb trace to see where it goes, and infer based on context what its purpose is based on what it connects to

sometimes if it's too hard to visually follow you can use a multimeter's continuity detector to help but that's context dependent since the continuity detector's behavior in an unknown circuit is undefined
ranix
actually I guess there is another way - you could ask the designer directly since he lurks here cool
Dave Peck
Try this -

1. Patch a relatively fast-running sawtooth LFO through the mixer, like 15 Hz (high enough so even if the board has DC blocking capacitors the LFO signal will still make it through).

2. Now send the mixer out to the pitch mod input of an audio osc, turn up the knob, and note if the LFO is causing the audio osc to ramp UP or ramp DOWN.

3. Now use that mystery header instead of the regular mixer output and check the audio osc again. If it is now ramping in the opposite direction from the way it was before, you have confirmed that this header inverts the mixer output.

If you want to do a similar experiment with all-audio-rate signals, here's another option:

1. Patch an audio osc to a multiple and send one branch to a mixer input (NOT the mixer you are investigating, a separate mixer).

2. Send another branch of the multipl to the mixer under investigation, and send that mixer out to a second input of the first mixer and listen to the output of that mixer. With the first mixer knob (the signal directly from the audio osc/multiple branch #1) already turned up so you can hear the osc, when you turn up the knob for the signal that has been passed through the mixer under investigation, you should just hear the audio osc get louder.

3. Now use that mystery header instead of the regular output of the mixer under investigation and send THAT to the second input of the first mixer. Now, when you turn up the knob to hear the signal that has passed through the mixer under investigation, if the mixer is now inverting the signal, the audio osc will get quieter and will CANCEL when the two knobs are at the same level.
Rex Coil 7
^ the phase cancellation test seems pretty viable. Thank you Member *Dave Peck ... thumbs up

I suppose I could also just write Roger (Arrick) directly at the tech address on the Dot Com website. But that's not as much fun.

cool

And thanks to Member *ranix. Reverse engineering the board is an option, but not one that fits within my skills or education level. I would be BOMBING this thread with dumbass questions! LOOOOONNNNGGG winded doofus questions. I'm already far too long winded, nobody wants more of that.

help
sbuge
Quote:
Think of how COOL it would be to have either an additional inverted summed out jack , or even a toggle switch to swap between inverted and non-inverted summed out.


Keep us informed with your findings (and thanks for doing the dirty work for the rest of us Rex Coil 7)
Rex Coil 7
sbuge wrote:
Quote:
Think of how COOL it would be to have either an additional inverted summed out jack , or even a toggle switch to swap between inverted and non-inverted summed out.


Keep us informed with your findings (and thanks for doing the dirty work for the rest of us Rex Coil 7)
Thank YOU for the acknowledgement.

BTW, I wrote to Roger. We'll see!

cool
diophantine
Answer is in your previous thread, and yes, it is the inverted output razz
https://www.muffwiggler.com/forum/viewtopic.php?p=2208031#2208031

Also, I'm 99% sure that it is DC coupled. IIRC the single electrolytic (not in the power conditioning circuit) is for the AC coupled output. But, based on your usage descriptions, you probably don't have a need for AC coupling.
ranix
that's awesome, I'm totally going to drill out a hole right above the combined out of my q113 and add an inverted output jack w00t

interestingly the first result on a Google Images search for "dotcom q113" appears to be my synthesizer woah
Rex Coil 7
diophantine wrote:
Answer is in your previous thread, and yes, it is the inverted output razz
https://www.muffwiggler.com/forum/viewtopic.php?p=2208031#2208031


We already know it's an inverted out ... no revelation there ... it says so right on the datasheet image of the circuit board.

I've read it only applies to the left ~bus~ of the board, but I've read other comments testifying that "Roger said" this or that.

I'll still wait to hear what Roger replies to me with. There may be deeper answers yet to be revealed.

And it could apply to my synth, the VCOs won't always be used as audio sources ... from time to time, one or another of the VCOs may also be used as LFOs. At which point we're dealing with AC/DC coupling issues.

Mr. Green
kindredlost
I got a little giddy there for a minute thinking this was the common board shared between a few modules (which it is), but not the same as the common board shared between the Q111 Pan/Fade and Q116 Ring Modulator. The Q112 (4 channel mixer) used to share this same board before the introduction of the Q113. Roger redesigned the Q112 to use this board (I think) on the latter incarnations. At least that was my understanding.

The reason for my giddiness (besides being silly) is the way the Q111 Pan/Fade module works. It has a normal and inverted output when in Panning Mode which really irks me. angry
I modified mine years ago to make both outputs normal so I can use it as a standard stereo pan module. It would have been wonderful if Roger had reworked the board to include an inverted (re-normalized) output for those of us who wanted this feature. But no. waah

Q111 Pan/Fade PCB


QUESTION: If this PCB on the Q112 & Q113 does have an inverted output on channels 1-4 then couldn't you use this as a Ring Modulator by crossing an inverted out (modulator signal) into the input section 5-8 which will output a normal wave form and mix it with the carrier there? Like the modulator in one of the first three or four channels and the output of that section back into the 5-8 channel area to mix with another signal. I may be all wrong but isn't that essentially what is going on in an R/M module?
Rex Coil 7
kindredlost wrote:
I got a little giddy there for a minute thinking this was the common board shared between a few modules (which it is), but not the same as the common board shared between the Q111 Pan/Fade and Q116 Ring Modulator. The Q112 (4 channel mixer) used to share this same board before the introduction of the Q113. Roger redesigned the Q112 to use this board (I think) on the latter incarnations. At least that was my understanding.
Ok. I'm confused (but I had a really bad night and I feel like hell today, so my head is full of oatmeal right now). Use of the phrase "this board" is what's throwing me ("this" meaning the board that is the topic of this thread ... or "this" referring to the Q111/Q116 board?). That said, I'm going to attempt to word this as I know it to be.

The 4ch mixer known as the Q112 used the same PCB as the Q111 Pan/Fade and Q116 Ring Modulator in the earliest versions of the Q112 4 channel mixer (the Q112 only had 2 knobs in that earliest of configurations). On (or at some point before) April 29th 2002 the Q112 PCB was changed to the same PCB as the Q113/Q161/Q162 but still only had two knobs. I know this because I have a 2 knob Q112 that was outfitted with the current PCB, and it's test date is 4/29/02.

When looking at the Q111 Pan Fade I own (dated Feb/2010) it still says "Pan-Fade/Mix/Ring Mod" on the PCB, however there are no model numbers ("Q111" and so on). My own guess as to why that is so would be that in 2010 the Q111 and Q116 were using PCBs that still had "MIX" written on them. However, that particular PCB was no longer used in any of the multi-channel mixers (other than the Pan/Fade, which I suppose you could call a "mixer" if you wanted). The Q116 Ring Mod I had also used the PCB that had "Pan-Fade/Mix/Ring Mod" on it.

On or prior to April 29th 2002 the Q112 was outfitted with the PCB that is shared by the Q113/Q161/Q162. It should be noted, however, that the latest Q112 I purchased (built in late 2017) had a PCB that was only partially populated with components. Still the same board as the Q113/Q161/Q162 but only populated with enough parts to create a 4 channel mixer (what a drag!).

kindredlost wrote:
The reason for my giddiness (besides being silly) is the way the Q111 Pan/Fade module works. It has a normal and inverted output when in Panning Mode which really irks me. angry
I modified mine years ago to make both outputs normal so I can use it as a standard stereo pan module. It would have been wonderful if Roger had reworked the board to include an inverted (re-normalized) output for those of us who wanted this feature. But no. waah

Q111 Pan/Fade PCB


QUESTION: If this PCB on the Q112 & Q113 does have an inverted output on channels 1-4 then couldn't you use this as a Ring Modulator by crossing an inverted out (modulator signal) into the input section 5-8 which will output a normal wave form and mix it with the carrier there? Like the modulator in one of the first three or four channels and the output of that section back into the 5-8 channel area to mix with another signal. I may be all wrong but isn't that essentially what is going on in an R/M module?


So, if I follow, remove the pigtail that connects the "Section 1 Output" jack to the ~normal~ Section 1 Output header and reconnect that jack to this mystery "Inv" header .... then connect a patch cable to the Section 1 Output Jack (now inverted) and connect the other end to one of the attenuated Section 2 inputs .... then connect a VCO into Section 1 and another VCO into Section 2 .. mix them ... and this will create a ring modulated output from the "Section 2 Output" ... do I have that right? Or would the "Combined Output" jack (which is a summed out for both Section 1 and Section 2) be used as the output for the ring mod configuration?

If so ... I'll need to rewire my repanelled dual VCO setup to somehow take advantage of this! The only wildcard is whether the "Inv" header is AC or DC coupled ... although I have zip clue how AC or DC coupling would affect things when attempting to reconfigure the Q112 PCB as a ring mod. Cuz I can haz dumbshit.

lol

Going back to the Q111/Q116 ... I've asked several times in threads (I even authored a thread dedicated to the following question) if there is a way to use the Pan/Fade module as a Ring Modulator? From everything I can see on either PCB (Q111 and Q116) they appear to have the exact same components. The image of the PCB of both modules' datasheets confirms this. However I cannot seem to wrap my peanut brain around ~how~ to go about it.

Sorry if I contorted things here ... I am really not feeling well today. I stopped drinking (totally and completely) over 15 years ago, but I feel really ~hung over~ today. Maybe I've caught something, I was at the VA a few days ago for a hearing test (turns out I need hearing aids to handle the severe ringing that certain meds cause) .. so hard telling if I caught some kinda creepin' crud while in the VA clinic. Ya never know what's on door handles or anything else touched by other humans in medical facility!! And after all, it is "the VA", notorious for it's problems.

Anyhow ... Cheesy!
kindredlost
The exact history of the board on the Q111 Pan/Fade is unclear for me and I was just going off memory from a long lost thread or conversation with Roger Arrick. Not that it's in any way important.

I think you have the general idea of my question about the Q113 mixer. Moving the jack of Section 1 OUT to the INV OUT header would be the only modification. Then send the output of that section (with a cable) to an input of Section 2 (inputs 5 - 8) on the front panel. Take the output of Section 2 - NOT the COMBINED OUT. I think it is worth the experiment to find out if it will act like a Ring Modulated circuit. All the inputs should be full gain or turned all the way up.

I'll try it when I can. If you beat me to it, fine. I'll take your lab test as a scientific proof. Mr. Green

After moving the SECTION 1 output jumper to inverted out...

coyoteous
I'm pretty sure it's the DC inverted out of one side.
ranix
Just checked it with a scope - on the Q113, this is the right side inverted output (5,6,7,8)
Rex Coil 7
kindredlost wrote:
The exact history of the board on the Q111 Pan/Fade is unclear for me and I was just going off memory from a long lost thread or conversation with Roger Arrick. Not that it's in any way important.

I think you have the general idea of my question about the Q113 mixer. Moving the jack of Section 1 OUT to the INV OUT header would be the only modification. Then send the output of that section (with a cable) to an input of Section 2 (inputs 5 - 8) on the front panel. Take the output of Section 2 - NOT the COMBINED OUT. I think it is worth the experiment to find out if it will act like a Ring Modulated circuit. All the inputs should be full gain or turned all the way up.

I'll try it when I can. If you beat me to it, fine. I'll take your lab test as a scientific proof. Mr. Green

After moving the SECTION 1 output jumper to inverted out...



So, actually go in to Ch8 (which has no attenuator) as shown in your diagram? Or does the ability to attenuate the inverted Section 1 signal not really matter?

OH WAIT!! Woa!! ... I wonder if I can configure the feedback loops thing into the whole works somehow? That might also create some nasty bitchin-ness out of the ring mod ~mod~ set up you're displaying here! Hmm .... lots of questions that are begging for answers! This whole thread is really becoming intriguing.

coyoteous wrote:
I'm pretty sure it's the DC inverted out of one side.
Could be!! Hey, I know ... let's ask *ranix since he went all Dr. Scopey on this one!

ranix wrote:
Just checked it with a scope - on the Q113, this is the right side inverted output (5,6,7,8)
... so if I get you right, it's the "Section 2" channels that come out of that ~Inv~ header? If I'm following *kindredlost properly, that contradicts his info.

kindredlost wrote:
........ Moving the jack of Section 1 OUT to the INV OUT header would be the only modification. Then send the output of that section (with a cable) to an input of Section 2 (inputs 5 - 8) on the front panel. Take the output of Section 2 - NOT the COMBINED OUT .......
seriously, i just don't get it hmmm.....

Oh ... btw *ranix .... was it DC or AC?

ANY-OLD-HOW .......


This is all EXCELLENT info .. I have one ~mixer~ PCB left that isn't already installed into something, I can try a few things with that one. Oddly enough, that PCB is the mixer for the Quad Ring Mod set up in my project synth. But I can use it as a test bed before I install it into the synth for it's permanent assignment. It'll be rough looking and ugly (kindof like that ring mod test panel I made to test out LEDs as diodes for use in a passive ring mod).

As of yet, still no word from Roger (I wrote him Wednesday 5/2/18) ... but that's fine ... I'm sure he's very busy. Being the world's largest 5U manufacturer has GOT to be one hell of a task. Perhaps he'll write over the weekend.

In any case, thanks for following up on this you guys. This has been a super interesting discussion. Hopefully if we work out it's quirks some folks will take full advantage of this feature (like *ranix .... like me! .. and hopefully others as well) thumbs up
ranix
DC for sure
Rex Coil 7
It's been eight days since I wrote to Roger about this, still no reply. hmmm.....

Either he's too busy, or hasn't seen it for whatever reason (internet/tech issue of sorts), or he's just not interested in a reply.

I may try again. Then again ...... seriously, i just don't get it
Rex Coil 7
I heard back from Roger, it was dated May 3rd ... I guess it was missed.

"Brian,
Yes, that's inverted output on the Q112/Q113 mixer PCB.

Thanks for the feedback and glad you're enjoying the modules."

So that's it. He didn't verify anything else (such as which bus it is dedicated to, is it AC or DC, and so on).

But it appears the *ranix covered all of those bases. So nothing new to add. I just wanted to acknowledge that Roger did, in fact, reply. I didn't want to leave the impression that he's unresponsive, that would be unfair to him.

All done ... thumbs up
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