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Room Correction help needed

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September 26, 2005 5:45:19 AM

Archived from groups: rec.audio.high-end (More info?)

From text I sent to Stereophile

I have been a subscriber for about 15 years. In that time I have
learned, and tried to put in practice, good room treatment techniques. I
use test CD's and a sound meter to aid in placement and I treat all the
room hot spots like first order reflection, echo flutter and deaden the
area behind my head (my Triangle Celius speakers sounds their best in a
spot that forces me to the rear wall- I have an odd room). What confuses
me is the double speak on tone controls and equalizers as well as
exactly which test tones I should use when running the tests.

On equalizers/tone controls. I can't count how many times I have read
that these are either the bane of our collective electronic existence or
a necessary tool to help make some recordings sound right (specifically
tone controls). On equalizers I read that they induce too many problems
but your magazine has recommended several of them (all in the digital
domain I believe).

In my room I have several strong nodes below 300hz (as do most people I
am sure). I have a small dent at 50hz, huge plus ups at 60hz and 120hz
and a dip at about 250hz (Here is where the test tone confusion comes
in. With warble tones the aberrations are far lower. With straight tones
I have a 16db shift from 120hz to 250hz - with warble tones the shift is
about 5db. Which am I to use? Seems to me warble tones are more
effective because the approximate the changes that occur in music?).
After studiously using my test gear/tones, set up programs, several
suggestions from professional sources (read in your mag and others) as
well as installing some room treatment (albeit none for bass control) I
am left with the predicament described. As far as I can tell room
treatments, designed to help in the low end, are not discriminate
enough. While they will tame my hot spots they will also negatively
affect my dips(?). Using a bass tone control won't work for basically
the same reason. At the end of the day (which I assure you is a grossly
understated metaphor) I decided to try a cheap 10 band EQ I had on hand
(I would try the digital products but they are way too expensive).
Utilizing the EQ and other associated items I was able to smooth out the
bumps, in both directions, to a very significantly measurable degree.
Now here's the rub. When I asked my daughter to help me A/B the
difference (which is easy with an EQ - one button) I had to work at
hearing the difference - more often than not. (I should note that I
could go flat to 40hz and only 3db down at 31.5hz). While I was able to
discern the difference on some recordings (bass notes ended sooner - no
bloat) it was not a startling difference. As such is it "better" that I
use the EQ to settle the bloat or run away from the wretched beast, and
all it's detriments, and deal with the bloat because its less damaging?
(I should also note that I heard no negative artifacts with the EQ - no
imaging change or high frequency issues). Finally – does anyone make an
affordable analog EQ that only affects the range below 300hz? (Or a
digital unit that is affordable and isn’t meant for subwoofers?)

More about : room correction needed

Anonymous
September 27, 2005 6:07:03 AM

Archived from groups: rec.audio.high-end (More info?)

MD wrote:
> From text I sent to Stereophile
>
> I have been a subscriber for about 15 years. In that time I have
> learned, and tried to put in practice, good room treatment techniques. I
> use test CD's and a sound meter to aid in placement and I treat all the
> room hot spots like first order reflection, echo flutter and deaden the
> area behind my head (my Triangle Celius speakers sounds their best in a
> spot that forces me to the rear wall- I have an odd room). What confuses
> me is the double speak on tone controls and equalizers as well as
> exactly which test tones I should use when running the tests.
>
> On equalizers/tone controls. I can't count how many times I have read
> that these are either the bane of our collective electronic existence or
> a necessary tool to help make some recordings sound right (specifically
> tone controls). On equalizers I read that they induce too many problems
> but your magazine has recommended several of them (all in the digital
> domain I believe).
>
> In my room I have several strong nodes below 300hz (as do most people I
> am sure). I have a small dent at 50hz, huge plus ups at 60hz and 120hz
> and a dip at about 250hz (Here is where the test tone confusion comes
> in. With warble tones the aberrations are far lower. With straight tones
> I have a 16db shift from 120hz to 250hz - with warble tones the shift is
> about 5db. Which am I to use? Seems to me warble tones are more
> effective because the approximate the changes that occur in music?).
> After studiously using my test gear/tones, set up programs, several
> suggestions from professional sources (read in your mag and others) as
> well as installing some room treatment (albeit none for bass control) I
> am left with the predicament described. As far as I can tell room
> treatments, designed to help in the low end, are not discriminate
> enough. While they will tame my hot spots they will also negatively
> affect my dips(?). Using a bass tone control won't work for basically
> the same reason. At the end of the day (which I assure you is a grossly
> understated metaphor) I decided to try a cheap 10 band EQ I had on hand
> (I would try the digital products but they are way too expensive).
> Utilizing the EQ and other associated items I was able to smooth out the
> bumps, in both directions, to a very significantly measurable degree.
> Now here's the rub. When I asked my daughter to help me A/B the
> difference (which is easy with an EQ - one button) I had to work at
> hearing the difference - more often than not. (I should note that I
> could go flat to 40hz and only 3db down at 31.5hz). While I was able to
> discern the difference on some recordings (bass notes ended sooner - no
> bloat) it was not a startling difference. As such is it "better" that I
> use the EQ to settle the bloat or run away from the wretched beast, and
> all it's detriments, and deal with the bloat because its less damaging?
> (I should also note that I heard no negative artifacts with the EQ - no
> imaging change or high frequency issues). Finally – does anyone make an
> affordable analog EQ that only affects the range below 300hz? (Or a
> digital unit that is affordable and isn’t meant for subwoofers?)

I could give you another way of looking at the problem. Sometimes we get
too absorbed in hi-fi trivia, trying to get some sort of perfect curve
to our frequency response and reduce all contributions from the room,
which is based on a misunderstanding of the system.

Imagine hiring a piano quartet or similar to come to your home and
perform in place of your system. Would they sound real or not? Stupid
question, right? Now, the point of the exercise is to make your room
sound good for MUSIC, and let your system simply play in this good
sounding room. Sure, if there is some ridiculous resonance at some bass
frequency you want to dampen it. But the system itself will be basically
playing flat into your room, just as the quartet live is playing "flat"
and sounds perfectly real without even any EQ! So set up a reasonable
system, get a good balance between your mains and your subs, between the
fronts and the surrounds, and enjoy the music! If you didn't need any
fancy digital room correction for the live music, you don't need it for
the reproduction either. And remember, EQ is not supposed to be flat at
the listening position. The room gives it a natural taper at the high
frequencies, which is part of the deal, so don't go to any lengths to
"correct" that.

Gary Eickmeier
Anonymous
September 27, 2005 6:08:32 AM

Archived from groups: rec.audio.high-end (More info?)

>>Finally – does anyone make an
>> affordable analog EQ that only affects
>> the range below 300hz? (Or a digital
>> unit that is affordable and isn't meant
>> for subwoofers?)

I use a Rane 1/3 octave equalizer. I have several sub-woofers and find
that corner placement is NOT a good choice (in my room). I use
considerable boost at 40 and 50 Hz and cuts at 80, 100, and 120. Again,
this works for MY room. The Rane equalizers are not too expensive.


---MIKE---
>>In the White Mountains of New Hampshire
>> (44° 15' N - Elevation 1580')
Related resources
Anonymous
September 27, 2005 7:21:36 AM

Archived from groups: rec.audio.high-end (More info?)

I find you need 1/3 octave control to make it work well usually.
1/5 octave is better. And I am referring to using warble tones.
I would EQ to the listening position.

You don't want to boost dips in response too much. I usually limit
it to 6 dB. I drop peaks as much as needed. I find it makes a fair
amount of difference when done.

I use software to make 1/5 th octave warble tones. Measure the
speaker up close and at the listening position. Helps you figure out
what the room is doing. I then EQ digitally with software to flatten
things out. Seems to do a good job. Just not convenient. Using this
approach you would need to EQ and re-burn all your CD's if that is
your source. A piece of consumer digital gear to give you this
control would be extremely useful.

Dennis
Anonymous
September 28, 2005 6:24:54 AM

Archived from groups: rec.audio.high-end (More info?)

Get yourself a TacT Room Correction preamp. They even have refurbished RCS
2.0 models for less than half price with full warranty.

http://www.tactlabs.com/

Tim McTeague
Anonymous
September 28, 2005 6:32:51 AM

Archived from groups: rec.audio.high-end (More info?)

I haven't heard them in action, but Behringer makes a line of equalizers and
most interesting to me, three-way crossovers, some of which have adjustable
equalization and time delay which I hope to test with my JBL S8R fairly soon
(using two Hafler 500's and a Halfer 225 for the amplifiers - my neighbors
will probably hate me).

neIed the time delay because there is no way to mount
a 375 with either the 2350 horn or 2309/2310 horn/lens assembly (to get
a 500Hz low horn cut-off) in the same plane with the LE15A bass driver and
075 tweeter.

The most popular 1/3 octave equalizer in the 70's was made by Soundcraftsmen,
and I've seen one on eBay recently.

Mike Squires
--

Mike Squires (mikes at cs.indiana.edu) 317 233 9456 (w) 812 333 6564 (h)
mikes at siralan.org 546 N Park Ridge Rd., Bloomington, IN 47408
Anonymous
September 29, 2005 5:59:42 AM

Archived from groups: rec.audio.high-end (More info?)

"Tim McTeague" <mcteague@comcast.net> wrote in message
news:D hcutm01efc@news3.newsguy.com...
> Get yourself a TacT Room Correction preamp. They even have refurbished
> RCS
> 2.0 models for less than half price with full warranty.
>
> http://www.tactlabs.com/
>
> Tim McTeague
>

Although the TacT RCS 2.0 is very good there is a valid reason why they can
now be got for less than half price. This is because of the huge advances
made in the RCS 2.2. There was a time when you could get a RCS 2.0 upgraded
to RCS 2.2, sadly this time has now past, (unless of course you actually
mean this upgrade by the word 'refurbished') IMO once you've heard the RCS
2.2 there is just no going back! May I just add that customer support from
TacT is truly excellent.
I don't own TacT RCS myself but have been greatly involved in the setting up
of friends TacT based systems.

-=Mike=-
!