Audio Compressor using AD SSM2167 (Speech Processor for more AAAAA-DEE-OHHH!!)

[Michael M]

Guys, I do not see any postings for Audio Compressors using AD SSM2167.
There are plenty of posts for the CB City International speech processor, which are unavailable. I used one back in the day...

Here we are 2025.... Just FYI, Assembled compressor boards, based on the Analog Devices SSM2167, are available on E-Bayz for <$7 by searching "ssm2167 module"

Ready for a new project for the new year??
Give it a try !



There are also postings on goob-tuber with folks demonstrating this board:



AD SSM2167 Datasheet:

https://www.analog.com/media/en/technical-documentation/data-sheets/SSM2167.pdf

Any experience you have, please share!

 

[Cable Guy]

I ordered a few to try out. Just glazing over it, looks promising. I've built a few of the CB intl. boards and they were finicky to get set right. Excited to try these out.

 

[Shadetree Mechanic]

Interesting little board. Amazon has them too:

https://a.co/d/8vOGe8x

Might pick up a few for my next microphone victim.

Edit:
It has a noise gate too. Some of the Amazon comments say that it works best if the resistors for the compressor and noise gate are reversed. I wonder what it uses for negative feedback? Might be able to add a tone control.

 

[sp5it]

I was playing with 2166 back in a day while it had more adjustment options. Still got it somewhere.
Mike

 

[Michael M]

Yep, I bought a few myself, Cable Guy

As Shade Tree noted, & M0NTV also found, R1 and R2 were misloaded on the boards he received: no compression was taking place as received off ebay! :-OO

So verify the values of R1 and R2:
R1(gate): 15K ohms for 2:1 of compression (or use a pot)
R2(comp): 1K ohm for a -48 dBV gate (knee) (or use a pot)

Let us know your results !
Michael

 

[Cable Guy]

Yeah, I noticed that from the video you put up, but I don't care, I'll probably put both on a concentric stacked pot. I ordered mine from China, yeah it will take a while to arrive, but at about half the price of the Amazon listings, I don't care really. If they are legit, they will make a nice drop in addition to any radio. Thanks for pointing them out Michael.

 

[Cable Guy]

They arrived today and they are tiny.

 

[Cable Guy]

Something I didn't think about, how to power this baby. It takes 3-5vdc. Rather than probe around for a usable source, I decided on this 7805 regulator.


And again, with it's supporting components.


And, a unit ready to go, sans shrink wrap.


The 7805 is capable of 1.5 amps current. It should be heatsinks if tasked to deliver. However, the board draw is so negligible it didn't even register 4ma on my supply during testing. Given the small power, I think the regulator will be fine without sinking.



I will install it today and let you know how it goes.

 

[Michael M]

Nice one, cable guy! Crazy the size
I'm thinking of the same concept of the 7805 and dual-gang pot adjusting. My boards arrive at the end of the week.

Post what find once you get it going. It should be interesting to mess with.
Thanks,
Michael

 

[Cable Guy]

I wasn't thinking when I first wired the pot with plain wire. I replaced the wires with a shielded cable due to rf feedback. The mic in and out i had already used shielded cable. Also, I added a toroid choke to the power wires. Once set, seems really stable. It has a lot of gain, so don't go crazy on the compression pot. I used a dual 50k because that's what I had on hand.

 

[Michael M]

I wasn't thinking when I first wired the pot with plain wire. I replaced the wires with a shielded cable due to rf feedback. The mic in and out i had already used shielded cable. Also, I added a toroid choke to the power wires. Once set, seems really stable. It has a lot of gain, so don't go crazy on the compression pot. I used a dual 50k because that's what I had on hand.

Came across a schematic of the SSM2166 with variable low (bass) an high (treble) gain controls + an input attenuator (pot). Credit goes to WA1QIX