2520 opamps. Who knows the story?

I just got some API modules for Xmas. Boy do they have a variety of 2520's in them. Can anyone provide a timeline and description of the various incarnations of this component? I've got "automated processes inc", "automated processes inc" with "studio systems division" at the bottom, a datatronics one with reston, va on it, some with new york cities on them and some white ones. Any help would be greatly appreciated, greatly appreciated! Act early for places on next years "nice" list.
Thanks
P

In a general way all of the NY ones are earlier than the Virginia ones, obviously, and I have the sense that the "studio systems division" ones are later than the 'Huntington, NY" ones, but I can't swear to it. I'd love to know more specifically as well. Anyone know Paul Wolff?

Hi fluxivity,

Here is what I think can be the different issue/edition for the API 2520 amps around the years, but maybe I have miss something.

Automated Processes Inc, Studio System Division.
(black/silver metal foil label)
the first issue around 1970 ??

Automated Processes Inc, Melville NY.
(black/silver metal foil label)
around 1972 to 1975.

Automated Processes Inc, Huntington.
(black/silver metal foil label)
from 1976 and up.

API/Datatronix, Reston VA.
(black/white paper label)
around 1980 to 1985.

API Products inc, Springfield VA. (API/Wolf Associated)
(blue/silver metal foil label, without T-terminal)
take over from 1986 and up.

Automated Processes Inc, Jessup MD. (API/ATI fusion)
(black/silver metal foil label, without T-terminal)
from 1999 and up.

--Bo

What are some of the design/sound differences between these parts? Are they generally considered to be pretty much the same, or are they wildly differrent?

Shane

Sorry to revive such an old thread, but trying to recycle a bit

I want to bump Shane's question on this -- Has anyone heard an API Products inc op amp?  They are the op amps with a white face and blue printing on it.  How do they sound in comparison to other vintage ones?

I know that I don't like the sound of new silver/black api 2520s and I like the sound of the Melvilles and Studio Systems Division op amps (and the gar2520 clones that Gary has)... but anyone heard the api products inc op amps blue text on white/silver from 86 on?  Do they sound similar to the Melville's etc?

I was going to write Jeff about this, but I decided not to bug him as I'm sure he is getting 100s of emails a day (and somehow still answers all of them!)  8)

On a related note, here is a really old (May 2000) posting from Mr. Wolf himself regarding these opamps.  Enjoy!:

MELCOR and API by Paul Wolff
this is excepted from a posting on the rec.audio.pro newsgroup by Paul Wolff - former owner of api - Audio Products, Inc. and torch bearer of the product line and designs from API - Automated Processes, Inc... The entire thread of this article can be found on deja news or deja.com if they have solved their archiving problems

------------------------------------------------------------------------
 
Subject: MELCOR and API
Date: Wed, 17 May 2000 04:44:51 GMT
From: Paul Wolff <DELETED.com>
Organization: @Home Network
Newsgroups: rec.audio.pro
This is for Brad, I'll title it "MY COLORFUL RESPONSE"
A few people left Melcor and started API with some others. The original
2520 was "stolen" from Melcor, but the guy who designed it was one of
the ones who left. Many early API and Melcor op-amps have an RCA
sticker on them, as that is what they were. Melcor never went anywhere
after that, but the basic theory behind the amps and eqs were very
similar early on. Many people get Melcor and MAP (Modular Audio
Products) mixed up. MAP had a clone 550 and other stuff with an
IC/trans op-amp that was marginal at best.
API made as many as 20 changes over the years to the 2520, most of them
during the original 60-70's era. The changes were made because of
stability, heat, current, discontinued parts (TIS Transistors), Quieter
input devices and technical masturbation. Most of the changes made it
sound different. Datatronix made the same ones as API did,
After I purchased API, we built 2500 original 2520's and then were
forced to go to surface mount as they could not be built for less than
$200.00 each by hand. We preserved as many of the parts as possible.
As time and surface mount devices got better, so did the 2520. Just
before I sold API to ATI, Jeff and I found a matched input pair that is
almost identical to the original input pair that API settled on in the
70's. It is about the size of a crab (for those who got some on the
road and for those who didn't, it is very small) and has placed the 2520
back where it was. We did this about 2 years ago. I won't tell you
what the part is 'cause I'm a dick, and it is NOT a LM391. We started
placing the black foil labels back on them so everyone would feel fuzzy,
just like they did when we put the blue knobs back on the 550's.
Nothing will ever sound the way it used to, but we have done better than
anyone else has, so shut up. There is no product out there that
compares.
The Lord Paul

Strange -- I have a M.A.P. op amp which sounds very similar to an old Melcor to my ears.  Miko in Detroit (Melcor guru) can confirm this.

Anyone else on the api op amps with a white face and blue text though?  How those sound compared to Datatronix and before days?

Thanks!

What of the black/silver 2520 opamps that just have "Automated Processes Inc." on them -- how do they fit into the timeline?

That appears to have a date on the side. June something.....

You're right. Well spotted. It's marked "JUN X 2013" as far as I can tell.

I had no idea API made 312 cards so recently.

Thanks!

More likely a new 2520 in an old 312 card!