I know I asked this a while back, but what are you thinking of doing for the power supply Kevin? You thinking of tailoring something for this specific build, or do we just come up with our own solution (ie, o22)?

Edited March 28, 201214 yr by Horio

Have not even thought about the power supply yet. In the simplest version the

smallest power one tripple works great. If you go with the outboard amplifier modules

then you need something that does +/-20, then you can regulate that down to +/-15 with

simple 3 terminal regulators, and +12 to drive the relays.

Do you have a rough idea what the current draw is for the various voltages? Seems like the 12V line is going to be very small, but the 5V line might see some current with the Arduino. I have no idea what the +/-20V and +/-15V might see though.

Edited March 29, 201214 yr by Horio

Fully loaded, on the 20v lines about 500ma

On the 15v lines about 250 ma

12v line peaks of 30 ma

5v line I gotta look up

How is the progress coming along? Is the testing going well?

Kerry still messing with the multi amp

I'm waiting on hopefully final preamp boards

Edited April 27, 201214 yr by kevin gilmore

I was out on vacation and came back to a ton of work. I'll have some time to finish playing with the servos next week and hopefully we'll be good.

hi kevin, is there a schematic somewhere?

Sure there is a schematic. Its in my head somewhere.

There will be an official schematic at some point.

There is a bunch of different ways to build it including

single ended only, and balanced/single ended

The on board buffer which you don't have to use is

an lme49710 driving an lme49600 closed loop with

a tl071 as the servo, optionally the lt1150.

The onboard single ended to balanced is an opa1632

with a tl071 servo. you don't have to use that either.

multiamp works for both. Single ended there are

x1 buffer opamps.

Clear as mud right?

There are a couple of people on amb's forum that think i have

sold out to ic's... But they should hear the thing. Just about

impossible to tell between the chips and the multiamp.

Edited May 23, 201214 yr by kevin gilmore

There are a couple of people on amb's forum that think i have

sold out to ic's... But they should hear the thing. Just about

impossible to tell between the chips and the multiamp.

Blasphemy!!!!!!!!

They've been making good progress on the display front for the raspberry pi:

Kerry,

How is the testing of the multi-amp boards going? Just curious.

I just finished reading through this thread and want to build one of these. I will definitely be on the lookout for the boards when they become available. Thank you KG.

Anything new going down, on the KGITSOJC front?

waiting on kerry for any final changes to the multiamp board.

preamp board is finished.

So which processor did you guys decide on using?

I've been out-of-pocket a bit on a new consulting gig and traveling as well. Will get to the multiamp next week. Just playing with the servos at this point. I've built it with the THAT bjt's but I'll try the jfets just to make sure.

Sweet! Looking forward to hearing your findings Kerry.

Kerry, have you had a chance to play around with the multiamp boards at all or does the new job still have you swamped?

Has there been any progress on this? After the T2, I'm hoping this will be my next big project.

No time for a while but I do want this done

http://gilmore.chem.northwestern.edu/kgitsoch.pdf

 

An even sweeter way to do unbalanced/balanced to balanced.

Indeed. Nice.

here is another one i like, buildable with currently available parts

http://gilmore.chem.northwestern.edu/fcnf.pdf

 

input can handle 10 volts peak to peak, its another operational transconductance amp.

input can also handle 2 volts of common mode or differential mode offset with 0 volts

dc output, something just about no other circuit can do. No feedback, and distortion

approaching .01%.  Flat to about 500khz.

 

Needs +/-45 volt power supplies, and plenty of heatsinks.

Otherwise cheap to build.  Add a unity gain output buffer (2 of them) and set the

gain with 2 resistors (or a 3 position switch) and a constant impedance attenuator

and have something very slick.

No feedback, and distortion

approaching .01%.  Flat to about 500khz.

 

at what load?