API 312 Thread!

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
thanks PRR.

Chrissugar.
what to do with the centertap, simply joining.
I'm gonna use the LL1636 in the 1:10 configuration (100ohm/10K) in the 312.
What do you think ?, suggestions?
 
I used the 1636 at 1:10. Seams to work fine, but have not really put it to serious work yet. I do have to admit that I?m a newbie and this was a fairly arbitrary choice on my part, much of the group was using 1:5 so I thought I might learn more by doing the wrong thing first. Haven?t noticed any problems (some noise issues, but I don't think they are related). Next time around I may try 1:5 or even switch them just for comparison, but that is months away.
 
Hi Andre

Look at the pdf:
http://www.lundahl.se/pdfs/datash/1636.pdf
At the last page you do it like configuration C on the right side and do not use the central tap. You do not need it.
Connect the primary and ground to the mic and if you need phantom power use the classic pair of 6.8k resistors but keep in mind that this is an amorphous core transformer and it do not like DC. The solution to minimize the DC that flows through the primary is to have the two 6.8k resistors of very close value. Buy a pair of precission, 0.1% rezistors or select from a bunch of 1% ones.

chrissugar

P.S. DO NOT FORGET THAT THE VIEW IN THE DATASHEET IS FROM PIN SIDE!
 
Chrissugar, I studied the PDF with all the possible connections.
So it is 1:10., right ?
But I'm hungry to learn, so can you explain why not to use the
connection as on C -Left ?

thanks.
 
Chrissugar, I studied the PDF with all the possible connections.
So it is 1:10., right ?
But I'm hungry to learn, so can you explain why not to use the
connection as on C -Left ?




Can someone check that for me please?
I want to finish my 312 and am still in doubt.

On the Lundahl page , you see all possible connections.
In the 1:10 configuration (fig. C) you have on the right , the one with the centertap , and on the left the one without.
Why should I use the configuration on the right as opposed to the one on the Left., Or doesn't it really matter ?

thanks
 
Sorry Andre for the late response.

My 12 channels of API type preamps are wired this way and they work wonderfull for more than 10 month. I used these preamps on some major projects [ MTV Music Awards winner band last year for my country, other bands and some film sound recording] and people were amazed by the sound.
At least you can be sure that it will work good as long as it works here. I forget to say that this is only API topology but all the components are diferent , jfet based discrete opamp, Lundahl in and out transformer.

chrissugar
 
Check this out...I bought these with the intention of putting them into Fabio's 312 kit:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=3832175223&ssPageName=STRK:MEWN:IT

I need to verify the ratios and phase...any ideas?

Could it be like a 2623?

Was this a score?

-Mark
 
Looks interesting Mark!
I didn't check the model number but you can find the windings measuring the DC resistance. There're 4 windings so you just need to group the wires in pairs, look for low resistance. Use one pair for input and put other 2 in series to output.
I think you'll need a scopt to check for correct phase... or maybe someone here got some trick to do this other way...

cheers!
Fabio
 
Hi,

Just to let you know that the last files for API312 boards, version3, are in here:

http://www.thediypill.phx.com.br/forumfiles/

under R312* names you got the partlist, the schematics and the board (component side and ready-to-transfer solder side).

I´ll post the PSU data to use with it soon...

ENJOY!

cheers!
Fabio
 
:grin:

This is going to be a lot of fun!

http://www.thediypill.phx.com.br/r312_v3.htm

Warm up the soldering iron!!!

cheers!
Fabio
 
alright!!!

Fabio, which on one of those 2520 is the real A*P*1 version? The first one is the Melcor, I'm not sure about the 2nd and 3rd.
 
There are 2 original layouts: the PP*2*5*2*0 is one Peter P. sent me on the last minute. The other 2 are also a work from Pete, but I did the component silk according to the schemo we have. I did 2 versions, the 2*5*2*0 is the ´real´one, with the original componets footprint (2Ns, TIS transistors) facing down and with long pins. The 2*5*2*2*0BC is a modified one with BCs/BDs transistors, facing up, and short pins...

btw many thanks to Mikkel MCS for the use of his gerberlizer! program :)

My goal with this work is to spread them all over the world so we can collect technical and musical impressions, compare to originals and so on.
Fun fun fun!

cheers!
Fabio
 
[quote author="Bauman"]There are 2 original layouts: the PP*2*5*2*0 is one Peter P. sent me on the last minute. The other 2 are also a work from Pete, but I did the component silk according to the schemo we have...[/quote]Cool! :thumb:
Got schematics?
 
Ruel, I choose to leave it online, here:

http://www.thediypill.phx.com.br/forumfiles/

cheers!
Fabio
 
Hi,

I've uploaded the opamps info today, link on the post above.
Let me know if something is missing.

cheers!
Fabio
 
HEY!

Here are some pics of my API312 babies :grin:


r312_1_peq.jpg

1 channel with CM75101APC and Profile 4804, all panel switches still to arive...

The big pics:

http://www.thediypill.phx.com.br/forumfiles/r312_1.jpg

http://www.thediypill.phx.com.br/forumfiles/r312_4.jpg

gonna pay visit to metalworks man on Sat.

cheers!
Fabio
 
Looks fantastic!!! :razz:

How did you mount the opamp? DId you solder it in place in some way or did you have any type of sockets?

Thanks

Robert
 

Latest posts

Back
Top