Topic: DPA High boost grid vs soft boost grid

[redbook]

Ok I know the theorical specs of the grids, but I'd like to hear feedback of live tests.
Any experience on these?

[M]

I have never seen it listed in the source info which grids were used.  I think that if more people did this it could be helpful.

I wonder why people list all the source info except which grids they used?

[Craig T]

I mostly ran with no grids (flat response), but if I was far back from the sound source, I'd run the soft boost grids to compensate for the HF loss.

[divamum]

Which are the ones that come with the mics new - soft or high boost?  I put them on just as protection, but I'm as yet unclear about the properties they provide... Any info welcome (I've been searching -a s this old thread shows - but still not entirely clear on their function or effect)

Thanks!

[Gutbucket]

New mics come with both.

Here's a freq graph from the DPA site:


I use the 'short' grid.  That's the one that comes installed on the mic with more grid showing.  I find the slight high end boost useful and pleasant, especially from farther back as Craig mentions, but don't find the boost objectionable up close.  Sometimes I'll EQ a little dip up there on playback if needed, but I wouldn't really know in advance if or when I'd do that so I've never run them without grids except for not very applicable tests at home around the yard, in front of the stereo, etc.

There is one thing I plan on trying the high boost grids for.. I did some tests a while back with a 8" foam Nerfball as a baffle.  I recorded a short segment of live music at a festival with the mics taped to either side of the ball facing forwards and with the caps flush in the ball facing directly to the sides. Both tests used short grids.  In the end I didn't care for either, at least not in that scenario, the sound was rather dull and lifeless (decent low end fwiw). But I did do some further ambient recording back at camp and using the high boost grids flush in the surface of the ball which were much, much better sounding, for ambient sound-scape stuff at least (mostly high frequency birds, frogs & forest noises).  I plan on investigating this further.

[Gutbucket]

..I recorded a short segment of live music at a festival with the mics taped to either side of the ball facing forwards and with the caps flush in the ball facing directly to the sides. ..using the high boost grids flush in the surface of the ball which were much, much better sounding...

FWIW the best results with the ball were with the caps completely flush to the surface facing out, not taped on tangentially facing forwards.

I recall reading that Schoeps' KFM8/360 Sphere mic has "the required equilization 'built-in' to the electronics".  I now assume this is a pretty healthy dose of high frequency boost, similar to a diffuse field curve, but more so since they probably use their diffuse field omni's in there to start with.  To make that test recording (with the short grids) more aceptable when I played it back, I added a rising EQ curve that started lower than the high-boost grid curve does, so the high-boost grid may not be exactly right to optimally to correct the ball baffle effect, but it sounded very good with the ambient (non-musical) campsite stuff. 

The longer, flat-ended high boost grid also fit perfectly flush to the surface of the ball when installed which was somehow more satisfying to my design eye than leaving that little bit of screen sticking out with the short grids.   My high boost grids are completely flat on the end with no screen visible form the side, unlike the drawing on the DPA chart above.  Yours?

[divamum]

Thank you!  That totally clears up my confusion.

I took off the extra caps tonight and I think I prefer the sound. Seems slightly cleaner to me.

I'm so blown away by these little gems I can hardly stand it!

Of course, now I'm jonesing for the M6k... I don't think it'll be too long before you see my PS in the yard sale...

[divamum]

RTFM. Because I'm an idiot, I will True Confession here:

Finally had time to look at the manual (gee, ya think?!) and now realise that you have to EXCHANGE the grids, not just snap them on to the existing ones.

However, next question - how do you get the installed ones off? I pulled a bit, but they seem VERY tight and I'm afraid of pulling too hard lest I break something!    I like the sound with those installed grids so I think we're good anyway, but I figure I should at least know about my options and how to access them....

 

[Church-Audio]

When you remove the grid the mic is not flat... The grid is a way of controlling the polar pattern on the microphone and adding high frequency correction. There is a "flat" response grid that is used on the 4090, I have not seen this grid anywhere and I wonder if it is even available separately. But removing the grid means you lose top end around the 14-20k region. DPA like Sennhieser uses a cap as a means of acoustic equalization and correction for the capsule. That’s because it’s pretty hard to find such a small capsule that will be flat to 20k with out using some sort of correction. This is also the basic principal behind Earthworks that’s how they take a $4.00 capsule and make it flat. So when you look at the cap the longer the cap is the more high frequency correction is going (boost)

Chris

[Gutbucket]

^^^
I've wonderd about this since there is no published response graph without the grid and it just sounded rolled off on the high end with out any grid on there (more than just eliminating the 10khz bump) to me.  I also notice the polar pattern modifying effect at high freqs you mention.  Is the 4090 grid on your measurment mic the same size & would it fit the 4060, Chris?

divanum, The grids are pretty snug on there. You just pull them off, but try to hold the capsule body and not pull too hard on the cable.  Difficult I know since they're so small and tapered.

[it-goes-to-eleven]

divanum, The grids are pretty snug on there. You just pull them off, but try to hold the capsule body and not pull too hard on the cable.  Difficult I know since they're so small and tapered.

Oh, I'd Never pull on the cable!

I've never taken them off but assumed I'd do it this way...  Gently hold the body with a pair of needle nose pliers and then lever the grid up a bit at a time with a small screwdriver, wedging against the pliers?

[Gutbucket]

I pinch the housing and wiggle the grid off.  Sometimes they're snug, but I've never had too much trouble.  The mic body is so small that I'm pinching both the housing and cable, together.  I certainly wouldn't pull on the cable, either.

[Gutbucket]

Anyone ever try one of these on their 406x's?


Windjammer for 4071, Grey Fur
Miniature Windjammer for use with 4071 in heavy wind. The windjammer fur coat is sewn to the mesh. This will make it totally insensitive to handling noise from any possible friction between the two materials. The presence boost of the 4071 microphone will be virtually unaffected by the windjammer, however the high frequency roll off will set in a little earlier.

Since the DUA0572 Miniature Mesh is inside the fur coat, a high frequency boost is done, which will make the loss of high frequency less prominent than normally seen (heard!) with windjammers.

[Church-Audio]

divanum, The grids are pretty snug on there. You just pull them off, but try to hold the capsule body and not pull too hard on the cable.  Difficult I know since they're so small and tapered.

Oh, I'd Never pull on the cable!

I've never taken them off but assumed I'd do it this way...  Gently hold the body with a pair of needle nose pliers and then lever the grid up a bit at a time with a small screwdriver, wedging against the pliers?

Just a friendly bit of advice never use pliers on the body of an electret or any other condenser microphone. You could cause a distortion in the mic housing and damage the capsule forever.. That mic must never be subjected to any force on the body other then holding it to remove the cap with your hands only..

Chris
 

[Church-Audio]

^^^
I've wonderd about this since there is no published response graph without the grid and it just sounded rolled off on the high end with out any grid on there (more than just eliminating the 10khz bump) to me.  I also notice the polar pattern modifying effect at high freqs you mention.  Is the 4090 grid on your measurment mic the same size & would it fit the 4060, Chris?

divanum, The grids are pretty snug on there. You just pull them off, but try to hold the capsule body and not pull too hard on the cable.  Difficult I know since they're so small and tapered.

The capsule in my 4090 is a 4060 capsule with a flat frequency response correction grill added.. And they epoxied it on Smart little fellas at DPA I think this capsule is subjected to a few more tests then the regular 4060 but its the same capsule. This grill to my knowledge is not available for resale. But I have not contacted DPA to find that out.

Chris

[divamum]

divanum, The grids are pretty snug on there. You just pull them off, but try to hold the capsule body and not pull too hard on the cable.  Difficult I know since they're so small and tapered.

Oh, I'd Never pull on the cable!

I've never taken them off but assumed I'd do it this way...  Gently hold the body with a pair of needle nose pliers and then lever the grid up a bit at a time with a small screwdriver, wedging against the pliers?

Just a friendly bit of advice never use pliers on the body of an electret or any other condenser microphone. You could cause a distortion in the mic housing and damage the capsule forever.. That mic must never be subjected to any force on the body other then holding it to remove the cap with your hands only..

Chris
 

Good grief - I was afraid even to pull them too hard with my fingers so I'd never consider using a pair of pliers! 

For the time being, they can stay as shipped; once I have a little more time I'll sit down in some good light and see what I can do!

Thanks, boys, as ever - have I mentioned recently how much I love TS?  I am SO busy at the moment that I've had little time to read at length and/or run tests with this new gear, so being able to ask a question (however dufus a one) and get a kind, clear and exactly-what-I-needed-when-I-needed it answer in time to USE the new stuff properly is HUGELY appreciated! 

[Church-Audio]

Pliers are merely a tool.. Whether you crush something with them is another discussion entirely. You need to use the right kind of plier.  My fingers cannot grasp the body of the mic effectively so I would use a tool.

If you crush the mic housing you will damage the mic.. And the neat thing is you might not even notice it but any distortion on the electret mic housing will result in a "stretching or distortion of the mics diaphragm" this will have a direct and dire consequences to the mics performance. Even with the " right " set of pliers I would never use a tool to take the cap off. You can if you have big fingers use the rubber finger condoms they work great and give you good grip over the mic cap.. Allowing you to take if off with a minimal pressure. I am sure you have fine motor skills with your hands like I do.. But Its just not worth the risk IMO.

Chris

[Gutbucket]

The capsule in my 4090 is a 4060 capsule with a flat frequency response correction grill added.. And they epoxied it on Smart little fellas at DPA I think this capsule is subjected to a few more tests then the regular 4060 but its the same capsule. This grill to my knowledge is not available for resale. But I have not contacted DPA to find that out.

Chris

Sure would be nice for them to make those available. 

It seems one could shorten a standard grid somewhat more to lessen the boost and make it flat, retaining the ~14khz response and polar pattern.  The tough part would be figuring exactly how much to trim it.  File it down until it's response matches a 4090 (or other flat 'measurement' mic) I guess.  Do you think the metal grill part of the grid has any effect other than protecting the capsule, or is it just the tube length that is effecting the response?

Hey boys and girls, here's a fun experiment to hear this effect in action: fire up your mics and monitor through some closed or in-ear phones (to eliminate potential feedback), then hold the capsule and form a little tube with your hand or fingers.  The tube doesn't have to be round.  Squeeze the opening down to a tiny hole.  By changing the volume inside the 'tube' you can easily hear the exaggerated HF boost and the relationship between the size of the opening (or is it the volume of the tube?) and the frequency of the boost.   

[Church-Audio]

The capsule in my 4090 is a 4060 capsule with a flat frequency response correction grill added.. And they epoxied it on Smart little fellas at DPA I think this capsule is subjected to a few more tests then the regular 4060 but its the same capsule. This grill to my knowledge is not available for resale. But I have not contacted DPA to find that out.

Chris

Sure would be nice for them to make those available. 

It seems one could shorten a standard grid somewhat more to lessen the boost and make it flat, retaining the ~14khz response and polar pattern.  The tough part would be figuring exactly how much to trim it.  File it down until it's response matches a 4090 (or other flat 'measurement' mic) I guess.  Do you think the metal grill part of the grid has any effect other than protecting the capsule, or is it just the tube length that is effecting the response?

Hey boys and girls, here's a fun experiment to hear this effect in action: fire up your mics and monitor through some closed or in-ear phones (to eliminate potential feedback), then hold the capsule and form a little tube with your hand or fingers.  The tube doesn't have to be round.  Squeeze the opening down to a tiny hole.  By changing the volume inside the 'tube' you can easily hear the exaggerated HF boost and the relationship between the size of the opening (or is it the volume of the tube?) and the frequency of the boost.   

The metal grill is acoustically transparent. Its absolutely the length of the plastic tube that determines the frequency response. If you really want to try and figure it out buy some brass tube from a hobby store and play around with the length of it until you can see the difference in a program the trick is to use a RTA with a good tweeter.

Chris

[Gutbucket]

Yup, I too was thinking hobby store brass tubing. 

[edit] can you determine how long (or short, rather) the grid tube is on your 4090?

[Church-Audio]

Yup, I was thinking hobby store brass tubing. 

It works great but! you have to make sure you get the exact size of the cap or it will be moot..

Chris..

[Gutbucket]

It works great but! you have to make sure you get the exact size of the cap or it will be moot..

Right size diameter you mean? Can you determine how long the grid tube on your 4090 is?

[Church-Audio]

It works great but! you have to make sure you get the exact size of the cap or it will be moot..

Ok the length of the tube from base to top where the screen starts is 0.1635 inches the Diameter is 0.215 inches. The other issue is the fact that the cap is very thin so you must make your inside diameter be the same as your caps inside diameter or this will not work...

Chris

[Gutbucket]

[quote author=Church-Audio link=topic=59502.msg1114945#msg1114945
Ok the length of the tube from base to top where the screen starts is 0.1635 inches the Diameter is 0.215 inches. The other issue is the fact that the cap is very thin so you must make your inside diameter be the same as your caps inside diameter or this will not work...

Chris
[/quote]

Cool, this is now on my extensive list of potential projects. Someday I'll give it a whirl.

Thanks Chris,
Lee