Topic: DPA 4060 modifying frequency response?

[fransbart]

Hello to you all!

I'm new on this forum, but I've read somewhat on this topic.
I've recently bought 2 DPA 4060 miniature mics, which I'm using with KORG MR 1000 and JLM audio preamp for recording classical stuff. Basically I think the mics are nice (almost true omni etc). also when compared to my Neumanns KM 83i.
The problem I am experiencing after enough recordings to know it's a consistent finding for me:
With the (short) soft boost grid I find the treble too much emphasized. But without any grid at all ("nude capsule") I would just like some more treble boost. So I think my preference for the frequency response would be somewhere in between.
Would it be possible to someway use/make (myself) a grid which would render me the "in between" frequency response?
Just the same grid, but half the length? (the capsule then would be half burried/covered in/by the grid).

Also I've read about applying APE's on omni mics for modifying frequency responses (direction-dependent). Would these be applicable to the DPA 4060 too? Or does this not make any sense because of then loosing the true omnidirectionality of the DPA 4060? (Member GutBucket has applied EPA's for DPA 4060?, I read somewhere in the forum?)
My most important question is: do you know ways to modify the frequency response (altering the curve: a lower boost than the soft boost grid gives (+3dB? according to DPA))?
Another question: do you know the way in which these grids enhance the frequency response? I cannot easily understand: 10 kHz approx. corresponds with a wavelength of 3 cm (approx. 1 inch) and 20 kHz.  corresponds with half that length. So I could understand that a cavity of approx. 0.5 * 0.5 inch would give the boost. BUT the cavity of the DPA soft boost grid is much smaller!
Could someone explain it to me?
Thank you very much in advance!!

[Church-Audio]

Hello to you all!

I'm new on this forum, but I've read somewhat on this topic.
I've recently bought 2 DPA 4060 miniature mics, which I'm using with KORG MR 1000 and JLM audio preamp for recording classical stuff. Basically I think the mics are nice (almost true omni etc). also when compared to my Neumanns KM 83i.
The problem I am experiencing after enough recordings to know it's a consistent finding for me:
With the (short) soft boost grid I find the treble too much emphasized. But without any grid at all ("nude capsule") I would just like some more treble boost. So I think my preference for the frequency response would be somewhere in between.
Would it be possible to someway use/make (myself) a grid which would render me the "in between" frequency response?
Just the same grid, but half the length? (the capsule then would be half burried/covered in/by the grid).

Also I've read about applying APE's on omni mics for modifying frequency responses (direction-dependent). Would these be applicable to the DPA 4060 too? Or does this not make any sense because of then loosing the true omnidirectionality of the DPA 4060? (Member GutBucket has applied EPA's for DPA 4060?, I read somewhere in the forum?)
My most important question is: do you know ways to modify the frequency response (altering the curve: a lower boost than the soft boost grid gives (+3dB? according to DPA))?
Another question: do you know the way in which these grids enhance the frequency response? I cannot easily understand: 10 kHz approx. corresponds with a wavelength of 3 cm (approx. 1 inch) and 20 kHz.  corresponds with half that length. So I could understand that a cavity of approx. 0.5 * 0.5 inch would give the boost. BUT the cavity of the DPA soft boost grid is much smaller!
Could someone explain it to me?
Thank you very much in advance!!

Actually with the grid removed these mics are NOT flat. DPA made a 4090 mic with a true flat grid I am not sure if its available separately but it might be worth a phone call to Bruce at DPA in Colorado to find out.

Chris

[Gutbucket]

When I asked, the 4090 grid was not available.  Doesn't hurt to ask again, though.  If you get a different answer please let me know.

DIY APEs will boot the high mid / low treble more, so that's probably not what you want.. and yes, they also change the polar pattern, making them more directional as the frequency goes up and less perfectly omnidirectinal, but that and the presence boot is the whole point of using them.

I'm no acoustician, and hopefully someone will confim or correct what this, but as I understand it the tube acts as a resonant chamber, with the frequency of that resonance determined by the length and diameter of the tube.  I think it's the 1/4 wavelength where the boost begins to become significant, the boost is reduced as the wave starts to to cancel at 1/2 wavelength, then reinforces again at 1 wavelength, etc.  In practical terms, the shorter the grid, the higher frequency at which the onset of that frequency boost sequence starts and the less apparent it will sound.  I suspect the grid on the 4090 (which may be permanently attached) is shorter than the 4060 soft boost grid, but I don't know by how much.  I've considered trimming some high boost grids which I never use down to something shorter than the low boost grids, or making shorter ones of various length out of plastic or brass tubing of the same diameter, but haven't done that.  It would require careful test measurements in comparision with the standard grid to figure out how exactly the response is being changed.. or lots of careful listening to dial it in by ear to something that sounds like the target response you prefer- tricky or a good bit of work.

The easier answer and the reason I've never done any of that is to simply apply corrective EQ.  I prefer using the low boost grids and making an EQ adjustment later anyway, since I can then alter the shape of the EQ curve as required for each particular recording and they are all somewhat different.  So I'm usually going to EQ in any case, and even if I'm reducing the grid induced boost with EQ to something that is the equivalent of flat or rolled off, the grid's high frequency boost is still useful as 'pre-emphasis', effectively lowering the apparent self noise of the microphone since the self noise in that region is also reduced when the correction is applied.  That can be very helpful for clasical recording with the 4060 even though it is relatively quiet for a mic with a such a tiny diaphram.

[edit- BTW, welcome to the forum!]

[Church-Audio]

When I asked, the 4090 grid was not available.  Doesn't hurt to ask again, though.  If you get a different answer please let me know.

DIY APEs will boot the high mid / low treble more, so that's probably not what you want.. and yes, they also change the polar pattern, making them more directional as the frequency goes up and less perfectly omnidirectinal, but that and the presence boot is the whole point of using them.

I'm no acoustician, and hopefully someone will confim or correct what this, but as I understand it the tube acts as a resonant chamber, with the frequency of that resonance determined by the length and diameter of the tube.  I think it's the 1/4 wavelength where the boost begins to become significant, the boost is reduced as the wave starts to to cancel at 1/2 wavelength, then reinforces again at 1 wavelength, etc.  In practical terms, the shorter the grid, the higher frequency at which the onset of that frequency boost sequence starts and the less apparent it will sound.  I suspect the grid on the 4090 (which may be permanently attached) is shorter than the 4060 soft boost grid, but I don't know by how much.  I've considered trimming some high boost grids which I never use down to something shorter than the low boost grids, or making shorter ones of various length out of plastic or brass tubing of the same diameter, but haven't done that.  It would require careful test measurements in comparision with the standard grid to figure out how exactly the response is being changed.. or lots of careful listening to dial it in by ear to something that sounds like the target response you prefer- tricky or a good bit of work.

The easier answer and the reason I've never done any of that is to simply apply corrective EQ.  I prefer using the low boost grids and making an EQ adjustment later anyway, since I can then alter the shape of the EQ curve as required for each particular recording and they are all somewhat different.  So I'm usually going to EQ in any case, and even if I'm reducing the grid induced boost with EQ to something that is the equivalent of flat or rolled off, the grid's high frequency boost is still useful as 'pre-emphasis', effectively lowering the apparent self noise of the microphone since the self noise in that region is also reduced when the correction is applied.  That can be very helpful for clasical recording with the 4060 even though it is relatively quiet for a mic with a such a tiny diaphram.

[edit- BTW, welcome to the forum!]

Yes its all about the length the shape inside is the same on all of these that I have seen. Its the length of the tube that determines boost or cut of HF. If you can get your hands on a 4090 and look at the tube it would be pretty easy to figure it out and cut one down to size to match. But I also suspect DPA is using a premium 4060 or 4061 capsule with very flat response as measured.
At one time I had a 4090 and compared it to my 4006 B&K and they were close but the 4006 still have a depth of sound and a real quietness that could not be matched. And side by side on an acoustic guitar the 4090 was very good but the 4006 was just that much better.. Was it $1500 better well. I would have to say no.

[Gutbucket]

Interesting to hear your thoughts on the comparison between them, thanks Chris.

I just posted the DPA 4060 response chart without grids here.