[sdiy] PT-80 delay for Synth Modular

[Csaba Zvekan]

Thanks florian ! I was just reading that this particular circuit has a  
very low set LowPass Filter cutoff set at 2kHz . Which supposedly  
gives a analog feel for guitars because they  have a very high  
frequency end and tend to distort this chip. I will try your circuit  
modification and let you know if it worked.
I am aware that is low cost , but still I 'd like to have a module or  
two of them for a little effect. A little low-fi in my equipment setup  
is just what the doctor ordered . :)
By the way which part is the Low Pass Filter . I would  like to make  
some changes to  the cutoff frequency . Maybe set it to 18kHz fix  or  
with a trimmer to some better range.


Csaba

On Jun 30, 2008, at 1:43 PM, Florian Anwander wrote:

> Hi Csaba
>
> this contains ASCII-graphics so you need to look at it with a fixed  
> font like courier.
>
>> My questions are : Where do I modify the circuit to have less  
>> original  signal and more effect signal?
> The right TL072 is the mixing opamp for the delay and the dry  
> signal. The delay comes via a potemtiometer from the SA571, the dry  
> signal from the connection marked with "A".
>
> I'd change it the way to make the delay level to a crossfader  
> between dry and delay:
>
>        10k       10k(*)
> delay---RRR---+---RRR---to TL072 as exists
>              |
>              P
>              P<--Gnd
>              P
>              |
> dry-----RRR---+---RRR---as TL072 exists
>        10k       10k(*)
>
>
> The RRR's which are marked with (*) are the existing 10k resistors  
> of the mixing stage. The "PPP" is a potentiometer with 50k (or 47k)  
> linear.
>
>
>> How can I have a more cleaner delay  sound ?(If this is even  
>> possible with the PT2399).
> The possibility of the PT2399 is to buy a TC-Electronics D-Two. ;-)
> Sorry, this is a low price and low quality chip...
>
> Florian
>