SRS 1.2TL with Blackhole 5 Damper

I made my first set of BH5 for the left speaker. It took me 4 hours to complete it. If all works well, the next set for the right speaker should take less time. Here is what it looks like.

I applied the BH5 only to the midrange drivers and tweeter area. No BH5 was applied to the PR area.

I did not pull off the back adhesive for now. This allows me to take out the BH5 if I want to experiment or if I want to remove it in case I am not happy with the results. If I like the results, I will remove the back adhesive for a permanent fixture.

Here is what the polyfill looks like - in the nude.

Its time to send the drivers and PR back "home" and test the sound. I need to make some final touches with the BH5. If this sounds good, those final touches will be complete.

I forgot to mention a few additional items you will need to complete this project, so I will sumarize it here -

steel wool
a vaccuum cleaner
scissors
pen or pencil and paper - to record the measurements of each cut you make on the BH5 for the first speaker. It will help make the cutouts for the second speaker go more qickly.
A Permanent Marker - I find this helpful to mark the measurements of the larger panels you will be cutting on the back of the BH5.
a measuring tape
a screwdriver or drill
A flashlight
A utility knife
A dust mask - in case when working inside the cabinet, the wood may give off a unique scent that some may find overwhelming to take in (like me).

You may find other items helpful to complete this project. This list should

OK, I tried out the BH5 in my left channel speaker for a couple of hours. I figure to share the experience with fellow polkies on what my initial reaction is. My first reaction is that thi stuff works too well. It dampend so much that I did not hear anything coming from the speaker. The effect was silently deafaning. I went checking around to see what was going on and I think I found the culprit.

Now it was time to do some critical listening. At first, I was pleasently surprised. I heard more midrange and trebble with the polyfill being replaced. However, I felt something was... missing. The sound felt lighter, without impact, and a lack of bass coming from the left side of the speaker. I was tempted to remove the BH5 and put back in the polyfill. I removed the grille and discovered what was missing. Only a trained eye can discover this small detail on what is missing. I leave it to you to see if you can find it.

Before I get into what it sounds like, I will start with where the BH5 was applied - it was applied only to the back wall, starting from the midrange and tweeter area, working my way up to the top of the speaker. I did not apply the BH5 to the top pannel or the sides. This may change in the future. If I apply any damping to the top pannel or sides, I may use Sonic Barrier. I am not certian yet in which direction I will go. I did not try using the BH5 with polyfill as some people have with their speakers. This may change in the future.

OK, so, what does it sound like? Well, lets say that once I took care of a couple of "problems", I was able to take it for a test drive for a couple of hours.

My initial thoughts is that the sound is very pleasing. The sound on the left speaker with BH5 applied was more lively. The mids seemed to be a bit more stronger, and tweeters were brighter comparing it to the right side. I did not notice any stronger bass or an expanded SDA presence, but my ears may need to adjust. (Hint - Bridezillas and the We channel does not make an effective test platform for an SDA speaker. This was not done out of will.) I will give more feedback on this later in the week when the We channel has been effectively blocked.

To sum it up, I really like the results I hear so far. I am looking forward to applying it to the right side, which I hope to get to it later in the week, or by the new year. After applying it to the right side and doing some critical listening, I will give my recommendations - yea or nay.

Once trebble balance was restored, I wanted to take on the challenge that was posed by Tool for Life - to try polyfill with the BH5 damper. My first thought about this idea was that the speaker would be completely dead and lifeless. The thought of this was discouraging. However, I rethought the idea since the BH5 is applied only to the back wall (no padding on the sides), I became concerned with the lack of polyfill would have an effect on the bass - it may not be as effective as it would be with the polyfill in place. I do sense the bass slightly favoring the speaker with polyfill over just the BH5. I am not sure if my thoughts are real, or if it is all in my head.

Despite my thoughts, I proceeded to fill the right speaker with BH5 and add the polyfill as of last night. So now, both speakers have BH5. Only the right speaker has polyfill added. The polyfill and BH5 is added only to the midrange area. No fill is in the PR area, and should be avoided at all costs!!! If anyone is thinking of taking this project, remember not to apply any fillers in the PR area. Keep it in the midrange area and above!!!

So with the limited sampling for the past couple of hours, I do not sense any difference in the midrange and trebble areas. But I do sense that the right speaker (filled with BH5 and polyfill) has a slight edge in bass output. I still need to perform more sampling between the speakers and will update my progress.

I am considering cutting the polyfill taken from the left speaker to cover just enough of the first set of midrange speakers over the PR area in an attepmt to even the bass without covering the entire midrange area.

Thanks Outfitter03.

I will answer what I can.

Outfitter03 wrote: »

A couple of questions for the OP or anyone else who may know the answers.

Is the adhesive on the Black Hole 5 better than on the Sonic Barrier or does it also require additional glue or mechanical attachment to remain in place?

Although I have not pulled off the adhesive covering yet for permanent fixture, the Blackhole 5 does have its own adhesive and it feels pretty good. For best adhesive results, lightly scouer the areas where you would place the BH5.
I have not used Sonic Barrier, so I cannot make comparisons. ToolForLife may know the answer to this.

Outfitter03 wrote: »

Are the two small pieces of polyfill shown in Post #9 all the polyfill that is placed in the 1.2TL? This would not seem to provide much damping.

The polyfill picture can be deceiving - they are not small at all. The two peices of polyfill covers the entire midrange area. Each peice is 13 inches wide by 32 inches in height - unfolded. When you insert them into the SRS, you will fold them. The folded measurement is ~7 inches by 32 inches.

Outfitter03 wrote: »

Why would you not want to have polyfill behind the tweeters? Do the magnets/base prevent the high frequencies from going into the speaker enclosure?

Your assumption is correct. Some additional info:

The polyfill can reach the tweeter area quite easly, but because the tweeters are sealed (unlike a driver which has a gasket) and because of the internal bracing inside the cabinet, there is no need to emphasize polyfill in the tweeter area. The bracing does keep the polyfill seperated in their own areas, but the bracing does not impede on the polyfill from forming around the tweeters.

I used the BH5 behind the entire surface of the midrange area, so the wall behind the tweeter area is also covered. Someone can chime in if they want to add any input to this question.

Outfitter03 wrote: »

Very nice thread PolkMaster1 and thanks for sharing your progress. Those are incredible looking speakers!

Thanks again. I hope to share more with other projects I have for this speaker.

dcoil wrote: »

Just when I think I've got all the mods done to my Polkies, someone comes up with another one!! Cut it out already

Seriously, thanks for the write-up!

Your most welcome.

I should mention two things:

1. that ToolForLife had done this not to long ago in the past and wrote a thread about it. I am not the first to post about BH5 in a Polk speaker. I do not know if other threads exist about BH5 in their PA Speakers.

Tool was not satisfied with his results. I spoke with various people regarding the BH5 (including Tool) on where it would be best to apply it. I took the project in a slightly different direction and got satisfactory results.

2. After visiting the Sonic Craft website many times and reading about BH5 on their website, I was leaning in this direction on if I should apply it to my speakers for a couple of months before taking on this project (a sale also helps!). I only found out about Tools writeup after I made my decission to take on the project and his input helped point me in the right direction on where and where not to apply the BH5.

If you decide to take on this project and follow the instructions I laid out, keep in mind that most of your time will be spent measuring and cutting - measuring 60%, cutting 40% on the first speaker. Then 40% measuring, 60% cutting on the second speaker - assuming you recorded your measurements on the first speaker. You may need to take secondary measurements when applying it on the second speaker - some of the bracing is opposite for each speaker.

This stuff is thick, so cutting is a challenge, even with a utility knife and really good scissors. I dont have carpet scissors, so I cannot say how that will work on BH5.

And the backing makes it difficult for permanent markers, pens, and pencils to make a solid permanent mark. I find pencil is the best when I make lines, but you do have to go over the lines several times to make the mark stand out. Pen is very difficult to use on the backing, and permanent marker looks like a water marker on this backing.

Face -

I read somewhere that they used a saw to cut through the BH5 with good results. Cant remember where I read it. Again, I have not tried this, nor do I have access to carpentry items - most of us apartment dwellers do not have such things lying around, unless we do carpentry for a living. I am not one of them.