Aikido based mic-preamp (again)

[nickt]

Hello,

First PCB and first design. I've caught the DIY bug and so here's some output for comments/criticisms/sharing/etc.

Basically I picked the aikido because it's simple and others have claimed good results. I also want something that could fit two preamps in a 1U case. The REDD47 or V72 came to mind but as this is a first effort I'm really just playing with the software.

First version of the schemo is below. The PS and standard input circuits (pad, phase, 48V) are TODO as is the output trannie. (any suggestions what I should use? The aikido seems to have reasonable drive ability so maybe a 2:1 rather than a high range one? dunno...)

Preliminary board below. The idea is to mount it sideways in the 1U case. I haven't got any mounting holes placed as yet and all the per-channel TODO stuff is missing from the trannie end of the board.

Any thoughts most welcome :!:

cheers
Nick

BTW the software is Diptrace 30 day eval :wink:

 

[zebra50]

I've just been wiring an Akido point to point for a mic preamp but haven't got round to finishing it off. I have a sowter 8940 3:1 5K:600 left over from another project that I was going to try as output tranny.

What are you doing about a level/volume control/attenuator ?

Also, I have a swtchable output cap, so I can dial in a HPF.

Will let you know how it works / sounds.

 

[nickt]

[quote author="zebra50"]What are you doing about a level/volume control/attenuator ?[/quote]
The idea of the two preamps in the one box was so they could be cascaded if more gain was necessary (same as the fixed gain V72). Current idea is for a stepped attenuator between stages on cascade - but it's early days so not really sure what I'll end up doing. First cut is likely to be just three switches per channel (phase, 48V and pad). Simple as possible.

Just thinking out loud but doubling the first SRPP stage could solve the gain issue but would really need a feedback network to calm it down. Hmm... maybe for version #2 :grin:

Also, I have a swtchable output cap, so I can dial in a HPF.

Will let you know how it works / sounds.

Cool - haven't thought about a HPF as yet.