[sdiy] Re: Source of 2N5459 FETs

[Oren Leavitt]

Hi Fabio,

Try it on breadboard, with and without buffers, and see what you get.
The url gives me some 'page not found' error.

Oren

fmg wrote:

>Hi Oren,
>
>Oren Leavitt wrote:
>  
>
>>Hi Fabio,
>>
>>The way Z5 is  set up, as a differential amp with the 10.7K and 787K
>>resistor dividers on both inputs, the input impedance will be 797.7K at
>>either input regardless of the op amp used. Load on the filter ladder
>>output needs to be kept minimal so that it will perform its best. That
>>is what the JFETs or JFET input op amp buffers accomplish.
>>The capacitors, C6 and C7, block DC offsets from reaching the diff amp.
>>
>>Oren
>>
>>    
>>
>
>I understand that this mod lead to a degradation (don't know if this is
>the correct term) of the filter characteristics. My point is if these
>changes are noticeable for a ear accustomed to the original filter
>sound. That's why I asked to the list, I don't have an original ARP filter
>and a modified one to compare.
>
>I made this (url below) based on the Oakley Sound System schematics, but
>again, this is a modified version and I've never made the original to
>compare.
>
>http://www.geocites.com/eqys/var_tmp/01_lpf_2.pdf
>
>Regards,
>
>Fabio
>
>
>
>  
>

-- 
Oren Leavitt
oleavitt at ix.netcom.com