Audio compressor circuit

[VE3ELQ]

I would like to build a simple audio compressor to provide about 2 to 3 db variable compression.  A google search turned up a bunch of different designs but I have no experience trying this. Can anyone recommend a design that will do job.  TIA.

73 Nigel

[WBear2GCR]

That's pretty light compression.

But there was a multipin chip a few years back that did a range of functions.
It was also  offered in a product made for hams that fit in to the base of a D104. Not sure if it is
still in production, or who the chip mfr is/was. Might have been THAT corp, for the chip.

Or for <$100 and a lot less used, you can buy various different models of outboard
processors from Behringer.  

[WBear2GCR]

Guess what?

Don't have to go far...

http://www.classeradio.com/mic_preamp_rev_c.pdf

There was a "fancier" version of this chip, think they dropped it... iirc.

[KD6VXI]

Ssm2166.   Available on eBay.

--Shane
KD6VXI

[KQ6F]

The SSM2166 has been superceded by the SSM2167.  Available from Digikey.  K7DYY uses it in his D104 mic preamp.  

http://
http://www.k7dyy.com/p/d104-preamp-mark-ii-new.html

From all accounts it sounds good....

[KD6VXI]

The '67 is not a line item upgrade from the' 66,  they don't have the same functions as I remember.

Although it's harder to find,  the '66 is what I'd build around.  It being available in DIP is also a plus.

It was EOL years ago.

I used Steve' s schematic and a couple others as the basis for my mobile processor when I had my legal limit AM mobile setup.   

--Shane
KD6VXI

[pa0ast]

May be this is some thing for You. http://www.kent-electronics.nl/hoofdpagina_bestanden/image009.jpg [/img]

This is a HF  audio proc as a kit , cheap less than 30 dollar. Works very nice. on the pa0fri principle.

A LIMITING RF SPEECH PROCESSOR http://www.pa0fri.com/

Have fun  Anton

[WBear2GCR]

RF speech processors are generally for SSB only.
Like the old Waters unit, I forget what that was called.

[WBear2GCR]

The SSM2166 IS Available!

Here are a few sources:

http://www.mouser.com/_/?Keyword=SSM2166SZ
http://uk.farnell.com/analog-devices/ssm2166sz/pre-amp-microphone-2166-nsoic14/dp/9994459

These are all surface mount packages.
You'd probably want an adapter board to go back to a DIP package.

Here's one that comes that way!

http://smallbear-electronics.mybigcommerce.com/ic-ssm2166-sbe-reissue/

Some searches will show up a number of possible circuit implementations.

[VE3ELQ]

Thanks Bear and the others for the good advice.  Looks like the SSM2167 might be best, easy to use, have added some to my latest DK shopping list soon to be ordered.
Bear no problem with SM parts, most of what I build is SM.
Several years ago a friend gave me an EQ/compressor made by the junk maker that was un-usable around RF. I dragged it out and in there is a SSM2166 chip so will see if I can salvage it and play around.

73s  Nigel

[WBear2GCR]

Maybe with proper bypassing, some ferrite beads the box you have can be made to work.
Maybe look at the grounding scheme too...

Keep in mind that the 2166 has functions that the 2167 does not have.
I'd look carefully at those difference before deciding.

[N1BCG]

RF speech processors are generally for SSB only.
Like the old Waters unit, I forget what that was called.