My little prototype mic preamp I'm working on...

I'm working an all discrete mic preamp that I plan to develop into a project Kit.

Here are some pics of my adventures.

Prototype #001 and #002. Number 001 above is just the line driver output stage. Number 002, I added the mic preamp input stage, plus the line driver output stage. Also rearranged components for prototype PCB#002. This is the 7th iteration of my PCB design layout.


Closeup.


Wired and ready. The piggytail potentiometer is only there temporarily. I'll replace it with a resistor ladder/selector switch to control gain. You can also see the phantom power switch, and -20dB pad switch. I didn't cut the wires of the Sowter transformers because I may use it for other prototyping and don't want to cut it short.


I've tested it with my cheap MXL mic, applied phantom power, and it works... sounds very nice too At present it's powered by 40VDC (because that's as high as my bench PSU can go... but this will be eventually powered with a single 48VDC PSU.

Whoa. :shock:

Looks cool. is this a Neve type circuit?

Nice project!

[quote author="bluebird"]Whoa. :shock:

Looks cool. is this a Neve type circuit?[/quote]

It's not a Neve clone but is Neve-inspired

I did use the same Sowter equivalent input and output transformers used by Neve, and TO-3 transistors for that "Neve look". Actually, a tried it with TO-220 and it works just fine with that too. But I like the look of the TO-3.

I guess it´s a neve input stage (with plain lytics instead of tantalums) and that yamaha output stage you posted some weeks ago. Looks like a nice combination...

Hoe does the lytics compares to the tantalums?

Panasonics have electrolytics that are designated "Tantalum subsitute" on the digikey website. I like it. It's about the same price more or less as the FC series.

What is the series?

Any schematics yet? I'd be interested to see what's happening there. Are you using the gapped transformer?

[quote author="rafafredd"]What is the series?[/quote]

Example: Type P823-ND in digikey.

Series KA
Features Possible Tantalum Substitute

I'm using this one.. Sowter 8751

http://groupdiy.com/detail.aspx?ID=303