API 312 Thread!

[babyhead]

I think I have it figgered out. A 30v series CT transformer will power these to +/- 24v, right?

I also want to put a header at GAIN. It looks just shy of a 2mm spacing as far as I can tell. Is there a part reference for this?

I am sooo jacked up to put these together. I'm doing 2 Forssell 992 servo out pres according to his schematic into the Fabio boards. :twisted:

 

[jrmintz]

I think +/-24V is too high for a 312. The API spec sheet says +/-12V to +/-20V, and I think most people settle on 15V or 18V.

 

[CJ]

I am running +/- 15 on my Melcor and it is the bom, biatch! :razz:

Secret trick #1: put some kind of mu can or copper foil around the square opamp package and ground the mofo.

 

[jrmintz]

Babyhead,

I'm not sure I understand your application exactly so forgive me if I'm giving you information you don't need. There was a thread here about Forssell 992s and API output transformers that might have a bearing on what you want to do.

:sam:

 

[babyhead]

Yeah. That thread was the inspriation for the idea of stuffing the Forssell JT-16 mic amp into the Fabio board. I figured this thread would be a better place to talk about it, though. It seems like it just plugs right in to the Reliquia. It also ups to 24v. which can be done on the 312PSU board. So...I'm still unclear about the mystery R1 R2 R10 R11 and if that is the cool power transformer. I know have just enough knowledge to do something stupid, so I'm leaning on you guys! :grin:

As for the GAIN header, I should mount my resistors on the switch...duh.

Thanks!
:guinness:

 

[fum]

My API lunchbox runs at 16V.

ju

 

[Bauman]

That thread was the inspriation for the idea of stuffing the Forssell JT-16 mic amp into the Fabio board. I figured this thread would be a better place to talk about it, though. It seems like it just plugs right in to the Reliquia. It also ups to 24v. which can be done on the 312PSU board.

I've stuffed one of my boards just like this. The other 2 Forssell 992 I'll use with CMMI10b and CMMI5C, to test.


So...I'm still unclear about the mystery R1 R2 R10 R11 and if that is the cool power transformer. I know have just enough knowledge to do something stupid, so I'm leaning on you guys!


You can use a 22R5W for R1 and R2 if C1 and C2 is 3300uF/35V.
R11 can be 1k.
R10 I dunno. This is to prevent more that 40V across the LM317 (48V - 5V)... necessary?
On the prototype I got 5V from the 20V amp supply...

The transformer can be 24+24VAC with 20VA for 2 channels or 35VA for 4, more than the micpres need...

:guinness:
Fabio

 

[daArry]

w00, just got these fellaz in today!

api-a-commeth! :thumb:

 

[Greg]

deArry:

I got six of those babies last week. :grin:

Too bad I sent 4 off them off to other members. Now I only have 2.

 

[daArry]

eheh nice greg, you've had good last cpl weeks for iron then eh

oi just noticed, we playing match the post count ere!? :green:

 

[Greg]

yup, I had all six Profiles and the 4 Sowter's on my bench and caught myself just staring at them for 10 minutes...

I've never had that much iron in my possession at one time... EVER !

 

[babyhead]

It is getting so close. I am about to order all of the parts for these badboys.

The transformer can be 24+24VAC with 20VA for 2 channels or 35VA for 4, more than the micpres need...

Will it fry anything if it were 27+27VAC 200VA? Can it go as low as 22+22?

I've stuffed one of my boards just like this. The other 2 Forssell 992 I'll use with CMMI10b and CMMI5C, to test.

I will be using a Jensen JT-11SSP-6M 150:600

http://www.jensentransformers.com/datashts/11ssp6m.pdf

The only dampening network I have found for this trafo is a 600R across the secondary. Is this cool in this application?

Will phantom hurt this trafo?

This is going to ROCK! Thanks Fabio et al.

 

[Bauman]

Will it fry anything if it were 27+27VAC 200VA? Can it go as low as 22+22?

Nope. Just what out the voltage rating of the filter can. Go 35V and you are kinda safe. To be really safe go 50V.

200VA!!! Is too much, even for 8 channels, but it works.

I will be using a Jensen JT-11SSP-6M 150:600

Pls let us know if it works ok.

:guinness:
Fabio

 

[Bauman]

The first guy to finish one, with the 2.5.2.0BC opamp on it, Dan Ovie from Argentina, my neighbour!

Jensen JT110k and JT-123ALCF as output...

:guinness: :guinness:
Fabio

 

[rafafredd]

looks nice!

 

[Greg]

Looks good !!!

It looks like the gain switch is missing though... might be hard to use with that missing :wink:

 

[jeff8houses]

Does anyone have a USA partlist going for this? Even if partial? I have a few of the board on their way and am trying to get the my stuff going, but this is my first project and am pretty unsure of myself.

While I certainly don't mind spending the time looking through and researching stuff, I just want to make sure I'm buying the right stuff. Just so many options!

I'll be happy to share my list once I get it further along. Right now all I have is everything layed out in Excel with a whole lotta blank cells where the part numbers are supposed to go. Digikey or Mouser as the main places would be sweet! I'll post as I get a little more info. Thanks!

-=Jeff Merkel=-
[email protected]

 

[Bauman]

Yea Jeff,

Both Paul M. and Greg (at least) are working hard on a list using US suppliers partnumbers.
I´ll try to append this info on my list asap.

cheers!
Fabio

 

[jeff8houses]

Thanks Fabio,

You absolutely rock! You are so fast and so helpful. I've been lurking here for many months and all you guys rule! Thanks.

-=Jeff Merkel=-
[email protected]

 

[Greg]

I'm definitely working on a US parts list (primarily Digikey and Mouser), but some parts will definitely have to be ordered elsewhere. I'm going to wait to post it until I'm confident it's correct. The last thing I want to do it spec out some parts that turn out to be wrong and cause someone to lose money on wasted parts.

More details:
My power supply will be external, so my parts list might be a little bit more expensive because it will need another small chassis and a couple additional 5 pin XLRs (+15,-15,COM,+48,+5). Keep in mind this can power more than a pair of 312s, so if you want another pair a PSU will be done. As for the 312, I'm planning to have Jensen I/P and Profile 4804 O/P with mic input, line input, and high impedence input. At the moment, I have no plans for a VU. I will also have part numbers to populate Fabio's 2520 discrete opamps. The PSU and 312 part numbers are almost done, but I have not started the 2520.

I estimate the cost for the PSU to be $100 (including enclosure), and the cost of a pair of 312s (including enclosure) to be about $350-$400. Any type of panel graphics/engraving additional.

Basically, I'm shooting to have 4 channels of API 312s and PSU with all panel engraving for less than $1000.