[Amps] Audio/RF compression

[Fern Rivard]

Get a  hold of a Drake SP-75 speech processor. It will work with any rig and 
works very well.
It also has a noise gate.
Fern  VE7GZ


-----Original Message----- 
From: Christopher Brown
Sent: Tuesday, January 10, 2017 4:41 PM
To: amps at contesting.com
Subject: Re: [Amps] Audio/RF compression

Given that most radios don't have all of this built in, or at least a
poor version the critical question in my mind is...

Is there a good single box to do this on and is there anything available
that is 12VDC nominal powered?

I happen to like and use older Icoms rigs for 2M and up.

But, I absolute _hate_ the APC/ALC setup on these things and how it
functions as a cheap compressor (nasty overshoot and similar issues).


To me it seems like a box with...

Input gain dial

Output driven dial settable AGC/limiter with fast attack 1 second hold
and slow decay.

0-10db soft-knee compressor with dialable level and threshold.

would be very useful...

Set AGC/Limiter to backoff just before APC/ALC circuit kicks in the radio

Dial up 6db compression

Twiddle input gain and compression thresh for best balance.

Better yet if it is a single brick that can run off of DC, I do have AC
powered AMPs in the shack, as well as computer and batt bank charger but
all basic functions are DC only and can run for many hours on air or
days monitoring without firing up the generator.

As tempting as cleaning things up on the 271, 471 and 1271 is, I have
not been able to bring myself to allowing AC powered gear being required
just to transmit.

Chris
WL7CLA


On 1/10/17 14:05, Jim Brown wrote:
> I agree with Steve -- having retired from a career in pro audio and
> broadcasting, I know quite a lot about audio processing. Manfred's
> description is requirements is wildly exaggerated, and Jim Thompson's
> processing rig is wretched excess. It's the sort of thing I might do in
> a broadcast station for the mental midgets who do most of the talking,
> but never for ham radio.
>
> If you're working close to a well-chosen microphone and rolling off the
> low end, 10 dB of compression is quite good for ham radio.  I have a
> closet full of world class microphones and signal processing gear to to
> with them. I'm a contester and a DXer, and find that I'm quite
> competitive with a Yamaha CM500 boom mic headset and that level of
> processing, all of which is built into my Elecraft K3. Indeed, I even
> push that to the limits by running QRP in most DX contests!
>
> 73, Jim K9YC
>
> On Tue,1/10/2017 2:44 PM, Steve Wright wrote:
>> On 11/01/17 06:53, Manfred Mornhinweg <manfred at ludens.cl> wrote:
>>> The problem with that is that 10dB of control range is far too small to
>>> accommodate the variations in the audio level coming from the
>>> microphone, as the operator moves closer or farther away, and speaks up
>>> or speaks softly. And to maintain the 10dB compression you first need to
>>> have a stable audio signal. So, in order to achieve that 10dB
>>> compression, you need to place this compressor after an automatic gain
>>> control system
>>
>> Operators are cleverer than that.  It's easy to keep an eye on the
>> metering and keep the Po and the ALC in the ballpark - that's just
>> normal use of a SSB radio - for those who get it anyway.
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