Re: tascam hd-p2 + gracedesign lunatec v3 + rode nt4 stereo mic ?

dear Mike,

thank you very much for your time and your detailed reply! this is the
kind of reply i was hoping to receive to my post - pretty
straightforward!

now:

Mike Rivers wrote:

after reading a few earlier posts in this forum i decided
that i need a better preamp to use with my recorder if i want
significantly less noise and distortion.

I'm not sure that this is really going ot help you unless you get a
very specialized preamp, and perhaps choose a particularly quiet mic.
What you'll need is a preamp with a lot of gain, more than the 55-60 dB
that's the norm. If you put 75 dB of gain after a mic, you'll need a
quiet mic. And if you just amplify a low level recording, you'll
amplify the noise of the preamp and the mic (as well as some unwanted
ambient sound).

this is clear.

[...]
Depends on how quiet the Rode mic is. Rode seems to strive of low self
noise as one of their general design parameters, so you might be in
pretty good shape. Judging by the thread about a pad built in (or not,
it seems) to the unbalanced mini-plug cable that's supplied with this
mic, it might have plenty of sensitivity (volts out for a given SPL in)
from the XLR outputs, and the preamp noise when run wide open won't be
a big problem.


as far as i understand, rode nt4 stereo mic is quite a sensitive
condenser. here is a part of the specs:

Output Impedance: 200O per side
Frequency Response: 20Hz - 20kHz
Sensitivity: -38 dB re 1v/Pa ± 2 dB equivalent to 12mV/Pa where 1 Pa =
94dBSPL
Equivalent Noise: <16 dBSPL, (A-weighted per IEC268-15).
Maximum Output: +13.9 dBu @ 1% THD into 1k_
Dynamic Range: >128 dB
Maximum SPL: 143 dB @ 1% THD into 1k_
Signal/Noise Ratio: 78dB
Power Requirements: 4 mA, P48 (38V-52V) 2 mA,

as far as i understand, Lunatec v3 preamp is going to get me 60dB
maximum gain. my application for ambient sounds is to use those sounds
in their natural volume, without extra amplification. this is for my
ambient music/sound design project.

The real issue is what you intend to do with your ambient recordings.
Remember that birds and insects at night are really very quiet. If you
intend to amplify those to normal listening levels, or maybe use them
as waveform sources for a sampler or beat pattern, they're going to be
highly unrealistic anyway, and you may be able to use common noise
reduction techniques to clean them up without spending a ton of money
on a specialized input chain.

yes, i have experience with BIAS SoundSoap plug-in, which works very
well for me when i plan to clean up audio signal from noise. i need to
make it learn the pattern of the noise itself, but how would i possibly
feed the noise only to get the noise itself without the extra night
ambience? i apologise in advance for dumb questions, which were
possibly discussed before somewhere in this forum.

If you're planning to add them to a recording as sound effects, you'll
probalby want to add them at the level that they're recorded if you
just use a "normal" 60 dB mic preamp, so it's not really a worry.

not really sound effects, but i think my tracks will combine piano
music and these recordings. i would use them like a natural
instrument, without colouration.

There's nothing wroing with a Grace preamp - it's surely better than
what's in the TASCAM, and the A/D converter in the Lunatec might be
better than what's in the recorder as well (or maybe not - it's a few
year old design and they make a lot of progress fast with these
things).

here are the specs from lunatec v3:

A/D CONVERTER SECTION

DYNAMIC RANGE
44.1kHz-192kHz, 22Hz-20kHz bandwidth = 107dB
44.1kHz-192kHz, A-weighted = 110dB

THD+N:
44.1kHz-192kHz, -3dBFS, 22Hz-20kHz bandwidth = -101dB

MICROPHONE AMPLIFIER SECTION

FREQUENCY RESPONSE
@ 60dB gain -3dB = 6Hz-250kHz

THD+N
@ 20dB gain +20dBu out = 0.0011%
@ 40dB gain +20dBu out = 0.0011%
@ 60dB gain +20dBu out = 0.0046%

NOISE - REFERRED TO INPUT
@ 60dB gain 50 Ohm source = <-130dB

more at: http://www.gracedesign.com/products/V3/lunatecV3.htm

is there any other mobile dual microphone portable preamp on the
market, with A/D converter, 60dB gain and comparable specs as those of
the lunatec v3 has got that you possibly know of and could recommend?

2. my suspicion is about quieter bass frequency response when recording
through the mic. maybe i am wrong about it, i am going to make a few
more recordings in the near future to see if this is true.

There may be a low-cut filter that you have engaged. Dig through the
menus. Try running a test with sine waves of a known frequency .There
are several programs that will make your computer into a test generator
which will be fine for this.

no, i surely am aware of the low-cut filter and it's in the off state.

3. lack of remote control.

Well, the advantage of a portable recorder is that you always have it
handy so you don't need remote control. Tiny recorders like Minidisks
need remote controls because the buttons are too small and crowded for
real human beings. But of course adding the outboard preamp makes it
even less handy.

:-)


I think you're on the right track and you just need to do some
experimenting. I suppose you're in one of those places where it's
difficult to buy something, try it, and return it for a refund if it
doesn't suit your application. Here in the dot com world, I'd just ask
my dealer to lend me an NT-4 and a Grace preamp, and pay him if I
wanted to keep it. ;)

you are so right! it is very difficult to buy anything here in latvia,
and so i usually order what i need from the u.s. we have got
ultimately nothing in the local stores when it comes to mobile
recording, simply because there is no market here for this kind of
dedication. therefore, unfortunately, i cannot just go to a local shop
and just ask them to give me a preamp for a test...

andrew

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