"Corrective EQ"

[Recording Engineer]

Do you mean it's response EQ'd? Actually Martin told in a FB video that they developed a new capsule to get rid of the resonances and all pre-EQ's stuff (compared the NU100K to U47 at that point and claimed that the resonance of U47 cannot be EQed out) so that it could EQed in post. Anyway, would like to know more about the capsule.

I meant EQed response. While I’m pretty sure you’re right about his new capsule vs a Neumann M7 or K47, I’m also pretty sure Martin says he gives a somewhat 47-inspired response (or at least in one range) with EQ in the mic.

 

[snigglepit]

The use of EQ to correct for diaphragm resonance was apparently one of the many things that Alan Blumlein invented! See the 'Footnote' at the bottom of this page:

http://www.orbem.co.uk/tapes/blattner.htm

Also, am I right in thinking that the rectangular diaphragms used by Pearl/Milab require internal EQ to correct a falling HF response?

 

[abbey road d enfer]

The use of EQ to correct for diaphragm resonance was apparently one of the many things that Alan Blumlein invented! See the 'Footnote' at the bottom of this page:

http://www.orbem.co.uk/tapes/blattner.htm

Interesting historic point.

Also, am I right in thinking that the rectangular diaphragms used by Pearl/Milab require internal EQ to correct a falling HF response?

Hmmm... Large diaphragms shift down the frequency of the peak due to diffraction, so the 8kHz sibilance that occurs with typical SDC's would result in a peak in the upper midrange that would sound nasal, and much more nagging. I would think it is even more necessary to EQ it.
EQ'ing a falling HF response would impair noise significantly, I think.

 

[Gus]

There is an older AKG patent that shows a tube circuit with multiple LRCs to EQ a tube microphone.
I am searching for the patent number.


EDIThttps://pdfpiw.uspto.gov/.piw?PageNum=0&docid=03393271&IDKey=2346209B4398&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetahtml%2FPTO%2Fpatimg.htm

 

[Winston OBoogie]

The use of EQ to correct for diaphragm resonance was apparently one of the many things that Alan Blumlein invented! 

I'd forgotten about that.    This principle of his carried through into later years - 1940's - '60's.  Len Page, who worked and studied under Blumlein at EMI,  built up various eq boxes which were microphone specific.  These boxes housed the appropriate LCR elements and were placed 'in line' at low level before the pre amplifier.

 

[abbey road d enfer]

I think we can establish a parallel with loudspeakers.
For many years, loudspeaker designers have tried to linearize them by purely acoustic and mechanical means, a method that found its limits when the need for smaller and more spl-capable systems arose.
It is now accepted that a SR speaker does not have an intrinsic linear frequency response, and that serious signal processing must be associated with it. Most studio monitors have also followed that trend. Only HiFi speakers remain in the "non-processing" camp.
Until now, extensive processing in microphones has been an exception, with only a few drifts with sub-zero noise from B&K and other, dual capsule such as AKG200's. The typical U67/u87 sibilance EQ cannot be considered "extensive".
Indeed, all the Mic modeller's and Slate/Townsend mics use extensive processing, but not with the intended goal of simply correcting the intrinsic defects of inherently imperfect transducers.
This can be considered by many as a perversion (claiming to make a $0.50 ECM sound like a U47 is one), and thus has put suspicion on any attempt to use active EQ for improving the performance of a mic.
I believe it's up to respected mfgrs to pave the way and overcome this suspicion.
Me, I have been a long-time adept at using EQ for making mics sound right, without any prejudice.

 

[mhelin]

3U Audio Warbles have switchable voicings, three on this mic, though not to compensate any capsule resonances:

https://www.ebay.co.uk/itm/3U-Audio-Warbler-MKIV-Condenser-Microphone-Switchable-Sound-Style/111820764886

 

[Gus]

A link. Note the LRC EQ.
http://www.sdiy.org/oid/ldc/RSchulein.pdf

 

[kingkorg]

Indeed, all the Mic modeller's and Slate/Townsend mics use extensive processing, but not with the intended goal of simply correcting the intrinsic defects of inherently imperfect transducers.

I am not sure how familiar you are with Townsend mic, it is doing some pretty advanced stuff, besides modelling classic mics.

There is a flat model as well. There is off axis correction in case one is recording source which is placed at any angle off axis, and compensating for that. There are filters that control proximity effect. Software also corrects rear diaphragm response with a different curve. Amount of signal coming from  rear diaphragm is also adjusted for different models so it compensates for different capsule construction differences. I really can't think of a function which could be added to go even further.

Austrian audio software which can be used with any stereo mic controls pattern response for several frequency bands. Although i see this as a bit of a gimmick, as some bands are pretty much limited just by physics. 

 

[abbey road d enfer]

I am not sure how familiar you are with Townsend mic

Not too much, as witnesss the fact I ignored this.

 

[Gus]

This is another reason for external powered solid state microphones with an EQ in the power supply or microphone.

Or installing EQ in a tube microphone power supply

The above is obvious to people trained in the art.

This is more for the users that have 1 or more channels of USB etc. interfaces to their PCs and not a desk with EQ

 

[Winston OBoogie]

This is another reason for external powered solid state microphones with an EQ in the power supply or microphone. 

+1