Doepfer

Hi Dieter,

I decided to try it and used the LT1014DN with an offset of 60uV. I now have 8 channels of pitch quantisation that track well. I would suggest it to anyone using multiple A-156 quantisers.

The limitation now appears to be the integrity of the patch cabling. If all the transpose input connections are clean the tracking is spot on.

Best wishes
John

> On 12 Jun 2018, at 11:20, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> Yes, two of the opamps of the TLC274 are the input buffers. You may try it
> out but from my point of view it would be more reasonable to add an offset
> circuit (trimming potentiometer + resistor) than to try out to find another
> opamp with a different offset.
> 
> Best wishes
> Dieter Doepfer
> 
> 
>> -----Ursprüngliche Nachricht-----
>> Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com]
>> Gesendet: Dienstag, 12. Juni 2018 10:45
>> An: Doepfer_a100@yahoogroups.com
>> Betreff: Re: [Doepfer_a100] A-156 input threshold tracking
>> 
>> 
>> Hi Dieter,
>> 
>> Thanks for your response. I have now had a chance to pull an
>> A-156 out of the rack. From what I can see it looks like that
>> TLC274 is the input buffer. If that chip has a 10mV offset I was
>> wondering if it might be worth swapping out the TLC264 for
>> something like an LT1014 (150uV offset).
>> 
>> Do you think it’s worth trying or am I doomed to get the
>> soldering iron out?
>> 
>> Best wishes
>> John
>> 
>>> On 4 Jun 2018, at 09:47, yahoo@doepfer.de [Doepfer_a100]
>> <Doepfer_a100@yahoogroups.com> wrote:
>>> 
>>> Hello,
>>> 
>>> unfortunately there is no offset trimming available at the
>> A-156 module. P1,
>>> P2 and P3 are just attenuators (with buffers) but do not offer an offset
>>> feature. One would have to add an offset externally or modify
>> the A-156 (by
>>> adding trimming potentiometers and resistors for offset
>> adjustment). I can
>>> tell you details if required.
>>> 
>>> Best wishes
>>> Dieter Doepfer
>>> 
>>>> -----Ursprungliche Nachricht-----
>>>> Von: Doepfer_a100@yahoogroups.com
>> [mailto:Doepfer_a100@yahoogroups.com]
>>>> Gesendet: Freitag, 1. Juni 2018 19:33
>>>> An: yahoo@doepfer.de [Doepfer_a100]
>>>> Betreff: [Doepfer_a100] A-156 input threshold tracking
>>>> 
>>>> 
>>>> Hi Dieter,
>>>> 
>>>> I am using 4 x A-156 together. The input threshold tracking is
>>>> usable but a bit tricky with one of the modules being slightly
>>>> different. I have read the A-156 adjustment guide and have the
>>>> correct tools to hand. I understand how P1, P2 and P3 adjust the
>>>> input scale but would like to understand if recalibrating them
>>>> might help with a little input offset. Any thoughts appreciated.
>>>> 
>>>> Many thanks for your time and attention.
>>>> 
>>>> Kind Regards,
>>>> 
>>>> John Hollis
>>> 
>>> 
>>> 
>> 
>> 
>> 
>> ------------------------------------
>> Posted by: John Hollis <john@hollis.co.uk>
>> ------------------------------------
>> 
>> 
>> ------------------------------------
>> 
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