SSlmixed.com Forum

Tech discussion => 4K,6K,8K Series => Topic started by: gertius on February 21, 2022, 07:40:55 PM

Title: Racking 82e149 as Line Amp
Post by: gertius on February 21, 2022, 07:40:55 PM
Hello,
I plan to rack a pair of 82e149 cards as Line amps. I have successfully racked an SSL EQ card before so I have some experience.

So far I gathered a symmetric +-18V power supply, one card and a chassis. The other card and edge connectors are in the mail.

I have looked at the schematic and so far it seems pretty straightforward. I plan to connect power, line input, output, and the line trim pot.
I would just use unbalanced output.
Also a star ground for all ground lines, audio and power.

What I'm not totally clear ist the input selector switch, before pin 23, or looking at the FET RC2.
I guess normally you would apply +5V to it's gate to select the line source.
Could I just short it's drain and source and be done with it? I do not plan to use the mic pres (one board isn't even fitted with the pre components).

I plan to hardwire the phase button as I do not need it's functionality.

Also, my power supply is 2*300mA. Is that enough for 2 cards?

Is there anything else I might be missing, or some tips from you guys?

Thanks and best,
Christian


Title: Re: Racking 82e149 as Line Amp
Post by: amillar on February 21, 2022, 10:09:03 PM
Hi,
If you're not going to switch it then I would take the FET out and wire across it! It will sound much better...
Cheers,
Andy
Title: Re: Racking 82e149 as Line Amp
Post by: gertius on February 22, 2022, 06:24:54 PM
Thanks for your valuable input, Andy, as always!
I will take out the FET completely then.
Cheers!
Title: Re: Racking 82e149 as Line Amp
Post by: gertius on March 18, 2022, 12:41:24 PM
The project is now finished. Not the prettiest build, but it works and sounds great!
I decided to leave the FET inside anyway, to be most close to the sound in the console.
I read in the console service manual that you can simply apply 18V to the gate to switch it (I thought before I had to create a +5V supply).

Attaching a picture so you can poke some fun at my untidy build  ;D

Cheers!