Soundeasy Jig...........your thoughts please.

[Gavinator68]

Hello All,

I have been wanting to build a Jig for use with Soundeasy that would have everything I needed in one box. This would include the Neil/Wallin Preamp, a TDA2040 Amplifier, the PSU for both, and the appropriate components to complete all driver measuring. Something similar to this:




First, is there a detriment to the measurement results by going this way and if so how?

Second, I need a little guidance for finalizing the design. The Neil/Wallin Preamp used a 9v battery for power and I would prefer the jig to feed the preamp the necessary power instead. I would also like the TDA2040 Amplifier to also get its power from the same source if possible. I am ok with the PSU only supplying 9vdc to the amp if I can can intelligently only use one transformer and PSU to feed both. Does that make any sense?

These are the schematics for the Amp and Mic Preamp:





And finally, the schematic of the the original jig viewed in the first pic up top:



Thank you for your thoughts and consideration.

Cheers

[wintermute]

The main concern I would have is whether or not you would have noise problems with the mic pre running off the powersupply rather than from battery. At a minimum I'd suggest a a regulator circuit for the mic pre. You could pick up off the -ve rail for the amp.

You may also have noise pickup problems in the mic pre from emi from the transformer. My walin mic preamp is in a diecast aluminium case and runs off battery and I don't seem to have any problems, but I've never tried it out of the box near a transformer.

Tony.

[Gavinator68]

The gentleman that built the one I am trying to emulate indicates that he has no problems with EMI issues.......

Hmmmmm

[Gavinator68]

Winter,

Would you have any insight into the PSU issue I speak of?

Cheers

[wintermute]

Looking at the schematic for the amp it is set up to use +ve -ve and zero volts rails. you will not be able to run it off a single 9V supply.

What I would suggest is that you make a suitable supply for the amp (I don't know what voltage it should use, maybe +- 15V? and to have a separate reg circuit running off the positive rail which drops the voltage to 9V for the mic pre. That is if you only want to use a single transformer, for both the amp and the mic pre.

You will need a dual secondary or centre tapped transformer to get the +ve and -ve rails for the amplifier circuit.

regards,

Tony.