# mic level signal voltage ?

Tags:
Last response: in Home Audio
Share
Anonymous
May 1, 2005 10:05:35 PM

I have an old signal generator in which i am measuring the output voltage
to get a basic mic level [ my math is not so good , but .7 v is considered
+ 4 Line level ? ] for checking out a preamp i built .

tia for any help , regards Greg
Anonymous
May 1, 2005 10:05:36 PM

"GKB" wrote ...
> I have an old signal generator in which i am measuring the output
> voltage
> to get a basic mic level [ my math is not so good , but .7 v is
> considered
> + 4 Line level ? ] for checking out a preamp i built .

There is a FAQ for this newsgroup at...
http://www.recaudiopro.net/faq/index.htm

But, to my surprise, this question is not actually addressed there.

I'm sure someone will be along shortly with a good link to a dB
levels FAQ somewhere.
May 1, 2005 10:05:36 PM

GKB wrote:
> I have an old signal generator in which i am measuring the output voltage
> to get a basic mic level [ my math is not so good , but .7 v is considered
> + 4 Line level ? ] for checking out a preamp i built .
>
> tia for any help , regards Greg
>
>

Professional Line Level equals 1.228v. +4dBu=1.228v.

--
Eric

www.Raw-Tracks.com
Related resources
Anonymous
May 1, 2005 10:05:36 PM

In article <PT8de.1186302\$6l.202027@pd7tw2no> gboboski@shaw.ca writes:

> I have an old signal generator in which i am measuring the output voltage
> to get a basic mic level [ my math is not so good , but .7 v is considered
> + 4 Line level ? ] for checking out a preamp i built .

0 dBu is 0.775V. +4 dBu "nominal line level" in round numbers is about
1.2V. A good healthy mic levl is around -35 dBu which equates to
0.014V (14 millivolts).

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 2, 2005 5:23:37 AM

GKB wrote:

> I have an old signal generator in which i am measuring the output voltage
> to get a basic mic level [ my math is not so good , but .7 v is considered
> + 4 Line level ? ] for checking out a preamp i built .

0.775V is 0dBu

1.23V is +4dBu ( 0VU ) commonly taken as the 'line level' reference.

Graham
Anonymous
May 2, 2005 3:04:02 PM

-35dBU might be a good o/p from a capacitor mic. What if it's not that
genre?
A good dynamic mic reference level for speaking voice is -54dBU or about
1.5mV rms. Add 8dB above that for peak (to -46dBU).
Some dynamics give a lower ref level (about 0.9mV).
A ribbon mic produces even less voltage and usually that needs to be
increased with the use of a step-up transformer by about 7-10dB to nurture
lower-gain preamps.

Line-up (ref) line level in UK is 0dBU or 0.7746mV, at 400 Hz, 800 Hz, or
1kHz.
Peak is strictly 8dB on top of that.

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
>
> In article <PT8de.1186302\$6l.202027@pd7tw2no> gboboski@shaw.ca writes:
>
>> I have an old signal generator in which i am measuring the output
>> voltage
>> to get a basic mic level [ my math is not so good , but .7 v is
>> considered
>> + 4 Line level ? ] for checking out a preamp i built .
>
> 0 dBu is 0.775V. +4 dBu "nominal line level" in round numbers is about
> 1.2V. A good healthy mic levl is around -35 dBu which equates to
> 0.014V (14 millivolts).
>
> --
> I'm really Mike Rivers (mrivers@d-and-d.com)
> However, until the spam goes away or Hell freezes over,
> lots of IP addresses are blocked from this system. If
> you e-mail me and it bounces, use your secret decoder ring
> and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 2, 2005 3:04:03 PM

In article <COnde.15725\$Y46.2684@newsfe1-win.ntli.net> jim.greg@ntlworld.com writes:

> -35dBU might be a good o/p from a capacitor mic. What if it's not that
> genre?
> A good dynamic mic reference level for speaking voice is -54dBU or about
> 1.5mV rms. Add 8dB above that for peak (to -46dBU).
> Some dynamics give a lower ref level (about 0.9mV).

Because of all the idiots hooking mics to recorders today and saying
things like "my mic isn't hot enough" or "my mic is too hot" without
considering things like gain structure, manufacturers are making mics
with pretty much similar sensitivity. It's no longer univerally true
that condenser mics have a higher output level for a given SPL than
dynamics.

It's very true, however, that speaking a foot or so from a microphone
will give an eyeball average output level around 20 dB lower than
someone singing into a mic at a few inches. This is why a microphone
preamp needs to have good performance over a wide dynamic range.

The original poster was looking for a test signal to run through a mic
preamp, and something in tne order of -35 dBu is a good middle-of-the
scale level - not high enough to overload, not so low that noise
becomes a problem.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 2, 2005 4:06:40 PM

Thanks for all the replies , Mr Rivers was the closest to what
i was looking for [ thanks Mike ] , and if that wasn't clear , it was "
what would
an " average " mic put out voltage wise so i can set the signal generator
in the ballpark !
something in the middle not a ribbon , not a modern condenser being yelled
into ,
perhaps a voltage down 50db from 0 , Not critical just a place to start
from .

spread the love , regards Greg

"Mike Rivers" <mrivers@d-and-d.com> wrote in message
>
> In article <PT8de.1186302\$6l.202027@pd7tw2no> gboboski@shaw.ca writes:
>
> > I have an old signal generator in which i am measuring the output
voltage
> > to get a basic mic level [ my math is not so good , but .7 v is
considered
> > + 4 Line level ? ] for checking out a preamp i built .
>
> 0 dBu is 0.775V. +4 dBu "nominal line level" in round numbers is about
> 1.2V. A good healthy mic levl is around -35 dBu which equates to
> 0.014V (14 millivolts).
>
> --
> I'm really Mike Rivers (mrivers@d-and-d.com)
> However, until the spam goes away or Hell freezes over,
> lots of IP addresses are blocked from this system. If
> you e-mail me and it bounces, use your secret decoder ring
> and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
May 2, 2005 4:33:18 PM

On Sun, 01 May 2005 18:05:35 GMT, "GKB" <gboboski@shaw.ca> wrote:

> I have an old signal generator in which i am measuring the output voltage
>to get a basic mic level [ my math is not so good , but .7 v is considered
>+ 4 Line level ? ] for checking out a preamp i built .

That's near enough 0. +4 is 1.228v.
Anonymous
May 2, 2005 9:43:07 PM

EricK wrote:
> GKB wrote:
>
>> I have an old signal generator in which i am measuring the output
>> voltage
>> to get a basic mic level [ my math is not so good , but .7 v is
>> considered
>> + 4 Line level ? ] for checking out a preamp i built .
>>
>> tia for any help , regards Greg
>>
>>
>
> Professional Line Level equals 1.228v. +4dBu=1.228v.
>
0=.775
Anonymous
May 3, 2005 1:08:58 AM

"GKB"
>
> I have an old signal generator in which i am measuring the output voltage
> to get a basic mic level [ my math is not so good , but .7 v is
> considered
> + 4 Line level ? ] for checking out a preamp i built .
>
> tia for any help , regards Greg

** There is no such thing as "mic level" - any fool here who says there is
is an ass.

Depending on the actual mic and its usage the output level varies from
almost nothing to several volts.

Why do you think mic pres have an input gain control with 50 - 60 dB range
????

............... Phil
Anonymous
May 3, 2005 1:08:59 AM

In article <3dmg24F6t603tU1@individual.net> philallison@tpg.com.au writes:

> ** There is no such thing as "mic level"

> Depending on the actual mic and its usage the output level varies from
> almost nothing to several volts.

There's no specific number for calibration, but there's a voltage
range that's usually considered "mic level" and a range that's
considered "line level." There are mics that put out line levels, and
there are lines that put out mic levels.

> Why do you think mic pres have an input gain control with 50 - 60 dB range
> ????

So that they can accommodate what comes out of most microphones most
of the time. But you won't find too many mic preamps that will take a
"line level" signal (say in the range of -20dBu to +24 dBu) at the
same input connector as a mic without at least switching in an
attenuator.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
May 3, 2005 1:31:56 AM

David Kowalski wrote:

> 0=.775

0 does not equal .775, it equals zero.
Always has, always will.

--
Eric

www.Raw-Tracks.com
Anonymous
May 3, 2005 8:08:50 AM

GKB wrote:

> I have an old signal generator in which i am measuring the output voltage
> to get a basic mic level [ my math is not so good , but .7 v is considered
> + 4 Line level ? ] for checking out a preamp i built .
>
> tia for any help , regards Greg

Ok - I think you got the numbers regarding the accepted reference levels.

When designing a mic amp you should consider the situations in which it is
likely to be used.

Quiet singing from a distance from the mic may require as much as 80dB gain.

Rock 'n roll usage with close miking may result in overload of your mic pre (
assuming typical circuitry ) if you can't wind the gain down to around 20dB (
or less even ! ).

Graham
Anonymous
May 3, 2005 3:40:35 PM

To perpetuate the story , it's an old tube model signal generator with
numbers for markings, as i've never had much for test gear [ check , check
! ]
and not even for design , more to trouble shoot .

thanks again ALL

regards Greg

"Pooh Bear" <rabbitsfriendsandrelations@hotmail.com> wrote in message
news:4276EB42.118A041C@hotmail.com...
> GKB wrote:
>
> > I have an old signal generator in which i am measuring the output
voltage
> > to get a basic mic level [ my math is not so good , but .7 v is
considered
> > + 4 Line level ? ] for checking out a preamp i built .
> >
> > tia for any help , regards Greg
>
> Ok - I think you got the numbers regarding the accepted reference levels.
>
> When designing a mic amp you should consider the situations in which it is
> likely to be used.
>
> Quiet singing from a distance from the mic may require as much as 80dB
gain.
>
> Rock 'n roll usage with close miking may result in overload of your mic
pre (
> assuming typical circuitry ) if you can't wind the gain down to around
20dB (
> or less even ! ).
>
> Graham
>
>
!