Midwest Analog Sale on Whisper Compressor and other things

[DiyFreaque]

In case anyone is interested, Midwest Analog is having a 25% off sale on selected products, one of which is the Whisper Compressor kit:

http://www.midwest-analog.com/news.html

Cheers,
Scott

[O]

Does anyone happen to have a parts list for this ckt?  :?

[Ben N]

Is that an OTA-based compressor?  Because I notice that their 3080 book is on clearance, too--big surprise.

[O]

Is that an OTA-based compressor?  Because I notice that their 3080 book is on clearance, too--big surprise.

dunno...

that's one of the reasons why I wanted to know if anyone had a parts list... Although, I might just break down and buy it to try it... (I have some b'day money burning a hole in my pocket)

[Mark Hammer]

The Whisper is essentially an improved version of the Anderton EPFM-II compressor project.

Like the EPFM Comp, it uses a bipolar (+/-9v supply), and uses 3 op-amp stages.  One stage is the gain reduction stage (where the ever-trusty CLM6000 sits in the feedback loop).  Another stage is the gain stage that drives the LED inthe CLM6000.  The third stage is the gain recovery stage.  It uses better op-amps than the original, and also includes a tone control.

I liked the original very much and still count it among my arsenal.  I would imagine this to be a bit of an improvement.

One of the advantages of LDR-based compressors is that the sluggishness of the LDR reduces envelope ripple for a smoother decay.  Another advantage is that LDR have no distortion since they are just resistors.

[Ry]

Thanks for the tip on the sale!  I was getting around to ordering two of the books, but I just got all three for 25% off!

COOL!

Ry

[DiyFreaque]

I don't know whether Thomas Henry is going to keep selling the CA3080 book past this, though I doubt if he discontinues it.  The CA3080 is now going out of production, but lord almighty there is a glut of them out there, and I think it'll be a long time until they decay into unobtainium.  Seriously.

That CA3080 book *is* awesome - Thomas has a good writing style and method for breaking things down to the simplest level and building from that.  It helped me a lot to understand OTA's after blindly (more or less) using them for years.

I've got an original manuscript from Thomas concerning some great work he did with VCO chips (this summer I beta tested the circuits, and also some other really cool synth stuff for a book that just hasn't made it out the door).  Thomas landed a good teaching position which sucked up exactly 99.998% of his time, and things kinda held up a bit (around that time he was talking about sending me a whisper compressor kit, too damn!!).

He's not going out of business, BTW, but there may be a name change coming down the pike.

I might mention that this summer I 'seeded' Thomas' snail mail box with some PT2399's and PT2395's, and in this last email, he mentioned he was thinking about diving into them.  I've always wondered what he would come up with using these chips.

Cheers,
Scot

[Ry]

I can't wait to get the 3080 book.  I bought a fairly sizeable stash of them from Mouser when I heard that they were being discontinued, then I found this book.  I have no understanding of how the 3080 works, and I've tried to figure them out a few times (both in college during my EE days and since).

I'm really interested in the noise book, too.  I have a perverse love of noise circuits.

The electronic drum book was bundled in for the sale, and I'm sure it will be interesting as well.

I'm interested to see what things will be coming out with the VCO book and delay chips.  It's quite inspiring to see someone still writing books on this stuff for the diy market.

[Ben N]

I don't know whether Thomas Henry is going to keep selling the CA3080 book past this, though I doubt if he discontinues it.  

"while supplies last"

[CS Jones]

My kit just came in today.  Looks very nice. Good parts, good pcb, 12 page assembly manual with schem, layout and other info. $31.50 shipped. Go for it O, I don't think you can beat the price.
No box, no knobs though... not a problem really.

DiyF...thanks for the heads up on this. I would have completely missed it had you not mentioned it. I've wanted to try this one for a while now but it had skipped my mind.

Clay

[amz-fx]

I designed the Whisper Compressor - that info must have been left out in one of the redesigns of the page -  so if you have any problems with it I will attempt to help you out.

Just some info about its development...  there were several different circuit topologies tested and I liked one of the others better but I was taking directions from Tom so we went with that one.  I also wanted it to use one 9v battery but Tom really liked the greater dynamic range from two of them so we went with two.  The original article we wrote about the design appeared in either Electronics Now or Nuts-and-Volts magazine; I cannot remember which but I have a copy of it somewhere.

This particular configuration has a compressor-limiter effect with a "soft-knee" -  there was a curve of its response on his site at one time. The more you crank up the compression, the more it acts like a limiter. There was also some discussion about different opamps to use in the circuit but it has been so long ago that I cannot really remember what we tried.

When I originally built the circuit, it worked perfectly.  Tom built a copy and it would not work for him.  He is an excellent tech so this had us puzzled. I traced it down to the CLM6000s...  he had a big lot of them that he had bought surplus and only about 1 out of 3 or 4 was good. He ended up having to sort through the CLMs to find the good ones to sell.  I then bought a handful of CLM6000s from one of the surplus outfits and experienced the same problem!  All of the old ones that I had in stock were perfect but the new units that were available were all over the place.  This was at a time when Clairex was almost out of business and they ended up getting bought by someone and the line revived.

I won't use a CLM6000 to this day because of that incident -- an NSL-32 will work in the Whisper Compressor just fine, but if you bought a kit, don't worry, Tom checks all the photocells.

I still have a prototype in my studio and I'm sure it would work if I put in new batteries.

regards, Jack

[Doug_H]

That does look like a good deal. If I was in the market for a compressor I would go for it.

I saw the schem (or a partial schem, can't remember) for this many years ago and it is a very elegant design.  Immediately made my "I'd like to get to it someday" list...

Doug

[DiyFreaque]

That's pretty cool, Jack!  Thomas told me a similar story about some SAD4096's found in a warehouse long ago.  Turns out a significant percentage of them were DOA.

As for the CA3080 book - I just don't know if he'll do reprints.  I've bugged him a few times about producing a few more Compandor Cookbooks (fooled around and never bought one, and now they haven't been in stock for a while).

Cheers,
Scott

[CS Jones]

I designed the Whisper Compressor - that info must have been left out

Boy, if that isn't a familiar refrain...seems like the story of your life.
Thanks for that information Jack. I look forward to this one and I'm glad you went with the bipolar supply.

Doug I remember talking to you a while back and you weren't a big fan of compressors. I'm somewhat a hoarder myself. I like compressors like some guys like ODs and like Mark Hammer I'm a fan of the Anderton one too.

[amz-fx]

Boy, if that isn't a familiar refrain...

Hahaha, that isn't the case in this instance...  Tom is a heck of a nice guy.  He redesigned his site sometime ago to concentrate on the kits, which doesn't really require info about the designers or the magazine articles.

We did a bunch of projects together; The Whisper, the Mod Box and the ADV series.  Tom is an excellent designer so I'm not sure why he enlisted me to work on the circuits in the first place but a series of kits and magazine articles came out of it.

BTW, I have long since been paid fully for my work on the projects and do not get any money from sale of the kits.

The Midwest kits are first rate and you can't go wrong with them!  Check out the Mod Box too.

regards, Jack

[Mark Hammer]

Somewhere, some lucky studentsare being taught by Tom.  I guess our loss is their gain.

I just wish Tom wasn't so damn fond of the old TI multifunction chip (the TI76477 or whatever the heck it was). He'd always come out with these great ideas...a few years after Radio Shack and Godbout stopped selling them.

[DiyFreaque]

Ah yes, the venerable SN76477 - heart of the Blacet Dark Star Chaos 2000 and Thomas' own Super Controller module (plus others of his as you mentioned).  Last I knew, they were still fairly available at the Akhibara (sp?) market in Japan....in that tiny format - not SOIC, but tinier leaded.  Oh, what is the name of that package?  Anyway, I got a few of those in trade with a friend in Japan a while back.  

Blacet used to sell adaptor boards for these critters, but I don't think they do anymore.  I've got one driving my Dark Star.

Someone on this list needs to write/record a song entitled "Where Have All The Good Chips Gone".  

Oh, now I'm getting all misty..

Cheers,

Scott

[Joe Kramer]

Somewhere, some lucky studentsare being taught by Tom.  I guess our loss is their gain.

I just wish Tom wasn't so damn fond of the old TI multifunction chip (the TI76477 or whatever the heck it was). He'd always come out with these great ideas...a few years after Radio Shack and Godbout stopped selling them.

SN76477 rules!  Anybody remember the Bullet SE-01 kit?  I'd give up eye teeth for that PCB now.  Wish I hadn't tossed it in a manic Spring cleaning fit . . . .

[Dan N]

I have one of his reprints books. I have checkmarks in the index next to stuff that use SEM/CEM chips. Pity so many projects are just hard to get parts for.

Debco just blew out SN76477's for $2.00 each a few weeks ago. You never know what will come and go from those surplus suppliers.

[Dan N]

SN76477 rules!  Anybody remember the Bullet SE-01 kit?  I'd give up eye teeth for that PCB now.  Wish I hadn't tossed it in a manic Spring cleaning fit . . . .

There is info here:
http://www.electronicpeasant.com/circuits/circuits.html

Someone could probably work out a pcb from the parts layout.