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 Forum index » DIY Hardware and Software » Jürgen Haible designs
Resonator Section of Polymoog ...
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Funky40



Joined: Sep 24, 2005
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PostPosted: Wed Aug 12, 2009 2:40 pm    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
I'll make it stackable. Buy 2 PCBs for 6 bands etc.!!

JH.

What makes sense here ?

would one not want to have smaller bands if having more Bands or does you control this with the Resonance ?
I'm stll confused about filtersteepness and how much you can control this with Resonance
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Funky40



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PostPosted: Wed Aug 12, 2009 2:45 pm    Post subject: Reply with quote  Mark this post and the followings unread

ufff...............
there is space ?
please, please add a Gainstage !!!
very important, really !



edit: or add better two Laughing
( a second one could be used to patch directly external gear into it. Your SSM2019 stage would be very welcome. )
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jhaible



Joined: May 25, 2007
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PostPosted: Wed Aug 12, 2009 2:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

Funky40 wrote:
jhaible wrote:
I'll make it stackable. Buy 2 PCBs for 6 bands etc.!!

JH.

What makes sense here ?

would one not want to have smaller bands if having more Bands or does you control this with the Resonance ?
I'm stll confused about filtersteepness and how much you can control this with Resonance


It's DIY - you choose the filter caps, you choose the resonance range, you choose the opamps ... the components shown on the PCB overlay are just a suggestion (taken from th eoriginal, of course).

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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jhaible



Joined: May 25, 2007
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PostPosted: Wed Aug 12, 2009 2:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

Funky40 wrote:
ufff...............
there is space ?
please, please add a Gainstage !!!
very important, really !



edit: or add better two Laughing
( a second one could be used to patch directly external gear into it. Your SSM2019 stage would be very welcome. )


There's an input amp and an output amp with mixer (for dry and resonator). You choose the resistors in these opamp stages, so you define the gain!
Did I mention that this is DIY? Smile Smile

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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Funky40



Joined: Sep 24, 2005
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PostPosted: Wed Aug 12, 2009 4:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
Did I mention that this is DIY? Smile Smile

JH.

I forgot to mention that i mean with a Gainstage something that you can manually adjust.

It has quite a lot of importance to me to have everytihng on disconnectable Headers.
there is space, you could add in the middle of nothing a gainstage..
Or maybe it would be possible to just add some more space to the pads of the feedbackresistors of the mixerstages that one could replace those resistors with pots,
and having the connections on headers


the use of such filters with maually adjustable Boost is lots more versatile than without.
Recommended to everyboy to have a manually adjustbale boost after the output,
or even better having behind this boost also a VCA................
the space is there.
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jhaible



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PostPosted: Wed Aug 12, 2009 11:37 pm    Post subject: Reply with quote  Mark this post and the followings unread

Funky40 wrote:
jhaible wrote:
Did I mention that this is DIY? Smile Smile

JH.

I forgot to mention that i mean with a Gainstage something that you can manually adjust.

It has quite a lot of importance to me to have everytihng on disconnectable Headers.
there is space, you could add in the middle of nothing a gainstage..
Or maybe it would be possible to just add some more space to the pads of the feedbackresistors of the mixerstages that one could replace those resistors with pots,
and having the connections on headers


the use of such filters with maually adjustable Boost is lots more versatile than without.
Recommended to everyboy to have a manually adjustbale boost after the output,
or even better having behind this boost also a VCA................
the space is there.


There must be some misunderstanding - and it's my fault because I've quickly posted a PCB screenshot before I have any other documentation! There are level potentiometers galore, pre- and post-resonator, plus the 3 individual resonator gains and the dry level. Don't worry. Smile

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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Funky40



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PostPosted: Thu Aug 13, 2009 8:41 am    Post subject: Reply with quote  Mark this post and the followings unread

I was not thinking to level attenuating my thinking is to boost the signal after the EQ.
( but maybe it"s me who's not understanding )


my point:
i like to filter out signals and then boost the remaining part up to full level.
this really needs very good circuits to be with as less artefacts as possible.

this is ofcourse not what a original moog is intended to do i guess,
but it makes the use of such a unit much more felxible and allows much more musical use when jamming.
My point in that certain case:
if the space is free on the PCB, why not adding a dedicated circuitry to boost ?
especially as it is to be expected that you would deliver a qood quality.( your SSM2019 circuitry e.G.)


yup, would make you some work, i know



and another plus:
if you "would" add a boosterstage, this would make it possible to add it also in front of the circuit for those folks who like to have direct Mic/Instrument patchability.
so it could be more versatile for modularsynthuseres AND for studio/ stompbox users.
I hoped i get you with that last point Wink
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jhaible



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PostPosted: Thu Aug 13, 2009 11:41 am    Post subject: Reply with quote  Mark this post and the followings unread

Funky40 wrote:
I was not thinking to level attenuating my thinking is to boost the signal after the EQ.
( but maybe it"s me who's not understanding )


my point:
i like to filter out signals and then boost the remaining part up to full level.
this really needs very good circuits to be with as less artefacts as possible.

this is ofcourse not what a original moog is intended to do i guess,
but it makes the use of such a unit much more felxible and allows much more musical use when jamming.
My point in that certain case:
if the space is free on the PCB, why not adding a dedicated circuitry to boost ?
especially as it is to be expected that you would deliver a qood quality.( your SSM2019 circuitry e.G.)


yup, would make you some work, i know



and another plus:
if you "would" add a boosterstage, this would make it possible to add it also in front of the circuit for those folks who like to have direct Mic/Instrument patchability.
so it could be more versatile for modularsynthuseres AND for studio/ stompbox users.
I hoped i get you with that last point Wink


That "post EQ" gain stage is already there!
As it's not part of the original circuit, I even have printed "OPA604" on the board as a suggestion. For higher gain, just increase a single resistor.

ETA: Added a sea of pads in 2.54mm grid, so everybody can make minor additions veroboard-style, whatever he wants.

Gerber files sent to PCB house for 1st prototype.

Now my focus is on something entirely different. Might be that I'm away from the PC for a few days quite suddenly ... Laughing

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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/mr



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PostPosted: Thu Aug 13, 2009 2:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Grrreat to find this thread, and also great to see that you're already off to something more important - so that I don't have to suggest that the board size would be suitable to house a dual unit, for the ones who wants a stereo or dual mono arrangement. Now I will never even mention how perfect it would be. Laughing

I never checked out the Polymoog resonator schematic before, and I've never played one. But it sounds amazingly real and acoustic in Elhardt's hands! (What a tautology btw.) What I did check out, however, is the schematics of the Moog Parametric Eq standalone unit, which I often wanted to clone but felt sick when I saw the pot values - and I notice now that the Polymoog resonator section is much much simpler to find the right potentiometers to! Oh, happiness! Very Happy
10k log, 10k lin, 10k dual lin... instead of
25k lin, 100k dual reverse log, 500R lin / 50k log bizarre dual combo! Shocked

The DIY Polymoog resonator design could even be made stereo by joining two boards, if you manage to find quad 10k lin pots for the frequency controls... or even cooler - since these pots are connected as rheostats - you can exchange them for Vactrols and easily have stereo connection AND voltage-controlled peak frequencies! Razz

Funky40 wrote:
jhaible wrote:
I'll make it stackable. Buy 2 PCBs for 6 bands etc.!!

What makes sense here ?
would one not want to have smaller bands if having more Bands or does you control this with the Resonance ?


My guess is that two units with alternately placed peaks would come handy. The peak frequencies are a bit strangely configured in the original Polymoog (60-300, 300-1500, 1500-7500 Hz) with completely separate ranges for the three peaks, "locking in" each peak in its own interval. Might be fool-proof but not as versatile as having overlapping bands like other EQs and mixers often have. Adding another of these DIY boards with halved frequency capacitors could add three new bands (e.g., 120-600, 600-3000, 3000-15000 Hz) to form a six-band unit with a handy overlap.

(If Dr Korg would have been around, I would have suggested parallel slide pots with knobs acting as physical stops a la multi-"Traveler", ye olde Korge style.) Wink
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elhardt



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PostPosted: Mon Aug 17, 2009 2:58 pm    Post subject: Reply with quote  Mark this post and the followings unread

As the only one who currently owns a stand-alone Polymoog Resonator, I should respond to some things people are saying.

First is regarding all the talk about an output gain stage. You can easily just increase the signal going into the unit to get more output. It seems to handle it quite well. In fact, most of the time, I'm having to keep the gains on the bands lower than max because especially when using a lot of resonance, you'll get too much output. When I ran that youtube video through mine, I had to set my mixer output really low that fed the resonator because the output of the resonator was overdriving my Zoom H2 digital recorder.

About number of bands and overlap. First keep in mind for comparison that the Polyfusion formant filter only has bandpass filters, and covers a more limited range than the Moog. For acoustic instrument formants, the bands work well. If an instrument has two predominant formant peaks, they always seem to fall into two different Moog bands, so Moog picked the frequencies well. Having a 6 band filter bank where the additional 3 are offset a bit for overlap doesn't really get you anything. Running two resonators in parallel to give you 6 bands means you're going to have plenty of overlap. You'll have 2 filters for each range, so there's not much of a need to change frequencies. And there's nothing about the 7.5K range that needs fine tonal control anyway. In addition, I mentioned to JH, that the more bands you use, the more you water down the result. I usually find that I only need one or at most two filters beyond the normal lowpass already in the synth I'd be running through it.

Also just to mention that my Resonator was just auctioned off for $1200. That's what happens when you end up with two people who really wanted one. But I can tell you, I don't believe it got that high based solely on its functionality. One of the losing bidders said he really wanted the unit with that nice wooden box and Moog logo on top. I'm pretty sure I could sell 2 to 3 more quite easily. That of course got me thinking that maybe I should buy some JH boards, build them up, put in a power supply, do some front panel graphics with the Moog logo in them, use real Moog knobs for vintage Moog looks and to match their Moogerfooger line, build the Oak cases with stain and semi-gloss clear coat (like the one I did), put the Moog Logo the top of that too, and add a couple of nice enhancements I have in mind, and sell them off at about the $550 price I originally list my current one at. If I had several people interested to make it worth while, I'd be tempted.

-Ken Elhardt
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TekniK



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PostPosted: Mon Aug 17, 2009 9:13 pm    Post subject: Reply with quote  Mark this post and the followings unread

elhardt wrote:
Having a 6 band filter bank where the additional 3 are offset a bit for overlap doesn't really get you anything. Running two resonators in parallel to give you 6 bands means you're going to have plenty of overlap. You'll have 2 filters for each range, so there's not much of a need to change frequencies.
-Ken Elhardt


yes ,u are right
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/mr



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PostPosted: Tue Aug 18, 2009 6:54 am    Post subject: Reply with quote  Mark this post and the followings unread

elhardt wrote:
About number of bands and overlap. [...] For acoustic instrument formants, the bands work well. If an instrument has two predominant formant peaks, they always seem to fall into two different Moog bands, so Moog picked the frequencies well. Having a 6 band filter bank where the additional 3 are offset a bit for overlap doesn't really get you anything.

I agree as well. My point was not really that it would necessarily be better with more bands. Smile At least not if using all bands as resonant peaks - maybe more if some of them are notches, then the module's possibilities could be more similar to a fixed filter bank. But hmm, maybe the Polymoog resonators only go from peak to flat, and not down to a notch?

Good to hear (almost even expected) that Moog's choice of frequency ranges seem well chosen for various acoustic instruments, because then it will probably be very useful for all kinds of electronic noises as well. It might be good to remember how our hearing works - after all, it's designed to analyze the human voice, which often has 2 or 3 important formants that form our vowels. Instruments with similar qualities tend to be interesting in our ears, and if we overdo it with lots of more advanced spectral shaping we might be missing the goal. Smile
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a100user



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PostPosted: Tue Aug 18, 2009 7:44 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi, Juergen,

Any idea when these boards we be available?

Thanks

DS
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jhaible



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PostPosted: Tue Aug 18, 2009 9:15 am    Post subject: Reply with quote  Mark this post and the followings unread

a100user wrote:
Hi, Juergen,

Any idea when these boards we be available?

Thanks

DS


In about two months if all goes as intended.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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elhardt



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PostPosted: Tue Aug 18, 2009 10:39 am    Post subject: Reply with quote  Mark this post and the followings unread

/mr wrote:
I agree as well. My point was not really that it would necessarily be better with more bands. :) At least not if using all bands as resonant peaks - maybe more if some of them are notches, then the module's possibilities could be more similar to a fixed filter bank. But hmm, maybe the Polymoog resonators only go from peak to flat, and not down to a notch?


The resonator in the Polymoog doesn't have a notch setting. But I noticed on JH's PCB a place where in addition to LP,BP,HP there was something called BN. Maybe that's Band Notch. But if it's like the notch setting on most state variable filters, it would have very little affect.

-Ken Elhardt
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jhaible



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PostPosted: Tue Aug 18, 2009 11:33 am    Post subject: Reply with quote  Mark this post and the followings unread

elhardt wrote:
/mr wrote:
I agree as well. My point was not really that it would necessarily be better with more bands. Smile At least not if using all bands as resonant peaks - maybe more if some of them are notches, then the module's possibilities could be more similar to a fixed filter bank. But hmm, maybe the Polymoog resonators only go from peak to flat, and not down to a notch?


The resonator in the Polymoog doesn't have a notch setting. But I noticed on JH's PCB a place where in addition to LP,BP,HP there was something called BN. Maybe that's Band Notch. But if it's like the notch setting on most state variable filters, it would have very little affect.

-Ken Elhardt


The funny thing is: That mode is on the original Polymoog board as well, but apparently it has never been used.

It is simply this: The "middle" filter section has an extra inverting opamp stage to bring out the BPF. This is to avoid phase cancellation from 3 Band Pass filters in parallel. (You often see this in vocoders, too: mixing every other channel with inverted phase.)
But there is also a mix of the un-inverted BPF, which *does* have the notches.
So on my PCB, as on the original Polymoog PCB, you can choose between 4 (not just 3) settings.

You can clearly see what difference it makes, in my Simulation plot:
http://electro-music.com/forum/phpbb-files/resonator_modes_151.jpg

Orange trace: ordinary BPF mode
Purple trace: BPF mode with notches

And look at those complex transfer functions in LPF and HPF mode (yellow and green)!

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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/mr



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PostPosted: Tue Aug 18, 2009 3:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

jhaible wrote:
elhardt wrote:
/mr wrote:
But hmm, maybe the Polymoog resonators only go from peak to flat, and not down to a notch?

The resonator in the Polymoog doesn't have a notch setting.

But there is also a mix of the un-inverted BPF, which *does* have the notches.
You can clearly see what difference it makes, in my Simulation plot:
http://electro-music.com/forum/phpbb-files/resonator_modes_151.jpg
Orange trace: ordinary BPF mode
Purple trace: BPF mode with notches

Ah, but that's "just" notches between the peaks, not parametric dips. Interesting nevertheless! Laughing
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jhaible



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PostPosted: Tue Aug 18, 2009 4:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

/mr wrote:

Ah, but that's "just" notches between the peaks, not parametric dips. Interesting nevertheless! Laughing


Right! - Never meant to say anything else; sorry for the confusion!

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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a100user



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PostPosted: Wed Aug 19, 2009 12:14 am    Post subject: Reply with quote  Mark this post and the followings unread

[quote="jhaible"][quote="a100user"]Hi, Juergen,

Any idea when these boards we be available?

Thanks

DS[/quote]

In about two months if all goes as intended.

JH.[/quote]

Look forward to the release.
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jhaible



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PostPosted: Tue Aug 25, 2009 2:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Prototype PCB arrived today.

This project is going faster than anticipated! Laughing

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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TekniK



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PostPosted: Tue Aug 25, 2009 3:10 am    Post subject: Reply with quote  Mark this post and the followings unread

i already ordered parts just based on the pics also for the flanger Very Happy
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jhaible



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PostPosted: Tue Aug 25, 2009 7:57 am    Post subject: Reply with quote  Mark this post and the followings unread

TekniK wrote:
i already ordered parts just based on the pics also for the flanger Very Happy


I've done most of the wiring of the Flanger Prototype, but all these posts and switches on the front panel ... I'll wait until I have the real front panel from Schaeffer in a week or so, then I'll make tests and circuit fine tuning.

Meanwhile, prototyping the "easy" project, the Polymoog Resonator.

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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2thick4uni



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PostPosted: Tue Aug 25, 2009 3:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hi Jurgen,

I'd like two of these pcb's when available.

The original poymoog seemed to use 9 of dual gang 10k sliders, these are now very difficult to obtain. I'd really prefer to use sliders to pots for this project, and chance you could redesign it to work with single gang pots? Or do you have a source for 10k dual gang sliders?

Allan
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magman



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PostPosted: Tue Aug 25, 2009 4:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've just done a quick Google search and it appears that Tyco have a range of dual gang sliders from 30mm to to 75mm which RS Components stock (so this should make them available just about anywhere).

Not cheap, at about 7GBP each, but at least they're not unobtanium. A group-buy might not be a bad idea if people want to follow the slider route.

Regards

Magman
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jhaible



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PostPosted: Wed Aug 26, 2009 12:59 am    Post subject: Reply with quote  Mark this post and the followings unread

At least the pots / sliders all have a "standard" value of 10kOhm !

I've taken a very pragmatic approach for the PCB layout.
There are connectors on the board, where you can wire any potentiometer or slider you choose (or rather, you find available).
And in addition to this, I have footprints for Alps RK11 (mono) and RK14 (stereo) potentiometers. These are rotary potentiometers, of course, but they are PCB mount and good quality, and they allow quick testing of the prototype. And they also allow a good rotary-pot-based frontpanel layout similar to the "other" Moog parametric Equalizer.

In order to keep track with a huge load of work, I'll build my own prototype with rotary pots. But yes, sliders are cool, and I encourage everybody to use sliders - as I said 10k lin (mono), 10k audio taper (mono) and 10k lin (stereo) should be rather easy to find. And if you can only get other values for the stereo type, you can easily re-calculate the resistors and capacitors on the board.

Say, you have 50k lin (stereo) sliders:
Then the 2k4 resistors become 2k4 * 5 = 12k, and the 68nF caps become 68nF / 5 = 13.6nF = 10nF || 3.3nF (change other rcaps accordingly).

JH.

_________________
"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours." (Mk 11,23f)
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