The $5.00 USD mic pre

[Bill @ Irie Lab]

I posted this in a "Gear" thread but you DIY guys might like to hear of it (and hopefully build a few and report back to us).

I wrote (with grammatical editing):

"Folks,

Check this out: http://www.record-producer.com/learn.cfm?a=3062

And then this: http://www.record-producer.com/learn.cfm?a=3071

The ICs he is speaking of has the latest audiophile wiz-bang circuit topology - 'current feedback'.

Worth getting out the ol' soldering iron, everyone needs a couple extra channels of pres from time to time.

Too many irons in the fire for me right now - so to speak. But, I think I'll build a pair some time for the hand percussion station (another work in progress).

Human feedback would be cool on this should some of you try building some,

Bill"

Up for the challenge? Can modern (and ridiculously cheap) technological advancement upset the applecart and drive the money changes out of the temple?

[RodC]

$5.00 ?? OK, now lets make it usable, what do you think the total will be?

Nice rack mountable enclosure?
Some input jacks?
Some output jacks (XLR and 1/4")?
We may want a pot to adjust the gain?
Maybe a pot for the volume?
A knob would be nice.
A nice clean power supply
And one of those black things to plug it into the wall.

"ELite" options:
Power switch
-10 db pad switch and resistor
-20 db pad switch and resistor
High pass switch and Cap
Fuse holder and a fuse
Phantom power, and a switch to turn it off.
Phase reverse switch
A printed circuit board with some holes to mount it to stand offs

"ELite of ELite" options:
Balanced inputs, trannys or circuit whatever to make this thing usable more than 10 feet away from a mic.
DI input, to match the impedance of some instruments.

Now we really need 4 or 8 channels so multiply all this by 4 or 8.

I could build a nice descrete pre for $5, but to make it usable.....

[Bill @ Irie Lab]

Rod,

Yes all of those assets are what constitutes a premium pre.

Most are necessary for a marketable commercial pre.

A power supply and input/output jacks are a bare minimum so signal will flow in and out.

Still, if high performance is available in a package newbies and the impecunious can obtain and apply, isn't that an 'empowering' thing.

Thanks for getting the ball rolling,

Bill

[TooLoFi]

A knob would be nice.

yes it would!

[RodC]

Rod,

Yes all of those assets are what constitutes a premium pre.

Most are necessary for a marketable commercial pre.

A power supply and input/output jacks are a bare minimum so signal will flow in and out.

Still, if high performance is available in a package newbies and the impecunious can obtain and apply, isn't that an 'empowering' thing.

Thanks for getting the ball rolling,

Bill

Go buy a SM Pro Pr 8, you will get all these parts and prob sound better for about $90 You cant buy the parts for that.

If you dont like it, gut it and put this circuit in it.

[Bill @ Irie Lab]

I supposed I got a little bit razzed because I'd been reading about the benefits of current feedback topology in audio jourmals and application sheets and was intrigued to see it implemented in an inexpensive chip.

I knew their were more cheap channels out there than you could shake a baton at. I didn't know if any of those reading the board who are more knowledgable than myself could comment on promise of this technology.

I still think it's cool to be able to experiment with state-of-the-art concepts without needing a government grant.

[lancebug]

Go buy a SM Pro Pr 8, you will get all these parts and prob sound better for about $90 You cant buy the parts for that.

If you dont like it, gut it and put this circuit in it.

I actually think you might be onto something there. Black Lions mod on the pr8 is cheap @$275 but this could be really outta hand. I like the idea of trying some diy stuff but being a novice dont want to to spend $300+ on a kt that I will probly ruin with poor soldering technique. If I made it out at the end of the day with only 6 out of eight channels working I might not cry too hard. Even 4 would be ok. Anybody ever sawed a circuit board in half with a dremmel tool?

[Bill @ Irie Lab]

I think I will get one of those S&M proaudio boxes as I could use the husk, as has been suggested, to try some DIY; after having heard the out-of-box performance.

But, Maybe, just maybe, the pres have a use, too. There are 8 of them, so mic everything with in the studio with selected mics and common (in every sense) pres, that's a sound. Record multiple channels of B/G vocals with cheapy stage mics, there's a sound.

Could be big fun!!

Bill

[pandatone]

EDIT: nevermind.. its 3 AM, im just not trying anymore. found the stuff online.
though maybe a way to hook up a gain and output knob would be cool..


-----------------------
so, i can't look at the small picture and know how to build one.
anyone got any kind of schematic / parts ?

or is it there somewhere, and i missed it?

panda

[lancebug]

This is the funniest part:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 6432&fvi=1[/quote]

[marc]

This is the funniest part:

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 6432&fvi=1

[/quote]

Mind...being...blown. Must...avert...gaze...

[Bill @ Irie Lab]

I thought we could have some discussion on this new series of ICs.

The auction business for a handful of parts is just bizarre!

[lsn110]

I really really like the Phantom Power Supply in that pic. It would be even better if it used 9 9V Wall Warts.

"No...you can't plug your amp in...I need all those outlets for my pre."

[Bill @ Irie Lab]

BTW -

Application Notes and mic pre schematic can be found here:
http://focus.ti.com/lit/ds/symlink/ina217.pdf

[YOUR KONG]

Good gravy. $5 of components and a little labor going for 5 times as much. There is a deep, profound, hilarious truth about capitalism somewhere in here.

PS - Thanks for sharing, Bill!