[BC] AMPRO picture can be seen at this link --

[Harold Hallikainen]

> A picture of an Ampro console can be found here --
>
> http://www.jimprice.com/prosound/bcast-cnsls.htm
>
> in both rotary and linear fader models --
>
> Mike Langner
> Albuquerque, NM
>
> PS -- the units used, as I recall, the 1458's I've offered. What were they
> inside?  Dual 709's, as I recall.  This was actually a good move in an era
> when so many manufacturers were moving to the simpler circuitry of the
> 741.
> 741 op amps have absolutely terrible TIM and SID (transient
> intermodulation
> distortion and slewing induced distortion) as they were internally
> compensated for absolute stability which limited their performance.  The
> 709
> takes external compensation, so it could be -- and was -- used in circuits
> where it provided superior high-slew-rate (for the time) performance.  The
> difference really shows up on acoustical guitar, harpsichord, and the
> like -- still, nothing like the 5532/5534's and later of today --

I worked on some Ampro rotary pot consoles way back. One thing I remember
about them was the rather small solid wire coming up to the pots and
switches. It tended to break and get shorter as you replaced parts. And
the lever switches mounted in a 3/8 inch round hole. This compares with
the lever switches that mounted in a slot and used four small screws to
hold them in (like the one in our old TVA series at
http://louise.hallikainen.org/BroadcastHistory/index.php/HallikainenAndFriends
. I found that the lever switches with the round hole mount tended to jam
after a while. I never saw the other ones jam.

Speaking of the 709, I seem to recall it was the output amplifier in the
Moseley PCL-303/C. It carried composite stereo. So, it was a pretty fast
amplifier.

Harold

-- 
FCC Rules Updated Daily at http://www.hallikainen.com