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Author Topic: DPA 406x grids, their subjective HF response & potential grid mods  (Read 1185 times)

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Offline Gutbucket

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I've noticed a quality that sometimes bothers me about my DPA 4060's.  I love the mics and the recordings I've done with them, yet sometimes I notice a bit of brightness or granularity or something.  That can work to my advantage at times but isn't nearly as smooth sounding as the bigger more costly DPA mics.  Like most people here, I'm using the 4060's with the short grids.  I've listened with the long grids briefly and that quality seems more exaggerated with the larger, peakier frequency bump the long grids produce.  I imagine the quality I'm talking about may be related to or at least accentuated by the bump in frequency response either grid produces around 10khz.  Although I haven't recorded any actual music without grids (or with the long grids), I've listened without the them and the high frequencies seem overly rolled off to my ears.

What I should do is switch between short grids, long grids and no grids for a recording of some non-important music and compare (not just record my stereo). I will do that when the opportunity arises, but I figured I'd post here for discussion as well and what I'm thinking about is more to do with the principles behind the different length grid tubes rather than an opinion as to weather to use one or the other (or none).

If I find the high end lacking without the grids (which I suspect will be the case), I wonder about making a shorter version of the stock short grids.  Maybe just removing the grill portion of the grid and leaving the tube extension will make a difference, or perhaps then trimming the extension tube shorter will reduce or modify the bump without sacrificing too much top end.

I'm interested in other's experiences with these mics concerning use of the grids (or no grids) and also interested in the thoughts of those here who know much more about the mic engineering/ & acoustics issues that are involved here.  I imagine the grids create the frequency bump by means of a resonant frequency produced by the length of tube and I suspect that resonant reinforcement may introduce some minor phase issues or resonant weirdness that I'm hearing.  Even with the grids removed, the capsule is still half buried in the tube portion of the mic body.  I'm not planning to start grinding away at the mics themselves, but Guysonic modified some 10 years back to trim back that tube section of the body among other mods and reports great results, though too difficult and painstaking and costly to be a viable product for him.

I love these little mics, just wonder about making them even better sounding & versatile, Ideas?
volition > vibrations > voltages > numeric values | numeric values > voltages > vibrations > virtual teleportation time-machine experience

"Narrow or widely spaced microphone configurations are preferred. It is well-known experience that pure coincidence microphone concepts are not able to produce a satisfying natural spatial impression, due to the lack of adequate interchannel temporal relations (time-of-arrival, phase, correlation)" -Günther Theile
"The mix of the Double M/S signals with a large A/B configuration of omnis results in the spacious sound that is often desired. This option also provides decorrelated low-frequency signals." -Helmut Wittek

Offline guysonic

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Re: DPA 406x grids, their subjective HF response & potential grid mods
« Reply #1 on: February 28, 2007, 04:43:10 AM »
My experience suggests loss of high frequency noticed with no grids is more due to being used to hearing 'bump'd up' mid-high frequency response common with many types of mics.  This gives, in my opinion, a hyped high frequency sound that many come to prefer hearing. 

Having done some research with DPA 4060 series 10 years ago for getting these suitable for HRTF omni array use, it seems the longer the grid used, the more 'hyped' the microphone response.   Removing the grid entirely minimizes the response bump, but not enough for my flat response purposes.  Removing the tube that surrounds the actual rectangular upright capsule does remove the bump effects for smoother response.  Molding the capsule to seal the capsule back helps extend the lower octaves bass response. 

While I very much liked the natural sound of the 'naked' capsule, the cost/time/waste of the modification process made using this capsule not so practical for me.

JUST BEFORE receiving my first capsuled order from DPA, I posted on DAT heads digest my intention to make DSM versions using these capsules.  Core sound's L. Moskowitz picked up on this and within a year was very successful offering his HEB version using these capsules unmodified.

My experience was less successful as posted recently at: http://taperssection.com/index.php?PHPSESSID=dc5cb19c3eae03a2a98a47d2a8b6b290&topic=80233.msg1068944;topicseen#new
and my take years ago about HEB product at http://www.sonicstudios.com/faqpg1.html
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Offline Gutbucket

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Re: DPA 406x grids, their subjective HF response & potential grid mods
« Reply #2 on: February 28, 2007, 09:14:41 AM »
Since I'm dealing with totally subjective measurements by ear, it could very well be that I've become somewhat accoustomed to the frequency bump and miss it without the grids.  A longer test recording with actual music should help me determine that.  It's not the very high end that seems overly bright sometimes though and I think I may miss that extention without any grid.  After thinking about it last night and listening to various recordings of mine and others using these mics I also think that my mic'ing configuration may be what is contributing to a HF rise.

Regardless, I think it may be useful to have a variable boost between that of the standard short grid and 'no' grid, so I may experiment by trimming the longer grids I have that I never use.  I wonder if I can lower the Q (flatten/broaden the bump) by trimming the grid tube at an angle so that the length of tube will vary from the front edge to the back edge and possibly spread out the resonance somewhat.
volition > vibrations > voltages > numeric values | numeric values > voltages > vibrations > virtual teleportation time-machine experience

"Narrow or widely spaced microphone configurations are preferred. It is well-known experience that pure coincidence microphone concepts are not able to produce a satisfying natural spatial impression, due to the lack of adequate interchannel temporal relations (time-of-arrival, phase, correlation)" -Günther Theile
"The mix of the Double M/S signals with a large A/B configuration of omnis results in the spacious sound that is often desired. This option also provides decorrelated low-frequency signals." -Helmut Wittek

 

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