I wanted to run a freq analyser over the output of my SPL meter.
Straight out into my soundcard gives about -16dBFS level without
pinning the meter on the SPL unit. Should I put it into a pre? Putting
it into the Hi-Z DI (much easier cable-wise) will screw with the EQ,
right? Strangely the DI option sounds much more natural when I talk
into it than a normalized direct in.

wrote:
I wanted to run a freq analyser over the output of my SPL meter.
Straight out into my soundcard gives about -16dBFS level without
pinning the meter on the SPL unit.

That's a perfectly reasonable recording level. Use it as is.

Straight out into my soundcard gives about -16dBFS level

If you simply turn the SPL selector to the next lower setting the meter will
put out 10 dB more signal. Though as Mike explained, -16 dB isn't terrible.

--Ethan

wrote in message
oups.com...
I wanted to run a freq analyser over the output of my SPL meter.
Straight out into my soundcard gives about -16dBFS level without
pinning the meter on the SPL unit. Should I put it into a pre? Putting
it into the Hi-Z DI (much easier cable-wise) will screw with the EQ,
right? Strangely the DI option sounds much more natural when I talk
into it than a normalized direct in.

I don't know if I would trust the audio coming out of the radio Shack SPL
meter, especially if you want to analyze it. It's been many years since I
tried it but I had a pair of them and tried to record a band rehearsal with
them and I thought it sounded pretty bad.

Best of luck!

John L Rice

"John L Rice" wrote in message

wrote in message
oups.com...
I wanted to run a freq analyser over the output of my
SPL meter. Straight out into my soundcard gives about
-16dBFS level without pinning the meter on the SPL unit.
Should I put it into a pre? Putting it into the Hi-Z DI
(much easier cable-wise) will screw with the EQ, right? Strangely the DI
option sounds much more natural when I
talk into it than a normalized direct in.

I don't know if I would trust the audio coming out of the
radio Shack SPL meter, especially if you want to analyze
it. It's been many years since I tried it but I had a
pair of them and tried to record a band rehearsal with
them and I thought it sounded pretty bad.

"correction curves" for the RS SPLmeter are all over the web. They show the
the expected deviations from flat suggest that it should sound pretty bad.

John & Arny,

I thought it sounded pretty bad.

Yeah, they do sound pretty bad, but they're okay for analyzing low
frequencies in rooms. When I first got the ETF software I compared my Radio
Shack digital SPL meter with my AKG C451 mike and CK22 calibrated omni
capsule. Below about 800 Hz they were within 1 dB. Above a few KHz all bets
are off. Here are the graphs showing the two side by side:

www.ethanwiner.com/misc-content/etf_calib_lf.gif
www.ethanwiner.com/misc-content/etf_calib.gif

Note that the high-frequency version shows the RS meter with and without the
correction curves applied. Also note that the LF graph does NOT have these
corrections, and the RS meter is still within 1 dB of my "good" microphone.
This tells me that those correction curves are mostly BS.

--Ethan

On Mon, 8 May 2006 10:12:39 -0400, "Ethan Winer" ethanw at ethanwiner
dot com wrote:

John & Arny,

I thought it sounded pretty bad.

Yeah, they do sound pretty bad, but they're okay for analyzing low
frequencies in rooms. When I first got the ETF software I compared my Radio
Shack digital SPL meter with my AKG C451 mike and CK22 calibrated omni
capsule. Below about 800 Hz they were within 1 dB. Above a few KHz all bets
are off. Here are the graphs showing the two side by side:

www.ethanwiner.com/misc-content/etf_calib_lf.gif
www.ethanwiner.com/misc-content/etf_calib.gif

Note that the high-frequency version shows the RS meter with and without the
correction curves applied. Also note that the LF graph does NOT have these
corrections, and the RS meter is still within 1 dB of my "good" microphone.
This tells me that those correction curves are mostly BS.

--Ethan


I have a jig I use to set SPL in headphones - very useful as it is
often hard to tell what you have got. It uses the RS SPL meter. I will
use it later with my Stax phones, which I know are really flat, to
assess the flatness of the meter using white noise. I will post here;
it will be an interesting comparison with your findings.

http://81.174.169.10

d

--
Pearce Consulting
http://www.pearce.uk.com

In article , "Ethan Winer" ethanw at ethanwiner dot com wrote:
John & Arny,

I thought it sounded pretty bad.

Yeah, they do sound pretty bad, but they're okay for analyzing low
frequencies in rooms. When I first got the ETF software I compared my Radio
Shack digital SPL meter with my AKG C451 mike and CK22 calibrated omni
capsule. Below about 800 Hz they were within 1 dB. Above a few KHz all bets
are off. Here are the graphs showing the two side by side:

www.ethanwiner.com/misc-content/etf_calib_lf.gif
www.ethanwiner.com/misc-content/etf_calib.gif

Note that the high-frequency version shows the RS meter with and without the
correction curves applied. Also note that the LF graph does NOT have these
corrections, and the RS meter is still within 1 dB of my "good" microphone.
This tells me that those correction curves are mostly BS.

I find that interesting. The AKG is a cardiod. You can't take these RS units as
being that reproducable over the years., and circuit differences
will exist as far as tolerances. I was trying to work with a fellow
that had access to an aneoic chamber, and his
preliminary testing of a unit was very different from typical curves given. He was not able
to his continue testing as far as I heard. These plots above certainly look room influenced.
I would not use the RS unit to do much of anything as far as testing, however they
are just fine for relative measurments.

greg

Greg,

I find that interesting. The AKG is a cardiod.

That's why I specifically mentioned my CK22 omni capsule. :-)

You can't take these RS units as being that reproducable over the years.,
and circuit differences will exist as far as tolerances.

Absolutely agree. I assume Radio Shack buys whatever electret element
happens to be cheapest on the Asian market at any given time. I wonder how
much each one costs? 50 cents? 30 cents? So the idea that someone can
measure their own RS meter and offer up a "correction table" for others to
use seems suspect.

... aneoic chamber, and his preliminary testing of a unit was very
different from typical curves given.

The graphs I posted were measured in a room, not an anechoic chamber. So of
course the room is the largest part of what's shown.

--Ethan