Blackhole 5 (1 Viewer)

[PaulDF]

I plan to order my A/V 3 kit in the next few days and have a few more questions I'd like everybody's opinions on... Rather then drudge up the longish thread I started a few weeks ago, I thought I'd start a new thread to keep things simple and quick.

I've decided to definitely get the sonicap upgrade, but am undecided about Blackhole 5. I have read all I can find on this site and others about BH5, and have seen mixed rewiews. Most of the posts I've found are at least 6 months old, so I thought there might be more opinions about it by now.

Since I live in Canada, the final cost, as far as I can figure, for the two required sheets of BH5 will be about $180.00 after shipping. That is a lot of money for something that my untrained ears might not even notice. A lot of people will say to use other products, which may be effective to some degree, but I doubt any will provide as much improvement as BH5. Since I am a beginner at most of this, I don't want to cut any corners or try to improvise. I don't want to have any doubt when all is built and done. I plan to keep these speakers for many years.

I do not doubt Danny or his opinion of the BH5, as he recommends I use it.

The improvement the A/V 3s will be over my current speakers is going to be tremendous. With such a huge upgrade, is it really necessary to take those few extra steps further? I seem to be talking myself into it as I type...

All opinions appreciated! Thanks.

 

[Pete Mazz]

You could substitute BH5 with felt. Make sure the felt has a high wool content and use 1/2" or more.

Pete

 

[Hank Frankenberg]

I called an acoustical engineering company the other day and had an interesting discussion. The company analyzes sound control situations, from speakers to industrial applications. The bottom line of their advice was that BH5, like some other audiophile products, is a very expensive product that has features that don't really help (mainly, the barrier layers. The engineer said a layer of foam is hard to beat. Regarding felt, as Pete notes, I understand that it must be thick and real wool. Personally, I use the vinyl dampening sheet material from P.E.
That's all I know and will shut up now. This subject is dangerously close to interconnect and power conditioner discussions.

 

[Brian Bunge]

Danny recommends using 1" thick foam if you don't go with the BH5. As a matter of fact, on the pair of cabinets that we built for him he told me just to glue in some 1" foam.

I do like the added rigidity the BH5 adds to A/V-1's and A/V-2's, but with all the bracing in the A/V-3's I don't see it as being as much of an issue. The cabinets are already around 50lbs. each without the drivers and XO's installed.

 

[MikeSRC]

I've just started on a pair of A/V-3s (and A/V-3S center channel). Like Paul, I got the Sonicaps but not the Blackhole to save a few bucks. Danny told me that I should use a fiberfil material behind the drivers and foam on the front and back walls of the transmission line. I was planning on going with the PE 1-1/2" convoluted foam.

This forum is an incredible resource and I'd be lost on this project without it (I may still be lost, but at least I've been told the right way to do things ).

Thanks to all.

 

[Chris Tsutsui]

Hank, I'm wondering why you would use the PE Vinyl damping sheets in a speaker cabinet? Isn't that unrelated to the effects that fiberfil, wool, and blackhole5 would have on the internal resonances?

It would be like putting dynamat on the enclosure to prevent actual resonance of the wood itself changing the cabinet resonance if the cabinet isn't braced well.

IMO, adding some sort of foam, polyester, wool, etc really does add to the detail in bass and often the frequency response of the speaker. I just wouldn't go as far as to pay $180 for blackhole 5, but would settle fine for something that costs a fraction of that.

BTW, good luck with your AV3s Mike.

 

[AllanRW]

You want something to try for econ best results.
Go buy a few cheap clearance peal and stick floor tiles.
Cost $1.00 each at the most.
Line the back wall top and bottom of the cabinet with this.
Line the cabinet with 1" foam bed pad purchased for around $10.00 CND at a dollar store.
Glue the pad onto the peel and stick tiles.
The tiles the thicker the better.As you are trying to stop the cabinet vibration with this or the BH5 layer it uses.

Ultra cheap with results that are worth the time.

Good luck.
As well just to let you know Bob at CSS has some BH5

Al

 

[MikeSRC]

BTW, good luck with your AV3s Mike.

Thanks Chris. I apologize for not geting back to you, but my father-in-law has offered to help me with the cabinets. He's an amateur woodworker and has the tools I don't. So somehow, we'll muddle through.

BTW Chris, have you ever purchased any veneer from these guys: www.arborveneers.com? They're not that far away so I could actually look at the stuff before I buy it.

 

[PaulDF]

Well I looked for felt today with a high wool content, with no luck. Got some stupid looks from the ladies though. I have been back and forth today on the BH5, but now the foam suggestion is looking pretty good to me. Just ordinary 1" foam?? How dense does the foam need to be?

Brian, did you use the foam behind the drivers too? Or something else? And did you line the sides as well as the front and back walls?

I can see how the peel and stick tiles might work for resonance, but I'd be afraid they'd fall off inside the cabinet! The A/V 3s do look to be quite extensively braced, so maybe all I need is foam...

 

[Brian Bunge]

Paul,

I only installed the foam on the front/back walls below the woofers. Danny handled the rest after we shipped the cabinets to him.

 

[ThomasW]

Paul

You are confusing a couple of things.

Mass damping, adding weight to the cabinet via an adhesive metal foils, elastomeric membranes or other means to increase the weight of the cabinet therefore lowering the cab Fs.

absorbent/friction damping, these are materials such as felt/foam/fiberglass/etc. They are used to control/absorb the rear wave coming off the drivers.

Products like BH5 offer small amounts of mass damping and some absorbent damping. But IMO they are too pricey for the benefit they provide.

The best cabs have adequate mass damping simply from proper construction. They then can be fine tuned with absorbent damping materials.

You can find high wool content felt from custom gasket makers/materials in the yellow pages or it can be ordered from McmasterCarr.com

 

[Dean-P]

Solen.ca out of Quebec sell damping pad,special foam,ect.

 

[PaulDF]

Brian, that makes sense...

ThomasW, I'm not too confused yet! But you're saying there is no need to absorbent damp the side walls, correct?

I'll ask again, what kind of foam can I use? Dense or soft?

Thanks

 

[MikeSRC]

Paul, Danny told me just to do the front and back walls below the drivers.

 

[Brian Bunge]

Paul,

I just bought some cheap 1" thick stuff from an arts and crafts store. It wasn't all that dense. IIRC, it was a local Hobby Lobby.

 

[ThomasW]

Paul,

Nope I'm saying that absorbent damping should be used in cabs. Use foam or fiberglass or felt to line the interior walls.

Parts Express sells low buck acoustical foam. The thin stuff is fine for your needs. You can 'tune' the cab to your taste by varying the amount of it you use

 

[PaulDF]

ThomasW, sorry what I meant was should I line the front and back walls, but not the sides?

So I put foam up and down the transmission line of the cabinet when I build it, and I can also play with whatever I put behind the drivers by removing the drivers, then hearing what kind of a difference it makes? Should I foam behind the drivers, or use some kind of fiberglass or batting? I'd rather not use fiberglass.

I'll admit I am getting quite ahead of myself, as I haven't even ordered the kits as of yet... Just wanted to know wheteher or not to order the Blackhole 5 along with the rest of my stuff.

Mike, I'm quite interested in your thoughts on the A/V3s. From building them to finished product, if you are done yet. Keep me posted if you have the time, thanks.

 

[ThomasW]

I can't specifically comment about Danny's designs having never seen or heard one.

TL's are a different kind of animal. Unlike regular ported boxes they can be lined or stuffed and or lined and stuffed. And the stuffing can be several configurations; high density to low, low density to high, or even density through out the length of the line.

The answer to your question is EXPERIMENT, there are no right or wrongs when it comes to personal taste.

Start by lining the back wall (with foam) from the area behind the driver all the way to the outlet (port). Then listen to the results. Then line the length of the front wall and listen. Better or worse? If better, then line one side and so forth.........

 

[MikeSRC]

Thomas, that brings up a question I had on testing. Do you, and others, assemble and solder everything with the rear panel off, then temporarily attach it to test? Since the drivers need to be installed after veneering, I assume you just unsolder them when you're done testing and ready to veneer.

 

[Danny Richie]

Looks like two things really being discussed here.

Is Blackhole 5 worth the cost?

What will be ideal in the A/V-3?

First of all, I use recommend and sell Blackhole 5 for good reasons. All cost issues aside, it's is currently the best product available on the market to do what it does.

It has three main functions.

It dampens, isolates, and absorbs.

By added a less resonant mass to the enclosure it lowers the resonant frequency of the enclosures and dampens it. You can add mass with anything. You can add more MDF, you can add a sheet of Steel, etc. But those materials will also transmit resonances as much as anything.

Ever play croquet? You know, the lawn game played with wooden balls and wooden mallets? Okay. probably not and I haven't played it since my youth as well. Anyway here is the example. Take two of those balls laying in the grass touching one another. Place your foot on one to hold it down and strike it hard with the mallet. The other ball goes shooting off just as if you had hit it. Ever action... equal and opposite reaction....

Now try it again with a bag of sand between the two balls. The second ball is not likely to move much.

Blackhole five is kind of like that. It will spread energy out some and absorb it rather than transmit it. Not as well as a bag of sand, but much better than another layer of wood.

This element of Blackhole 5 can be duplicated just as Al suggested with heavy vinyl flooring. The plane vinyl is not as good of a dampener as the mineral composite BH-5 layer. But the BH-5 layer is not as thick and heavy as it could be either. Thicker vinyl flooring panels will get you close.

The second thing that BH-5 does is isolation. This is a very important function. The heavy barrier layer in the middle acts as a dead wall. It further controls vibrations by not allowing them to reach the cabinet walls. It is suspended freely in the foam layers and can move freely with pressure changes.

In sealed box applications this can even mass load the driver to a small degree.

This function of BH-5 is hard to replicate with foam/dynamat, etc. Plus, buying all the materials separately, breathing contact cement etc, is just not worth it to try to replicate.

Then there is the foam layer of BH-5. This layer is of coarse for absorbing standing waves. This can also be accomplished with fiber glass, poly fill, wool, or any other open cell foam.

But BH-5 has an advantage here also. All of those products not only absorb standing waves but also slow down the air flow in the box. It re-tunes the box the more of it you add.

BH-5 slows down the air flow in the box a small amount. Just enough to make up for the air space taken up by the barrier layers. But since BH-5 has a thin polyurethane film surface that does not allow air to pass through it into the foam, it does not slow down the air flow in the box.

For instance. Adding a lot of dampening around a port makes the port less effective because you slow down the air flow around the port allowing less air to pass.

This is a highly overlooked function of BH-5. Sound will pass right through the thin film, but air does not.

But is it really worth it? Well you have to decide that for yourself.

With the A/V-3's that I designed and what to do, here are the options.

I had Brian add a 1" layer of open cell foam in the transmission line when he built them. One because I knew he did not have BH-5 on hand. Two, I tried it that way in testing and development and it worked out okay.

Down through the transmission line there is little wall space between the braces used to create the transmission line so vibrations on those panels are minimal. However dampening (absorption) was needed down through the line. The open cell foam was used on the front and back walls of the line to control any resonance in the line. The thickness of the foam was allowed for in the design.

BH-5 in this area would be ideal but not necessary. If I were building a pair here for myself, I would use BH-5 throughout.

Now in the areas behind the drivers and the side walls around them I highly recommend the BH-5 as panel size does increase in these areas.

Still, in this design, the addition of poly fill or fiber glass materials is still needed in the air space behind the drivers and in the top area of the TR line, even with the use of BH-5.

If BH-5 is not used I would recommend some type of vinyl flooring squares, open cell foam, and or poly fill or fiberglass combinations for this design.

For some, home brewing their own dampening material is a waste of time compared to how simple and easy it can be to install BH-5. For me time is money. For others it is just all part of the fun of DIY.