[BC] Achieving good S/N

[Phil Alexander]

On 27 Dec 2005 at 14:12, Robert Orban wrote:

> I built a copy of the Sta-Level for our AM college carrier current station, 
> driving into a Collins 26W limiter. Of all the '60s compressors I've heard, 
> the Sta-Level was the best sounding to me. Combine it with one of the 
> original Volumax 400s and you had a great-sounding AM station, although one 
> that would not be competitively loud by today's standards.
> 
> I've often wondered who designed it and if he hit the magic formula by 
> accident (without quite knowing what he had accomplished), or if he fine 
> tuned it like we do with today's processing. It was certainly atypical of 
> the Gates processing line.
> 
> I heard a Sta-Level not too many years ago, and the sound held up to my 
> memories of it.

As I remember it, the secret was the forgiving nature of the variable gain
amp tube whose number I can't recall. Before the day of the Max brothers,
a Sta-Level, a Collins limiter and a negative peak clipper were the ultimate
for AM. However, a modified Sta-Level, all by itself, was a major advance for
FM. In the days before limiters on FM (and I can say that most of the plants
where I worked in pre-1960 did NOT have a limiter in the FM chain) the
Sta-Level with the LF audio rolled off at the bias generator was a major
advance and boosted average modulation several dB taking advantage of the
pre-emphasis curve which eliminated any need for compression below about
250-300 Hz. It was great for an early '60's top 40 format because the bass
could blast without pumping even though the recovery was cut down to around
750 ms.  It was strange to watch the compression meter follow the mid-range. <g>


Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037





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