Vintage API 550 Help

[EisenAudio]

I believe I repaired one a few weeks ago, and it appeared to be just a 550A with different PCB layout. Same parts, sounded and measured the same, sitting in the same console as a bunch of other 550As. I could be wrong, though. I didn't look too carefully.

[superwack]

Interesting... I usually go to Avedis' document on all thing API EQ Avedis Audio: 550A, 550B, 553, 554, 560 Professional Audio Electronics, Vintage Pro Audio, ProAudio, API, Equalizer but it doesn't even list the 550C (you might want to email Avedis - I had a question about a weird mod done to my vintage 550A and he helped figure out what it was) a google search turned up a place called Cue Recording who lists 10 of them under the Mic Preamp section of their gear list but I know that's not right. Please let us know if you find anything out.

[jrod9900]

I'll post a pic later. Its def not a 550A, but I think it is actually a 550. 2 2520s. 3 bands, 3 freqs per band.

JROD

[AllAboutTone]

If they are anything like the old 525 70s then they are keen.
Sorry for mixing compressor with eq thread.

[druhms]

Could it be one of the transition 550's between 550 and 550a? Didn't API switch hands around then? Just a thought. No actual knowledge on the c model.
JJ

[jrod9900]

Not even sure its a 550c. Says on the board, but Paul Wolff said its a 550. Sounds pretty good. I'm guessing that one of the opamps is out.

[druhms]

Ahh, cool.
I had an opamp go out on one of mine not too long ago. I sent it to Alex Welti at Creation Audio Labs in Nashville. He built a new one for me and installed it at half price of an original API 2520. I swear I can't hear the difference and it saved a few bucks.
Good luck,
JJ

[AllAboutTone]

Originally Posted by druhms

Ahh, cool.
I had an opamp go out on one of mine not too long ago. I sent it to Alex Welti at Creation Audio Labs in Nashville. He built a new one for me and installed it at half price of an original API 2520. I swear I can't hear the difference and it saved a few bucks.
Good luck,
JJ

I bought some Yamaha 2520s off ebay, 25.00 bucks each, I cannot hear any difference, if anything the Yamahas sound a tad better, could just be in my mind though.

[jrod9900]

Cool, thanks for the input. I'll check it out.

JROD

[127Riot]

I also have an API 550c it's from Wally Heiders Demedio console from 1968 and it sounds beautiful. I have a regular late 60's API 550 that also sounds amazing.

[EisenAudio]

Yeah, that's it. Different PCB layout. Plus, those pacer caps (Sprague 192P, R.I.P.) sound like nothing else!

[wurly200]

I have a few 550 EQs and some are PCB revision B and some C.

I would love to know the difference.

[cheu78]

Originally Posted by jrod9900

Hello all,

Does anyone have any information regarding an API 550C? I know the 550s, 550As, and 550Bs, but what is the C?

Thanks,

JROD

Hey Jrod,
look at this page on Avedis website, it's full of good information:

Avedis Audio: 550A, 550B, 553, 554, 560 Professional Audio Electronics, Vintage Pro Audio, ProAudio, API, Equalizer


Afaik he repaired thousands of them, so if you have any question about the C version, just give him a call..he's a very nice guy and has a tremendous knowledge on everything neve and api.



Cheu

[mart]

I've aquired a AP-550 C circuit diagram model 550 a short time ago.

Those 2520 sure do get hot in there. Sometimes there is continuous noise for about 30 min after switch-on, then usually it goes away after warming up. I believe it is one of the opamps (tantals and electrolytics had been renewed), too bad they are not in sockets, which would make it a piece of cake to switch them out.

Though I have not compared to other 550 models, it sounds good to my ears.

Ahhm, what was question? Oh yeah, it is basically a 550A with less frequency positions on the high and low bands (3 each)

[jrod9900]

Hey guys, totally forgot to put up pics. Did do some work on it, and it turned out to be a bad 2520 Huntington opamp. The date was April 1990. They were soldered in too, what a PITA.

It is a 550, and its a PCB revision C. Not sure the date, but its old as Methusala. Sounds great though. We tried it on a bass track after the fix. Wowowoowoww. Sounded so incredible.

I'll post some pics this weekend since I have some time.

Thanks,

JROD

[127Riot]

Originally Posted by EisenAudio

Yeah, that's it. Different PCB layout. Plus, those pacer caps (Sprague 192P, R.I.P.) sound like nothing else!

What do you mean the pacer caps (sprague 192p, R.I.P.)?

[shortstory]

I think the C denotes 'console' PCB. It just means it came out of a console originally. I have a bunch of 550s & 525s with the C - and to put them into 500 racks I had to change the pin assignments. I thought they were dead at first because they lit up but no signal; but it turned out the card pins are wired differently for a console then a 500 rack- which I guess makes sense. Good luck- they'll probably sound amazing.

[jrod9900]

I'm guessing someone has made some adjustments to it along the way, cause it works with my 500 rack. Sounds damn good too. Lots of vibe. I promise I'll get some pics up this weekend for you junkies. Had to order another 2520 as well.

JROD

[127Riot]

Originally Posted by shortstory

I think the C denotes 'console' PCB. It just means it came out of a console originally. I have a bunch of 550s & 525s with the C - and to put them into 500 racks I had to change the pin assignments. I thought they were dead at first because they lit up but no signal; but it turned out the card pins are wired differently for a console then a 500 rack- which I guess makes sense. Good luck- they'll probably sound amazing.

This makes since To me, but back then (1968) what did they make besides the console EQ ? Did they have lunch box / 500 series?

[jrod9900]

I'm gonna go with "NO" for $500 Alex.

When did 500 series gear start anyways? Just curious.

Thanks for all the input guys. The eq sounds great. It's crazy to compare the old stuff to the new.

JROD

[NEWTON IN ORBIT]

Originally Posted by 127Riot

This makes since To me, but back then (1968) what did they make besides the console EQ ? Did they have lunch box / 500 series?

Consoles and console parts. Many people also built their own using their parts, or used their stock consoles as a modification platform. eg. the aforementioned Wally Heider and Sunset Sound consoles.

The 500 was (decades) later late 80's early 90's?, and after that the 200 series around the time of the Legacy consoles.

john

[jsteiger]

The 550's originally had the "tally lamp" connection on pins 6 and 7. This was usually disabled and the "lamp" was powered from either the +16V or -16V rail. I have 4 of the 550's and all the boards are labeled 550C. The SN's range from 2132 to 2584. My guess is the "C" has nothing to do with console but only the revision of the PCB.

I think you can say that the 500 series format was born with the first API consoles in the late '60's. I also think that the first standalone 500 racks or LB's were released in the mid to late '80's under Paul's reign. I don't think the format did much until Brent came out with his version to house all the vintage 312 cards he was racking back then. IMHO, Brent kept the format alive and kicking until the much later major resurgence that we are still in the midst of now.

[rob S]

Just for the sake of clarity , the original 550 had 3 freqs on the top and three freqs on the bottom.
And i think the q is different.
The 550A had the expanded freqs on the top and bottom.
1st version 550
2nd version 550A
etc
Kinda makes sense.

The 550 is not a 550C