Schematic / Pin out for Quad 8 LA24's

[JustinS]

Hi all,

Just scored 2 LA24 line amps :grin:, and they're on their way to me now... The aim is to get 2 nice Quad 8 pre's out of them, so does anyone have schematics / pin outs for these??

Thanks in advance, Justin.

 

[wilebee]

which amp style 10 transistors of am4's ? I havent heard of la24's
you might try Quad Eight .net Wil

 

[JustinS]

Hey Wil,

It's AM-4 based with a couple of extra transistors, some bits and pieces and input / output transformers (the input transformer kinda looks like a UTC)... I'm pretty excited, I managed to swap my Orban spring reverb for them and a bunch of CN-28 summing amps with 2 AM4's in each! Yeah, I was thinking of checking on the Quad Eight web site, but the board there doesn't seem to get a lot of traffic... I was hoping someone here might have an idea... I'll try and post some pictures shortly.

Justin

 

[Helsing]

Should be able figure out the +/-28vdc by the protection diode directions. This should be just like an API312/325/550a/525...

Common/Ground is usually pretty easy to figure out if there is some sort of ground plane.

You can trace the signal path from the output transformer to card edge for outputs.

Post some pics and we'll have a race to see who can figure it out first!

Helsing

 

[wilebee]

is it a 15 pin card edge style connector? if so I have one for the ca37 that maybe close. I noticed that several of the different revision dual amp cards have the same pinout so maybe let me know. If not try Ken Hersh at orphanaudio.com

 

[JustinS]

Hi Guys,

Here are the pics, that does look like 15 pins there Wil...

Justin

 

[wilebee]

Hey Justin it does look like it is similar in pinout to the ca227 by comparison. It should be really easy to figure out the pinout take a look at nw soundman's web site I think he has the pinout for the ca227 there and compare the connections Wil

Wilebee

 

[wilebee]

http://www.home.earthlink.net/~nwsoundman/id1.html
I think this should help Its not the same card but compare the pinouts I think from what I can see they are the same. You may want to varify that the am4 can can handle +/- 28vdc before you fire it up. The am4's are getting to be like hens teeth Wil

Wilebee

 

[JustinS]

Hey Wil,

Thanks for that link... Interestingly enough I found a schematic on my hard disc from PeterC's site that's labelled as being for a mic pre based on an AM-4, here's a link to it on his site:

http://1176neve.tripod.com/id20.html

It's got +/- 28v going into it... but there's no amp on that schem, it's all discrete. So is that what the insides of an AM-4 looks like?

Justin.