Foam or Fiberglass in my corner 'absorbers?"

[RFP]

This is probably a who cares, but Im pressing on with this little project.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

OK, I finished the basic framework of my two corner absorbers and am ready to proceed with filling the insides with whatever, and then covering them with grille cloth.

I can use either acoustic foam or the Owens-Corning 703 fiberglass stuff. I had been thinking the OC 703, but the foam would be a lot easier to cut and fit inside the cavity, positioning the wedge face of the foam toward the front to minimize any unwanted reflections (per my warnings from Dr. Who!).

In comparing the acoustic absorbing specifications for both the foam and the fiberglass, I found no sure winner apparently both would work with only a very minor difference.

So, what say ye acoustic wizards, does it make a lick of difference (I dont know squat about this!)?

Photos of one of the finished frames, below maybe it makes more clear the cavity into which Ill be putting the absorbing material foam or FG.

Thanks a lot,

Rob

[Guest " "]

how about cd's or Lp's.....looks liike it will make a heck of a rack.

 but then again...the wife probally has some candles, statues or mini flower arrangemnts in mind...

[mas]

In
comparing the acoustic absorbing specifications for both the foam and
the fiberglass, I found no sure winner apparently both would work with
only a very minor difference.

OC705

Foam sux at low and low-mid frequencies.

OC703 is much better than foam.

OC 703 is not nearly as efficient as OC705 at low frequencies.

But I am concerned with the lack of sufficient absorbent mass...

[johnyholiday]

nice johny hates corners

[RFP]

But I am concerned with the lack of sufficient absorbent mass...

Thanks, Mark

<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

True, there wont be a whole heck of a lot of mass (profound understatement). The fillable part of these things measure 21.5 each side, 2 deep at their narrowest, increasing to 8.5 deep at the apex of the corners. They are 36 high.

But, I figure, heck whatever I do, its just gotta be better than those bare sheetrock corners!

Thanks again!

Rob

[RFP]

how about cd's or Lp's.....looks liike it will make a heck of a rack.

but then again...the wife probally has some candles, statues or mini flower arrangemnts in mind...

No, no, no Mike! Those curved thingamajigs are not shelves, they are formers. They get covered with grille cloth, giving [what I hope will be] a nice plain curved face. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Rob

[rcarlton]

In

comparing the acoustic absorbing specifications for both the foam and

the fiberglass, I found no sure winner apparently both would work with

only a very minor difference.

OC705

Foam sux at low and low-mid frequencies.

OC703 is much better than foam.

OC 703 is not nearly as efficient as OC705 at low frequencies.

But I am concerned with the lack of sufficient absorbent mass...

I agree with mas...OC705.

Have you found a source locally?

I think the OC705 can be found at the following places in the DFW area. Haven't checked yet.

SPI Service Center

Ft. Worth, TX

6504 Midway, Suite 110

Haltom City, Texas 29505

817-831-4501

817-831-7104 FAX

800-839-4622

ftworth@spi-co.com

Dallas, TX

11232 Leo Lane

Dallas, Texas 75229

214-956-7781

214-352-1309 FAX

800-927-7742

dallas@spi-co.com

Drove by the Dallas location, looks like a warehouse. Close to where I work.

[RFP]

Thanks, Mark & Ron... Based on your input, I'll quit thinking about foam. From the chart shown in the link, Rockboard 60 is even better than OC 705 (especially in the low frequencies), and it's a whole bunch cheaper .

http://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html

Rob

[anarchist]

At the Pilgrimage, we got to see a variety of well-treated and thoroughly evaluated rooms. Quite a few of us left with the intention of leveraging what we heard and learned. The company who worked closely with Klipsch to create those rooms also attended the town hall. They provide products, faq's, and will also evaluate your particular room.

You can bet Dean and I will be doing some of this. There are also some lower budget ways of accomplishing the same thing.

How do I treat my room

[DrWho]

At the Pilgrimage, we got to see a variety of well-treated and thoroughly evaluated rooms.

This might be coming way outta left field, but I would not consider any of those rooms in Indy as "well-treated" []

[anarchist]

Please elaborate. What was wrong with them? Obviously not the hotel conference room we are talking about.

Auralex (sp) has measurements on their site showing one of the Klipsch rooms before and after treatment. Those measurements sure seem to indicate dramatic improvement in early reflections and bass response which would lead me to assess it as "well-treated."

Perhaps "well" is the problem. Maybe you can explain the difference between the HT room with the 700's and a "well-treated" room as you would define it.

[Deang]

The weekend was a big long painful lesson on how rooms and noise floor can make or break the sound. The sound at the mixer was horrendous. I would never even remotely consider a Jubilee purchase after hearing those setups. I told Roy, never let your speakers bleed in public like that. The chatter in the room (distortion:) was as loud as I usually listen, and there were times it was probably peaking at 85dB. The only time you could actually hear the speakers is when they were pushed to 110dB, where the lousy room acoustics completely took over and just made you want to duck for cover.

How about the Cornwall III's on Saturday? Anyone itching to buy a pair after hearing that? It would have taken Christ himself to bring those things to life -- that room could probably be used as an anechoic chamber. Hey, I'm no big fan of the Cornwall, but I must say -- I've never heard them sound bad.

The 60th Anniversay Klipschorns sounded very good. I couldn't find a single thing in the sound that I didn't like. Even an old recording of Hello Dolly with some muted trumpet sounded good. Some highly compressed recordings fell short, but on the whole the Klipschorns aquitted themselves nicely. Everytime I was in that room, people would end up doing the same thing after a few songs -- looking at the diffusion panels on the ceiling and treatments on the walls. Folks knew intuitively that something else was at work in that room. I told someone, "Ignore what you heard, Klipschorns don't sound that good."

The next year will be spent addressing my room. I will probably buy a higher powered amp first -- but every dollar spent after that will be on the room.

The CS700 HTIB System and Reference in-walls was some of the best sound I heard Saturday. If I had to make a purchasing decision based soley on what I heard Saturday -- I would take either over the RF-83 set-up or Cornwall III's.

[anarchist]

You aren't lying Dean.

I think your criticism of the Jub's though is based on hearing their potential in a much more promising location. For those who hadn't heard them, you can assess how good they would sound. There were times they were very, very good. There were also times the noise floor was so loud, they could have been anything and it wouldn't have mattered.

The Cornwall III's. I wouldn't say bad but they weren't impressive and certainly didn't live up to all the hype they receive on the forum. I don't know that the room was the problem. The programs they were running under and a too hot center channel did not show their abilities - of course, I don't know what those abilities given what I heard. Maybe the worst demo Klipsch could have given - it basically made the little HT speakers seem every bit as capable.

Btw, the surround sound in this room when compared to the other HT room proved to me that the "virtual" surround systems utilizing two speakers could not begin to "trick" the mind into believing you were hearing surround sound. That being said, the 700 speakers were amazing in their output (although driven close to max output) and would do most proud. Buy your parents, kids, or inlaws these things.

Hmmm. I would gladly take 7 of those reference in-wall speakers over the Cornwalls. If you are planning a dedicated HT, think "inside" the box here. I am still amazed by them. I will undoubtably buy a set of those in the next year. Maybe more. I really have to question whether to sell some of my speakers now and go in new directions. Jubs/Heresies for a two channel system and those inwall speakers for a HT are possibilities. Or I may just buy in-walls and build a killer master bathroom. The outdoors here will also become speaker-fied.

[HarryO]

I've already started "foaming" my listening room. I did a "rough in" and even with my minor room mods the sound cleaned up quick. The room was much noisier than I would have imagined. It's already a big jump ahead from before. I'm starting my research in my available spare time.

I left the Khorn room with the same impression. The soundproofing greatly enhanced the sound characteristics. Now it's up to me to learn what it takes to be efficient in this area. With a little help from my friends.

I also thought the Aurelex? treatments were way cool and had a good look to them.

Harry

[DrWho]

Please elaborate. What was wrong with them? Obviously not the hotel conference room we are talking about.

Auralex (sp) has measurements on their site showing one of the Klipsch rooms before and after treatment. Those measurements sure seem to indicate dramatic improvement in early reflections and bass response which would lead me to assess it as "well-treated."

Perhaps "well" is the problem. Maybe you can explain the difference between the HT room with the 700's and a "well-treated" room as you would define it.

Do you have a link for the Auralex measurements?

As far as the problems....the rooms were way too dead, and that 'deadness' was nonlinear with frequency. There is absolutely no reason that a room should have that much absorbtion - especially considering the size. I have had the opportunity to enjoy other listening rooms in the past that have sounded infinitely better than anything we heard during the Pilgrimage. Perhaps it wasn't Auralex's goal to make the rooms sound good? [^o)] I did hear a few times that they wanted the rooms to sound different.

I gotta agree with Dean (though we already talked in person about it)...the mixer room sucked (but everyone knew that from years past with the lascalas) and the heritage HT room sucked too. Them inwalls and CS-700 rocked the heeze though....perhaps it was all intentional to get us buzzing about the lessor speakers? Man, them lemmings are walking all over the green mushrooms!

http://www.rpginc.com/residential/index.htm

[Guest " "]

DeanG

"I told someone, "Ignore what you heard, Klipschorns don't sound that good.""

You were doing good til the last sentence....maybe the silver coated interconnects in those things added some polish.

[anarchist]

Measurements of Klipsch room

[mas]

Klipsch Before and After...

[mas]

At quick glance of about 2 minutes, its evident that the room really did get the treatment!

Wow! Can we say "dead"?!

A
fascinating before and after ETC. One wonders just what they were
trying to accomplish as there are MANY significant issues still
remaining!

It seems Klipsch wanted the underpinnings of what is commonly referred to as an LEDE room.

But exactly what Auralex was doing other than to deaden the room is unclear. But they certainly provided a 'dead room'.

Earlier some had wondered what the differences between approaches to absorption and diffusion were. Well, first, its not a focus on the tools, but a focus on knowing what you are trying to achieve. This room fails to meet even their own stated goals and is a poster child for absorption run amuck.

What they got was a room that has a very ill defined ITD, the realm where first order early reflections are absorbed and intelligibility enhanced. The ITD is essentially designed to be anechoic, with the latter arriving the semi-reverberant field adding to the sense of spaciousness of the room. Well, that is the concept, anyway...but no where apparent here!

Instead, what we have is an ill formed ITD that never stops. It just keeps going and going! The later arriving semi-reverberant field if absorbed so that it is lower in intensity than the supposed ITD! This is simply absorption out of control.

Note that the measurements are very confusing in that they have changed the sweep
intensity between the trials, evidenced by the fact that the direct
signal intensity varies almost 13 dB between the before and after
measurements!!! 13 dB!!! So what you are actually seeing is a change in the
general trend. A great way to intentionally obscure direct comparison.

And while you can tell that there is essentially no difference between the 'anechoic' ITD and the later semi-reverberant field,
what you don't see well is that the entire later arriving sound field is
dramatically reduced in total! They had to make the direct sound
dramatically hotter just to get the later field to even display!

The
sound field at scale 80 ms (ignoring the normalized arrival offset -
and wondering why they didn't let the TEF normalize the reading to make
the direct sound "0ms" on both measurements???...) the 'after' scenario
is almost 21 dB less {Before: 64 dB direct, 45 dB at 80 ms non-normalized vs. After: 74 dB direct, 35 dB at 80 ms non-normalized}.

Well, I will give them credit... their absorption works.

What a shame... Now where is the diffusion?

Oh yeah, they say they used 1" diffusion! If this isn't already readily and apparently humorous to you, it should be! We're talking at best, a lower effective frequency of almost 3500 Hz!. And noting the later arriving specular reflections that are still defined, but so absorbed that, well...quite frankly it is humorous to speak of the late arriving sound field. I can only ask why Klipsch paid for the diffusors!?

So
the later arriving energy has been radically reduced (deadened), while
preserving what appears to be a significant amount of comb filtering
and remaining defined (and non-diffused) specular reflections at 27,
~50, 113, 138, and 157 ms. But their intensity is so diminished that,
well, one
wonders just exactly what diffusion was used, as proper diffusion would
have diffused these specular anomalies while retaining much of the
acoustic energy which here has been radically absorbed.

Also note the remaining significant reflection at ~25 ms which is most likely from the floor.

Absorption was certainly over-used as evidenced by the almost
13 dB greater direct energy difference and the radically reduced late
sound field. This has been rendered into a dead room, not just a
rather non-reflective front room with a sense of spaciousness reminiscent of a larger room.

This is a great example of what can be done if you follow the 'absorbers are us' philosophy of room treatment advocated by the preponderance of the web sites who have only discovered absorption and how to make absorbers, but have only learned to mouth the word diffusion.

And while the use of the TEF is fascinating, it seems to not assume an understanding of other current thoughts regarding acoustical space design...well, other than the 'no reflection is a good reflection' theory derived from the classic Steven King acoustical engineering tomb entitled The Dead Zone.

Obviously this was done prior to their picking up the Russ Berger pArtScience line of Space Arrays and Space Couplers.

[Jay481985]

The weekend was a big long painful lesson on how rooms and noise floor can make or break the sound. The sound at the mixer was horrendous. I would never even remotely consider a Jubilee purchase after hearing those setups. I told Roy, never let your speakers bleed in public like that. The chatter in the room (distortion:) was as loud as I usually listen, and there were times it was probably peaking at 85dB. The only time you could actually hear the speakers is when they were pushed to 110dB, where the lousy room acoustics completely took over and just made you want to duck for cover.

How about the Cornwall III's on Saturday? Anyone itching to buy a pair after hearing that? It would have taken Christ himself to bring those things to life -- that room could probably be used as an anechoic chamber. Hey, I'm no big fan of the Cornwall, but I must say -- I've never heard them sound bad.

The 60th Anniversay Klipschorns sounded very good. I couldn't find a single thing in the sound that I didn't like. Even an old recording of Hello Dolly with some muted trumpet sounded good. Some highly compressed recordings fell short, but on the whole the Klipschorns aquitted themselves nicely. Everytime I was in that room, people would end up doing the same thing after a few songs -- looking at the diffusion panels on the ceiling and treatments on the walls. Folks knew intuitively that something else was at work in that room. I told someone, "Ignore what you heard, Klipschorns don't sound that good."

The next year will be spent addressing my room. I will probably buy a higher powered amp first -- but every dollar spent after that will be on the room.

The CS700 HTIB System and Reference in-walls was some of the best sound I heard Saturday. If I had to make a purchasing decision based soley on what I heard Saturday -- I would take either over the RF-83 set-up or Cornwall III's.

Dean can you give me your impressions on the rf-83 setup?