A-185-2 Precision Adder Thread

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Fidi
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Post by Fidi » Thu Jan 24, 2019 3:44 pm

I bought an A185-2 about a month ago. Worked well, but now switch 2 and 3 are only adding/subtracting around 0.79 Volts, 1 and 4 are working normal... tried a different case/psu - same behaviour. Jumper is removed. Any ideas what could be wrong?

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Plugler
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Post by Plugler » Sat Jan 26, 2019 5:20 pm

Fidi wrote:I bought an A185-2 about a month ago. Worked well, but now switch 2 and 3 are only adding/subtracting around 0.79 Volts, 1 and 4 are working normal... tried a different case/psu - same behaviour. Jumper is removed. Any ideas what could be wrong?
I don't have this module, but I can recommend you, to ask Dieter Doepfer directly via E-Mail: hardware - at - doepfer.de

Dieter Doepfer always helps, if you have problems or questions.

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Post by Zube » Sun Mar 24, 2019 5:29 am

Fidi wrote:I bought an A185-2 about a month ago. Worked well, but now switch 2 and 3 are only adding/subtracting around 0.79 Volts, 1 and 4 are working normal... tried a different case/psu - same behaviour. Jumper is removed. Any ideas what could be wrong?
Did you find a solution from Dieter? My a185 has the same issues, even down to similar output readings. Never used the middle channels for pitch cv in the time I've had it so not sure whether I damaged it or it came that way.

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Post by Fidi » Sun Mar 24, 2019 11:26 am

I didn’t contact Doepfer, but I suspect one of the two „LT1014“ IC‘s is faulty... module is still under warranty, so I‘m going to send it for repair (haven‘t done it yet).

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Post by Zube » Mon Mar 25, 2019 2:06 am

Fidi wrote:I didn’t contact Doepfer, but I suspect one of the two „LT1014“ IC‘s is faulty... module is still under warranty, so I‘m going to send it for repair (haven‘t done it yet).
Interesting... thanks so much, maybe I can find those ICs locally today and get this module back in action.

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Post by av500 » Sun Mar 31, 2019 2:24 pm

Fidi wrote:I didn’t contact Doepfer, but I suspect one of the two „LT1014“ IC‘s is faulty... module is still under warranty, so I‘m going to send it for repair (haven‘t done it yet).
so Doepfer is now shipping it with LT1014? can you post a picture of the (new) PCB please?

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Post by Plugler » Sun Mar 31, 2019 3:08 pm

av500 wrote:
Fidi wrote:I didn’t contact Doepfer, but I suspect one of the two „LT1014“ IC‘s is faulty... module is still under warranty, so I‘m going to send it for repair (haven‘t done it yet).
so Doepfer is now shipping it with LT1014? can you post a picture of the (new) PCB please?
You can see high-res pics of all sides here:
https://www.thomann.de/de/doepfer_a_185_2.htm
Click on a picture and zoom in with the "+" icon on the right...

These pictures show "Version 2" of the PCB, equipped with two LT1014.

Thomann is my preferred source for high-res pictures of Eurorack modules, if I want to see the PCB or the electronic parts used. :mrgreen:

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Post by donpachi » Sun Mar 31, 2019 3:51 pm

Plugler wrote:
av500 wrote: so Doepfer is now shipping it with LT1014? can you post a picture of the (new) PCB please?
You can see high-res pics of all sides here:
https://www.thomann.de/de/doepfer_a_185_2.htm
Click on a picture and zoom in with the "+" icon on the right...

These pictures show "Version 2" of the PCB, equipped with two LT1014.
There's also now a TL431. I guess it would be easy to upgrade the first version with a voltage reference IC and LT1014s.

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Post by av500 » Mon Apr 01, 2019 1:12 am

thx for the link, I would have looked online but I assumed they all still have pics of v1. Dieter told me about v2 coming out eventually after I pointed out to him the v1 was not so "precise" :)

yes, modding v1 to be like v2 is fairly simple, I did that on a few units for friends in the past. but now I can point people to just buy a v2 one :)

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Post by deke » Wed Jun 19, 2019 12:22 pm

adnauseam wrote:
bonjourmyfriends wrote:...

Great for transposing but really great for mixing multiple sources for pitch sequences.
I have been using this module and as long as I don't let it sit for too long and forget what I was doing, I have been successful in using t to transpose a single sequence, but you could say my mental model on what is actually happening and why is a bit fuzzy. Can you or anyone post some patch examples, especially ones that refer to "mixing multiple sequences." Of course I should just experiment and will, but much appreciated if you have the time.

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Post by Foghorn » Wed Jun 19, 2019 1:14 pm

I bought a vpme.de T-43 which is like a Doepfer precision adder.
But it can do more such as add or subtract 1, 2, 4, 12 or 24 semitones.
It can also transpose over 3 octaves using all switches at once.
.
But, unlike the Doepfer precision adder, it only adds 2 CV inputs instead of 4, does not have an attenuated input, has only one output, but can add or subtract a 3rd CV input.
It is very accurate as far as 1V/oct.
I really like it.
I do have a Doepfer A-185-2 but only use it for mixing modulation anymore.

I do not know whether the T-43 is presently available, but it is worthwhile.

Foghorn

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Zymos
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Post by Zymos » Wed Jun 19, 2019 2:01 pm

...but it doesn't have only 2 inputs, like you said, there's a 3rd that can either add or subtract...
maybe you’d like to buy some nice used modules? Free cables with purchase!!

viewtopic.php?f=74&t=235367&p=3313562&h ... s#p3313562

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Post by cptnal » Wed Jun 19, 2019 2:34 pm

deke wrote:
adnauseam wrote:
bonjourmyfriends wrote:...

Great for transposing but really great for mixing multiple sources for pitch sequences.
I have been using this module and as long as I don't let it sit for too long and forget what I was doing, I have been successful in using t to transpose a single sequence, but you could say my mental model on what is actually happening and why is a bit fuzzy. Can you or anyone post some patch examples, especially ones that refer to "mixing multiple sequences." Of course I should just experiment and will, but much appreciated if you have the time.
The mixing sequences thing can go either way because there's no guarantee that any two notes added together will result in a third that's still in key (assuming you want it to be). Of course you could add a quantizer after, but then why use a precision adder rather than a plain mixer in that case...

Anyway, with the Doepfer you can patch a faux-T43 by patching different offsets into each row. For instance, an offset that gives you a perfect 5th with give you a 4th an octave down if you go negative...

If I'm using an oscillator with no octave shifter, it's useful to put the A185-2 in the path...

And of course it's a buff mult too...

I have the A185-2 and the T43, and it's useful to have both in a medium-sized system. Before I upsized I'd traded the Doepfer for the T43 and a buff mult because it's just that teeeeny bit more flexible.
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Post by ugokcen » Wed Jun 19, 2019 8:07 pm

I recently got one and it is super useful. I should have bought it earlier.

I mult my sequencer (Rene) CV output to both an oscillator and the precision adder. Then the output of the precision adder goes to another oscillator. So now I can switch between both oscillators playing the same sequence, playing in octaves or fifths, or one droning and the other sequenced at the flick of a switch. Sweet :bananaguitar:

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Post by R.U.Nuts » Thu Jun 20, 2019 5:17 am

ugokcen wrote:I recently got one and it is super useful. I should have bought it earlier.

I mult my sequencer (Rene) CV output to both an oscillator and the precision adder. Then the output of the precision adder goes to another oscillator. So now I can switch between both oscillators playing the same sequence, playing in octaves or fifths, or one droning and the other sequenced at the flick of a switch. Sweet :bananaguitar:
So you haven't yet plugged a second sequencer into another channel of the A-185-2? Do it and go full on :bananaguitar: :nana: :banana:

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deke
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Post by deke » Thu Jun 20, 2019 10:29 am

Not so much a tutorial, but easily the best description of this module and its capabilities I haver found and the author is actually using complete and grammatically correct sentences! http://blog.alllthingsmodular.com/2016/ ... kdown.html

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Post by WaveRider » Thu Jun 20, 2019 5:56 pm

what a shame this module: (I have one)
-does not even add 1.000 volt with the switches (not precise)
-does not precisely sum 2 cv (some offset voltage)
-I use a simple intellijel 2hp mixer to add 2 quantized cv, and it works
:hihi:

I now prefer to sum before the quantizer anyway...

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Post by Zymos » Thu Jun 20, 2019 9:25 pm

Maybe needs to be calibrated?
maybe you’d like to buy some nice used modules? Free cables with purchase!!

viewtopic.php?f=74&t=235367&p=3313562&h ... s#p3313562

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Post by av500 » Fri Jun 21, 2019 3:06 am

Foghorn wrote:I bought a vpme.de T-43 which is like a Doepfer precision adder

...

I do not know whether the T-43 is presently available, but it is worthwhile.
it is available, from retailers or directly from me ;)

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Does not play nice with seq switch

Post by Sherbrick » Mon Sep 02, 2019 5:12 am

I thought it would be a nice idea to use a sequential switch to slowly toggle between voltages to change the root pitch of a sequence, but it doesn't work while the seq switch sends an ungrounded nothing signal to it. It just decides to output a little over 10 volts instead of 0.

Possible to work around by plugging in cables sending zero voltage but are also grounded by being plugged in to something else, but like, why doesn't the module do that by design?

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Re: Does not play nice with seq switch

Post by Risc_Terilia » Mon Sep 02, 2019 5:33 am

Sherbrick wrote:I thought it would be a nice idea to use a sequential switch to slowly toggle between voltages to change the root pitch of a sequence, but it doesn't work while the seq switch sends an ungrounded nothing signal to it. It just decides to output a little over 10 volts instead of 0.

Possible to work around by plugging in cables sending zero voltage but are also grounded by being plugged in to something else, but like, why doesn't the module do that by design?
I'm not sure I understand the patch, which switch are you using? A151? What's the input to it?

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Re: A-185-2 Precision Adder Thread

Post by deke » Sat Jan 11, 2020 11:13 am

Okay, I have this module, but I am 99.9999% certain it needs to be calibrated. I have the instructions from Doepfer, but I am a total electronics noob. If only there were a YouTube video on this...

I have these two meters, so first question is, are either of these sufficient? Second question, can I screw up my module trying this? Third question - any general advice appreciated.
IMG_5206.JPG
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Re: A-185-2 Precision Adder Thread

Post by msboude » Sat Jan 11, 2020 12:15 pm

To check your voltages:

First things first. Three is a jumper on the back of this module that connects it to the system bus. Check that before you go looking for issues. So heads up there.

To check the output voltages, make sure nothing is connected to the module. Turn the trim pot all the way clockwise and put all the switches in the middle. Now, take a patch cord and plug it into the + outupt of the module.

Get out your red multi-meter you got there and clip the black clip on the barrel of the patch cord and the red clip on the tip of your patch cord.

With all switches in the middle, it should read 0v. if you flick a single toggle switch to the left it should give you -1 volts. If you flick one to the right, it should be +1 volts. If you flick two to the left, it will read -2v, two to the right should read +2v.. And so on.

It might not be EXACTLY 1 volts a flick, but should be pretty darn close! Hope this makes sense?


Edit for newbs.. your multi-meter needs to be on the DC setting.

No you won't hurt the module.

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Re: A-185-2 Precision Adder Thread

Post by kpreid » Sat Jan 11, 2020 1:03 pm

deke wrote:
Sat Jan 11, 2020 11:13 am
I have these two meters, so first question is, are either of these sufficient?
“Sufficient” depends on how much you care. The calibration will only be as good as your meter. You can find the manual for the meter and check its specifications, and expect up to that much error (1% of one volt is 1% of an octave or 12 cents). If you use the analog meter then you also need to consider your ability to read the needle while it's only at the "1" mark 20% of full scale, so I wouldn't recommend it.

You could also listen to a VCO for the octave part of the calibration procedure — record and loop it with the switches at zero, switch an octave up, then listen to both and use the trimmer to tune them an octave apart. Then you're guaranteed it will sound good, because you're copying the calibration of the VCO to the adder — which might be good if the VCO is known good or you're using the adder specifically with that VCO, or might be bad if the VCO's own calibration is off.

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Re: A-185-2 Precision Adder Thread

Post by deke » Sat Jan 11, 2020 8:19 pm

kpreid wrote:
Sat Jan 11, 2020 1:03 pm
deke wrote:
Sat Jan 11, 2020 11:13 am
I have these two meters, so first question is, are either of these sufficient?
“Sufficient” depends on how much you care. The calibration will only be as good as your meter. You can find the manual for the meter and check its specifications, and expect up to that much error (1% of one volt is 1% of an octave or 12 cents). If you use the analog meter then you also need to consider your ability to read the needle while it's only at the "1" mark 20% of full scale, so I wouldn't recommend it.

You could also listen to a VCO for the octave part of the calibration procedure — record and loop it with the switches at zero, switch an octave up, then listen to both and use the trimmer to tune them an octave apart. Then you're guaranteed it will sound good, because you're copying the calibration of the VCO to the adder — which might be good if the VCO is known good or you're using the adder specifically with that VCO, or might be bad if the VCO's own calibration is off.
Thanks to you and everyone else. I don’t mind buying a digital meter. Any particular brands or price points that would be... sufficient? Edit. I see there are posts on this.

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