Peavey CDS 2 Dual Channel compressor/limiter/ Deesser

[JohnRoberts]

Peavey parts might still have some old wall warts. I used that same WW on a ton of different products. It looks like they don't use it on any current products, but it may be worth asking service.

My recollection which may not be accurate was something like 71190660 for the PV in house PN (for domestic mains voltage).

You can use any roughly 16V AC power transformer that plugs into it. That product doesn't draw more than 100 mA or so, but the standard Peavey/AMR wall wart was rated for 1A (that it delivered on a cool day).

There are lots of universal AC PS that will probably work (if they plug up, As i recall there was more than one size pin jack/connector for PS. )


=====

That compressor was designed for early AMR -10dBV entry level bedroom recording (4tr cassette deck, etc), so you can overload it with strong +4dBu signals. The VCA was of my own design, and not as quiet or clean as a modern DBX IC VCA, but it didn't sound bad (in my memory).

I tried to make the controls pretty simple and easy to use. The 3 position attack/release switch dialed in pretty useful time constants for both att and release, the de-esser was tuned for around 8k. IIRC I think I built in a simple downward expander to keep the noise floor under control when dialing in a lot of compression.

Not a pro +4dBu unit, but not bad for what it cost, and the market intended for it back in the day, but of course I like all (most) of my aging children.

JR

[pepe44]

Hi John Thanks for the reply.
The best thing in all of this is that today the studio owner found the PSU , its quite funny that i posted this here yesterday and i´ve been looking for it for ages and now he found it!! life has amazing things sometimes.
But thanks for the reply! You built this unit ??
Can you tell me exactly what are the pre defined times for the attack and release on fast, normal and slow?

Best Regards

[JohnRoberts]

I can barely recall the general design let alone specific time constants (25+ years ago), while as I mentioned the VCA is my own design. It doesn't use a logarithmic control law, but linear. This results in a side chain that is faster for large signals and slower for small signals.

The final speeds were mainly dialed in by ear (sorry if this disappoints). The attack-release ratio is similar at all settings, so the speed of both gets switched between fast-fast, med-med, slow-slow.

If it still works, you can tell us...

JR

[pepe44]

I´ll let you know as soon as possible
Thanks a lot for the advices.

[pepe44]

I´ve tested it today using PT .
I conclude that It might need some "tuning". The electronics are old and need some attention maybe.

The first test I did was to send the signal from a mono out from my M-audio Profire 2626, which is balanced +4dBu signal, into the patchbay and then route it to the unit and it sounded at first very saturated ( might be due to the inputs of the CDS2 (-10dBV ? are they balanced!! i dough it ) .

Second test was to determine how the dual channels works , so i´ve set up a stereo send from the profires to the patchbay and into the unit and send it back to a stereo track in PT , it was out of phase! with the link ON and tested with link OFF...just analysed it with PAZ Analyser in RMS Stereo Slow mode and it was almost all Anti-phase.

I´ve tested as well plugging a guitar straight to the unit and send it back to a track in Pro tools, it sounded very poor! The compression works, but in a very strange way!! didn't like it that much to be true, but..probably on different situations it might be handy! we never know.


With a Jack cable i´ve inserted a few times in all ins, outs and side-chain slots just to "clear up"..

I´ll have another go someday, wasn't a waste of time . Thanks for the all replies John, appreciated man.

[repa]

Hello,

My story about the CDS2.
I've just picked up a CDS2 on ebay for like nothing. It was sold as defect.

I was looking for some schematics without fortune, I did not want to pay for it and I've only saw a corner of the drawing where I said it is built of discrete components, that might be easy to fix. When the unit arrived I've gave it a go. LED-s light but no sound, with maximum volume even when it was bypassed only very quite distorted sound.
I've opened it up looking for burned parts inside, but everything just looked fine and untouched. Okay, next thing to do was looking for the power supply. I just started to do a map of the PCB what is connected and noticed that it had a diode bridge inside... if the unit is DC powered a single diode is enough for polarity protection. I look at the back plate where it says 16V AC... I check the psu which said 16V DC.
There were no screws so I grabbed a saw and opened the PSU, got the rectifier out and checked again the function. Much better, it works but it is very noisy and even without a signal the gain reduction meter showed on both sides -6 dB reduction. I measure the voltage of the PSU which was slightly bellow 16V which also probably drops a bit it there is some current and it might be that some components do not get their stable +/- 15V.

So I started looking for a PSU which outputs enough AC to drive it. It was not easy because due to some cleaver EU regulations only switching PSUs are allowed to sell which is bad for getting AC out. I've found that some turntable (Thores) uses also 16V AC and started looking for a spare PSU. I found one in a local shop for 2,5x the price which I paid for the compressor itself so I've got a new one from ebay which was only a bit more expensive than the compressor but it got 16V AC 500mA and a no load voltage of 19V.

Finally I've got the compressor working and I kinda like it. It is very straightforward so there is not much what you can do wrong with it. The de-ess is pretty effective and in my opinion even better than the UAD Precision De-esser.

I think it is a decent unit which was worth the total investment of 40 EUR.
I might prepare a demo of the unit if somebody is interested.

@John: Do you still have the schematics of this unit? I've the datasheets of all active parts inside and it would be nice the have a complete documentation of it.

[JohnRoberts]

Originally Posted by repa

Hello,

My story about the CDS2.
I've just picked up a CDS2 on ebay for like nothing. It was sold as defect.

I was looking for some schematics without fortune, I did not want to pay for it and I've only saw a corner of the drawing where I said it is built of discrete components, that might be easy to fix. When the unit arrived I've gave it a go. LED-s light but no sound, with maximum volume even when it was bypassed only very quite distorted sound.
I've opened it up looking for burned parts inside, but everything just looked fine and untouched. Okay, next thing to do was looking for the power supply. I just started to do a map of the PCB what is connected and noticed that it had a diode bridge inside... if the unit is DC powered a single diode is enough for polarity protection. I look at the back plate where it says 16V AC... I check the psu which said 16V DC.
There were no screws so I grabbed a saw and opened the PSU, got the rectifier out and checked again the function. Much better, it works but it is very noisy and even without a signal the gain reduction meter showed on both sides -6 dB reduction. I measure the voltage of the PSU which was slightly bellow 16V which also probably drops a bit it there is some current and it might be that some components do not get their stable +/- 15V.

So I started looking for a PSU which outputs enough AC to drive it. It was not easy because due to some cleaver EU regulations only switching PSUs are allowed to sell which is bad for getting AC out. I've found that some turntable (Thores) uses also 16V AC and started looking for a spare PSU. I found one in a local shop for 2,5x the price which I paid for the compressor itself so I've got a new one from ebay which was only a bit more expensive than the compressor but it got 16V AC 500mA and a no load voltage of 19V.

Back then we used a common 16VAC 1A wall wart in many Peavey and AMR product so there should lots of them out in the world. Peavey service may still sell them (i don't know if they do or not).

Finally I've got the compressor working and I kinda like it. It is very straightforward so there is not much what you can do wrong with it. The de-ess is pretty effective and in my opinion even better than the UAD Precision De-esser.

Yes, it was designed for -10dBV bedroom recording market that was popular back in the mid '80s, mostly using cassette or small format open reel as recording media. It will not handle +20dBu without overload, since that is almost 30 dB above nominal 0VU.

I intentionally made it hard to get a bad result, anticipating inexperienced entry level consumers. Don't look for extreme dynamics effects, but it should be useful.

I think it is a decent unit which was worth the total investment of 40 EUR.
I might prepare a demo of the unit if somebody is interested.

@John: Do you still have the schematics of this unit? I've the datasheets of all active parts inside and it would be nice the have a complete documentation of it.

I do not save old product design schematics, especially work done for other companies, either as a consultant, or employee. I worked at Peavey for 15 years and designed a number of products while there (try asking Peavey service).

I don't recall specific details, in general the CDS2 was designed back before DBX started selling their VCAs to other manufacturers for reasonable prices, so I designed my own VCA. I got a patent (US04818951) for an approach that eliminated the need for factory trims, so I could use unselected transistors. Since the VCA was class A it is not as low noise as modern VCAs (that operate class A/B).

I think the CDS was good for it's time and what it was, but may be marginal dynamic range for use with modern recording media. Since the VCA is class A you can't even drop a modern VCA in there without completely redesigning the side chain too. Best you could do is perhaps substitute lower noise transistors in the VCA, but this will not buy you that much noise improvement (or I would have done it back then). IIRC this was <$200 retail back in the mid-late '80s so not exactly a high end unit.

Thanks for the memory... enjoy.

JR

[Macky]

I have one of these units coming in a day or two and it also needs a power supply.

John.. if you would be so kind as to advise me.
Could i use the Power Supply from my Symetrix SX202 ?
Here are the details from the manual. It seems to match what has already been mentioned.
-------
Power..5mm coaxial socket. Use Symetrix PS-2 power supply (16V ac, 500 mA), included with domestic units. The PS-2 is both UL and CSA certified. Accepts plugs with 2.5mm center pin (Switchcraft 760).
------

Does the Peavey use a Switchcraft 760 ?

Cheers
Macky

[JohnRoberts]

Originally Posted by Macky

I have one of these units coming in a day or two and it also needs a power supply.

John.. if you would be so kind as to advise me.
Could i use the Power Supply from my Symetrix SX202 ?
Here are the details from the manual. It seems to match what has already been mentioned.
-------
Power..5mm coaxial socket. Use Symetrix PS-2 power supply (16V ac, 500 mA), included with domestic units. The PS-2 is both UL and CSA certified. Accepts plugs with 2.5mm center pin (Switchcraft 760).
------

Does the Peavey use a Switchcraft 760 ?

Cheers
Macky

Do you guys remember details about products you designed more than 25 years ago?

OK, for what I do remember, 16VAC 500ma should be more than adequate power. I do not have any idea of what the pin diameter in the power supply connector is. IIRC there were mainly two popular pin sizes so your odds are 50/50.

We used some switchcraft audio connectors, while the power connector was probably sourced from a cheaper offshore vendor.

Did anybody try asking Peavey service, about replacement PS?

JR

[Macky]

Thanks for the quick response John

16VAC 500ma should be okay, thats great ..


Yes, a bit dull of me to ask you about the connector..
Especially as i,ll find out soon enough when i see it.

Cheers
Macky