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Q114++ Mixer - OVERDRIVE TESTS!
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Author Q114++ Mixer - OVERDRIVE TESTS!
Rex Coil 7
EDIT: January 30th, 2018 - I posted the actual test today a few posts down. This thread had a different title prior to the tests being done ("Q114++ Mixer - anyone overdriven it?"). I retitled it so others would not think the tests I posted were just some more of my useless jibber jabber. Nope ... there's some actual content posted in the test results! .... read on ...

*****************************************************

I've been thinking of using my Q114++ in place of using a CP3 clone (as a VCO mixer). It would also double as an external instrument interface (rather than using the Q118 for that).

Since the Q114++ offers some pretty high gain multipliers, I was wondering how it sounds when overdriven? Anyone try this yet?

My own system is waiting for me to git off my lazy ass and complete the modifications to it, so it's still in a box full of various parts, otherwise I'd patch it up myself and try it.

Thanks for your help. Brian.
trentpmcd
I haven't had a lot of time since I received it, but I did check it out with a single saw and the x100. Obviously very sensitive so you have to be careful to get the distortion you want. But it sounded pretty good. I didn't A/B it with my STG mixer, so can't tell how it compares. It is useful, though. (Honestly, I only played with it for about 10 minutes and then had to leave)
Rex Coil 7
trentpmcd wrote:
I haven't had a lot of time since I received it, but I did check it out with a single saw and the x100. Obviously very sensitive so you have to be careful to get the distortion you want. But it sounded pretty good. I didn't A/B it with my STG mixer, so can't tell how it compares. It is useful, though. (Honestly, I only played with it for about 10 minutes and then had to leave)
Interesting.

Hmmm... hmmm..... ... thinking .... thinking ....

In fact, interesting enough that I think I'll attempt to cobble together some type of abbreviated system using an outboard synth into the Q114++ to see how it deals with A.) Outboard instruments ... and 2.) overdriving it. I have just enough power and rack space to piece together a basic signal pathway with the Q114++ involved. I'll have to use my Rompler (Kurzweil PC3A6 ... the King of digital synths) as "VCOs", then I'll pipe it into the other modules starting out at the Q118 Instrument Interface, then into the Q114++, then out to the output VCA (Q10-sumthin). If the Q118 proves to be unnecessary then I'll remove it from the path, and go at it again with just the Q114++. Hopefully some working data will be obtained and provide foundational infos for comparative tests between the Q114++ and the STG CP3 clone (named "Mixer" .... geez STG, did it take you all week to work out that name? Haa!).

I should add that I am installing an Oakley Overdrive II between the VCO Mixer and the VCF array. I'll also be adding an Oakley Dual VCA to provide Voltage Control over the gain levels hitting the VCO Mixer (be it the Q114++ or the STG CP3), which will also in turn control the gain levels that ultimately hit the Oakley Distortion II. Just in case any of that stuff matters .... only reason I mentioned it. To be clear, the two mentioned Oakley units will NOT be used in the testing (hells bells I haven't even bought the PCBs for those yet). It will be ACES UP to be able to control distortion with velocity (or any other voltage control source).

So:

** Kurzweil (as the VCOs).
** Q118 Instrument Interface (this may not be required depending on how the Q114++ handles outboard signals).
** Q114++
** STG CP3.
** VCA for output.

This simple chain will hopefully allow for removing both the Q118 and the STG CP3. At least that's the idea here ... eliminating the unnecessary.

I'll post results here in this thread ..... wish me luck!

thumbs up
trentpmcd
Just FYI - I never turned up more than about a quarter of a turn! By then it was getting pretty distorted. x100 is pretty out there for high gain...

Other thing I played with, the reason I got it sooner than later, is to use with my Moon VC envelope. I wanted velocity to act in the opposite way. So, I took the straight +5 from 1, had it go unchanged to 2, put velocity into 2 and had 2 inverted. Now velocity acts exactly how I wanted it.
Rex Coil 7
trentpmcd wrote:
Just FYI - I never turned up more than about a quarter of a turn! By then it was getting pretty distorted. x100 is pretty out there for high gain...

Other thing I played with, the reason I got it sooner than later, is to use with my Moon VC envelope. I wanted velocity to act in the opposite way. So, I took the straight +5 from 1, had it go unchanged to 2, put velocity into 2 and had 2 inverted. Now velocity acts exactly how I wanted it.
Yuh ... sooper versatile module, no doubt!

Only thing, on the "use sheet" for the Q114++, Roger says "2x = 200%" .... if that is so, how is it that he then states "100x = 1,000%". Using his logic, wouldn't TENx (not 100x) = 1,000% (since 2x = 200% ... again by his logic)?

I've only been out of bed for a few minutes, so I may be AFU (all fuddup) on this and not recalling my basic maths properly. It just seems out of whack ... but then again, so do I!

thumbs up

ANNNDDD ..... really nice use of the Q114++ features there, member *trentpmcd ... very clever indeed! I suppose the Q114++ is made for clever folks anyhow, with all of it's possibilities.

Only thing, it needs to have an "aid" module that has a rotary switch for each channel, thereby allowing full access to each channel's full list of features especially for CV use. A per-channel on/off toggle would be stupid helpful as well. I may end up designing and building just such an expander panel for it.

Again, right on with figuring out how to use it to suit your needs! Very sharp thinkin' !!

Brian.
Rex Coil 7
OVERDRIVING THE Q114++ ... COMPARISON TO STG CP3 "Mixer":

Ok ... the testing went EXCELLENTLY! The objective was to find out if the Q114++ would work as an instrument interface, as well as find out if it distorted in a musically useful manner while also providing enough rudeness and upper harmonics to excite the sound and the musician. In short, Roger hit a HOME RUN with the Q114++ Mixer. Read on .....

Signal chain: Let's recall that I do not have access to my VCOs presently. That said, I used my Kurzweil PC3A6 synth as a faux VCO. This is really ok since these tests will now serve two purposes .... how well the Q114++ boosts outboard instruments to modular levels, as well as how it does when pushed into breakup/clipping. Movin' on ....


TEST 1 =

** Kurzweil - raw mono sawtooth patch - VA, not samples, no filter - signal level less than 1 volt.
** Q118 Instrument Interface to boost Kurz signal to modular levels.
** STG CP3 clone, after leaving the Q118 the Kurz is piped into this mixer, various level settings for distortion were used.
** Q108 VCA for output to desk mixer.

TEST 2 =
** Kurzweil - raw mono sawtooth patch - VA, not samples, no filter.
** Q114++, Kurz going into channel 3 (ch3 had the 1X, 2X, and 100X multipliers available).
** Q108 VCA for output to desk mixer.

Test 1 observations: Meh ... worked as expected. The Q118 did a grand job of boosting the Kurz' output level to modular synth level. Push the input gain into the CP3 and of course it distorts a bit.

Test 2A observations: Place option toggle of the Q114++ ch3 in the "2X" position, crank the level knob to max, adjust the Q108 VCA output gain to wrangle the output level to proper levels that my desk mixer likes. Sweet and musical distortion, gain sensitive so when I use velocity on the Kurz to control the sawtooth patch output levels the distortion is controlled by keyboard fingering dynamics. Nice!

Test 2B Observations: Same modules and configuration as Test 2A, however place option toggle in the "100X" position, and back that channel 3 level knob down! Adjust the Q108 output VCA levels down to keep the signal level usable. Well and good, nice warm overdrive sound. But, increase the channel 3 level knob to anywhere between 75% and 100% and the distortion is thick and meaty, very useful, very musical. With certain Kurz patches the ensemble becomes downright despicable! Pulse wave sounds become downright mighty! HO YEA! Very colorful distortion, very analog sounding, quite playable, brings out loads of harmonics, super useful!

CONCLUSIONS: Simply put, the CP3 is out of a job. I think the Q114++ will work just as nicely with actual analog VCOs (4 Q106s set up as two 2 VCO voices) and an Oakley Dual VCA to control the gain levels with any type of modulator you can think of. The Q114++ also permits per-channel signal inverting, something the CP3 cannot do. That is helpful in my synth since I will be using my two filters in parallel at times, and one of those filters inverts the output (which when the two filters' outputs are mixed back together will cause phase cancellation). So having the ability to do per-channel signal inverting will be very helpful.

And since the Q114++ does a great job of boosting instrument level signals to modular levels, the Q118 Instrument Interface may be repurposed, or not used at all.

Now then .... what to do with a lightly used Suit and Tie Guy CP3 clone? ..... (wink wink).

... bst ...

thumbs up
coyoteous
Rex Coil 7: Great rundown... really, but remember the CP3 does an asymmetrical/tiered moogy clipping thing some can't live without (also has a much more subtle 'warmth' due to its discrete circuitry when not clipping, as compared to IC opamp topologies, that I quite like)... just sayin'.
Rex Coil 7
coyoteous wrote:
Rex Coil 7: Great rundown... really, but remember the CP3 does an asymmetrical/tiered moogy clipping thing some can't live without (also has a much more subtle 'warmth' due to its discrete circuitry when not clipping, as compared to IC opamp topologies, that I quite like)... just sayin'.
Thanks for the reminder! I'll most likely hang on to it until I get some more tests done that will include a 2 channel Oakley Overdrive II, one channel per voice. If I cannot arrive at the same type of sounds the CP3 produces, it will still have a spot earned in the synth.

I get a bit excited sometimes, and say things hastily and thoughtless. I suppose I was just happy to learn that the Q144++ is so multi talented and not over hyped by Roger in his marketing of the Q114++. Not that I've known Roger to ever do that.

So ~yes~, you are handing out some good advice .... slow goin' is the most productive way to go about configuring one's modular.

Thank you for the reminder regarding applying the brakes.

cool
Rex Coil 7
coyoteous wrote:
Rex Coil 7: Great rundown... really, but remember the CP3 does an asymmetrical/tiered moogy clipping thing some can't live without (also has a much more subtle 'warmth' due to its discrete circuitry when not clipping, as compared to IC opamp topologies, that I quite like)... just sayin'.
One question; Isn't a large part of the channel interaction on the CP3 due to it's use of a passive mixer (unbuffered channels, the signals of all input channels interact with one another)?

"Unbuffered" may be an inaccurate description ... perhaps "non discrete" works better.
coyoteous
Rex Coil 7: Thanks for thanking me... sorry, I missed your second post earlier.

I don't know that it would be a 'large part,' or honestly, a part at all (could be, though... let me think on it, and maybe research).

In the meantime, I can talk out of my, uh... other end (often smarter, anyway).

OK, just reread... channel interaction, eh? Is that a thing with these? How so? Do you mean like crosstalk between channels? Or, channels attenuating as one is turned up? (sorry about all the questions in a row)

Most (all?) mixers use passive summing... then, unless it's a fully passive mixer, there is amplification/'make up gain' to make up for summing losses (in the case if a fully passive summing buss, external amplification is usually used).

There is 'non-linear' mixing, like mixing two signals together with a mult... without any summing resistors (kind if a no no, but if I recall, can work depending on the input and output impedances on the front end).

If you put an amplifier or driver (even at unity gain or less) on each input, then you've got what I think of as an fully active mixer... so, as you say, you've got buffering on the inputs (and on the output from the summing amp/line driver).

Also, you can change channel levels by changing the gains of the amps and/or by attenuators before or after... I think if you can 'fade to zero' (minus infinity?), it's probably an attenuator.

Let me find and look at the CP3 circuit vs. what I'd guess Roger's is like.

(remembering you can also mix with transformers, though that's not pertinent here... I made a little box a long time ago with pretty high-dollar Jensens from one of their application sheets, that sums two balanced low impedance mics to a single mic pre input, for example)

Anybody that knows/remembers this stuff, feel free to jump in... if I've misstated something, please correct.
ranix
I had it in my head that all "mixers" were nonlinear and "summing" was linear. I got this idea when I was learning about resultant organ stops. A resultant tone at the least common denominator frequency between two higher frequency sinusoids is generated when they are mixed in a nonlinear system (such as a mixer or the air) but not when summed.
Rex Coil 7
Ok fellas (members *coyoteous and *ranix) ... although I'm on a self imposed reduction of activity here in the forums, I'm allowing myself to be active just in the mornings while my coffee is taking root in my bloodstream .. heheh. That said, here's what I have on the CP3 that has been sitting in my hard drive for a while.



Note how all of the input channels are not discrete from one another. It is a completely passive mixer until the sum hits that first transistor (a 3392 in that schematic).

Passive mixers allow the input levels of all of the channels to interact ... when one signal is adjusted to higher or lower levels, it affects all of the other channels. It's a part of how the CP3 does it's ~thang~ as the signals come in and out of phase (we're presuming that the signals are tuned to some harmonic relative to each other, or perhaps even unison).

Now, when I said "interact" it doesn't actually mean that if one channel is adjusted louder that all of the other channels will go up or down by the same amount as the one that was adjusted up or down. But adjusting one channel (or increasing the input gain on one channel by making that device put out more signal level on it's own) it will affect the sum. That is because the channels are not "discrete" ... hmmm ... I think better said would be "buffered" from one another.

You could chop off that entire first chunk of the schematic ... all four input channels just before they hit that first transistor (the 3392 in the schematic), stick a 1/4" jack in place of the 3392, and you'd have a fully functioning 4 channel passive mixer ... without a single additional component involved. This is why I said previously that the CP3 uses a passive mixer with unbuffered non-discrete channel architecture.

Y'know ... I just had a thinkage ... I wonder if using a passive mixer (easily DIY'd or purchased from companies such as a Rolls or even a Behringer ... which retail for less than $25.00 bucks or so) and running the sum of the VCOs into ~various~ mixers or manglers (et al) would produce a pleasing sound in the same manner as the CP3? Think of it, you could have the same mixer type as the CP3, but run the sum into different circuitry than the CP3 uses ... but still have an interacting affect just like the CP3 offers?

In other words, use the passive mixer, run the sum into different circuitry of choice. Passive mixers all have that same interactive property. Alot of the interaction has to do with the varying input impedance that mixing 2,3,4 sources to sum without being individually buffered from one another. That changing impedance changes how the signal is shaped, because the changing impedance changes the load placed on the input devices. I know that happens when passively mixing guitar signals (think large pedalboard with different goodies on it, add a passive mixer into the mess and you can create sounds otherwise not possible if an "active" mixer were used).

So ok ... there's all I have in my head on this issue.

cool

EDIT: Re; the Q114++. That is a totally active mixer. Each channel is a discrete buffered channel that may (might possibly) be summed with the others after they're buffered. Additional inputs do not (seem to) affect the other channels, by way of varying input impedance or other interacting issues. We know this about the Q114++ since we have individual channel control over things such as gain levels (x1, x2, x100), per-channel inversion, AC/DC coupling. None of that is available on each individual channel of a passive mixer, since the input stages (eg; "channels") have no powered components to offer things such as per-channel gain stages, inversion per channel, as well as coupling per channel.

Ta da! Mr. Green
coyoteous
Rex Coil 7: Still digesting that, but wanted to say that when I initially said 'discrete,' I meant it only and contextually for common usage specifying circuit topologies... as in, 'discrete' transistors and passive components making up an amplifier, buffer, etc. vs. 'integrated circuits' (IC/chip).

They can be functionally the same, but chips aren't known for the mojo of discrete circuits and, even though they have there own more subtle differences in how they affect audio.

Same goes for linear, passive, etc.

Know thy context and common parlance/jargon... I think it's better to avoid multiple meanings of the same term in a technical discussion to avoid confusion.

Rex, now find you an IC opamp 'cookbook' schemo for a mixer that's functionally the same, and I think you'll see the actual summing is passive there, too... kinda has to be because it's resistors and they're passive components.

OK, back to your post now (could mean: 'Rex, get back to your duty,' or 'I'm going to continue reading what you wrote,' right?).

Semantics, can't live with 'em... can't live without 'em.

One can be literally right and contextually wrong (happens to me in social situations all the time).

Guessing you're at least literally right in some sense, though.

Added: http://www.devo.com/bladerunner/sector/2/interrogation.html

More added: I'm afraid you're contextually butchering 'interact' and some other terms here other than what I already mentioned... lost count.

On the bright side, you've possibly reinvented not only spokes, but hubs... got rims?
Rex Coil 7
What in the absolute .... geez ... Wow ... you are reading WAY too far into my words. I was not comparing what you said to anything, nor was I being critical of the way you used the word "discrete". All I did was try to help folks understand why a CP3 acts as it does. I wasn't trying to correct you, or point to some misuse of grammar. I placed quotations around that word (as I do many times when I type) because I didn't have a better word to use. I wasn't even referring to your post(s) ... not even a tiny little bit. My post stands on it's own. Please try not to take things I say as something directed at you, or take them personally.

Discrete .... simply meaning constituting a separate entity; individually distinct. That is ALL I meant.

Interact ... simply meaning to act in such a way as to have an effect on another; act reciprocally. That is ALL I meant.

I would have written precisely the same thing(s) whether you had posted or not. My words were not a critique of your usage of any words. We good?

So all I am meaning .... when comparing a mixer that has active channels (that is to say "powered" channels) to a mixer that has passive input channels (unpowered circuitry) the two types behave differently ... and hence sound differently. It has alot to do with input impedance that changes as you add more signals (this is a passive mixer). This is not my opinion, this is a fact.

I've already described what I mean "ad nauseam" by this point as it pertains to why I feel the CP3 does what it does. So I'll not pound that issue any harder.

Just to be clear, had I been referring to "discrete componentry" (individual components rather than integrated components) I would say precisely that.

But thanks for the English lesson. thumbs up
coyoteous
Wow!
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