Room conditioning on the cheap?
David Abrahams
Hi,
I'm hoping for some sage advice. I've been trying trying to improve
the sound conditions in the practice room I have in my basement.
Here's the basic layout (look at this with a monospaced font like
courier):
|<--- 14'---->|
+----------. ---------- .+ ---
|futon couch\ / | ^
| here ` ' | |
| | |
+-------+ | 12'
| | |
| | |
| | V
+ +----------------------+ ---
\ /
\ /
\______/
My band mostly practices in that 12x14 region. The drummer is set up
in the upper right -- we only plan to use that door in an emergency.
I gather the drums should come out of the corner, but that's a
different issue, I hope.
My biggest problem right now is that the whole room/PA setup rings
like crazy at what sounds like around 67 Hz, with just one SM58 on.
At some reasonable volumes you can just stomp on the carpet or thump
one of the walls (especially the doors) and it will start. I can get
most of the ringing to stop by patching in my Behringer Feedback
Destroyer Pro, but that doesn't really change how the room sounds;
it's still going to suck for the bass player, for example.
I've got dropped "acoustic tile" ceilings with a layer of 1
lb.-per-square foot mass-loaded vinyl for soundproofing on top (in
case it matters). I recently replaced the lightweight hollow-core
doors with the heaviest wood doors I could find at Home Despot. The
walls are 4 inch thick concrete block; I've placed squares of
convoluted ("eggcrate" shaped) acoustic foam around the part of the
room we play in to try to knock out some of the reverb, but as I
learned, that stuff doesn't do anything for bass frequencies.
So, thinking I need bass traps I looked around at prices. Most
"serious equipment" looks to cost thousands of dollars per room, but
I'm not trying to build a pro recording studio down there -- at least
not yet -- and my wife is growing weary of seeing all the money going
into the basement. The Auralex LENRD wedges seemed to be the only
thing that might be in the ballpark for me.
I picked up 4 of them today. I figured that I might have to get more
pieces, but that at least I could try these and find out if I'm on the
right track. I tried putting them in various configurations in the
rightmost corners of the room, but there was NO discernable
difference. So now I'm at a loss.
I've obviously been flailing about without a clue here for some time,
and pretty soon it's going to get seriously expensive. So, I'm asking
if someone can set me on the True Path Towards Passable Sound at a
Reasonable Cost.
Thanks in advance for your indulgence,
--
Dave Abrahams
Boost Consulting
www.boost-consulting.com
play_on
<da...@boost-consulting.com> wrote:
>So, thinking I need bass traps I looked around at prices. Most
>"serious equipment" looks to cost thousands of dollars per room,
You should have skipped the Auralex and bought some 2" fiberglass and
built your own traps. They make a huge difference. Ethan Weiner's
site has plans for the traps. Doing it yourself or with a friend's
help you can treat that room for under $800.
Al
David Abrahams
> On Mon, 14 Feb 2005 18:11:34 -0500, David Abrahams
> <da...@boost-consulting.com> wrote:
>
>>So, thinking I need bass traps I looked around at prices. Most
>>"serious equipment" looks to cost thousands of dollars per room,
>
> You should have skipped the Auralex and bought some 2" fiberglass and
> built your own traps. They make a huge difference. Ethan Weiner's
> site has plans for the traps.
I guess you mean http://www.ethanwiner.com/basstrap.html (it's
"Winer"). I saw that site, but it seemed a lot of information I'd
need was missing. Like for example, how many of these do I need?
What sizes? Where would I place them? I see some hints at the
answers on that page, but I'm really and truly clueless in this
department, so I'd need some help filling in the gaps.
> Doing it yourself or with a friend's help you can treat that room
> for under $800.
Well, my total outlay so far was $115, and I can return them to Guitar
Center, so it seemed like a safe experiment and a whole lot faster
than more hacking at the room (of which I have done much already)
without complete information. Mr. Winer said he spent a week on traps
for his studio -- full-time, I presume.
Unfortunately, $800 is pushing the budget a bit at this point, but if
that's what I need I'll probably find a way to do it.
offpeak808
speakers. Try moving speakers, mic position, whatever to see if it gets
better. If you can't avoid this, you can try a "tighter" microphone. Do a
search on RAP for hypercardiod vocal mics and feedback then see if you can
get one on a trial policy from a store. May take care of the problem right
away.
If not, then you can do some complicated math (which you should eventually
do if you want to understand the weird nature of sound) and buy some
expensive "treatments," but in the end here's a simple easy and effective
solution that will get your room sounding better:
1) You'll want to get about 50% of the walls and ceiling covered in 6"
Corning 703 acoustic panels that you can make yourself. This will take care
of a majority of your practice room acoustic problems. I use and really
appreciate their improvement to my club acoustics and it's adjoining
practice room.
http://www.livingroomtaipei.com/archives/2003/12/08/000027.php
2) If there is still an issue, you'll have to walk all around your room (as
a cube) with your eyes closed and a finger in one ear concentrating on where
stuff is getting trapped and reflected, and where the boom or ring is, and
essentially where it sounds like crap.If bass is still a problem, you can
put an L bracket on the frames and get them off the wall a few inches,
improving LF absorption.
3) If there is still an issue, you can also make tall skinny ones and place
them in the corners for bass traps. (ceiling corners count as well)
The amount of wall/ceiling space will decide how big to make the panels.
Maybe since you already have dropped ceilings, you can cut the 703 into long
fat skinny wrapped-in-cloth-so-you-won't-itch-like-hell-strips which you can
slide through your dropped ceiling struts, and let them just hang there
above the acoustic tile. Or you can make the boxes and hang them from the
struts with some hooks or wires. Be creative.
Good examples how to build them: http://www.geocities.com/jonrisch/a1.htm
The microphone (if that is the problem) will cost a couple hundred bucks.
The treatment (if you end up needing it) will be about the same, with a
couple days of scratching from the fiberglass.
David Grant
more for larger areas. Auralex is pretty ineffective in comparison to
Ethan's traps, but you can do much better than Auralex for under $800. It's
talked about a fair bit in Ethan's forum
(http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?ubb=forum;f=26) but the
basic procedure is to take 4" thick sheets of Owens Corning 703 fibre glass,
wrap them in fabric to keep the fibres in, and lay them across the corners
of your room. I did this with my own 10 foot square room and the improvement
is remarkable.
Dave
"David Abrahams" <da...@boost-consulting.com> wrote in message
news:uvf8u5...@boost-consulting.com...
Don Nafe
Addressing your room is a great idea...might want to check out the ETF room
analysing program and read up on DIY absorbers too. Don't forget speaker
placement...that too will effect feedback.
go to Recording.org (acoustics) John Sayers.com (forums) or the Yahoo
acoustics group..great info
Don
"David Abrahams" <da...@boost-consulting.com> wrote in message
news:uis4u7...@boost-consulting.com...
David Abrahams
> I'm pretty sure he recommends 8 for any small sized (10ft square) room and
> more for larger areas. Auralex is pretty ineffective in comparison to
> Ethan's traps, but you can do much better than Auralex for under $800. It's
> talked about a fair bit in Ethan's forum
> (http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?ubb=forum;f=26) but the
> basic procedure is to take 4" thick sheets of Owens Corning 703 fibre glass,
> wrap them in fabric to keep the fibres in, and lay them across the corners
> of your room. I did this with my own 10 foot square room and the improvement
> is remarkable.
Oh, that forum looks like a great resource! I'm sure I can find the
answer somewhere online, but can you tell me how to evaluate the
differences between these corner panels and the flat panels described
at http://www.ethanwiner.com/basstrap.html? Is it just a matter of
how much space is occupied? The room is already a little bit crowded
and I'm not sure I want to cut that much off of the corners. And how
can I get an idea whether just putting panels in the corners will be
enough? It seems like I will still have some large expanses of hard,
parallel wall surfaces, which are likely (?) to cause problems
David Abrahams
> How about a 31 band EQ with 80 and below pulled out ?
That's what the Feedback Destroyer Pro does. Actually you get
something like 10 automatically-tuned parametric notches, and as I
said it does improve things mightily. But that's really just fixing
the PA. It doesn't fix the room (right?), and I'd still expect the
bass player to get bad sound (right?)
> Addressing your room is a great idea...might want to check out the ETF room
> analysing program and read up on DIY absorbers too. Don't forget speaker
> placement...that too will effect feedback.
>
> go to Recording.org (acoustics) John Sayers.com (forums) or the Yahoo
> acoustics group..great info
Heh, you see, this is my problem: it looks like a few weeks of study
in my "copious spare time," and then at least another week or so to
sort through all the conflicting information/recommendations that are
out there. I'm genuinely interested in learning what I need to know,
but I don't cope well with uncertainty. I'm hoping y'all can narrow
it down for me a little.
Anyway, thanks for the references; I think I'd better start by doing
some more reading. Can't expect advice to seem useful until I get the
basics.
Anahata
> Oh, that forum looks like a great resource! I'm sure I can find the
> answer somewhere online, but can you tell me how to evaluate the
> differences between these corner panels and the flat panels described
> at http://www.ethanwiner.com/basstrap.html?
Far be it from me to speak for Ethan, but the advice he gives on his own
forum is that wideband absorbers (4" thick 703 fibreglass panels,
preferably spaced up to 4" away from the wall) are the thing to use for
small rooms; the flat panel resonant absorbers are really for large
rooms, especially when it's mostly/only bass you want to absorb.
> And how
> can I get an idea whether just putting panels in the corners will be
> enough? It seems like I will still have some large expanses of hard,
> parallel wall surfaces, which are likely (?) to cause problems
It's hard to have too much bass absorbtion in a small room! You'll end
up making a compromise, but anything is better than nothing. You could
estimate which room mode is exciting the 67Hz resonance by calculating
(distance between walls = 1 or 1/2 wavelength), or by generating a tone
at the most resonant frequency and listening around the edges of the
room. If you hear it loudest in one pair of opposite corners or walls,
those are the ones you need to treat first. If space is a problem and
the ceiling's high, put then high up, even across the angle between wall
and ceiling.
Given the ASCII-drawn shape of you room, I might first try hanging a
thick drape between the extension shown in the bottom left and the main
rectangular part, if there's room to fit your band all in the rectangle.
But you're right about the parallel walls - even if you reduce the bass
ringing, your next problem maybe flutter echoes between those walls. The
same wideband absorbers on one or both walls should help.
Anahata
David Abrahams
> First off, make sure you are not standing directly in front of your PA
> speakers.
They're Mackie SRM350s set up as floor monitors. Neither one
points directly at the main vocal mic -- one is basically at 90
degrees, pointing at the drumkit. The other points in the general
direction of the vocal mic but it would have to move 5 or 6 feet to
one side in order to be right in front.
Since the SRM350s are supposed to have really good dispersion, and
bass isn't very directional anyway, I wouldn't expect those factors to
make much difference. Am I wrong?
> Try moving speakers, mic position, whatever to see if it gets
> better. If you can't avoid this, you can try a "tighter" microphone. Do a
> search on RAP for hypercardiod vocal mics and feedback then see if you can
> get one on a trial policy from a store. May take care of the problem right
> away.
Actually I started down there with an EV N/D 457A, which I bought
maybe 10 years ago because I hated how I sounded through an SM58. But
as soon as I got the EV down there it started screaming like a
banshee. HF feedback galore, and it sounded brittle
When I went into the store to buy the SRM350s I demoed a vocal mic
that was supposed to have a tighter pickup pattern than the Shure, an
Audix OM5, I think(?) It seemed to have a similar response to the
EV. Then we A/B'd it with an SM58, just to get a reference point.
The SM58 was great, and much less susceptible to feedback.
> If not, then you can do some complicated math (which you should
> eventually do if you want to understand the weird nature of sound)
I used to be pretty good with that stuff, but, heh, haven't done an
integral in 20 years.
> and buy some expensive "treatments," but in the end here's a simple
> easy and effective solution that will get your room sounding better:
>
> 1) You'll want to get about 50% of the walls and ceiling covered in 6"
> Corning 703 acoustic panels that you can make yourself. This will take care
> of a majority of your practice room acoustic problems.
So you're using the Ethan Winer plans?
> I use and really appreciate their improvement to my club acoustics
> and it's adjoining practice room.
> http://www.livingroomtaipei.com/archives/2003/12/08/000027.php
Looks like a nifty club. No info on sound at that side, though, is
there?
> 2) If there is still an issue, you'll have to walk all around your
> room (as a cube)
I assume you mean both crawling and on tiptoes? 'Cuz the room is
twice as long in one direction, i.e. not a cube.
> with your eyes closed and a finger in one ear concentrating on where
> stuff is getting trapped and reflected, and where the boom or ring
> is, and essentially where it sounds like crap.If bass is still a
> problem, you can put an L bracket on the frames and get them off the
> wall a few inches, improving LF absorption.
>
> 3) If there is still an issue, you can also make tall skinny ones and place
> them in the corners for bass traps. (ceiling corners count as well)
>
> The amount of wall/ceiling space will decide how big to make the panels.
> Maybe since you already have dropped ceilings, you can cut the 703 into long
> fat skinny
"Fat skinny?" You're going all Zen on me.
> wrapped-in-cloth-so-you-won't-itch-like-hell-strips which you can
> slide through your dropped ceiling struts, and let them just hang there
> above the acoustic tile.
_Above_ the tile? Don't you think the tile is already reflecting most
of the bass back into the room?
Also, don't forget that I already have sheets of mass-loaded vinyl up
there, so even inserting and replacing anything as small as tiles is
painful -- though I may have to go back up there and re-do it -- it
doesn't seem to be making enough difference in keeping sound out of
the room above. I might need to seal up the floor above, or add
fiberglass or something -- but that should really be a separate
discussion thread ;-)
> Or you can make the boxes and hang them from the struts with some
> hooks or wires. Be creative.
That sounds plausible, though I'm a tall guy and don't want to make
the room much shorter.
> Good examples how to build them: http://www.geocities.com/jonrisch/a1.htm
Thanks, I'll read it.
> The microphone (if that is the problem) will cost a couple hundred bucks.
> The treatment (if you end up needing it) will be about the same, with a
> couple days of scratching from the fiberglass.
Been there, don't want to go back. I've got a cartridge respirator
and leather gloves. Maybe I'll get a Carhartt suit. ;-)
Thanks for all the feedb... er, advice.
Mike Rivers
> How about a 31 band EQ with 80 and below pulled out ?
That sounds like a low frequency roloff or shelf to me, not a 31-band
equalizer.
You can use EQ to fix some low frequency problems caused by boundary
conditions around the speakers, but not for fixing room mode problems.
Room problems tend to be at specific frequencies that change depending
on where you measure them. Boundary problems start around a specifif
frequency and actually are effectively speaker radiation problems.
--
I'm really Mike Rivers (mri...@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
David Abrahams
> David Abrahams wrote:
>> Oh, that forum looks like a great resource! I'm sure I can find the
>> answer somewhere online, but can you tell me how to evaluate the
>> differences between these corner panels and the flat panels described
>> at http://www.ethanwiner.com/basstrap.html?
>
> Far be it from me to speak for Ethan, but the advice he gives on his own
> forum is that wideband absorbers (4" thick 703 fibreglass panels,
> preferably spaced up to 4" away from the wall) are the thing to use for
> small rooms;
Well, that sounds pretty easy, actually. Since I have those hung
ceilings I should be able to suspend them from the grid.
> the flat panel resonant absorbers are really for large rooms,
> especially when it's mostly/only bass you want to absorb.
>
>> And how can I get an idea whether just putting panels in the
>> corners will be enough? It seems like I will still have some large
>> expanses of hard, parallel wall surfaces, which are likely (?) to
>> cause problems
>
> It's hard to have too much bass absorbtion in a small room! You'll end
> up making a compromise,
Between ________ and _________ ??
> but anything is better than nothing. You could estimate which room
> mode is exciting the 67Hz resonance by calculating (distance between
> walls = 1 or 1/2 wavelength), or by generating a tone at the most
> resonant frequency and listening around the edges of the room.
Are there good computer tools for generating tones, noise, and
analyzing the results? I have Macs and PCs; my Linux box is not
really accessible for that purpose.
> If you hear it loudest in one pair of opposite corners or walls,
> those are the ones you need to treat first. If space is a problem
> and the ceiling's high, put then high up, even across the angle
> between wall and ceiling.
>
> Given the ASCII-drawn shape of you room, I might first try hanging a
> thick drape between the extension shown in the bottom left and the main
> rectangular part, if there's room to fit your band all in the rectangle.
Hum, I thought that area might be _good_ for the sound, since it's so
irregular. Right now that's where the recording mixing station and
studio monitors live; I had been thinking I might put up a wall across
that opening at some point.
> But you're right about the parallel walls - even if you reduce the bass
> ringing, your next problem maybe flutter echoes between those walls. The
> same wideband absorbers on one or both walls should help.
The live recordings we've been making down there sound half-decent,
surprisingly, so maybe that won't be an issue. But according to my
wife I'm a fussy virgo, so I'm sure once I get into this and start
handling the bass I probably won't be satisfied until it's
world-class ;-)
Thanks for your attention,
Dave
Anahata
>> You'll end
>>up making a compromise,
>
> Between ________ and _________ ??
Between having enough bass absorption and having any space left to play
in the room :-)
> Are there good computer tools for generating tones, noise, and
> analyzing the results? I have Macs and PCs; my Linux box is not
> really accessible for that purpose.
http://www.interstudio.co.uk/sndchk.htm
I have the Sound Check 1 CD, but as I'm half way though setting up a
room that will be used as a home studio I'm thinking of getting the
version with spectrum analyser to check the results.
> Hum, I thought that area might be _good_ for the sound, since it's so
> irregular. Right now that's where the recording mixing station and
> studio monitors live; I had been thinking I might put up a wall across
> that opening at some point.
The idea was that an acoustically resistive barrier (a.k.a. curtain)
with space behind it will absorb low frequencies better than a curtain
with a wall behind it. Maybe if you put a wall with a carefully measured
hole in it you'll turn that area into a giant resonant bass trap. Good
luck...
Anahata
S O'Neill
> Are there good computer tools for generating tones, noise, and
> analyzing the results? I have Macs and PCs; my Linux box is not
> really accessible for that purpose.
You can have both.
http://www.nt-instruments.com/X0-ASP-pLngCateId_217-pIntLevel_4-pLngPageId_276-X1-default.htm
Look for the virtual NT1 (free) on this next link if that link doesn't
work. You have to look for the hardware version, the virtual one is on
that page.
Ethan Winer
> the whole room/PA setup rings like crazy at what sounds like around 67 Hz
<
You've gotten great advice from David Grant and a few others. By all means,
stop by my Acoustics forum at the MusicPlayer web site and ask away. Also
see the Acoustics FAQ, second in the list on my Articles page:
www.ethanwiner.com/articles.html
--Ethan
Don Nafe
1/2 your problems are gone.
And yes Mike addressing the source of the problem is the only real way to
go...try cutting a 2'x4' - 4" thick corning 703 rock wool insulation into 8
triangles and fill your corners with it...then place 2 more 2'x4' sheets in
front of that and cover with some sort of acoustically transparent
material...there's a place to start...
or try hunting down a DIY helmholz resonator tuned to the offending
frequency
Don
"Mike Rivers" <mri...@d-and-d.com> wrote in message
news:znr1108472486k@trad...
Mike Rivers
> Are there good computer tools for generating tones, noise, and
> analyzing the results?
There are a number of tools for generating test signals. I like the
stand-alone free VB-Generator from http://www.vb-audio.com but many
DAW programs have a signal generator function built in.
There are spectrum analyzers but they really don't tell you want to
fix. You have to figure that out on your own. So, I'd give a "no" to
analysis tools - it's mostly in your head and gut once you have some
measurements.
David Abrahams
> David,
>
>> the whole room/PA setup rings like crazy at what sounds like around 67 Hz
> <
>
> You've gotten great advice from David Grant and a few others. By all means,
> stop by my Acoustics forum at the MusicPlayer web site and ask away.
Thanks very much! I have followed up there: http://tinyurl.com/4ueqj
> Also see the Acoustics FAQ, second in the list on my Articles page:
You can bet I will.
Roger Christie
--
Somewhere in Texas, a village is missing its idiot.
"David Abrahams" <da...@boost-consulting.com> wrote in message
news:uis4u7...@boost-consulting.com...
>
I cannot endorse Real Traps products for this application strongly enough.
Roger Christie
Black Cat Crossing
www.blackcatcrossing.net
David Abrahams
> I cannot endorse Real Traps products for this application strongly
> enough.
Thanks, but they're out of my price range, so I'll have to make do
with their vendor's generous and free advice for the time being.
Norm!!
In article <u1xbgq...@boost-consulting.com>, David Abrahams
<da...@boost-consulting.com> wrote:
> "Roger Christie" <rochrist@<REMOVETOEMAIL>charter.net> writes:
>
> > I cannot endorse Real Traps products for this application strongly
> > enough.
>
> Thanks, but they're out of my price range, so I'll have to make do
> with their vendor's generous and free advice for the time being.
Ethan Winer knows his stuff. I have his site bookmarked. There are
lots of tips there that aren't costly. There's also alot of good info
there that will help you to determine where your efforts would be best
spent.
Norm!!