[sdiy] Replacing CA3080 with CA3046 ??

[karl dalen]

--- Antti Huovilainen <ajhuovil at cc.hut.fi> wrote:
> On Sat, 9 Apr 2005, karl dalen wrote:
> 
> > The thing with the 13600 and 700 is that the offset is not constant,
> > it responds in a somewhat eliptical fashion depending on varying Iabc,
> > from some 500uV to 25mV and back, i tested this long time ago about
> > 12-15 13700 they all shows this in varying amount. Used the classic PNP
> > Iabc source expo.
> 
> You don't happen to have a curve plotted of that?
Sorry no, i whised i had!

> Is it possible to take that into account and trim the input for minimum 
> worst case bleedthrough?

Yes and no, it becomes a avarage trim then either you have
to for hand go trough all 40 of your 13700 and match each and
every one of them and as Ian says match even each dual pair!!
But thats waht we do in normal case anyway the big difference 
we most likely use 5 or 6 units not 40! :-)

> How does the use of linearizing diodes affect this?
It worsens it a bit in some cases!! In some cases, not at all!

> Or should I just 
> forget about them for the voice final VCAs?

No, the BIT 99 and BIT01 used them as final voice VCA
and sounded splendid (i have owned both once).

> How bad is the CV bleedthrough for untrimmed 13700 circuit?

As said its varying, the BIT99 used the standard way of triming,
one pot each VCA. BTW the designer of the BIT99 was the same 
fellow that designed the famous ELKA!

reg
KD