schoeps and dpa comparison on my guitar

[Nate Najar]

on my guitar. I have a B&K 4011 that I just took receipt of. And a schoeps cmc6 mk41 I have had for years.

in my little mixing room (corner bass trapping and a little broadband absorption on the walls but not enough to hurt myself). The mics were in the general same spot except that the schoeps was pulled back a little further. The distance of the mics to the guitar were as close as possible but for the mics to be "flat" according to their polar patterns. With the B&K that is about 12 inches and the schoeps was 18 inches.

on another take I tried a 414 in omni but disliked it so much I put it away. I don't own a schoeps or DPA omni.

for close miking, it seems you really need 2 mics, and probably preferably omnis, to get the full sound of the instrument. But I digress.

The files are 24/48 with zero processing. See if you can name which mic is which. They are reasonably gain matched. Which do you like better? I like them both but i prefer one of them over the other, and for either one if this were a real recording I would probably apply some light low shelf eq reduction.

and please don't comment on the playing, I just filed my nails so they'll be too short for a day or two so my fingers were sort of flailing in the wind so to speak.

https://dl.dropboxusercontent.com/u/48628343/mictest.zip

[geoff]

"Nate Najar" <na...@natenajar.com> wrote in message
news:347cfb55-d338-490d...@googlegroups.com...

***********************************

I love the C414 one, but can't tell if an EB, B-ULS or B-XLS ! !

geoff

[Matt Faunce]

Hi Nate. I like the second one better. But I think it's only because it
sounds like it's breathing better, which I'm assuming is the one that's
18" from your guitar, the Schoeps.

I think you should do it over and put both of them at 18". so they both
get the same amount of room. That is, if I'm right that a directional
mike stays flat after the distance they indicate.
--
Matt

[Matt Faunce]

I just checked some papers I downloaded from the DPA website. It
compares the relative distances from the sound source different mike
patterns need to get the same balance of direct to indirect sound.

If an omni is 1.0, a cardiod is 1.7, and a supercardiod is 1.9.

This means that the difference between the cardiod and super is 11% :

1.7 � 1.9 = 0.89; i.e., 1.7 is 89% of 1.9

The difference is 100% - 89% = 11%

Which means that to do a fair comparison you need to keep an 11%
difference between them.

You had a 12 � 18 = 0.66 ; 1 - 0.66 = 33% difference, which was too
much. To get them equal, keep the supercardiod at 18" and put the
cardiod at 89% of that, (11% difference) which is 16".

16 � 18 = 0.89 ; 1 - 0.89 = 0.11 or 11%

I think my math is right. If not, please, someone correct me.
--
Matt

[Matt Faunce]

On 5/8/13 6:43 PM, Matt Faunce wrote:

The division symbol didn't translate on google. So here it is with the
slash symbol for division:

I just checked some papers I downloaded from the DPA website. It
compares the relative distances from the sound source different mike
patterns need to get the same balance of direct to indirect sound.

If an omni is 1.0, a cardiod is 1.7, and a supercardiod is 1.9.

This means that the difference between the cardiod and super is 11% :

1.7 / 1.9 = 0.89; i.e., 1.7 is 89% of 1.9

The difference is 100% - 89% = 11%

Which means that to do a fair comparison you need to keep an 11%
difference between them.

You had a 12 / 18 = 0.66 ; 1 - 0.66 = 33% difference, which was too

much. To get them equal, keep the supercardiod at 18" and put the
cardiod at 89% of that, (11% difference) which is 16".

16 / 18 = 0.89 ; 1 - 0.89 = 0.11 or 11%

[Matt Faunce]

I re-did the math using the old cross multiplication trick for
equalizing ratios. I came up with the same answer. (The slight
discrepancy is from rounding.):

1.7 / x" = 1.9 / 18"

x" = 16.1"

So keep the supercardiod at 18" and put the cardiod at 16".

--
Matt

[Nate Najar]

Thanks for listening.

The 4011 is specified at 30cm to be flat, so that's roughly 12 inches. The schoeps is 50cm (I just had to look it up) which is roughly 20 inches, so I misremembered and had it too close still!

I will do another test on Friday....

Thanks!

N

[Matt Faunce]

Here's where I got my info:
http://www.dpamicrophones.com/en/Mic-University/Technology-Guide/Directional%20vs%20Omnidirectional%20Microphones.aspx

According to this link you do lose bass when you move back too much. So
without eq you'll have to compromise either having equally flat
responses of both mikes or having equal amounts of diffuse sound. 17.6"
and 19.7" will give you equal amounts of diffuse sound, but the cardiod
at 17.6" will have a slight loss of bass. I'd try to roll out the same
amount of bass with an eq on the supercardiod.

--
Matt

[Peter Larsen]

Matt Faunce wrote:


> I think you should do it over and put both of them at 18". so they
> both get the same amount of room. That is, if I'm right that a
> directional mike stays flat after the distance they indicate.

You are not, a mic like the 4011 - that one I happen to know the specs for -
is bass light in a plane wave sound field because it is designed for close
miking use and has a fairly small zone in which it its bass response
attempts to be linear.

Its design-intention is to keep the bass response shaping resonance(s) well
damped for optimum transient reproduction. It may well be possible - perhaps
not for the interested afficiado owner, but certainly for dpa to alter its
response for linearity in plane waves in which case your asumption would
hold true

Kind regards

Peter Larsen

[Matt Faunce]

That's interesting -- a trade off between 'transient response' and 'bass
response except at a certain distance,' -- yet another compromise that's
considered in designing, and choosing, directional microphones.

--
Matt

[Peter Larsen]

Matt Faunce wrote:

> That's interesting -- a trade off between 'transient response' and
> 'bass response except at a certain distance,' -- yet another
> compromise that's considered in designing, and choosing, directional
> microphones.

To get a cardioid mic "linear" in the bass range necessitates EQ via
acoustic resonance or electric eq in preamp, mixer or post. That LF
resonance seems to make poorly damped cardioids more susceptible to VLF
noise from air movements.

An example of this is the AKG CK1 capsule and its 23 Hz resonance - that is
what I have observed with my pair - causing it to augment traffic noise such
as bus and lorry exhausts. They still need EQ, mostly an upper bass boost
centered at 60 Hz, so they might as well have had lower Q acoustic EQ and
then needed only a simple shelving bass control.

Kind regards

Peter Larsen

--

Peter Larsen
Lange�s 20
4281 G�rlev
3582 1612