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Info about the 212 and the 512 series preamps is not hard to come by.

However, the 312 is more elusive. Were they manufactured for use in any of the 1970's consoles? If so, was there some sort of faceplate? Does anyone have pictures?

I've just purchased one of the vintage 312 cards and I'm looking for another in order to put together a 2 channel unit so I'd like to get as much background as possible.

I'm considering Brent Avrill's people for racking them up. Suggestions, recomendations?


RemyRAD Fri, 02/24/2006 - 00:32

The 312 IS THE difinitive original API mic pre-amp. The first series had APIs own mic transformer, which was not great, albeit many hits were recorded with them. It was a silver colered can. The later units used the Dean Jensen 110K series transformer, which is a lower, wider/fatter profile silver can with the "110K" showing on the can and were a definate improvement. The API 3124 1U mixer is 4 312s! So this mid 60's mic pre is still one of the choicest units that has stood the test of time.

The 512 is basicly the same thing in a different package (form factor). So all you really need now is an edge connector a couple of cables and a bipolar + and - 15 volt power supply at a couple of amps and you're cookin' with gas! (a utility project box is highly recomended for installing).

Another happy 312 and 3124M owner.
Ms. Remy Ann David

They don't sound anything like a NEVE.
It's like men and women. The're the same but different.

Kev Fri, 02/24/2006 - 17:04

Discrete Op Amp - DOA - 2520
built into modular cards
312 - mic card
325 - line card

cards built into modules
often you see the 500 series modules
512 - mic
525 - comp
5xx - EQs
see Dan Alexander
or even Fletcher
(dead link removed)

cards also built into complete mixers or rack units
the numbers seem to get to 4 digits like

1604 - mixer
2488 - mixer
3124 - rack unit - 4 x mic

from memory the new 3124 is actually one very large circuit board but you can see the origins of the 312 in there

I might be a little off base
but that's the general idea

the basic idea in the 312 and the new model 512 is near enough the same
you would need to look close to see if the transformers are exactly the same
but I think the output is the same trafo and I don't know about the input trafo
the 512 is a module and has the various controls fitted
mic, line, instrument
20 dB pad, 48v phantom switches
and does have the 2520 Op-Amp
and has a LED based VU meter

... the 312 is just the basic card.
the newer 212L is probably the closest current unit to the old 312
but they all have the same origins

for more detail go to API

anonymous Mon, 03/06/2006 - 12:08

Thanks for some great insight!

I read somewhere that the API 312 is more colored or fatter than the 512 or 212.
If all three series employ the 2520 op amp than any differences would have to be the result of input and output transformers? It certainly seems likely that over the years API switched out these components.

It seems odd, however that the 212 and the 512 are both modular designs for which API manufactures racks with power supplies and the 312 is just the card.

I wander what API intended the 312 for?

Brent Avrill's people want $1000 to rack up a pair of 312 cards. I know they have a reputation for doing quality work but I feel like I should shop around.

Thanks for all the input and suggestions!

FloodStage Sat, 03/11/2006 - 15:18

mrpatrick54 wrote: Thanks for some great insight!
I wander what API intended the 312 for?

Use in API boards.

Brent Avrill's people want $1000 to rack up a pair of 312 cards. I know they have a reputation for doing quality work but I feel like I should shop around.

Averill does do quality work.

However, I called Averill a year or so about racking a couple 312's for me and was told they didn't rack up customer's modules anymore.

Don't know if this is still the case.


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