I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

Best wishes,

Ignace.

Ignace Dhont wrote:
I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

OK... I'll recommend the Terrasonde Audio Toolbox.

Couple-o-thoughts...

if you are just doing comparative type studies, then you really may want
to measure Leq, which is a time averaged, often weighted sound pressure
level, and the Audio Toolbox can do that, for up to 24 hours - overkill
for you. I wish it had an output so I could see spikes, but...

if you are trying to meet a specific mark, then you probably want a
meter capable of making Noise Criteria measurements... the Audio Toolbox
does that too, but it doesn't sound like what you are describing.

I believe, and I don't have the manual handy, that the Audio Toolbox
goes down to 35 dB-SPL, which is pretty quiet. I think a low limit of 50
db-SPL would be unworkable for recording, but if you can find a meter
that goes down to 40 dB-SPL you might be OK.

There is an excellent web site that describes NC (Noise Criteria)
curves, and gives lots of examples. Sadly, I can't put my finger on it
right now.

Bill

Ignace Dhont wrote:
I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

You're going to have to rent a B&K, a Larson Davis, or something of that
grade for the weekend. You won't find that low a noise floor on any of
the cheapies.

You MIGHT find some older GenRads for used, in your price range. Some of
those go down accurately to 40 dB SPL.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

The TerraSonde ATB plus will read SPL starting at 30db and the RTA
functions
allow for a starting point of 25db

I have the standard grade mic that comes with it but you can upgrade
to a more accurate
external mic if you desire.

I use the ATB plus to do pa installs and studio troubleshooting and
have been very happy with the investment.

chris
wavetrap




(Scott Dorsey) wrote in message ...
Ignace Dhont wrote:
I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

You're going to have to rent a B&K, a Larson Davis, or something of that
grade for the weekend. You won't find that low a noise floor on any of
the cheapies.

You MIGHT find some older GenRads for used, in your price range. Some of
those go down accurately to 40 dB SPL.
--scott

Thanks for the info, now I know that I can stop searching and will
just have to rent one.

Well the Audio Toolbox has a lot of extra tools and looks interesting
but at $1850 it's way over what I intend (or can afford) to spend.

Best wishes,

Ignace

(Ignace Dhont) wrote in message . com...
I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

Mic capules and preamps having the low self noise necessary to make
such quiet measurements aren't easy to make nor cheap to build. I've
just been through this exercise. B&K / DPA, Schoeps, Sennheiser,
Josephson are the usual suspects for capsules with the performance
capabilities needed. I had been using mics of the Gold-Line MK-10C,
Audix TR-40, Sabine SQ-1001, Behringer ECM-4000 class and they had
sufficient self noise to preclude making measurements below NC 28 dB
(NC=Noise Criterion). I now have CMC62 (MK2 capsule) and see the self
noise floor below NC 10 dB, when used with a quiet mic preamp.

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com

although you probably want portability, couldn't you pull this off
with a DAW and a little doing? (equipment you possibly have, or have
access to)



cheers,
chris deckard




(Ignace Dhont) wrote in message . com...
I would like to buy a Decibel meter to determine the ambient noise
floor of the rooms I'm recording in. So, it has to go as low as 20-30
dB (let's be optimistic..). I've noticed that the few dB-meters that I
know of only go as low as 40-50 dB.
It doesn't have to be state of the art (well I preferably want to
spent no more than $150 - $250 on it..) but it shouldn't be crap
either. I could live with a deviation of about 2-3 dB.

I'd be grateful for any recommendations!

Best wishes,

Ignace.

Now that might be a good idea! Let's think how I can pull this off
with my PC, and still get a reliable reading.

Indeed I would need an extremely low noise mic & pre-amp. I am about
to order a Millenia HB-3 to upgrade my main tracking pre-amp. That one
might be quiet enough?

Regards,

Ignace

(Ignace Dhont) wrote in message . com...
Now that might be a good idea! Let's think how I can pull this off
with my PC, and still get a reliable reading.

Indeed I would need an extremely low noise mic & pre-amp. I am about
to order a Millenia HB-3 to upgrade my main tracking pre-amp. That one
might be quiet enough?

That preamp is quiet enough. You need to look at your A/D converter
too. Check the S/N ratio spec. Check out the following omni mics:

CMC62 Schoeps 10 dBA, 20 dB CCIR468-2
MKH20 Sennheiser 10 dBA, 20 dB CCIR468-2
4006 B&K / DPA 15 dBA, 27 dB CCIR468-2
606-KA11N Josephson 15 dBA, ?? dB CCIR468-2

Also look at:

http://www.trueaudio.com/rta_abt1.htm (inexpensive)

http://www.siasoft.com/products/smaart_live.shtml (comprehensive)

bobs

Bob Smith
BS Studios
we organize chaos
http://www.bsstudios.com