I read an intriguing quote from the RPG product info. If I read
correctly, what they are saying is that pourous absorbers (like
Auralex stuff) doesn't work well for bass trapping on walls/corners
(see below).

Does this mean those big huge Auralex Venus traps really don't work
that well for taming bass/room modes?



RPG corner trap info quote:
"Small rooms often exhibit poor low frequency response with
significant emphasis at modal resonances. They also have limited space
to make acoustical improvements. Porous surface absorption is
ineffective at these modal frequencies, because the air motion near
walls and in corners is essentially zero for these long wavelengths.
RPG® research solved this dilemma by developing a unique membrane
system that converts the high sound pressure fluctuations typically
found in corners into selective absorption in the modal frequency"

gap,
Foam corners don't make bass traps... no matter what bs.they are slinging.

Ethan, care to chime in?
Check out www.realtraps.com in the mean time. Ethan has some very good free
information and links about this stuff (acoustics) on his site. Read it
before you buy a bunch of foam and glue it on the walls.

They do trap something, but it isn't bass, more like your money.

Ethan explains it much better than I possibly could.

thx,
neil

"xy" wrote in message
om...
I read an intriguing quote from the RPG product info. If I read
correctly, what they are saying is that pourous absorbers (like
Auralex stuff) doesn't work well for bass trapping on walls/corners
(see below).

Does this mean those big huge Auralex Venus traps really don't work
that well for taming bass/room modes?



RPG corner trap info quote:
"Small rooms often exhibit poor low frequency response with
significant emphasis at modal resonances. They also have limited space
to make acoustical improvements. Porous surface absorption is
ineffective at these modal frequencies, because the air motion near
walls and in corners is essentially zero for these long wavelengths.
RPG® research solved this dilemma by developing a unique membrane
system that converts the high sound pressure fluctuations typically
found in corners into selective absorption in the modal frequency"

I beg to differ - although I won't go out on a limb and claim that the foam
thingies by Auralex or the generic models from Markertek are "Bass Traps" in
the true sense of the word - they really do tighten up the bass response in
a room - or at least they did in mine. The difference was very noticeable
even by my non-musician friends. Until I can justify Ethan's EXCELLENT
"realtraps" from a budget standpoint - the corner foam thingies have really
improved the sound in MY room - your mileage may differ...

Also important (at least to me anyway), I put my subwoofers (and speakers
too) for both my speaker systems up on those Auralex "Mo-Pads" in an attempt
to "decouple" the subs from the floor that they were on. That also helped -
and would probably be a minimum first step for apartment dwellers...

--
John Marsden
Little-Big Sound
audio for video, film & digital media; graphics & software solutions
www.lbsound.com

"neil davis" wrote in message
link.net...
gap,
Foam corners don't make bass traps... no matter what bs.they are slinging.

Ethan, care to chime in?
Check out www.realtraps.com in the mean time. Ethan has some very good
free
information and links about this stuff (acoustics) on his site. Read it
before you buy a bunch of foam and glue it on the walls.

They do trap something, but it isn't bass, more like your money.

Ethan explains it much better than I possibly could.

thx,
neil

"xy" wrote in message
om...
I read an intriguing quote from the RPG product info. If I read
correctly, what they are saying is that pourous absorbers (like
Auralex stuff) doesn't work well for bass trapping on walls/corners
(see below).

Does this mean those big huge Auralex Venus traps really don't work
that well for taming bass/room modes?



RPG corner trap info quote:
"Small rooms often exhibit poor low frequency response with
significant emphasis at modal resonances. They also have limited space
to make acoustical improvements. Porous surface absorption is
ineffective at these modal frequencies, because the air motion near
walls and in corners is essentially zero for these long wavelengths.
RPG® research solved this dilemma by developing a unique membrane
system that converts the high sound pressure fluctuations typically
found in corners into selective absorption in the modal frequency"

And yet another confusing perspective.

I had Auralex Lenrds in all my corners (4 in each corner) yes the bass
traps tightened up the bass a little bit (of course I was in a 14x11
room, so anything would have helped.) But did it make my bottom end
true? NO

What I heard in the bottom was not what I would get wqhen I went to the
car or any other reference for that matter. As a matter of fact when I
called Auralex for consultation about what it would take to even out my
room, they replied I would have to buy the venus Fly trap and use it
in Addition to the Lenrds. So in other words, 16 lenrds and 16 Venus
Fly Traps (about $3600.00). (They said I might be able to get away with
8 Fly Traps. 2 on each wall in the center) Still $2000.00

Well consodering the cost of Lenrds at $25/each (GC) and Fly Traps at
$200/each (GC)

It was easier to visit http://www.johnlsayers.com/phpBB2/index.php
and build me a studio (control room)

visit this link to see what I built.....

And because I did all the Labor myself, it came in around 1200.00 Of
course I live in Michigan so your prices on lumber and materials may
vary.

Now I have accurate acoustics. My room is relatively flat from 40Hz to
20 Khz (+/- 3dB measured)

http://www.johnlsayers.com/Studio/Pages/Giles.htm

On 2004-02-24 07:46:19 -0500, "John Marsden" said:

I beg to differ - although I won't go out on a limb and claim that the foam
thingies by Auralex or the generic models from Markertek are "Bass Traps" in
the true sense of the word - they really do tighten up the bass response in
a room - or at least they did in mine. The difference was very noticeable
even by my non-musician friends. Until I can justify Ethan's EXCELLENT
"realtraps" from a budget standpoint - the corner foam thingies have really
improved the sound in MY room - your mileage may differ...

Also important (at least to me anyway), I put my subwoofers (and speakers
too) for both my speaker systems up on those Auralex "Mo-Pads" in an attempt
to "decouple" the subs from the floor that they were on. That also helped -
and would probably be a minimum first step for apartment dwellers...

not sure if you're saying I'm confused, or just confusing the situation....

Let me reiterate that I'm NOT claiming that the foam thingies are Bass
Traps - they are NOT. But, for ME (and that's who's important here in this
equation...), they tightened up the bass in the room in which they were
installed. I neglected to mention that I also built 10 2' x 4' frames with
2" foam in them which were hung like artwork around the room to tighten up
the mid/high frequency slap. There were still areas of wall - I didn't
completely cover ALL walls with foam, etc. I needed space to hang my gold
records...just kidding.

The combination of the three products; wall art; corner foam & Mo-Pads
provided ME with a mix/tracking environment that translated well to TV, car
stereos, home stereos, headphones, other people's listening environments,
etc. Correct me if I'm wrong - but the point isn't an accurate room - it's
a room that translates well to other rooms and systems, right? All at a
total cost of around $300 + a weekends labor putting together the frames to
hold the foam (PEOPLE - RESIST the URGE to glue foam to walls - your
landlord or future homeowners will NOT like the results...).

Again - your mileage may vary - but it worked for ME. I'd love to have a
space that I could build out, but that's not a possibility in my current
location - hence MY solution to the issue.

--
John Marsden
Little-Big Sound
audio for video, film & digital media; graphics & software solutions
www.lbsound.com

"Bryan Giles" wrote in message
news:2004022408074016807%giles117@ameritechnetnosp am...
And yet another confusing perspective.

I had Auralex Lenrds in all my corners (4 in each corner) yes the bass
traps tightened up the bass a little bit (of course I was in a 14x11
room, so anything would have helped.) But did it make my bottom end
true? NO

What I heard in the bottom was not what I would get wqhen I went to the
car or any other reference for that matter. As a matter of fact when I
called Auralex for consultation about what it would take to even out my
room, they replied I would have to buy the venus Fly trap and use it
in Addition to the Lenrds. So in other words, 16 lenrds and 16 Venus
Fly Traps (about $3600.00). (They said I might be able to get away with
8 Fly Traps. 2 on each wall in the center) Still $2000.00

Well consodering the cost of Lenrds at $25/each (GC) and Fly Traps at
$200/each (GC)

It was easier to visit http://www.johnlsayers.com/phpBB2/index.php
and build me a studio (control room)

visit this link to see what I built.....

And because I did all the Labor myself, it came in around 1200.00 Of
course I live in Michigan so your prices on lumber and materials may
vary.

Now I have accurate acoustics. My room is relatively flat from 40Hz to
20 Khz (+/- 3dB measured)

http://www.johnlsayers.com/Studio/Pages/Giles.htm

On 2004-02-24 07:46:19 -0500, "John Marsden" said:

I beg to differ - although I won't go out on a limb and claim that the
foam
thingies by Auralex or the generic models from Markertek are "Bass
Traps" in
the true sense of the word - they really do tighten up the bass response
in
a room - or at least they did in mine. The difference was very
noticeable
even by my non-musician friends. Until I can justify Ethan's EXCELLENT
"realtraps" from a budget standpoint - the corner foam thingies have
really
improved the sound in MY room - your mileage may differ...

Also important (at least to me anyway), I put my subwoofers (and
speakers
too) for both my speaker systems up on those Auralex "Mo-Pads" in an
attempt
to "decouple" the subs from the floor that they were on. That also
helped -
and would probably be a minimum first step for apartment dwellers...

Neil & others,

Ethan, care to chime in?

There's no question that foam corners can improve a room and tighten up the
perceived bass. What a lot of people miss is that the most important bass
problems occur above 80 Hz, not below. Foam corners like Auralex LENRDs, and
less expensive but otherwise equal devices from Foam By Mail, do help above
200 Hz or so. You can look at the various published specs to see how well
these products work and at what frequencies.

That said, there's no way that foam corners are as effective as high
performance absorbers like MiniTraps, which work very well from about 60 Hz
and up. More important, when considering a total solution, foam is no
cheaper than better products. I'm amazed when I see people spend $1500 or
more on foam, which costs all of $20 to manufacture. If you have THAT kind
of budget you can do far better than foam. IMO foam is more appropriate when
you have only $200 or so to spend altogether.

As for the RPG membrane traps, I'm sure they work well around their center
frequency. I used to sell a similar product (though for about 1/3 the cost!)
so I know it's possible to get high absorption at fairly low frequencies.
The problem with standard membrane traps is the absorption is useable over a
range of only an octave or so. So now you need two or even three different
trap types. Which in turn means you need to buy twice as many traps since
each covers only part of the range. This is why I developed MiniTraps, which
offer the best features of each trap type. They're based on double density
rigid fiberglass, which alone absorbs three or four times more than the same
thickness of foam. A membrane is then added to increase absorption even
further at the lowest frequencies.

--Ethan

"neil davis" wrote in message
link.net

Foam corners don't make bass traps... no matter what bs.they are
slinging.

Right. If you figure out what depth of foam it takes to actually absorb 50
Hz you'll think twice!

Most 2" foam and 4" RPG diffusers start doing their thing above about
300-500 Hz. AFAIK, this stuff scales linearly so to go 10 times lower in the
frequency domain, you need about 10 times the depth of material. Check out
your basic good anechoic chamber to see what it takes to get good absorption
down to 20 Hz.

The 2" and 4" products do provide a perceived advantage in the bass range,
but they achieve that mostly by cleaning up the midrange. That leaves
problems that were basically in the bass, pretty much unchanged.

thanks for all the input guys