[joe h]

Hello, I saw this spec on a mic I'm interested in:

-49 dB re 1 V/Pa


That must somehow translate into millivolts per pascal. How do you do
that?

Among other things, I don't know what the "re" means. Is that
shorthand for "regarding" or "referencing" or something like that?

Thanks.

[Mike Rivers]

On 10/26/2011 10:18 PM, joe h wrote:
Hello, I saw this spec on a mic I'm interested in:
-49 dB re 1 V/Pa
That must somehow translate into millivolts per pascal. How do you do
that?

The easiest way is to use this on-line calculator:
http://www.sengpielaudio.com/calcula...sferfactor.htm

The answer is 3.548 mV/Pa

Among other things, I don't know what the "re" means. Is that
shorthand for "regarding" or "referencing" or something like that?

dB is a ratio. It's always relative to something. The
standard dB formula is:


dB = 20 x log (the ratio - like gain or furlongs per
fortnight or millivolts per Pascal)

Plug -49 dB into the formula and solve for the ratio and you
get
3.548 x 10(-3) or 3 mv/Pa


--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Meindert Sprang]

"Mike Rivers" wrote in message
...

dB = 20 x log (the ratio - like gain or furlongs per
fortnight or millivolts per Pascal)

That is too general. For voltage and current it is true. For power it is
db = 10 x log(the ratio).

Meindert

[Les Cargill[_4_]]

Meindert Sprang wrote:
"Mike wrote in message
...

dB = 20 x log (the ratio - like gain or furlongs per
fortnight or millivolts per Pascal)

That is too general. For voltage and current it is true. For power it is
db = 10 x log(the ratio).

Meindert



We were already talking about millivolts, so...

--
Les Cargill

[Mike Rivers]

On 10/27/2011 6:40 AM, Meindert Sprang wrote:

That is too general. For voltage and current it is true. For power it is
db = 10 x log(the ratio).

Aww, geez, not this old discussion again. For this
application, it's the correct formula.


--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

http://mikeriversaudio.wordpress.com - useful and
interesting audio stuff

[Tobiah[_4_]]

dB = 20 x log (the ratio - like gain or furlongs per fortnight or
millivolts per Pascal)

I had to look.

The furlong (meaning furrow length) was the distance a team of oxen
could plough without resting. This was standardised to be exactly 40 rods.

These days it's an eighth of a mile.

[John Williamson]

Tobiah wrote:

dB = 20 x log (the ratio - like gain or furlongs per fortnight or
millivolts per Pascal)

I had to look.

The furlong (meaning furrow length) was the distance a team of oxen
could plough without resting. This was standardised to be exactly 40 rods.

These days it's an eighth of a mile.

Same thing. 220 yards.

And an acre was the area a pair of oxen could plough in a day in the
15th Century. Now standardised as a furlong (220 yards) by a chain (22
Yards).

For amusement:-

http://en.wikipedia.org/wiki/List_of...of_measurement

And:-

http://en.wikipedia.org/wiki/List_of...of_measurement

My unit for estimating the volume for a disco is "How many excited
teenagers?" Anything over 15 *will* cause hearing damage.

--
Tciao for Now!

John.

[Tobiah[_4_]]

Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 milliHelen is the amount of beauty
needed to launch a single ship.

[Ron Capik[_3_]]

On 10/27/2011 12:39 PM, Tobiah wrote:
Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 milliHelen is the amount of beauty
needed to launch a single ship.
....and a microHelen would likely launch
a man overboard.

Later...
Ron Capik
--

[Neil Gould]

Tobiah wrote:
Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 milliHelen is the amount of beauty
needed to launch a single ship.

Doesn't that presume that they weren't trying to get _away_ from that face?

--
Neil

[William Sommerwerck]

"Tobiah" wrote in message
...

Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 millihellen is the amount of beauty
needed to launch a single ship.

That assumes a linear relationship.

[Ron Capik[_3_]]

On 10/29/2011 10:32 AM, William Sommerwerck wrote:
wrote in message
...

Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 millihellen is the amount of beauty
needed to launch a single ship.

That assumes a linear relationship.


Do you have another relationship in mind?

I know beer goggles and other factors can
seriously distort any such measurements.

Later...
Ron Capik
--

[William Sommerwerck]

"Ron Capik" wrote in message
...
On 10/29/2011 10:32 AM, William Sommerwerck wrote:
wrote in message
...

Helen of Troy (from the Iliad) is widely known as "the face that
launched a thousand ships". Thus, 1 millihellen is the amount
of beauty needed to launch a single ship.

That assumes a linear relationship.

Do you have another relationship in mind?

Well, they always had Paris...

How many of you didn't get that joke? You probably reacted with ablanc
stare.

[joe h]

Thanks Mr. Rivers!

I always wanted to know how to convert these numbers.

[joe h]

3.5mv/PA seems like a low number. I'm used to the TLM-103 putting out
something like 30, or on a quiet day something like a KM84 putting out
about 10-15mv/PA (don't quote me on this, I don't have the exact
numbers memorized).

On the other hand, the RE20 spec sheet says that mic only outputs
1.5mv/pa:
http://www.electrovoice.com/sitefile...ta%20Sheet.pdf

And the SM7B is even more ridiculously low at 1.12mv/PA:
http://www.shure.com/idc/groups/tech...ro_sm7b_ug.pdf

This mic captured my attention at AES:
http://www.mxlmics.com/products/Stud...C-1/bcc-1.html

It's like an RE20 idea, but in a condenser format. I found it to have
a rare blend of being articulate without being sibilant. It seemed
"fast". Like when I talk very fast it keeps up with the conversation
(I found the ribbon mics to be too slow for this when auditioning them
at AES). Also the plosives were handled very well even without a pop
filter. This mic is where I got the question about the mv/PA. I have
no idea about the noise floor or other specs (how much can you really
tell on the AES floor?). But I think you can clearly tell the "main
idea" of a mic at AES, and I was surprised how much I liked this new
mic from MXL. It was hooked up to MXL's new preamp/comp. I made sure
the comp was off. I think the preamp/headphones were average AES
playback stuff.

I went with the r.a.p.'s recommendation for the Centrance MicPort
Pro. Thanks for that tip, I never would have known about that little
gadget. I'm going to buy the BCC-1 and see how well it matches up
with the Centrance.

[Don Pearce[_3_]]

On Tue, 1 Nov 2011 11:18:48 -0700 (PDT), joe h
wrote:

It's like an RE20 idea, but in a condenser format. I found it to have
a rare blend of being articulate without being sibilant. It seemed
"fast". Like when I talk very fast it keeps up with the conversation
(I found the ribbon mics to be too slow for this when auditioning them
at AES).

Wow! If you speak at, say, 80 words per minute, how many words behind
you is a ribbon mic after a minute? And how does it achieve this
extraordinary feat?

D

[Scott Dorsey]

joe h wrote:
3.5mv/PA seems like a low number. I'm used to the TLM-103 putting out
something like 30, or on a quiet day something like a KM84 putting out
about 10-15mv/PA (don't quote me on this, I don't have the exact
numbers memorized).

Yes, these are very hot microphones, with the TLM-103 being so hot you can
run it into some line inputs.

On the other hand, the RE20 spec sheet says that mic only outputs
1.5mv/pa:
http://www.electrovoice.com/sitefile...ta%20Sheet.pdf

And the SM7B is even more ridiculously low at 1.12mv/PA:
http://www.shure.com/idc/groups/tech...ro_sm7b_ug.pdf

Right, these are not very hot microphones. They are both dynamic mikes with
very lossy magnetic paths. You can make a dynamic mike more efficient and
with a higher output but you sacrifice other things in the process.

If you think the SM7B is bad, check out the Beyer M160. Or any of the
RCA ribbons.

This mic captured my attention at AES:
http://www.mxlmics.com/products/Stud...C-1/bcc-1.html

It's like an RE20 idea, but in a condenser format. I found it to have
a rare blend of being articulate without being sibilant. It seemed
"fast". Like when I talk very fast it keeps up with the conversation
(I found the ribbon mics to be too slow for this when auditioning them
at AES). Also the plosives were handled very well even without a pop
filter. This mic is where I got the question about the mv/PA. I have
no idea about the noise floor or other specs (how much can you really
tell on the AES floor?). But I think you can clearly tell the "main
idea" of a mic at AES, and I was surprised how much I liked this new
mic from MXL. It was hooked up to MXL's new preamp/comp. I made sure
the comp was off. I think the preamp/headphones were average AES
playback stuff.

It looks like an RE-20, but it doesn't have any variable-D network. In
fact, it's really not much at all like an RE-20. The variable-D stuff is
what makes the RE-20 such a miracle when dealing with people who can't
stay on-mike.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[PStamler]

On Nov 1, 1:18*pm, joe h wrote:
This mic captured my attention at AES:http://www.mxlmics.com/products/Stud...C-1/bcc-1.html

It's like an RE20 idea, but in a condenser format.

No, it''s a condenser mic with a *case* designed to *look* like an
RE20. If the on-axis frequency response graph is to be believed (not a
given), the on-axis sound at a distance may be similar to an RE20's.

BUT -- the only polar pattern given is for a single (unspecified)
frequency, and there aren't frequency response graphs for off-axis
angles. As a result, we have no idea whether this mic shares one
vitally-important characteristic of the RE20, the fact that its off-
axis response is very close to its on-axis response.

AND -- we have no indication that this mic is "Variable-D", another
salient characteristic of the RE20 -- that is, the RE20 has much less
proximity effect than typical directional mics, so the sound doesn't
change as the source moves closer or farther away (although the level
does).

So what we have is a mic designed to look like an RE20 to novices. Not
an "RE20 idea" by a long shot.

Peace,
Paul

[joe h]

Great point, Mr. Dorsey.

I don't think they are even trying to copy that, there is probably a
patent on it. It's more the overall style. Even without the variable-
D, I did notice a rather good linearity of the sound of the BCC-1 in
terms of proximity (as far as an AES demo can reveal). If I spoke at
4 inches, 12 inches or about 14 inches, the character stayed very
similar. Mild off-axis seemed to do well also (I didn't try anything
like 90 off axis). It's an intriguing form factor. The U87 has been
copied like crazy. MXL is tapping into the look of the RE20 with the
side vents, etc. I'm surprised the RE20 has not seen more visual
copycats.

I think the diaphragm being set back inside the housing has something
to do with helping with the plosives. It's a condenser, and the RE20
is a dynamic. Definitely two different mics. But it's a pretty darn
competitive mic at about $300. I'm going to order one, and I'll post
what it's like here. I overheard someone from Guitar Center Pro
talking about how MXL used to have reliability problems, but now they
manage their factories better and you don't have to go through a bunch
of MXL's to weed out the rejects. Something like that anyway. One
thing is for su MXL comes out with a new mic model faster than I
can keep up with. It's like those "Tribble" things from Star Trek.
They must have some prolific designers. I don't know how they do it.
They are even coming out with some nice tube mics in the $1500 range.
Even if you know *how* to make all of these different models, how do
you tool up the factory and ship new products so quickly?

It's hard to describe, but the BCC-1 seems to do well for spoken
word. There is something different between speaking and singing. For
singing, I'd be looking at that $8500 Telefunken U47 interpretation.
But fast, no-nonsense solid state articulation seems to be good for
spoken word, and it's a whole lot less expensive! I don't remember
Electrovoice being at AES (epic miss if I somehow did not spot them).
Otherwise I would have compared the BCC-1 to the RE20.

[Scott Dorsey]

joe h wrote:
I don't think they are even trying to copy that, there is probably a
patent on it.

Variable-D patents expired in the late 1970s, and surprisingly nobody has
tried to copy the design. I don't know why. It wouldn't be a hard thing
to copy, really.


It's more the overall style. Even without the variable-
D, I did notice a rather good linearity of the sound of the BCC-1 in
terms of proximity (as far as an AES demo can reveal). If I spoke at
4 inches, 12 inches or about 14 inches, the character stayed very
similar.

This is because the pattern is so wide.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."