[BC] processing way back when

[Mark Durenberger]

Bob, the GE you're talking about was actually the second-generation.  The 
first generation used a lattice-network delay followed by an infinite:1 
limiter; 12 db max limiting IIRC.  20+ tubes; powered by a regulated bipolar 
350 volts or so!

The BA-6 nay have been the first to use Program-Controlled Release Time.

Mark Durenberger


----- Original Message ----- 
From: "Robert Orban" <rorban at earthlink.net>
To: "Broadcasters' Mailing List" <broadcast at radiolists.net>
Sent: Tuesday, December 19, 2006 6:50 PM
Subject: Re: [BC] processing way back when


> At 10:03 AM 12/19/2006, Mark Humpfrey wrote:
>>Not the first limiter, but possibly the first "look-ahead" limiter was
>>the General Electric BA-5-A, which is shown in my 1947 GE broadcast
>>audio catalog.
>>
>>According the the catalog blurb, its initial development was done by
>>the CBS technical staff, and it included a delay line in the signal
>>path, to "delay the signal until bias generator circuits have time to
>>reduce the required amplifier gain", and also had a dual-time-constant
>>release "anti-pump" circuit.
>
> When I was working at a summer job at WPAT in 1968, they had one of those 
> on their AM TX (an old Federal 5 KW with a separate vault for the mercury 
> vapor rectifiers and mod transformer!). The GE had LOTS of tubes. IIRC, 
> the audio was modulated as RF to permit gain control in the RF domain 
> without thumps. As far as I know, they also used an RF delay line for the 
> audio. I can attest that the unit had good peak control, probably thanks 
> to its look-ahead design.
>
> My recollection was that the GE unit sounded good by itself. Later that 
> summer, they added a tube-type Audimax to the chain.
>
> The Chief Engineer at the time was Paul DiSavino (sp?) who later left the 
> station and started a used broadcast/pro-audio equipment dealership.
>
> Bob Orban
>
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