12 May
2006
12 May
'06
9:29 a.m.
Just wondering if I am doing things right. Trying to record a 94 dB SPL
sinusoid using a B&K microphone connected into the analogue input of an
RME multiface card, I see levels at about -37 dB. This is when the
hdspmixer is set such the recording level is the most sensitive.
Is this about right? This means that I can potentially record very high
levels but I am worried about missing out the lower levels.
DS
12 May
12 May
9:58 a.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Fri, 12 May 2006 21:27:42 +1000
"D. Sen" <dsen(a)homemail.com> wrote:
...microphone connected into the analogue input of an
RME multiface card
not good practice; multiface inputs are at line level.
you need a microphone preamp between the mic and the multiface.
.pltk.
10:16 a.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
plutek wrote:
On Fri, 12 May 2006 21:27:42 +1000
"D. Sen" <dsen(a)homemail.com> wrote:
There is circuitry between the micrphone and the multiface to ensure
line-level outputs.
DS
...microphone connected into the analogue input
of an
RME multiface card
not good practice; multiface inputs are at line level.
you need a microphone preamp between the mic and the multiface.
.pltk.
11:22 a.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Fri, 12 May 2006 22:14:41 +1000
"D. Sen" <dsen(a)homemail.com> wrote:
plutek wrote:
ok... i can only question the design of that circuitry, whatever it is, because i have no
trouble getting full digital levels on my multiface when fed by any of my microphones and
preamps, from a 94dB acoustic source.
.pltk.
On Fri, 12 May 2006 21:27:42 +1000
"D. Sen" <dsen(a)homemail.com> wrote:
There is circuitry between the micrphone and the multiface to ensure
line-level outputs. ...microphone connected into the analogue input
of an
RME multiface card
not good practice; multiface inputs are at line level.
you need a microphone preamp between the mic and the multiface.
2:58 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Fri, 2006-05-12 at 21:27 +1000, D. Sen wrote:
Just wondering if I am doing things right. Trying to
record a 94 dB SPL
sinusoid using a B&K microphone connected into the analogue input of an
RME multiface card, I see levels at about -37 dB. This is when the
hdspmixer is set such the recording level is the most sensitive.
Is this about right? This means that I can potentially record very high
levels but I am worried about missing out the lower levels.
So you don't have a microphone preamp? The line inputs of your multiface
are meant for line level inputs. A microphone produces very low output
compared to line level, that is why microphone pre-amplifiers are used.
If you don't have one, you need one. Trust me. :)
--
Sampo Savolainen <v2(a)iki.fi>
4:18 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
This is what is being used between the microphone and the multiface:
http://www.bksv.com/pdf/4416B.pdf
This is providing line-level output to the multiface.
DS
Sampo Savolainen wrote:
On Fri, 2006-05-12 at 21:27 +1000, D. Sen wrote:
Just wondering if I am doing things right. Trying
to record a 94 dB SPL
sinusoid using a B&K microphone connected into the analogue input of an
RME multiface card, I see levels at about -37 dB. This is when the
hdspmixer is set such the recording level is the most sensitive.
Is this about right? This means that I can potentially record very high
levels but I am worried about missing out the lower levels.
So you don't have a microphone preamp? The line inputs of your multiface
are meant for line level inputs. A microphone produces very low output
compared to line level, that is why microphone pre-amplifiers are used.
If you don't have one, you need one. Trust me. :)
5:45 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen wrote:
This is what is being used between the microphone and
the multiface:
http://www.bksv.com/pdf/4416B.pdf
This is providing line-level output to the multiface.
What you have there isn't really a microphone preamp. Max gain of 10
isn't very much at all, it's what, 20 dB?
Commercial mic preamps typically have at least 60 dB of gain available.
--
Paul Winkler
http://www.slinkp.com
6:02 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
Look at the specs. The output is definitely line-level. The function of
a pre-amp is to produce line-level output and this does it. It is sold
by B&K and they swear by it.
DS
Paul Winkler wrote:
On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen
wrote:
This is what is being used between the microphone
and the multiface:
http://www.bksv.com/pdf/4416B.pdf
This is providing line-level output to the multiface.
What you have there isn't really a microphone preamp. Max gain of 10
isn't very much at all, it's what, 20 dB?
Commercial mic preamps typically have at least 60 dB of gain available.
6:28 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, 2006-05-13 at 06:00 +1000, D. Sen wrote:
Look at the specs. The output is definitely
line-level. The function of
a pre-amp is to produce line-level output and this does it.
Not really. Please compare to the specs of a real mic preamp, please,
for example:
http://www.rme-audio.com/english/micpreamps/quadmic.htm
(which would be an appropriate companion to the multiface)
In particular: "Amplification can be set between 10 and 60 dB". 60dB of
gain expressed as a voltage ratio would be amplifying the signal by
1000. I would imagine you would need to use 40 to 60dB to amplify a mic
to line level so you are at least a factor of 10 below what would be
needed.
It is sold by B&K and they swear by it.
(they can swear all they want but that's not gonna make it amplify the
signal more :-)
The key here (as outlined before in the thread) is gain. This signal
conditioner's gain is too low (probably by a factor of at least 10) to
act as a mic preamp _unless_ your line input has additional gain you can
dial in (which is probably why you can use it with other equipment).
-- Fernando
Paul Winkler wrote:
> On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen wrote:
>> This is what is being used between the microphone and the multiface:
>>
>> http://www.bksv.com/pdf/4416B.pdf
>>
>> This is providing line-level output to the multiface.
>
> What you have there isn't really a microphone preamp. Max gain of 10
> isn't very much at all, it's what, 20 dB?
>
> Commercial mic preamps typically have at least 60 dB of gain available.
>
6:44 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
Ok, so the gain option quoted by the device isnt the gain quoted by the
conventional pre-amps. However, you are assuming a lot here. In essence,
you are assuming that just because you dont see "60 dB gain", the device
is not amplifying the signal to line-level when in-fact, even at x1
gain, the device is producing line-level and the extra 20 dB gain using
the x10 setting is beyond what is required for line-level inputs.
The gain does not tell you anything about the voltage at the output. The
pre-amp from RME quotes an output of 21 dBu max. This converts to
about 24 V p-p. The device I am using produces an output of 10 V p-p.
This is a difference of slightly above 6 dB.
If at the end, the gain was the root of the problem, I would surely see
the same kind of low level recording on other digital recorders (namely
a FOSTEX and a SONY line-level input recorders), and I dont.
Fernando Lopez-Lezcano wrote:
On Sat, 2006-05-13 at 06:00 +1000, D. Sen wrote:
Look at the specs. The output is definitely
line-level. The function of
a pre-amp is to produce line-level output and this does it.
Not really. Please compare to the specs of a real mic preamp, please,
for example:
http://www.rme-audio.com/english/micpreamps/quadmic.htm
(which would be an appropriate companion to the multiface)
In particular: "Amplification can be set between 10 and 60 dB". 60dB of
gain expressed as a voltage ratio would be amplifying the signal by
1000. I would imagine you would need to use 40 to 60dB to amplify a mic
to line level so you are at least a factor of 10 below what would be
needed.
It is sold by B&K and they swear by it.
(they can swear all they want but that's not gonna make it amplify the
signal more :-)
The key here (as outlined before in the thread) is gain. This signal
conditioner's gain is too low (probably by a factor of at least 10) to
act as a mic preamp _unless_ your line input has additional gain you can
dial in (which is probably why you can use it with other equipment).
-- Fernando
Paul Winkler wrote:
> On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen wrote:
>> This is what is being used between the microphone and the multiface:
>>
>> http://www.bksv.com/pdf/4416B.pdf
>>
>> This is providing line-level output to the multiface.
> What you have there isn't really a microphone preamp. Max gain of 10
> isn't very much at all, it's what, 20 dB?
>
> Commercial mic preamps typically have at least 60 dB of gain available.
>
6:54 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, 2006-05-13 at 06:42 +1000, D. Sen wrote:
Ok, so the gain option quoted by the device isnt the
gain quoted by the
conventional pre-amps. However, you are assuming a lot here. In essence,
you are assuming that just because you dont see "60 dB gain", the device
is not amplifying the signal to line-level when in-fact, even at x1
gain, the device is producing line-level and the extra 20 dB gain using
the x10 setting is beyond what is required for line-level inputs.
We are just flabbergasted by the gear you are using. What sort of mics
are you using? what do you record with the gear?
Most of us use dynamic & condenser microphones which use XLR cables, the
XLR->XLR cables are plugged into our 10-60dB preamps which are normally
connected via XLR->plug or plug->plug cords to the soundcard. I for once
have never seen a microphone use a BNC connector, and even less heard of
anyone using a "POSITRON Conditioner" as a microphone preamplifier.
The multiface has a switchable input gain via a switch internal in the
box. Maybe your box is set to the lower gain instead of the higher +4dB
(so called consumer-grade) gain?
Sampo
--
Sampo Savolainen <v2(a)iki.fi>
8:16 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Fri, 2006-05-12 at 23:53 +0300, Sampo Savolainen wrote:
On Sat, 2006-05-13 at 06:42 +1000, D. Sen wrote:
Hmmm, I think it is the other way around, it should be set to -10dBv for
more sensitivity - the +4dB will be less sensitive, right? It is meant
to interface with "pro" equipment which will send hotter balanced
signals AFAIK.
That may fall short because he is getting a -37dB signal at full sound
pressure level, that switch may get that up to -23dB or so, still low I
guess (but better than no change).
-- Fernando
Ok, so the gain option quoted by the device isnt
the gain quoted by the
conventional pre-amps. However, you are assuming a lot here. In essence,
you are assuming that just because you dont see "60 dB gain", the device
is not amplifying the signal to line-level when in-fact, even at x1
gain, the device is producing line-level and the extra 20 dB gain using
the x10 setting is beyond what is required for line-level inputs.
We are just flabbergasted by the gear you are using. What sort of mics
are you using? what do you record with the gear?
Most of us use dynamic & condenser microphones which use XLR cables, the
XLR->XLR cables are plugged into our 10-60dB preamps which are normally
connected via XLR->plug or plug->plug cords to the soundcard. I for once
have never seen a microphone use a BNC connector, and even less heard of
anyone using a "POSITRON Conditioner" as a microphone preamplifier.
The multiface has a switchable input gain via a switch internal in the
box. Maybe your box is set to the lower gain instead of the higher +4dB
(so called consumer-grade) gain?
8:32 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, 2006-05-13 at 06:42 +1000, D. Sen wrote:
Ok, so the gain option quoted by the device isnt the
gain quoted by the
conventional pre-amps. However, you are assuming a lot here. In essence,
you are assuming that just because you dont see "60 dB gain", the device
is not amplifying the signal to line-level when in-fact, even at x1
gain, the device is producing line-level and the extra 20 dB gain using
the x10 setting is beyond what is required for line-level inputs.
AFAIK I'm not assuming anything about the box[I _am_ assuming that the
microphones you use produce typical mic level output]. I can only read
what the spec you posted says. It clearly states that the box can act as
a unity gain signal conditioner (X1 gain) or as a X10 amplifier. That's
all it says - it does not talk about line levels or anything like that.
It then says that the linear output voltage is going to be 10V p-p or
greater. In my understanding that is the clipping voltage or max voltage
at the distortion levels they specify (ie: you can't get more than that
without introducing distortion). The actual output voltage you get will
depend on the input voltage you feed it.
The gain does not tell you anything about the voltage
at the output.
The pre-amp from RME quotes an output of 21 dBu max. This converts to
about 24 V p-p. The device I am using produces an output of 10 V p-p.
This is a difference of slightly above 6 dB.
[I don't mean to patronize you]
Gain multiplied by the input voltage gives you the output voltage:
vo = vi * gain
You have a fixed gain (X10) and you want a given output voltage (10V
p-p, just an example), to get that you need to supply a 1V p-p input
signal. What I don't know is what output signal you are getting from the
http://www.bksv.com/pdf/Bp1380.pdf (BTW, very very nice :-) at the sound
pressure you are measuring, but your results would indicate it is not
enough to get full scale output from the signal conditioner, as seen by
the RME card.
If at the end, the gain was the root of the problem, I
would surely see
the same kind of low level recording on other digital recorders (namely
a FOSTEX and a SONY line-level input recorders), and I dont.
I imagine that depends on what kind of input stage you have in those
machines. Usually they have a gain control which you can use to increase
the input stage gain (and thus maybe compensate for the gain of your
conditioner box).
It could also be as Sampo suggested that the RME multiface is set for
the less sensitive input gain (both gains are considered "line level" -
quite confusing).
-- Fernando
Fernando Lopez-Lezcano wrote:
> On Sat, 2006-05-13 at 06:00 +1000, D. Sen wrote:
>> Look at the specs. The output is definitely line-level. The function of
>> a pre-amp is to produce line-level output and this does it.
>
> Not really. Please compare to the specs of a real mic preamp, please,
> for example:
> http://www.rme-audio.com/english/micpreamps/quadmic.htm
> (which would be an appropriate companion to the multiface)
>
> In particular: "Amplification can be set between 10 and 60 dB". 60dB of
> gain expressed as a voltage ratio would be amplifying the signal by
> 1000. I would imagine you would need to use 40 to 60dB to amplify a mic
> to line level so you are at least a factor of 10 below what would be
> needed.
>
>> It is sold by B&K and they swear by it.
>
> (they can swear all they want but that's not gonna make it amplify the
> signal more :-)
>
> The key here (as outlined before in the thread) is gain. This signal
> conditioner's gain is too low (probably by a factor of at least 10) to
> act as a mic preamp _unless_ your line input has additional gain you can
> dial in (which is probably why you can use it with other equipment).
>
> -- Fernando
>
>
>> Paul Winkler wrote:
>>> On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen wrote:
>>>> This is what is being used between the microphone and the multiface:
>>>>
>>>> http://www.bksv.com/pdf/4416B.pdf
>>>>
>>>> This is providing line-level output to the multiface.
>>> What you have there isn't really a microphone preamp. Max gain of 10
>>> isn't very much at all, it's what, 20 dB?
>>>
>>> Commercial mic preamps typically have at least 60 dB of gain available.
6:32 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, May 13, 2006 at 06:00:52AM +1000, D. Sen wrote:
Look at the specs. The output is definitely
line-level.
I did look at the specs! Maybe you posted the wrong link? What I'm
looking at has nothing in common with a mic preamp, except that
it provides some gain.
>http://www.bksv.com/pdf/4416B.pdf
Some relevant excerpts :
"Endevco model 4416B Battery Powered ISOTRON Conditioner"
... "is a small, battery-operated, low noise signal conditioner for use
with ISOTRON or other piezoelectric voltage mode transducers."
...
"TRANSFER CHARACTERISTICS
GAIN 1 or 10 selectable"
...
"CONNECTIONS BNC for both Input and Output"
To misuse Magritte: Leci n'est pas une microphone preamplifier.
Did you maybe post the wrong link?
--
Paul Winkler
http://www.slinkp.com
6:52 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
No, the relevant part of the specs is not the gain. Just because you
dont read "microphone preamplifier" anywhere or "60 dB gain" does not
mean it is not producing line level outputs.
The relevent part of the specs is:
LINEAR OUTPUT VOLTAGE 10 volts pk-pk (3.535 V rms) or greater.
Consumer equipment line-level requires 0.316 V RMS and professional
equipment line-level requires 1.228 V RMS. The link I posted provides
the required levels for a line-level input device (from my previous
posts, you will see that it works fine for other line-level input devices).
Paul Winkler wrote:
On Sat, May 13, 2006 at 06:00:52AM +1000, D. Sen
wrote:
Look at the specs. The output is definitely
line-level.
I did look at the specs! Maybe you posted the wrong link? What I'm
looking at has nothing in common with a mic preamp, except that
it provides some gain.
Some relevant excerpts :
"Endevco model 4416B Battery Powered ISOTRON Conditioner"
... "is a small, battery-operated, low noise signal conditioner for use
with ISOTRON or other piezoelectric voltage mode transducers."
...
"TRANSFER CHARACTERISTICS
GAIN 1 or 10 selectable"
...
"CONNECTIONS BNC for both Input and Output"
To misuse Magritte: Leci n'est pas une microphone preamplifier.
Did you maybe post the wrong link?
7:34 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, May 13, 2006 at 06:50:58AM +1000, D. Sen wrote:
No, the relevant part of the specs is not the gain.
Just because you
dont read "microphone preamplifier" anywhere or "60 dB gain" does not
mean it is not producing line level outputs.
The relevent part of the specs is:
LINEAR OUTPUT VOLTAGE 10 volts pk-pk (3.535 V rms) or greater.
But that depends also on the voltage present on the input, no?
--
Paul Winkler
http://www.slinkp.com
8:05 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
Yes, sure.
Here are the relevant links for the 4189 + 2671 microphone housing in
our setup, that connects to the Deltatron power supply.
http://www.bksv.com/pdf/Bp1380.pdf
http://www.bksv.com/pdf/bp2111.pdf
Thanks for the suggestion about an internal switch, Sampo. I will look
for it when I get back to the lab.
DS
Paul Winkler wrote:
On Sat, May 13, 2006 at 06:50:58AM +1000, D. Sen
wrote:
No, the relevant part of the specs is not the
gain. Just because you
dont read "microphone preamplifier" anywhere or "60 dB gain" does not
mean it is not producing line level outputs.
The relevent part of the specs is:
LINEAR OUTPUT VOLTAGE 10 volts pk-pk (3.535 V rms) or greater.
But that depends also on the voltage present on the input, no?
15 May
15 May
6:22 a.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, May 13, 2006 at 08:03:48AM +1000, D. Sen wrote:
Yes, sure.
Here are the relevant links for the 4189 + 2671 microphone housing in
our setup, that connects to the Deltatron power supply.
http://www.bksv.com/pdf/Bp1380.pdf
That is a microphone, indeed. A B&K measurement microphone, that is.
(A note to those not familiar with B&K measurement equipment: These are
not quite like "normal" microphones. But they are of very high
quality.)
According to your linke, this microphone has a sensitivity of 50mV/Pa.
And this is the preamplifier. (Which would, in audio, normally be
considered part of the microphone.)
This one has, according to the link, a peak output of 7 volts,
corresponding to an SPL of 138dB for a 50mV/Pa microphone. Your 94dB
signal is 44 dB below that. Which means that the output level after the
preamplifier will be
l = 7 * 10^(-44/20) = 0.044
And 0.044 volts is quite a bit below full scale line-level. However,
adding the 10x gain of your amplifier you should be at 0.44 v, which is
certainly in the ballpark of consumer line-level.
After looking closer at it, your setup actually seems to make some
sense. Your amplifier (the 4416) is not one normally used for
amplifying microphone signals, but rather accelerometers and the like.
(As your links says: "conditioner for use with ISOTRON(R) or other
piezoelectric voltage mode transducuers.")
But the preamplifier (the 2111) _seems_ to be of a special kind intended
just for interfacing microphones to this kind of amplifier, so you are
probably right in that it should work.
Asbjørn
16 May
16 May
5:38 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
Actually, after Sampo's hint, everything does indeed work fine (without
the 10x gain of the power-supply/conditioner, I might add).
Cheers,
DS
Asbjørn Sæbø wrote:
On Sat, May 13, 2006 at 08:03:48AM +1000, D. Sen
wrote:
Yes, sure.
Here are the relevant links for the 4189 + 2671 microphone housing in
our setup, that connects to the Deltatron power supply.
http://www.bksv.com/pdf/Bp1380.pdf
That is a microphone, indeed. A B&K measurement microphone, that is.
(A note to those not familiar with B&K measurement equipment: These are
not quite like "normal" microphones. But they are of very high
quality.)
According to your linke, this microphone has a sensitivity of 50mV/Pa.
And this is the preamplifier. (Which would, in audio, normally be
considered part of the microphone.)
This one has, according to the link, a peak output of 7 volts,
corresponding to an SPL of 138dB for a 50mV/Pa microphone. Your 94dB
signal is 44 dB below that. Which means that the output level after the
preamplifier will be
l = 7 * 10^(-44/20) = 0.044
And 0.044 volts is quite a bit below full scale line-level. However,
adding the 10x gain of your amplifier you should be at 0.44 v, which is
certainly in the ballpark of consumer line-level.
After looking closer at it, your setup actually seems to make some
sense. Your amplifier (the 4416) is not one normally used for
amplifying microphone signals, but rather accelerometers and the like.
(As your links says: "conditioner for use with ISOTRON(R) or other
piezoelectric voltage mode transducuers.")
But the preamplifier (the 2111) _seems_ to be of a special kind intended
just for interfacing microphones to this kind of amplifier, so you are
probably right in that it should work.
Asbjørn
12 May
12 May
6:04 p.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
Besides all of that, we have used the same setup, into a FOSTEX digital
recorder and DAT recorders and it works flawlessly.
Paul Winkler wrote:
On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen
wrote:
This is what is being used between the microphone
and the multiface:
http://www.bksv.com/pdf/4416B.pdf
This is providing line-level output to the multiface.
What you have there isn't really a microphone preamp. Max gain of 10
isn't very much at all, it's what, 20 dB?
Commercial mic preamps typically have at least 60 dB of gain available.
15 May
15 May
5:43 a.m.
New subject: [linux-audio-user] Recording Level using Audacity and a Multiface card
On Sat, May 13, 2006 at 04:16:28AM +1000, D. Sen wrote:
This is what is being used between the microphone and
the multiface:
http://www.bksv.com/pdf/4416B.pdf
This is not a microphone amplifier. It says "[...] signal conditioner
for for use with ISOTRON(R) or other piezoelectric voltage mode
transducers."
According to the figure, it is intended for accelerometers and the like.
This is providing line-level output to the multiface.
That depends on its input. It will give line-level output given the
input for which it is intended. But it will not give a line-level
output regardless of what its input is.
Asbjørn
6843
days inactive
6847
days old
linux-audio-user@lists.linuxaudio.org
20 comments
6 participants
participants (6)
-
Asbjørn Sæbø -
D. Sen -
Fernando Lopez-Lezcano -
Paul Winkler -
plutek -
Sampo Savolainen