YUSYNTH EMS-diode ladder filter

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

It's been long awaited but there it is !

YUSYNTH modular project page :
http://yusynth.net/Modular/index.html
YUSYNTH EMS diode ladder filter page :
http://yusynth.net/Modular/EN/EMSVCF/index.html

Enjoy it... I still have to contact R. Woods for possible copyright issues...

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Undergrind · Posted: Sun Mar 02, 2008 6:56 am Post subject:

Jeah!!

this will be part of the next Yusynth project. But now I'll have enough to do to finish the other yusynths.. Smile

I'm very happy about the CV Resonance!!

I like to use the Envelope that is assigned to the CVFreq also to the Reso but negated. This gives a nice movement into the sound because the sharp hights can be nicely warm that way. Also with minimal attack times a beautiful Click can be generated...

Thank you for Yusynth! For me this is the perfect start in DIY and slowly I begin to uncover the mysteries of SDIY.

When Im done with the first modules Ill take some pictures for you to enjoy! But it could last a while until then because music making is still my main objective.

Nevertheless Im really looking forward to this Big VCpanning mixer.

Sebo · Joined: Apr 27, 2007 Posts: 564 Location: Argentina

That´s great.
Another module to the list, but this one is going to be on the top of it.
Thank you.

Dave Manley · Posted: Sun Mar 02, 2008 3:34 pm Post subject:

Thanks for posting this. I like the resonance control circuit. One question: why couple the audio through R37, R38 and C13 into the CV path that controls Q12?

Also, how much does the discrete opamp (Q7-Q11 and associated components) contribute to the character of the filter?

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

zthee · Joined: Feb 20, 2008 Posts: 414 Location: Stockholm

I'd love to hear some samples from it - if possible?

Or I just have to record some - after I built mine Very Happy

This piece needs to be in my rack!

..ooh, by the way, any places that might cary CA3096? Or is Ebay the only way to go?

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Yves,

In the discrete version, should Q7-Q11 be matched in any way?

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

I get some spare time I might record few samples... but I am quite busy building modules Wink

The CA3096 was fairly easy to source before 2006 but nowadays it is quite difficult. In Europe you still find them at Conrad's but for a very high price...

As an alternative you may go for the discrete version Wink

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

Hi Louis

I did not match these (but picked them from the same batch though) in the prototype and it worked nicely.

v-un-v · Posted: Tue Mar 04, 2008 1:40 pm Post subject:

Yves, does this clone exhibit the pre or post '74 sound? (ie have you managed to capture that watery-ness that the original synthi VCS3 was so famous for? (listen to ¨early in the morning¨ by Kraftwerk some time if you don't know what I mean- those lovely 'bubbling mud' sounds Cool

)

PS- any plans to clone the EMS Trapezoid Generator too?

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

v-un-v · Posted: Tue Mar 04, 2008 3:28 pm Post subject:

It's the last track on ¨Autobahn¨!

Every electro-music fan should at least own this Kraftwerk LP!

What made the Synthi filter so famous was its ability to make 'bubble-like' noises. It was something about a voltage lag on the input that made the sound. I don't think it can be reproduced with a normal lag processor. You are more likely though to get a similar effect (perhaps?) with a vactrol, although I think it was a simple capacitor in line with the CV input, that produced this unique response.

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

Peake · Posted: Tue Mar 04, 2008 9:55 pm Post subject:

The Analogue Systems version offer a switch to select the vintage and the modern versions. I believe, offhand, that we're only talking about a capacitor in the CV path, much like with the Trine Pipe.

Congrats on the new module!

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

OK I checked the bubbly stuff in Autobahn and I understand what you mean.
I also checked the various EMS schematics I have and apparently I have two versions, one is a polarized cap connected to the base of Q4 (first transistor of the expo converter) which I considered as a design mistake and a second version where the very same cap is connected between the negative rail and ground which makes sense indeed. In my "clone" I suppressed this cap.
If you want to recreate this bug/feature of the old version you will have to add a 10uF cap between the base of Q4 and the 0V level.

v-un-v · Posted: Wed Mar 05, 2008 12:51 am Post subject:

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

As most Kraftwerk albums appear in two, three, or even four languages, I honestly thought it meant there was an English release that used that title. I wasn't critizing anyone's translation, just remarking I hadn't realized it was the same track because of the difference in title Very Happy

v-un-v · Posted: Wed Mar 05, 2008 9:29 am Post subject:

Kraftwerk were in fact the first ever band that I saw live that I chose to see (I did also see The Incredible String Band and Led Zeppelin too in 1970- but that was my parents choice!).

I saw Kraftwerk again in 1981, and in 1990 (well I think it was 1990. It was 'The Mix' tour, and they weren't as good as they were on the two previous concerts.

Radioactivity and "Kraftwerk 1" are my favourite LP's, with Autobahn and Ralf and Florian following a very close second (I love 'Ananas Symphonie', 'Tanzmusik' and 'Electricshe Roulette'!) .

If you like Autobahn, I URGE you to take a listen to Harmonia's "Deluxe". It's very similar, but exceptionally beautiful (and the production by Conny Plank is >1st rate< too!!!)

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Yves,

This might actually be the first module from your collection I'm having a bit of trouble with. The filter works fine, but I only have a bit of resonance if I turn the res pot fully CW and put a large CV into the red mod input. With large enough CV, the res pot works as expected, with no CV, the res pot doesn't do anything. I'm usually reasonably good at debugging, but I can't find anything obviously wrong.

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

Questions which version are you using ?
If using the discrete one are you using the C brand for the transistor ?
Have you tried different 2N3819 for the Q12, did you connect C14 the right way ? The FET (2N3819) is to be selected, a BF245 would not work (I know it because in my first design I used a BF245 without success), therefore try various 2N3819 to find the one that gives you the best range.

By the way a simple test for the resonance : simply disconnect C14, there the filter should wistle like a bird ! If this work, then check C14 and Q12.

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

I'm using the discrete one, with 557B as mentioned above. So it looks like 557B doesn't work after all?

Already tried replacing Q12. C14 is correct.

yusynth · Joined: Nov 24, 2005 Posts: 1314 Location: France

The C brand would give more gain but B brand is OK.

Did you try to remove C14 and check that it oscillates ?

etaoin · Joined: Jun 30, 2005 Posts: 761 Location: Utrecht, NL

Yes, it oscillates with C14 removed.

I did some further testing and found that I need at least 5V at the resonance mod input (both pots fully CW) for it to oscillate and the res pot to work as expected.

I also tried removing R45 to see if U1b was doing odd things, but no luck. C13 is okay, so there isn't any current flowing to ground that way.

One thing I did notice was that when I connect my DWM to the gate of the FET and have the res pot fully CW, I first see -3V (as expected from the 680k/220k divider?) but that changes to -1.3V almost straight away. But maybe that's just caused by the DVM itself?

I'll keep digging. It must be something very simple I'm just not seeing...