building your own mic preamp and a/d converter

M

marc

Guest
I just bought a creative nomad jukebox3 from ebay:
http://www.nomadworld.com/products/Jukebox3/
Bought it to do some field recording, sounds, concerts.

Ideally I'd like something like this:
http://www.sounddevices.com/products/302master.htm
I can't afford it though.

I was wondering if there are any do it yourself plans I can use to make my
own mic preamp and a/d converter. I would like to have professional quality
and it has to
be portable. What parts are recommended? How difficult is this to build
and how much would it cost?

I'd also like to have a meter for understanding the levels going out of/into
a
device so I can correctly set the input levels on the next stage, in my
case,
the NJB3 [which has input metering].
Any do it yourself plans for this?

Btw, I also own earthworks m30bx battery operated microphone:
(http://earthworksaudio.com/m30bx.html)
which I intend to use for the recordings; I was wondering if anyone knows
how to convert it
into a directional boom mic? Any advice on how to do this?

Thanks,
Marc
 
On Sun, 20 Mar 2005 14:18:48 -0500, in sci.electronics.design "marc"
<marc75D@nospam.net> wrote:

I just bought a creative nomad jukebox3 from ebay:
http://www.nomadworld.com/products/Jukebox3/
Bought it to do some field recording, sounds, concerts.

Ideally I'd like something like this:
http://www.sounddevices.com/products/302master.htm
I can't afford it though.

I was wondering if there are any do it yourself plans I can use to make my
own mic preamp and a/d converter. I would like to have professional quality
and it has to
be portable. What parts are recommended? How difficult is this to build
and how much would it cost?

I'd also like to have a meter for understanding the levels going out of/into
a
device so I can correctly set the input levels on the next stage, in my
case,
the NJB3 [which has input metering].
Any do it yourself plans for this?

Btw, I also own earthworks m30bx battery operated microphone:
(http://earthworksaudio.com/m30bx.html)
which I intend to use for the recordings; I was wondering if anyone knows
how to convert it
into a directional boom mic? Any advice on how to do this?

Thanks,
Marc

Bitof a ramble ahead.....
Click to expand...

Making a reasonable micamp isnt too difficult, INA217 from TI for
example. Dont bother with NE5534/2's these days for mic amps, ok for
the rest
Its all the other bitz that go around it, like monitoring, LF cuts etc
I think the 302 is nice, I havent played with one, but they seem to
squeeze a lot of functions out of 3AA cells. but condoms come in packs
of 3, not AA cells, what do you do with the spare one?

Getting the power side organised and efficient could be a problem.

First of all, what are your minimum requirements, there is a lot of
stuff on the 302 that you wont need (T powered microphones???) and an
MS matrix, unless you are using a mkh816? mic
If you are using 24bit, you could get away without limiters, if you
are careful.
You wont need +22dB out into 600 ohm, thats boring specmanship these
days.
You may want to beef up a good heaphone driver, I'm just pissed off
with the one I've got on my XL1s
Nomad leave so much out of the spec sheet, its difficult to work out
what the nomad could do, that you could leave out of the mixer without
playing with the toy first.

So start of with a basic stereo ina217 with gain switches, followed
with an LF cut, followed by a good dual gang stereo pot. Then for the
monitoring, have an A/B switch with gain makeup so you can matchthe
levels from the micamp to that of the nomad. Led drivers.. LM3915/6
use the PPM circuit (in dot mode to save power) fom the app note.

And for the power supply, ask Genome......




martin


Opinions are like assholes -- everyone has one
 
"martin griffith" <martingriffithX@Xyahoo.co.uk> wrote in message
news:e0tr31p38smve00nna7nkjkt50n003csre@4ax.com...
On Sun, 20 Mar 2005 14:18:48 -0500, in sci.electronics.design "marc"
marc75D@nospam.net> wrote:

I just bought a creative nomad jukebox3 from ebay:
http://www.nomadworld.com/products/Jukebox3/
Bought it to do some field recording, sounds, concerts.

Ideally I'd like something like this:
http://www.sounddevices.com/products/302master.htm
I can't afford it though.

I was wondering if there are any do it yourself plans I can use to make my
own mic preamp and a/d converter. I would like to have professional
quality
and it has to
be portable. What parts are recommended? How difficult is this to build
and how much would it cost?

I'd also like to have a meter for understanding the levels going out
of/into
a
device so I can correctly set the input levels on the next stage, in my
case,
the NJB3 [which has input metering].
Any do it yourself plans for this?

Btw, I also own earthworks m30bx battery operated microphone:
(http://earthworksaudio.com/m30bx.html)
which I intend to use for the recordings; I was wondering if anyone knows
how to convert it
into a directional boom mic? Any advice on how to do this?

Thanks,
Marc

Bitof a ramble ahead.....

Making a reasonable micamp isnt too difficult, INA217 from TI for
example. Dont bother with NE5534/2's these days for mic amps, ok for
the rest
Its all the other bitz that go around it, like monitoring, LF cuts etc
I think the 302 is nice, I havent played with one, but they seem to
squeeze a lot of functions out of 3AA cells. but condoms come in packs
of 3, not AA cells, what do you do with the spare one?

Getting the power side organised and efficient could be a problem.

First of all, what are your minimum requirements, there is a lot of
stuff on the 302 that you wont need (T powered microphones???) and an
MS matrix, unless you are using a mkh816? mic
If you are using 24bit, you could get away without limiters, if you
are careful.
You wont need +22dB out into 600 ohm, thats boring specmanship these
days.
You may want to beef up a good heaphone driver, I'm just pissed off
with the one I've got on my XL1s
Nomad leave so much out of the spec sheet, its difficult to work out
what the nomad could do, that you could leave out of the mixer without
playing with the toy first.
Click to expand...

Tom's Hardware has a thorough review of the nomad 3 with detailed specs:
http://www6.tomshardware.com/mobile/20020419/

So start of with a basic stereo ina217 with gain switches, followed
with an LF cut, followed by a good dual gang stereo pot. Then for the
monitoring, have an A/B switch with gain makeup so you can matchthe
levels from the micamp to that of the nomad. Led drivers.. LM3915/6
use the PPM circuit (in dot mode to save power) fom the app note.

And for the power supply, ask Genome......
Click to expand...

Here's a link I found on a diy portable mic preamp:
http://www.geocities.com/ferocious_1999/md/micpreamp2.html#board

http://www.fivefish.net/diy/

marc
martin


Opinions are like assholes -- everyone has one
Click to expand...
 
I read in sci.electronics.design that martin griffith
<martingriffithX@Xyahoo.co.uk> wrote (in <e0tr31p38smve00nna7nkjkt50n003
csre@4ax.com>) about 'building your own mic preamp and a/d converter',
on Sun, 20 Mar 2005:

And for the power supply, ask Genome......
Click to expand...
I would recommend a linear power supply, not a switcher. This is a low-
power application, and, while it's possible to keep switcher noise out
of a mixer, it isn't easy.

If it's not functionally inconvenient, an AC output wall-wart is the way
to go. Using on-board half-wave rectification, you can easily get + and
- rails, while retaining a simple 2-wire connection from the wart.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
doesn't the nomad have built in a/ds?

there are lots of mic mixers w/ preamps to be had.

Mark
 
Yes it has a decent a/d converter. But you can always get better ones.
It records up to 16bit/48kHz. In WAV format, you have a choice of sampling
frequency: 48kHz, 44.1kHz or 32kHz in 16 bits.
With a quality mic preamp you can get some excellent recording in
16bit/48kHz.
And the recorder only goes for $150 on ebay. It's an inexpensive solution
for quality portable field recording.

"Mark" <makolber@yahoo.com> wrote in message
news:1111416297.521763.98710@l41g2000cwc.googlegroups.com...
doesn't the nomad have built in a/ds?

there are lots of mic mixers w/ preamps to be had.

Mark
Click to expand...
 
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