Doepfer

Hello to everyone,

I'd like to change my A-176 potentiometers for slide pots (that I would attach to another front panel), but after a long search I can say that it's very difficult to find the right knob for the right slidepot.

Eventually I just found that Livid Instruments sell very good slidepots and the corresponding knobs, but they are 100k slidepots, and the A-176 pots are 50k.

Could you please tell me if there is something simple that I can do to make my A-176 modules to work as expected with 100k pots instead of 50k ones?

If I only need to change a few resistors and / or capacitors it's no problem for me.

Thanks in advance and have a nice day.

Thomas

> Hello to everyone,
>
>
> I'd like to change my A-176 potentiometers for slide pots (that I
> would attach to another front panel), but after a long search I
> can say that it's very difficult to find the right knob for the
> right slidepot.
> Eventually I just found that Livid Instruments sell very good
> slidepots and the corresponding knobs, but they are 100k
> slidepots, and the A-176 pots are 50k.
> Could you please tell me if there is something simple that I can
> do to make my A-176 modules to work as expected with 100k pots
> instead of 50k ones?
> If I only need to change a few resistors and / or capacitors it's
> no problem for me.
>
>
> Thanks in advance and have a nice day.
> Thomas

In the A-176 the potentiometers are used as voltage dividers (connected
between GND and 12V). Consequently the module should also work with 100k
potentiometers. But as input resistor of the circuit is 100k the CV scale
will be not exactly linear but follows the characteristic of P parallel to
100k (with P = current value of the potentiometer = 0...100k, the exact
formula is 100k*P/(100k+P)). If linearity is important you may have to
change some resistors.

Best wishes
Dieter Doepfer

Farnell.com do this one 
ALPS - RS6011Y50K - POTENTIOMETER, SLIDE, 50K  
 
http://www.wizardwoodcraft.co.uk/
 
Norfolk UK

>________________________________
> From: "thomas_escure@yahoo.fr [Doepfer_a100]" <Doepfer_a100@yahoogroups.com>
>To: Doepfer_a100@yahoogroups.com 
>Sent: Wednesday, 4 June 2014, 15:46
>Subject: [Doepfer_a100] Changing pots on my A-176 modules
>  
>   
> 
>Hello to everyone,
>
>
>I'd like to change my A-176 potentiometers for slide pots (that I would attach to another front panel), but after a long search I can say that it's very difficult to find the right knob for the right slidepot.
>Eventually I just found that Livid Instruments sell very good slidepots and the corresponding knobs, but they are 100k slidepots, and the A-176 pots are 50k.
>Could you please tell me if there is something simple that I can do to make my A-176 modules to work as expected with 100k pots instead of 50k ones? 
>If I only need to change a few resistors and / or capacitors it's no problem for me.
>
>
>Thanks in advance and have a nice day.
>Thomas
>
>   
>

I use these, Cliff CS10 Black Soft-Touch Slider Knob with Marker Line, available from http://www.rapidonline.com/  part number 32-1866, £0.40p each with quantity discount.
 
http://www.wizardwoodcraft.co.uk/
 
Norfolk UK

>________________________________
> From: "thomas_escure@yahoo.fr [Doepfer_a100]" <Doepfer_a100@yahoogroups.com>
>To: Doepfer_a100@yahoogroups.com 
>Sent: Wednesday, 4 June 2014, 16:31
>Subject: Re: [Doepfer_a100] Changing pots on my A-176 modules
>  
>   
> 
>Thank you Anthony, but do you know where I can find knobs that would go with these slidepots ?
>I found this ALPS product before, but I can't find a suitable knob.
>That's the difficult part...
>
>
>
>I'd like to use knobs like this one, and I need the knobs to be very close to the faceplate :
>Fader Knobs
>    
>             Fader Knobs  
>Fader knobs for DIY users or replacements for your Ohm64 or block controllers.       
>View on shop.lividinstruments...     Preview by Yahoo           
> 
>Thomas
>
>
>Thomas   
>

> Thank you very much for your detailed answer.
>
>
> And yes, linearity is important for me.
> If it's not too much work for you, could you please tell me which
> resistors I have to change, and what would be the new values ?
>
>
> Regards,
>
>
> Thomas

You have to increase the values of the resistors that define the
amplification of the circuit (nothing but the standard circuit of an
inverting amplifier with opamp) by the same factor. These are the 47k and
100k resistors of the unit in question (R1, R6, R11 = 100k and R4, R9, R13 =
47k for the sub-units 1, 2, 3).

You may replace e.g. 47k by 470k and 100k by 1M.

Good luck
Dieter Doepfer