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General Discussions => The Lab => Topic started by: al_p on September 10, 2004, 08:59:11 PM

Title: supposed API phono preamp?[identified!]
Post by: al_p on September 10, 2004, 08:59:11 PM
hi

i've got these 2 API cards that i have been told are phono preamp cards. they have a 2520 opamp, 2551 opamp, a couple of 4558 ICs, a 2623 output tranny and the usual peppering of caps and resistors. there is no card number etched in the usual place as per the 312 and 325. there is a much smaller number etched in the component side: "ASSY 1009-107" oh ya, these are double sided cards.

i can't turn up any documentaion regarding these cards. anyone see these before? or could verify if they are phono preamp cards or not? a schematic would be great...i can try to borrow a digital camera if there are any API guys who would like to take a look.

thanks
Title: supposed API phono preamp?[identified!]
Post by: jrmintz on September 10, 2004, 10:26:04 PM
I'd love to take a look. Is it possible it's a card by another manufacturer using API components?

If you go here (http://www.danalexanderaudio.com/api.html) and scroll down to the "card overview" document it refers to the model 330 series special purpose cards with the 330P (I'm guessing) being an RIAA phono amp. Does that look like it?
Title: supposed API phono preamp?[identified!]
Post by: al_p on September 10, 2004, 10:51:45 PM
Seth,

i saw that. it doesn't look like that. it got the 2 opamps side by side. errr at lest i think the "2551B" is an opamp. same size except a little shorter. doesn't have the sticker the 2520 has with the opamp graphic though, and it has 8 pins instead of 7. the API logo is etched on the trace side of the board. same 15 pin edge connector, same dimentions as a 312 or 325.

i'll try to post some pics. i also emailed API as i am really curious about this card. i would be super happy to get these up and running. i've been trying to get a UREI 1122 for a while but keep getting sniped when they do show up, but these would be great.
Title: supposed API phono preamp?[identified!]
Post by: soundguy on September 11, 2004, 12:25:03 AM
hey al-

I dont have anything really useful to ad other than with the boys here, always assume that someone will want to look at a photo if you got it!

If you need a good phono preamp, I would muster a bet that the borbley is probably pretty intense-

http://www.borbelyaudio.com/index32.htm

dave
Title: supposed API phono preamp?[identified!]
Post by: al_p on September 11, 2004, 01:04:30 AM
Dave

thanks for the link. that does look pretty intense. a touch pricey for me. one thing i really need is balanced +4 outputs though. i will post some pics soon.
Title: supposed API phono preamp?[identified!]
Post by: jrmintz on September 11, 2004, 01:11:54 AM
Hey Al,

Good luck. They're probably very cool sounding. I'm not by any stretch an expert, but I thought that API made the 2520 opamp and also the 2510 more recently. I've never heard of another opamp model. Maybe it's a potted RIAA EQ module or something? It's a really interesting mystery, anyway. I hope API is helpful to you - they used to be great but lately I've found them stingy with information and really snide. I have a dead 2520 I was going to send in with $75.00 for a new one, but the guy I dealt with was so rude I decided to put the money elsewhere.

Please keep us updated.

 :thumb:  :thumb:
Title: supposed API phono preamp?[identified!]
Post by: al_p on September 13, 2004, 04:55:20 PM
hey guys.

ok tooks some pics but they are a little blurry. hopefully good enough for you to have a look.

http://www.kimaguresound.com/apicard1
http://www.kimaguresound.com/apicard2
http://www.kimaguresound.com/apicard3
http://www.kimaguresound.com/apicard4

as you can see one of the 2520s had to be canabalized for something else. i think Seth may be right on about that mystery 2551 block being an RIAA EQ. anyone run into these before?

the pinout looks like it's close to the 325 amp which would make sense. i can trace power +/- and com, the 2 balanced outputs, and an unbalanced out. the rest i don't know.  the 2 trimmers beside the output transformer could be for hi and low RIAA curve?

getting dizzy from trying to trace the double sided board.
Title: supposed API phono preamp?[identified!]
Post by: Gold on September 13, 2004, 05:46:07 PM
Usually with an RIAA preamp you'll see some film caps. I don't see any but I could be wrong. My guess-and it is a guess-would be a VCA module with the unknown black thing being the VCA. I know Melcor/MAP made a VCA card that looked similar.
Title: supposed API phono preamp?[identified!]
Post by: jrmintz on September 13, 2004, 07:33:25 PM
Paul may be right as well, it could be a VCA. I suppose it's possible that these could be the only two of those cards in existence. The beauty of their card system was that they could run off all sorts of custom jobs using the same system building blocks and adding a few parts and etching a few new boards. It was very clever solution for a time when people mostly assembled consoles from premade amplifier modules and then hired a cabinetmaker. If I'm not mistaken, the idea of a standard configuration pre-made console didn't really take hold until MCI and Neve in the early-to-mid seventies.

Al, have you had any luck with API?
Title: supposed API phono preamp?[identified!]
Post by: al_p on September 14, 2004, 05:21:46 PM
identified :thumb:
"Those are API 350 VCA cards.  The 2551B is a discrete VCA, actually the original VCA that had the patent on it.  Class B, though.  Not much value now, except the op-amp."
from Paul Wolf.

good call Gold. too bad, i really need a phono pre. data sheets on the 2551B could be cool. i'd be curious to see how it stacks up to the 202.
???
thanks guys.
Title: supposed API phono preamp?[identified!]
Post by: CJ on September 15, 2004, 01:19:02 AM
Pull the 2520's and don't look back.