Finally the SR71 option is available for VMPS models

Pocketchange · « **Reply #20 on:** 2 Oct 2005, 11:51 pm »

Try not to get caught up with layering in a single piece over your speaker wall, like you are covereing a bed with a blanket. Cut as many pieces as needed to keep things simple and if you overlap or miss a few places don't be too concerned.
This little exercise is to add mass to an area which in most cases ends up being the central area of cabinet wall.
Rudy Bozak used to cover the inside of a few of his models with a hard wound material that looked like Angle Hair Pasta, held in place with Elmers.
Sorry, I don't remember the name of the stuff!
I'd bet a trip to a craft store would bring up some
alternative materials that would be a touch cheaper than BH5 and work equally as well. A sheet of plumbers blanket (lead) covered with a 1/2" wool
sound drop comes to mind. Check at you local theater supply outlet. I've used this in an orchestra practice room to keep the (next door) Ballet Dancers from getting miffed at the noise.
The test... was a large caliber stage ordinance which ended up being a low db thud. The dancers
were happy campers. ALSO this stuff doesn't produce vapors that may generate negative effects on interior speaker components or give you a headache...!
pc

John Casler · « **Reply #21 on:** 3 Oct 2005, 02:09 am »

Quote from: hifiguy

John:

My VMPS IIa/R LEs are coming apart this fall for a sub woofer loader replacement at the top of the speakers. Order for replacement speakers shortly.

Is it possible to try to apply the black hole option when the tops are off?

Thanks -

hifi

Hi HiFi Guy,

Sorry I didn't see this post before.

Black Hole is rather stiff and difficult to cut, but the equivlant "Sonic Barrier" from Parts Express could be applied.

It works best around the woofers enclosure area, but the more internal cabinet walls that have it the better.

CornellAlum · « **Reply #22 on:** 4 Nov 2005, 02:00 am »

Can someone tell me what the easiest way to cut bh 5 is. I just tried the old butter knife and it is still tough and those cuts sure aren't straight either. Any ideas are appreciated.

Daryan

warnerwh · « **Reply #23 on:** 4 Nov 2005, 02:13 am »

I'd try a straight edge and a utility knife. Also aviation snips would cut it.

John Casler · « **Reply #24 on:** 4 Nov 2005, 02:27 am »

Quote from: CornellAlum

Can someone tell me what the easiest way to cut bh 5 is. I just tried the old butter knife and it is still tough and those cuts sure aren't straight either. Any ideas are appreciated.

Daryan

I've heard the best method is a table of band saw.

If you use a blade it should be serrated like a bread knife, or electric carving knife, with light pressure. A straight edge knife will rip and shred the edges.

CornellAlum · « **Reply #25 on:** 4 Nov 2005, 02:37 am »

I live in a condo, I am fresh out of table saws

I got to thinking, and thought maybe a hack saw would work, I have one of those. My bread knife I tried wasn't serated nearly enough, though it cut through the material. Maybe I will try the hacksaw next

JoshK · « **Reply #26 on:** 4 Nov 2005, 03:25 am »

I used large straight tin snips, worked a charm.

CornellAlum · « **Reply #27 on:** 4 Nov 2005, 12:21 pm »

Josh,

Do you find those things at menards/home depot/lowes etc? Where would I look in the store?

BTW, the blade from a hacksaw worked much better, though I still have a ton to do. It takes a while to get it right!

Thanks guys.

~D

skrivis · « **Reply #28 on:** 4 Nov 2005, 02:12 pm »

Quote from: John Casler

Although Brian could be more specific, I don't think you can "over damp" the interior of the cabinet. It is subject to ringing, and standing waves also. It is best to do as many (and as much of all) surfaces as possible including "opposing walls" and all corners.

Ummm..... how will applying damping to the cabinet walls reduce standing waves?

My understanding is that they're governed by the shape of the interior volume of the enclosure....

JoshK · « **Reply #29 on:** 4 Nov 2005, 02:56 pm »

I think the BH5 is suppose to be highly absorptive, so it should reduce standing waves, atleast at some modes.

I got my tin snips at the orange box (home depot). I wasn't cutting BH5 exactly, I was cutting whispermat 2 which is basically the same thing. I used a razor blade & scissors at first but it makes a mess of the edges and my hand started cramping quickly.

John Casler · « **Reply #30 on:** 4 Nov 2005, 03:39 pm »

Quote from: JoshK

I think the BH5 is suppose to be highly absorptive, so it should reduce standing waves, atleast at some modes.

I got my tin snips at the orange box (home depot). I wasn't cutting BH5 exactly, I was cutting whispermat 2 which is basically the same thing. I used a razor blade & scissors at first but it makes a mess of the edges and my hand started cramping quickly.

I have heard the same as Josh.

I think while the it is said that the volume for practical purposes doesn't decrease, I think the "dimensional" lines "blur" a bit in respect to the creation of Standing Waves. I have heard that this "slightly" smooths or reduces standing waves, depending on how much BH5 is used and where.

I have no idea how much, other than it seems to make sense.

Also as far as cutting. I have heard that BH5 is much "stiffer" than Whispermat or Sonic Barrier.

I have a sheet of the "thickest" Sonic Barrier and it is easily cut with Kitchen Scissors, where I get the idea that BH5 has a "stiffer" barrier layer.

JoshK · « **Reply #31 on:** 4 Nov 2005, 03:42 pm »

The WM2 is pretty tought to cut with scissors, but the BH5 does has an extra thin layer that is suppose to be a moisture layer, otherwise the BH5 is spse to be equiv to WM2.

ctviggen · « **Reply #32 on:** 4 Nov 2005, 03:50 pm »

This winter (i.e., when I'm done doing home projects), I'm going to put BH5 in my RM40s. I can put a microphone in an RM40 and take a low frequency test (or several) with ETF. Then I can put in BH5 and perform the same tests at the same locations. This should prove whether there's a reduction in standing waves (or not).

CornellAlum · « **Reply #33 on:** 4 Nov 2005, 04:01 pm »

Can I use a standard cardioid microphone for the measurements or is omni an absolute necessity? I have a stereo matched pair of Microtech Gefell M200/210's, but no omni caps unfortunately.

Brian Cheney · « **Reply #34 on:** 4 Nov 2005, 05:29 pm »

I have just ordered 10 cases of the Blackhole 5 in order to get best price, so contact me or John Casler for special AC member pricing.

Be careful using the BH5 in ported speakers like the 626, too much will damp out most of your bass. Remove the fiberglass from inside the cabinet and go slowly, one 6x6" piece at a time, seasoning to taste.

I find the BH 5 a worthwhile stepup from the P.E. damping sheets and recommend it highly. On passive radiator systems you can use as much as you want.

CornellAlum · « **Reply #35 on:** 4 Nov 2005, 07:08 pm »

Yeah, I odered an entire case to save money, and it saves a ton. Per John Casker, I got mine from Andre at e-speakers, and real pleasure to deal with too.

I am going to do my larger this weekend as well!

ctviggen · « **Reply #36 on:** 4 Nov 2005, 08:05 pm »

I'm not sure about the type of mic. I'm just theorizing, anyway, although this would be a very easy test to do if you're taking the speakers apart.

John Casler · « **Reply #37 on:** 4 Nov 2005, 08:14 pm »

Quote from: ctviggen

This winter (i.e., when I'm done doing home projects), I'm going to put BH5 in my RM40s. I can put a microphone in an RM40 and take a low frequency test (or several) with ETF. Then I can put in BH5 and perform the same tests at the same locations. This should prove whether there's a reduction in standing waves (or not).

That would be interesting.

How would you get a mike into a sealed cabinets to do the readings?

I can see a whole new "niche" industry of acoustic treatment for the "inside" of your speakers.

You know "lambs wool", BH5, mini-bass traps, diffusors, all for the "INSIDE" of your speaker cabinet.

CornellAlum · « **Reply #38 on:** 4 Nov 2005, 08:16 pm »

One feasible possibility would be to run a microphone, assuming the cabinet is ported, through the port hole and tape it to a side wall perhaps.

ctviggen · « **Reply #39 on:** 4 Nov 2005, 08:21 pm »

John,

I was thinking that I when I open the speakers, I would route a thin set of wires into the cabinet. I would have to run them so that the bass/midrange could then be put over the wires. I'd then play the normal test tones from ETF. I'd tape the mic somewhere, near a corner perhaps. I could use several different locations. It would be interesting to go front to back (or side to side), but that might take more rigging than what I'd like to do. I could easily perform a test with stuffing/wool and none. I'm interested in this just because I saw a product that had ridges on it and the idea was that it would break up the standing waves.