[Amps] Audio/RF compression

Bryan Swadener bswadener at yahoo.com
Thu Jan 12 17:02:00 EST 2017

I tried software but, latency was horrid. That is why I use a Symetrix 528E 'Voice Processor'. In a 1U box, you get an excellent preamp, de-esser, expander, limiter/compressor, and three band parametric equalizer. Each section can be switched in/out or patched into. Output is line level, balanced, and transformerless. 

I had my hands inside the 528E when I was the engineering tech at Symetrix. While it's not DC-powered, the internal rails are +/- 15VDC, and a 30W DC-DC converter "brick" will run it. You'll give up +48V Phantom power but, oodles of fine & inexpensive non-powered microphones abound.

I have my 528E mounted on the underside of my operating table's shelf, above my rig. IMO, it's more convenient than anything else (including software). The 528E is long discontinued but, we made thousands of them (they're widely available). Symetrix also produced a digital version, the 628E, with more control features.

vy 73,
Bryan WA7PRC


Date: Wed, 11 Jan 2017 13:04:03 -0800
From: Jim K9YC
To: amps at contesting.com
Subject: Re: [Amps] Audio/RF compression

On Wed,1/11/2017 12:07 PM, Manfred Mornhinweg wrote:
> in addition to various circuitry that performs audio processing at 
> varying levels of versatility, quality, and cost, we should not forget 
> the possibility to do it in software.

Yes, certainly a possibility. But have you looked at latency? This may 
or may not be a problem.

Another question though. What's your ham call? How much operating do you 
do? What sort of operating do you do? DXing? Contesting? Casual 
rag-chewing? CW, SSB, RTTY, etc? What bands?

73, Jim K9YC

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