[sdiy] Re: Source of 2N5459 FETs

[fmg]

Hi Oren and list,

Why not just skip Q1, Q2, R20, R21, C6 and C7 and replace Z5 for a
LF357 or 411, including the reprograming of R25/R26 and R24/R27 ?

Does the FETs and LM301 participate substantially in the character
of the sound? I think they influence a bit, but can someone say "this
is an ARP filter" or "this is not an ARP filter" based upon this mod? [1]

Just my thoughts. What do you (owners of ARP filters) think ?


Fabio

[1] (ok, I know in this list that's possible :)


Oren Leavitt wrote:
> 
> Hi Steven,
> 
> Referring to:
> 
> http://www.arptech.synth.net/pdf/4035.pdf
> 
> Remove Q1, Q2, R20 and R21 from the circuit.
> Using a dual JFET input op amp, such as the TL072 (8pin DIP),
> connect pin 8(V+) to +15Vand pin 4(V-) to -15V
> connect pins 1(-in1) & 2(out1) together and connect these to C7 +
> connect pin 3(+in1) to where Q1's gate (G) went - pins 10 & 14 of Z4
> connect pins 6(-in2) & 7(out2) together and connect these to C6 +
> connect pin 5(+in2) to where Q2's gate (G) went - pins 7 & 5 of Z4
> 
> That should do it!
> 
> Oren
> 
> Steven Downhill wrote:
> 
> >Hi Oren,
> >
> >
> >
> >>Hi Steven and all,
> >>
> >>
> >
> >
> >
> >>You can probably ditch the JFETs all together and use JFET input op amps
> >>as non-inverting buffers, too.
> >>This would have been an expensive luxury back in 1974.
> >>
> >>
> >
> >
> >
> >>HTH,
> >>Oren
> >>
> >>
> >
> >You've lost me with this comment! (my electronics knowledge is limited at
> >the moment).
> >How would you go about doing this?.
> >
> >Regards
> >Steven
> >
> >-----Original Message-----
> >From: Oren Leavitt [mailto:oleavitt at ix.netcom.com]
> >Sent: 19 March 2004 04:33
> >To: Synth DIY (synth-diy at dropmix.xs4all.nl)
> >Subject: Re: [sdiy] Re: Source of 2N5459 FETs
> >
> >
> >Hi Steven and all,
> >
> >You can probably ditch the JFETs all together and use JFET input op amps
> >as non-inverting buffers, too.
> >This would have been an expensive luxury back in 1974.
> >
> >HTH,
> >Oren
> >
> >Steven Downhill wrote:
> >
> >
> >
> 
> --
> Oren Leavitt
> oleavitt at ix.netcom.com


-- 
Fabio Gonzalez
Posadas, Argentina