Doepfer

I just searched the list and found no posts regarding this modification. I purchased this module when it first came out and I thought it was great, except that the attack time was a wee bit too slow. I was surprised when I found on the Doepfer site a page which shows a way to mod the Attack/Decay time by changing one capacitor value. Here's the page:
http://www.doepfer.de/DIY/a100_capacitors.htm

It says that the timing capacitor (C1) is a 2.2 microfarad, corresponds to about 5ms shortest attack/decay time. Does "shortest attack/decay time" mean that it can't get any quicker? What if I lower the value of the cap? I wanted to ask if anyone has done this and what value did they use. I'm really hoping that it's possible to make the attack a bit more snappy (like 1ms) because the module is great but the attack time is too slow for my personal use. I'd love to hear any responses regarding this.

Regards,
John

Once again the MuffWiggler forum is THE place online for modular knowledge!

http://www.muffwiggler.com/forum/viewtopic.php?p=23126#23126

- the mod is way easy, John, you should totally do it. Oh, and sign up 
at the forum there and share your progress!

Best,
Andreas

j_inform3r skrev:

> I just searched the list and found no posts regarding this modification. I purchased this module when it first came out and I thought it was great, except that the attack time was a wee bit too slow. I was surprised when I found on the Doepfer site a page which shows a way to mod the Attack/Decay time by changing one capacitor value. Here's the page:
> http://www.doepfer.de/DIY/a100_capacitors.htm
>
> It says that the timing capacitor (C1) is a 2.2 microfarad, corresponds to about 5ms shortest attack/decay time. Does "shortest attack/decay time" mean that it can't get any quicker? What if I lower the value of the cap? I wanted to ask if anyone has done this and what value did they use. I'm really hoping that it's possible to make the attack a bit more snappy (like 1ms) because the module is great but the attack time is too slow for my personal use. I'd love to hear any responses regarding this.
>
> Regards,
> John
>
>
>
>

Hello John,

> http://www.doepfer.de/DIY/a100_capacitors.htm
> It says that the timing capacitor (C1) is a 2.2 microfarad, corresponds to about 5ms shortest attack/decay time. Does "shortest attack/decay time" mean that it can't get any quicker? What if I lower the value of the cap? I wanted to ask if anyone has done this and what value did they use. I'm really hoping that it's possible to make the attack a bit more snappy (like 1ms) because the module is great but the attack time is too slow for my personal use. I'd love to hear any responses regarding this.
This means: the shortest attack/decaytime is 5ms if you use a 2.2uF 
capacitor. If you use a smaller value for this capacitor, then you get 
shorter minimal envelope times.

btw: I once had the A-143-1 and to my estimation, the minimal attack 
time was longer(!) than 5 ms. But this can depend on the allowed 
varation of the true values of the different parts against the nominal 
values. Resistors can vary 5% or 10%, capacitors 20%.

Florian

Hi Andreas et al,

    I've seen the MuffWiggler thread you posted. Unfortunately it only deals with extending AD time. The opposite of my goal.
    Since Dieter is out of the office for a while I sent my question to another address at Doepfer. They replied and said that I CAN decrease the attack time by lowering the value of C1 but I will also be lowering the decay time. So now I'm wondering if it will be possible to get the attack around 1ms without ruining the decay time. Anyone know what the "stock" decay time is? I don't require super looooong decay's. Basically, I'm wondering what the proportion is between; attack time/decay time. Has anyone made their A-143-1 snappier? What basis should I go by to figure this out (value of C1) to get 1ms attack time?

    Thanks,
    John

--- In Doepfer_a100@yahoogroups.com, "Andreas- theCovertOperators.Org" <a@...> wrote:

>
> Once again the MuffWiggler forum is THE place online for modular knowledge!
> 
> http://www.muffwiggler.com/forum/viewtopic.php?p=23126#23126
> 
> - the mod is way easy, John, you should totally do it. Oh, and sign up 
> at the forum there and share your progress!
> 
> Best,
> Andreas
> 
> j_inform3r skrev:
> > I just searched the list and found no posts regarding this modification. I purchased this module when it first came out and I thought it was great, except that the attack time was a wee bit too slow. I was surprised when I found on the Doepfer site a page which shows a way to mod the Attack/Decay time by changing one capacitor value. Here's the page:
> > http://www.doepfer.de/DIY/a100_capacitors.htm
> >
> > It says that the timing capacitor (C1) is a 2.2 microfarad, corresponds to about 5ms shortest attack/decay time. Does "shortest attack/decay time" mean that it can't get any quicker? What if I lower the value of the cap? I wanted to ask if anyone has done this and what value did they use. I'm really hoping that it's possible to make the attack a bit more snappy (like 1ms) because the module is great but the attack time is too slow for my personal use. I'd love to hear any responses regarding this.
> >
> > Regards,
> > John
> >
> >
> >
> >
>

Hi John

The basic principal behind timing circuits is that the capacitance is proportional to the time constant.  So if you have a circuit with 2.2uF and it gives 5ms AD time then 0.44uF (i.e. a fifth of 2.2uF) will give about 1ms.  The nearest preferred value to this is 0.47uF or 0.39uF.

The delay time will also be reduced to about a fifth of what it was. It is worth experimenting and you can always go back to the original component.  Hope this helps.

Regards
Tony

--- In Doepfer_a100@yahoogroups.com, "j_inform3r" <abstract.express@...> wrote:

>
>     Hi Andreas et al,
> 
>     I've seen the MuffWiggler thread you posted. Unfortunately it only deals with extending AD time. The opposite of my goal.
>     Since Dieter is out of the office for a while I sent my question to another address at Doepfer. They replied and said that I CAN decrease the attack time by lowering the value of C1 but I will also be lowering the decay time. So now I'm wondering if it will be possible to get the attack around 1ms without ruining the decay time. Anyone know what the "stock" decay time is? I don't require super looooong decay's. Basically, I'm wondering what the proportion is between; attack time/decay time. Has anyone made their A-143-1 snappier? What basis should I go by to figure this out (value of C1) to get 1ms attack time?
> 
>     Thanks,
>     John
> 
> --- In Doepfer_a100@yahoogroups.com, "Andreas- theCovertOperators.Org" <a@...> wrote:
> >
> > Once again the MuffWiggler forum is THE place online for modular knowledge!
> > 
> > http://www.muffwiggler.com/forum/viewtopic.php?p=23126#23126
> > 
> > - the mod is way easy, John, you should totally do it. Oh, and sign up 
> > at the forum there and share your progress!
> > 
> > Best,
> > Andreas
> > 
> > j_inform3r skrev:
> > > I just searched the list and found no posts regarding this modification. I purchased this module when it first came out and I thought it was great, except that the attack time was a wee bit too slow. I was surprised when I found on the Doepfer site a page which shows a way to mod the Attack/Decay time by changing one capacitor value. Here's the page:
> > > http://www.doepfer.de/DIY/a100_capacitors.htm
> > >
> > > It says that the timing capacitor (C1) is a 2.2 microfarad, corresponds to about 5ms shortest attack/decay time. Does "shortest attack/decay time" mean that it can't get any quicker? What if I lower the value of the cap? I wanted to ask if anyone has done this and what value did they use. I'm really hoping that it's possible to make the attack a bit more snappy (like 1ms) because the module is great but the attack time is too slow for my personal use. I'd love to hear any responses regarding this.
> > >
> > > Regards,
> > > John
> > >
> > >
> > >
> > >
> >
>

>     Hi Andreas et al,
>
>     I've seen the MuffWiggler thread you posted. Unfortunately it
> only deals with extending AD time. The opposite of my goal.
>     Since Dieter is out of the office for a while I sent my
> question to another address at Doepfer. They replied and said
> that I CAN decrease the attack time by lowering the value of C1
> but I will also be lowering the decay time. So now I'm wondering
> if it will be possible to get the attack around 1ms without
> ruining the decay time.

Sorry - that's not possible because the same capacitor is used for both
attack and decay.

Best wishes
Dieter Doepfer

the A-183-3 amplifier looks like a useful utility module Dieter. I'm 
often wishing I had something simple like that onboard - In practise 
whether x4 is really enough for audio I'm not sure... maybe

Richard



yahoo@doepfer.de wrote:
> 
> 
> 
>  > Hi Andreas et al,
>  >
>  > I've seen the MuffWiggler thread you posted. Unfortunately it
>  > only deals with extending AD time. The opposite of my goal.
>  > Since Dieter is out of the office for a while I sent my
>  > question to another address at Doepfer. They replied and said
>  > that I CAN decrease the attack time by lowering the value of C1
>  > but I will also be lowering the decay time. So now I'm wondering
>  > if it will be possible to get the attack around 1ms without
>  > ruining the decay time.
> 
> Sorry - that's not possible because the same capacitor is used for both
> attack and decay.
> 
> Best wishes
> Dieter Doepfer
> 
> 

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Hi John, hi Dieter,

Not completely a separation of the two time rates, but some 
approximation (this assumes, that the potentionmeters are not used as 
electrical potentiometers, but as variable resistors):
- Reduce the Capacitor
- Insert a fixed resistor (lets say 20% of the potentiometer value) on 
the maximum side of the attack potentiometer
-Insert a fixed resistor (at least the same value as the R above or even 
more) on the minimum side of the decay potentiometer.

This will cause shorter attack times, and will keep the minimum Decay 
time where it is. If the addition decay-resistor is even larger than the 
attack-resistor, then the decaytime will stay the same as with the 
original capacitor.

Florian

yahoo@doepfer.de schrieb:

>>     Hi Andreas et al,
>>
>>     I've seen the MuffWiggler thread you posted. Unfortunately it
>> only deals with extending AD time. The opposite of my goal.
>>     Since Dieter is out of the office for a while I sent my
>> question to another address at Doepfer. They replied and said
>> that I CAN decrease the attack time by lowering the value of C1
>> but I will also be lowering the decay time. So now I'm wondering
>> if it will be possible to get the attack around 1ms without
>> ruining the decay time.
> 
> Sorry - that's not possible because the same capacitor is used for both
> attack and decay.
> 
> Best wishes
> Dieter Doepfer
> 
> 
> 
> 
> ------------------------------------
> 
> Yahoo! Groups Links
> 
> 
> 
>

> the A-183-3 amplifier looks like a useful utility module Dieter. I'm
> often wishing I had something simple like that onboard - In practise
> whether x4 is really enough for audio I'm not sure... maybe
>
> Richard

Within the A-100 or connected to other modular systems x4 should be
sufficient because the output signal has to be within about -10.5V....+10.5V
because of the +/-12V power supply (you cannot obtain an output voltage that
is higher than the supply voltage and in adddition there is some voltage
drop in the operational amplifiers). This means that any voltage in the
range -2.5...+2.5V can be amplified before clipping occurs. If you want a
higher amplification the module can be modified (changing the value of a
resistor for the ranges x2 and x4).

Best wishes
Dieter Doepfer

> Hi John, hi Dieter,
>
> Not completely a separation of the two time rates, but some
> approximation (this assumes, that the potentionmeters are not used as
> electrical potentiometers, but as variable resistors):
> - Reduce the Capacitor
> - Insert a fixed resistor (lets say 20% of the potentiometer value) on
> the maximum side of the attack potentiometer
> -Insert a fixed resistor (at least the same value as the R above or even
> more) on the minimum side of the decay potentiometer.
>
> This will cause shorter attack times, and will keep the minimum Decay
> time where it is. If the addition decay-resistor is even larger than the
> attack-resistor, then the decaytime will stay the same as with the
> original capacitor.
>
> Florian

These serial resistors are already available in the circuit. Both the attack
and the decay circuit use a 1M variable resistor in series with a 2k2 fixed
resistor (so the minimum overall resistance is 2k2 when the potentiometer is
fully CCW). The fixed resistors are R4 (attack) and R5 (decay). R2 is
located just behind the attack potentiometer, R5 near C1 (next to the 555
timer circuit). One could replace C1 e.g. by 0.22n (i.e. 1/10 of 2u2) or
0.47n (i.e. 1/5 of 2u2) and increase R5 to 22k (x10) or 10k (x5). It's not
possible to insert a fixed resistor to the "maximum" side because it does
not matter if the fixed resistor is added to the max or min side because
both resistance values (fixed + potentiometer) are always added.

Best wishes
Dieter Doepfer

Hi Dieter
> It's not
> possible to insert a fixed resistor to the "maximum" side because it does
> not matter if the fixed resistor is added to the max or min side because
> both resistance values (fixed + potentiometer) are always added.
You misunderstood me. It definitely does matter. But I am leaving now, 
so I will post tomorrowmy explanation.

Florian

Ok

After some sleep and cleaning the head from inside :), I see that Dieter 
is right. It does not matter, where the resistor would be positioned.

So the corrected description would be as Dieter wrote it:
- Reduce the Capacitor C1. This will cause the attack times to be 
shorter. The decay times would be shorter too, but we will...
- ...increase the Resistor R5 of the decay potentiometer. This will 
"compensate" the smaller capacitor value: the decay behaviour will be 
quite the same as before.

Sorry for the confusion.

Florian



Florian Anwander schrieb:

> Hi Dieter
>> It's not
>> possible to insert a fixed resistor to the "maximum" side because it does
>> not matter if the fixed resistor is added to the max or min side because
>> both resistance values (fixed + potentiometer) are always added.
> You misunderstood me. It definitely does matter. But I am leaving now, 
> so I will post tomorrowmy explanation.
> 
> Florian
>