Doepfer A-110-4 Thru Zero Quadrature VCO

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lud
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Post by lud » Thu Dec 08, 2016 11:44 am

Of course! :oops:

Thanks for the reply

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nectarios
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Post by nectarios » Wed Jan 04, 2017 12:34 pm

Loving the FM on this VCO

[soundcloud url="https://api.soundcloud.com/tracks/300917200" params="auto_play=false&hide_related=false&show_comments=true&show_user=true&show_reposts=false&visual=true" width="100%" height="450" iframe="true" /]

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nectarios
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Post by nectarios » Thu Apr 06, 2017 11:40 am

Linear and exponential (amounts stored in PP) FM.

[video][/video]

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handsomepanther
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Post by handsomepanther » Thu Apr 06, 2017 1:27 pm

nectarios wrote:Linear and exponential (amounts stored in PP) FM.

[video][/video]
Sounding Good! :stardance: :domodance: :band:

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Dcramer
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Post by Dcramer » Wed Apr 12, 2017 11:19 pm

I finally got mine :tu:

Had the same pitch change issue :cry:

Traced it to a DC offset problem :hmm:

Solved it by using an Attenuverting/Offset utility module on all my modulating oscillators. :hyper:

This is thing is extremely sensitive to DC offset! :woah:

Having something patched in the carrier chain to compensate makes a huge difference and allows me to crank the LFM wide open with hearing the pitch rise or fall as the modulation gain tapers off.

:nana: :banana: :nana: :banana: :bananaguitar:

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evasporque
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Post by evasporque » Tue May 16, 2017 12:23 pm

I am getting the blue one...

I like blue.
:tu:

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DJMaytag
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Post by DJMaytag » Thu May 25, 2017 6:53 pm

Just jumped on what I thought was a deal on a newer gray one, but found out I was wrong on the date code and bought an older one. Oops.

Is the amp upgrade kit still available and/or available in the US? I see it listed at Schnieders, but that's it. It's really soft in output compared to my Z3000's.
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handsomepanther
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Post by handsomepanther » Thu May 25, 2017 8:49 pm

DJMaytag wrote:
Is the amp upgrade kit still available and/or available in the US? I see it listed at Schnieders, but that's it. It's really soft in output compared to my Z3000's.
I've got a pair of the old ones.. been waiting for these amp kits for a while but I think they're due to arrive at analoguehaven soon.

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Post by shellfritsch » Mon May 29, 2017 7:40 pm

Dcramer wrote:I finally got mine :tu:

Had the same pitch change issue :cry:

Traced it to a DC offset problem :hmm:

Solved it by using an Attenuverting/Offset utility module on all my modulating oscillators. :hyper:

This is thing is extremely sensitive to DC offset! :woah:

Having something patched in the carrier chain to compensate makes a huge difference and allows me to crank the LFM wide open with hearing the pitch rise or fall as the modulation gain tapers off.

:nana: :banana: :nana: :banana: :bananaguitar:
would you mind explaining the details of your offset patch/fix? what utility module are you using? how much offset do you need to apply? and is it positive or negative?

is the signal flow modulation osc > vca > offset > a-110-4 ?

i'm experiencing the pitch shift when i fade in modulation. i have mutable shades which i believe can be used as an offset on channel 2 if you leave channel 1 un-patched.

thanks!

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Dcramer
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Post by Dcramer » Mon May 29, 2017 8:16 pm

Ask and ye shall receive :miley:


Check this thread out:

viewtopic.php?t=179343&postdays=0&postorder=asc&start=0

The secrets of my weeks of toil (10 mins tops :tu: ) lie within! :cloud:

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MRoyce
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Post by MRoyce » Tue May 30, 2017 4:59 am

Wouldn't a simple hi-pass set 5-10Hz between the modulator and 110-4 be enough to remove any DC?

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shellfritsch
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Post by shellfritsch » Tue May 30, 2017 4:50 pm

Dcramer wrote: Check this thread out:

viewtopic.php?t=179343&postdays=0&postorder=asc&start=0

The secrets of my weeks of toil (10 mins tops :tu: ) lie within! :cloud:
thanks that was very helpful!

blackelmo
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Post by blackelmo » Thu Jun 01, 2017 9:36 pm

Regarding the Doepfer A-110-4 Amplifier upgrade, I purchased the kit from Schneidersladen. I'm in NY and it arrived quickly via Fedex.
http://www.schneidersladen.de/en/doepfe ... p-kit.html

Since then I've learned that Detroit Modular carries them in the US.
http://www.detroitmodular.com/doepfer-a ... co-v1.html

The upgrade was fairly easy to install and I'm a DIY novice. The most difficult part for me was desoldering. I learned how to use desoldering braid and now my A-110-4 is louder.

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Dcramer
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Post by Dcramer » Thu Jun 01, 2017 11:53 pm

MRoyce wrote:Wouldn't a simple hi-pass set 5-10Hz between the modulator and 110-4 be enough to remove any DC?
Yes, this makes a lot of sense but I think we need a much steeper curve for a Highpass to work.
So far any filters I have tried aren't steep enough to leave the Osc while filtering out the DC offset. :hmm:

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Post by Josef_K » Mon Jul 10, 2017 9:36 am

Alright so I just went ahead and ordered this, although I don't have a decent sine oscillator to modulate it with, closest I can get is a triangle from my Little Phatty and in a month or so the sine from my polivoks VCF (the Little Phatty VCF is hard to get to track 1v/oct if I'm not mistaken). Hopefully I can make some interesting sounds with it, wasn't planning on getting one at all until I listened to the demos in this thread, which blow away those I've found on youtube so far :)

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brandonlogic
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Post by brandonlogic » Mon Jul 10, 2017 9:51 am

Josef_K wrote:Alright so I just went ahead and ordered this, although I don't have a decent sine oscillator to modulate it with, closest I can get is a triangle from my Little Phatty and in a month or so the sine from my polivoks VCF (the Little Phatty VCF is hard to get to track 1v/oct if I'm not mistaken). Hopefully I can make some interesting sounds with it, wasn't planning on getting one at all until I listened to the demos in this thread, which blow away those I've found on youtube so far :)
its a wonderful oscillator. one that i know i will never sell

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Shledge
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Post by Shledge » Sat Oct 07, 2017 5:30 pm

Noticed the LED on mine is starting to flicker on/off, although the module itself seems to work fine. Is it just a faulty LED or a bigger potential issue?

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porphyrion
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Post by porphyrion » Sun Oct 08, 2017 5:15 pm

Shledge wrote:Noticed the LED on mine is starting to flicker on/off, although the module itself seems to work fine. Is it just a faulty LED or a bigger potential issue?
Mine has it too. Just the LED dying I think, at least for now-

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Post by paul.j » Wed Oct 25, 2017 12:40 am

Hi, I'm kinda late to the party on this one (and i know i am not the first to raise the issue...), but I have a few questions for A-110-4 users ! I have bought mine +2 months ago, and have been struggling with the pitch instability on the carrier whenever rising the LFM knob. Since this is an issue many people seem to be encountering I wanted to check if any of you had any luck with calibration or any answer from Doepfer ?

To give a bit of context : i am using the A-110-4 as a carrier modulated by either a STO or Tides. Everything I have read on this thread and the other one mentioning this issue was extremely insightful (and the awesome demos you guys provided !) but I haven't been able to get anywhere near bell or even clean wooden FM sound when putting an envelope on the modulator, even after entire days of careful settings and trying every patch possible on my system.

And what is really frustrating is that when I can (almost) remove the carrier pitch shifting, the modulation index isn't high enough to allow for clear fm / more percussive sounds with the envelope ... As some have stated on this website, the only way to get dynamic fm is to have the LFq know around noon, and then in this configuration it isn't possible to get usual carrier/modulator ratios. I am also wondering if the STO has a clean enough sine for that type of sound.

So just a few questions to end it here :

- do you think that the miscalibration of the trimmers might be the cause ?

- it also seems like this issue is specific to the SE blue panel edition. Any thoughts on that ?

- finally, regarding dc offset, the only hp filters I possess are the A-106-5 SEM filter and the A-124 Wasp filter, which are both 'multimode' filter (you can mix the filter output between a lp and a hp). IYO do you think their circuitry would allow for dc offset blocking ? Or the fact that they also act as lowpass filters would mean they aren't ac coupled ?

Sorry for the long post, and many thanks for anyone who might answer !

Paul

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Navs
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Post by Navs » Wed Oct 25, 2017 1:50 am

Paul, if you bought this new you should be able to assume that it has been properly calibrated. There are some exceptions, but 99% of the time, trimmers on new modules should not need to be touched.

Just so we're on the same page, are you getting pitch instability without modulation or only when you try to FM it?

For a 'clean' modulator, I would trust a self-oscillating filter over a VCO, but there's no guarantee in that: some filters are better than others.

Yes, your SEM should be able to do the job of cutting DC. Or, if you have a mixer with an offset capability, you could try the patch described by Dcramer to 'balance' the modulator.

That said, I believe these external fixes don't address the key problem with this design: it is based on two oscillator cores and if these don't respond exactly to incoming voltage, you will not get perfect results.

Do you need perfect results to at least get a nice bell sound, which is what you're after? No. You should be able to achieve this ... assuming clean, DC-free paths: that includes the VCA used to gate the modulator!

Keep the XTune and LFreq at around 1 or 2 o'clock and modulate it with a lower frequency. Don't worry too much about the exact ratios, just play around until it sounds nice.

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Post by paul.j » Wed Oct 25, 2017 4:02 am

Hi Navs, thank you for taking the time to reply. I guess there's nothing magic about it. It 's only confusing because it kind of challenges what I learned in implementing digital FM synthesis in CSound/MaxMSP. I always assumed that higher modulator ratios where usually most suited for rich harmonic (or inharmonic for non-integers) mallet and bell tones, and that what I knew in digital FM applied to analog. But you're totally right about lower modulator ratios, they allow the best results with this module. I guess analog FM is a totally different beast and there is a lot to learn.

But whenever i reach a modulation index/modulator level high enough to get a proper attack (like a proper noticeable excitation if we were talking modal synthesis), the results sounds more like a pitchbend. Also, it often sounds like people who achieve bell sounds with the A-110-4 use very short decay/no sutain or little release on their modulator enveloppe.

It might also come from the fact that I the vca I use for the modulator aren't well suited for that purpose: i have a A-132-3 quadra exp vca (which gives significant volume distortion) and a A-101-2 lowpass gate in vca mode.
Navs wrote:it is based on two oscillator cores and if these don't respond exactly to incoming voltage, you will not get perfect results.
Sorry for the repetitive question, but do you think this could be addressed by (carefully) calibrating the trimmers ?

Anyway, thanks again for your lights,

Paul

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Navs
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Post by Navs » Wed Oct 25, 2017 9:51 am

Pitchbend could point to DC-offset in your modulator but it could also be that the thru-zero crossing point is slightly off. Can you be sure that your modulation path is clean? I would do that before fiddling with trimmers.

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Post by Dcramer » Wed Oct 25, 2017 10:56 pm

I would love to see some kind of simple HPF with a very steep curve that could be used to filter out and DC offset.
Using my very fiddler patch I've been able to get nice FM tones, with two modulators both with frequencies much higher than the carrier. :party:

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Post by Navs » Thu Oct 26, 2017 1:59 am

Dcramer wrote:I would love to see some kind of simple HPF with a very steep curve that could be used to filter out and DC offset.
Using my very fiddler patch I've been able to get nice FM tones, with two modulators both with frequencies much higher than the carrier. :party:
To cut DC all you need is a suitably sized capacitor in-line with your modulator.

If your modulators are 'much higher than the carrier' you're possibly not getting the most from the TZ effect; it will sound similar to normal lin-FM.

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Post by AndiSt » Thu Oct 26, 2017 2:40 am

This is an absolutely stunning VCO. In the patch below, I use one A-110-4 as a carrier. I like to FM it with triangles from an A-111-3 or a sinus from the A-143-9 (another underrated Doepfer module, in my opinion).

[soundcloud url="https://soundcloud.com/andreassteinermodular/delp" params="auto_play=false&hide_related=false&show_comments=true&show_user=true&show_reposts=false&visual=true" width="50%" height="450" iframe="true" /]

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