noise of arrays

[Joachim Verghese]

On Fri, 19 Jan 1996, Haible_Juergen#Tel2743 wrote:

> Short question:
> Does anybody know how noisy cheap transistor arrays (CA3046)
> are, compared with cheap low noise transistors (BC550)?

I built a phaser based on the ARP ladder in 1988. I did try
substituting the 3086s for BC109s, but for some reason it didn't
work very well. I'm not sure, but I probably used BC109Cs, which
have a much higher beta than the 3086. I then tried using BC184Ls
which worked ok, but the circuit was still quite noisy, so I
stuck with the 3086s and put NE570 companders on the input and
output. For the post-amp I used a differential amp built out of
3/4 of a TL074.

I've been planning to build this phaser again (with a voltage
controlled LFO), so please let me know if you intend to experiment
with different transistors, and how noise levels are affected.

Another question re arrays:

Has anyone tried measuring the bulk emitter resistance of the
3046/3086 arrays?

-joachim