Valley People TA101 transistor array

[NOON]

I had one of these units crumble on one of the cheap Valley MicroFX units, so a bit more scraping and you can read the transistor type. It's an MPS 8098, with I assume it's matched complement as the pair.

You can see how they're stacked in pairs and blobbed up in the potting compound.

These units are used in quite a few VCA designs, some mic preamps and a few other miscellaneous things, hopefully this helps someone repair something in the future because these modules are not easily available these days.

 

[user 37518]

 

[jensenmann]

The top of the potting says pnp and npn. Is it possible, that there are two different transistor types inside? If so would you mind scraping some more potting off to see what´s going on?

 

[Ilya]

My bet is they are 8099 transistors.

P. S. Really curious to peek inside the TA103 array.

 

[gyraf]

..data sheet, application note:

..also uploaded to tech. docs section

 

[richiyobs]

US Patent

 

[JohnRoberts]

Yup Paul Buff was one of the early VCA pioneers competing against DBX (Dave Blackmer).

I used Paul's VCA in my Loft/Phoenix audio Lab comressor/limiter/expander/everything back in the early 80s. I think the model number was something like 601 or 602. I can't find it with a search because some new company is calling itself phoenix audio these days making unrelated 500 series gear.

[edit- found it here... it was called the LOFT 410... this thread goes into deep dive about my compressor to end all compressors design philosophy (it didn't end all compressors). LOFT 410 expander compressor limiter /edit]

JR

 

[gyraf]

The TA101 was also used as VCA in our Calrec UA8000 console (1988). It felt significantly cleaner than DBX at the time (202C in our SSL..), at the cost of extreme temperature dependence (mainly DC offsets/clicks).

I was happy to see valley people resurrected a couple of years ago - although DBX/THAT long since has taken over lead in the clean game..

/Jakob E.

 

[musgrave]

I had one of these units crumble on one of the cheap Valley MicroFX units, so a bit more scraping and you can read the transistor type. It's an MPS 8098, with I assume it's matched complement as the pair.

You can see how they're stacked in pairs and blobbed up in the potting compound.

These units are used in quite a few VCA designs, some mic preamps and a few other miscellaneous things, hopefully this helps someone repair something in the future because these modules are not easily available these days.

Years ago I took a very old one apart and found MPS A42s and A92s. I was a bit surprised that they were not more hifi audio centric parts. These were from a Harrison film dubbing board made in the 70s. In the 90s I made VCA’s using THAT discrete transistor surface mount packs with two NPNs and 2 PNPS. I put a pad below them, and mounted one on either side of the board and connect the two pads together with several vias. Worked like a charm. They were thermally stable, but I had trouble with the 1206 resistors in the control voltage circuits changing value under different DC voltages. I wound up soldering quarter watt resistors vertical on the 1206 pads to cure the problem.

 

[Ike Zimbel]

I may be able to lay my hands on >50 of these if anyone is interested...PM me.

 

[alanhyatt]

Making the TA-101 is not as easy as you all think. We own Valley. We have all the original milling machines to mill the PNP and NPN's to the specified thickness for thermocoupling. We have all the original potting trays as well. You have to trim the leads to a specific spec. There is more to it as well for matching everything. We are making more TA-101's, but it takes a lot of time to get done. We are also going to release some of the old products n both 500 Series and rack mount in due time. Specifically for now, The Comander, Dyna-mite, Gain Brain and MaxiQ. We tried to do them a different way and it does not work. You have to follow the process done by Paul Buff and Doc Morgan....

 

[JohnRoberts]

Paul was a brilliant design engineer and a friend (RIP).

Studying his old schematics is a master course in log domain side chain control circuitry.

JR