Sound insulation on the front of the baffle

0 Members and 1 Guest are viewing this topic. Read 620 times.

Bumpy

  • Jr. Member
  • Posts: 221
Sound insulation on the front of the baffle
« on: 16 Jun 2019, 10:42 pm »
If I put my ear against the baffle on my OBs I can clearly hear the signal from the midrange driver. Unlike others have mentioned, I cannot sense any vibration by touch.

So, can I improve SQ by sticking sound insulating panels on the front of the baffle. Others seem to suggest felt, but surely this is too thin to be effective. I am thinking say 8mm neoprene sheet.

What are your experiences?

Bumpy

  • Jr. Member
  • Posts: 221
Re: Sound insulation on the front of the baffle
« Reply #1 on: 18 Jun 2019, 03:24 pm »
Well, 100 views and no comments. I cant believe this has not been considered before.   :popcorn:

richidoo

Re: Sound insulation on the front of the baffle
« Reply #2 on: 18 Jun 2019, 06:13 pm »
If you can't feel then vibration by touch then it's not a big problem. Direct ear contact is not a meaningful test. If you can hear midrange blurring in the music from your listening position, then you should add mechanical bracing and/or damping that is effective in the blurred frequency range. I have found truss style bracing attached close to the driver to be most effective for audible box vibrations.

Another good approach to damping vibes in OB is making a sand filled baffle. Check out this madman:  :D
https://www.audiocircle.com/index.php?topic=70871

A dozen years ago "diffractionbegone" was a fad here on AC. Felt pad on front bafle. You can search the several threads about it.

Neoprene will not work as vibration damping material because it is low mass and springy. Bitumen or thick roofing membrane is good damping but bracing where possible is an order of magnitude better. Admittedly bracing is easier applied to traditional boxes, but think truss and you can come up with effective bracing strategy for OB. Bracing will raise the resonant frequency of the surfaces, making a damping membrane more effective.

mcgsxr

Re: Sound insulation on the front of the baffle
« Reply #3 on: 18 Jun 2019, 07:56 pm »
If you search up the "Gravity well of a darkstar" thread here, it was discussed.

A few people used cork on baffles, or at least it was suggested.

I never found it an issue in my 10-12 year OB journey, so I never tried anything on the baffle.

Like those tweeter felt circles that were popular around 20 years ago I guess.

S Clark

  • Volunteer
  • Posts: 5770
  • measurement? We don't need no stinkin measurement
Re: Sound insulation on the front of the baffle
« Reply #4 on: 18 Jun 2019, 08:12 pm »
The DiffractionBeGone tweeter surrounds  worked (but their inventor, Jim Goulding, hasn't been around for a couple of years), and Danny Richie made measurements showing the smoothing effect.  I have used 1/2" felt on baffle edges- not the prettiest option but effective.  As far as thickness, for higher frequencies, it doesn't take much thickness to effectively reduce diffraction effects of the wave and boundaries. As you get to upper mids, the need for thickness increases. 
Here's a review of DiffractionBeGone from a few years back.  http://www.stereomojo.com/Diffraction%20Be%20Gone%20Review/DIFFRACTIONBEGONEREVIEW.htm

matevana

Re: Sound insulation on the front of the baffle
« Reply #5 on: 18 Jun 2019, 10:26 pm »
Hey Bumpy,

I built an 18" x 18" test baffle, with 1/4" carpet tiles on both sides of a 1/2" void free plywood core. It's an interesting building material as the carpet side tends to suppress reflections while the rubber base adds a degree of damping.  I could not hear sound coming off the baffle in the way you described. If anything, it sounds a bit dry when compared to the same size baffle w/o the tile. I built a stereo pair and discovered that any concerns over the sound being too dry were not warranted. It actually sounds quite good. 

bladesmith

  • Full Member
  • Posts: 1201
  • water quenching steel since 2001....
    • palmer knives
Re: Sound insulation on the front of the baffle
« Reply #6 on: 19 Jun 2019, 03:04 am »
 :popcorn:

Bumpy

  • Jr. Member
  • Posts: 221
Re: Sound insulation on the front of the baffle
« Reply #7 on: 19 Jun 2019, 08:09 am »
Thanks lads, some good stuff there.

I suppose I ask myself, if the midrange driver could magically be turned off but the sound it transfers to the baffle remain intact, would I be able to hear the baffle singing along?

Bumpy

  • Jr. Member
  • Posts: 221
Re: Sound insulation on the front of the baffle
« Reply #8 on: 19 Jun 2019, 08:12 am »
Hey Bumpy,

I built an 18" x 18" test baffle, with 1/4" carpet tiles on both sides of a 1/2" void free plywood core. It's an interesting building material as the carpet side tends to suppress reflections while the rubber base adds a degree of damping.  I could not hear sound coming off the baffle in the way you described. If anything, it sounds a bit dry when compared to the same size baffle w/o the tile. I built a stereo pair and discovered that any concerns over the sound being too dry were not warranted. It actually sounds quite good.

I suppose I could do the ear against baffle experiment then repeat with the sound panel (carpet tile) between the two.
« Last Edit: 19 Jun 2019, 10:41 am by Bumpy »

FullRangeMan

  • Volunteer
  • Posts: 11957
  • All Tweeters look like a target, then shoot them!
    • Never go to a psychiatrist, adopt a straycat or dog. On the street they live only two years average.
Re: Sound insulation on the front of the baffle
« Reply #9 on: 19 Jun 2019, 01:39 pm »
If I put my ear against the baffle on my OBs I can clearly hear the signal from the midrange driver.
No problem, this is the effect from a wide baffle need for OB.

Unlike others have mentioned, I cannot sense any vibration by touch.
There is no significant vibration on an solid OB panel as it dont retain sound waves as a boxed enclosure, this is normal.

So, can I improve SQ by sticking sound insulating panels on the front of the baffle.
It will lower SPL, the final result is a matter of personal taste, but as no one had used it so far...

Others seem to suggest felt, but surely this is too thin to be effective.
There is various thickness of felt, I have a roll of black felt 5mm and other massive 10mm that I was intend to use in a Line Array that never let the plans due lack of a 1 ohm FR driver. These felts were order made for a local brothel and I happend to being in the weaving plant on the day they were ready to ship so I could buy the footage I need it without major problems, it did not cost cheap but there was still another much more expensive thickness of 50mm in red colour for a suite floor.

Bumpy

  • Jr. Member
  • Posts: 221
Re: Sound insulation on the front of the baffle
« Reply #10 on: 19 Jun 2019, 03:10 pm »
There could be another approach to this issue of unwanted sound transferring to the baffle. Assuming that the drivers need to be mounted in a conventional way are there screws or gaskets that can reduce the transfer of sound.

matevana

Re: Sound insulation on the front of the baffle
« Reply #11 on: 25 Jun 2019, 05:22 pm »
Many have tried to decouple the driver from the baffle by using a rear mount, isolation clips, etc. But what if the baffle itself was unconventional? If a baffle's primary function in OB is to (1) support the driver while remaining non resonant and (2) reduce cancellation by putting distance between the front and back wave, what if the entire baffle was made of a material that accomplished these goals?  Perhaps something like alternating layers of high density foam, or acoustical sound tile, or both?

mcgsxr

Re: Sound insulation on the front of the baffle
« Reply #12 on: 25 Jun 2019, 06:36 pm »
I recall seeing people try styofoam or EPS for baffles. 

I never tried that, though it would be light to move around and super easy to shape.

That might address vibration.

matevana

Re: Sound insulation on the front of the baffle
« Reply #13 on: 25 Jun 2019, 07:20 pm »
I was thinking of something along the lines of mass loaded vinyl (MLV). It's used in underlayment and appliance panels, and is rigid enough to support a driver.  It has one of the highest soundproofing coefficients so it would be effective in reasonable thicknesses (like a baffle).   



chips666

  • Jr. Member
  • Posts: 7

matevana

Re: Sound insulation on the front of the baffle
« Reply #15 on: 26 Jun 2019, 04:58 pm »
Cool!  Would not have thought that a Styrofoam cello actually produces more volume.