[BrunoB]

Has anyone tried to line their VMPS speaker with Blackhole 5 ?

http://www.gr-research.com/blackhole_5.htm

It has been used to upgrade a NewForm Research R645.
http://members.aol.com/bvirgil311/upgrade2.htm. The owner of the upgraded 645 noticed a warmer and richer sound and a better integration between the ribbon and the woofer. I think that these improvements are related to the BH5 lining.

The bass/midrange and ribbons are now one tightly integrated system. My wife looked at me and said they now have such a richness and warmth. After another 10 minutes of listening, she said it was like we were sitting right in front of a live orchestra. Before the upgrade I felt like the ribbons were carrying the voices, now they blend so well, like the speaker is one big ribbon

BH5 is used in the GR Alpha, which has been compared to the RM 40 recently (http://www.audiocircle.com/index.php?topic=3380)

azryan (the owner of the Alphas) wrote:

bass sounded fairly thin compared to my system, and the speed and slam didn't seem quite as fast or dynamic (for 40 owners he had the neos at 11:00 and the spirals at 10:30).

I thought the 40's bass impact might've had the edge being in a smaller room than the Alphas but it didn't sound like they did.

The 'have to do' knuckle rap test on the side walls felt to be honest 'thin'.
I didn't know if there's maybe a soft damping layer between inner and outer walls?, or what the cabinet's made out of at all?, but it didn't feel that dead. The Alpha's cabinet which is double ply 3/4" MDF, heavily braced front to back and side to side. and black hole 5'ed feels quite a bit more solid. Much like the latest top of the line KEF's, or B&W's.

I suspect that the GR-Alpha had a better bass because of the BH5 lining.

One of my  626R is lined with foam rubber which results in more and deeper bass.
I ordered a sheet of BH5 and will line my other 626R. I hope to report the effect of BH5 in the next few weeks.


Bruno

[BrunoB]

I received a sheet of BH5. I was surprised how heavy it feels.  The total  cost is $60 . Unfortunately, I can line only one speaker with one sheet   . With the left over, I could line the mid subenclosure. It took me three hours to do the work (not easy to do- it might be impossible you have thick arms).

Here are the pictures:
http://www.audiocircle.com/index.php?action=gallery;area=browse;album=92





Note that the pictures were taken with a  PDA (Palm Zire 71, no flash) - they certainly  would look better with a "real" digital camera.


Sound comparison will come in the next few weeks.

Bruno

[wshuff]

Any news?  How's that Blackhole 5 treating you?

[BrunoB]

Any news?  How's that Blackhole 5 treating you?

wshuff, thanks for your interest.

Unfortunately, because of a sport related injury, I haven't been able to move the speakers around for A/B testing.  I lined only one speaker  with BH5 and I need to do a careful listening comparison before lining the other one. My other speaker is already lined with a black rubber foam and and stuffed with polyfill.  It seems that the latter has slightly more bass than the BH5 lined speaker when playing mono music. I wrote "seems" because the speaker that has more bass is also placed closer to a corner.

I like the way both speakers sound - the bass is very clear. I moved up the treble and mid pods from 12:00 to 1:30.

I will provide more details when I can.

Thanks,

Bruno

[Rocket]

hi bruno,

please keep up informed of your progress with the comparison.

i have been considering using blackhole 5 in my speakers, i would however need to use 4 sheets.  these cost approx $130 au per sheet quite expensive.

it is supposed to clean up the mids in the speaker.

regards

rocket

[BrunoB]

Here are some preliminary results about the effect of BH5.


With the help of a Radio Shack sound pressure meter, I measured the frequency response of my two 626R. Both were placed side by side on a coffee table. A dense polyurethane foam was used to isolate the speaker cabinet from the table wood. The Radio Shack microphone was placed about one foot from the two woofers. Measurements were repeated two times. The second time the L/R speaker connections were reversed. I used the Stereophile CD test for the test tones. The treble and mid pads were set to their minimum values (no sound from the ribbons).

RF :  speaker lined with black open cell rubberfoam (about 1/2 inch thickness), no stuffing
BH5: speaker lined with BlackHole 5 (about 1 inch thick), no stuffing

Freq (Hz)                   RF (db)                   BH5(db)
-------------------------------------------------------------
1000                          82/83                     86/86
 200                           101/101                 101/100
 160                          100/100                  101/100
 125                           100/99                   102/100
 100                           98/98                      99/99
  80                            98/98                      99/99
  63                            94/94                      95/95
  50                            91/91                      92/91
  40                            84/84                      86/87
  31.5                          81/81                      81/81
  25                            81/81                       82/82
  20                            75/75                       75/76
----------------------------------------------------------------


The first thing that surprised me is the level of the 1Khz tone, knowing that the crossover is set at 166 Hz - I thought that I would not have much sound at 1K. When playing music in this setup, I can hear much more than just the low frequencies.

I played two Jazz tracks from the test CD. I paid attention to the bass level and thightness. I did not notice a major difference between to two speakers. However, both speakers sound slightly different.

My conclusion is that lining the cabinet with rubber foam or BH5 increases slighltly the amount of bass. In a previous listening test, I compared an empty 626R with one already lined with rubber foam and there was a bass increase in the latter.


Rocket wrote:

it is supposed to clean up the mids in the speaker

I don't think that the VMPS speakers would benefit much from BH5 for the mid frequencies. Most of the mids are coming from the ribbon panel which has its own enclosure.


Bruno