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Welshsox
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Boomy bass response

Hi

My system is setup in a bedroom, approx 16x14 with highish ceiling.

The problem I have is that my bass response seems to be very muddy and heavy, i get lots of bass but i cant get any clarity or attack. Ive tried loads of different equipemnt so im fairly certain that its the room thats causing the issue.
Any advice please

Alan

dcstep
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Re: Boomy bass response

First tell us what speakers you have and what amp you're driving them with. Also, how are they placed in the room (long wall, short wall, distance from wall, distance from corners, carpets?, lots of furniture or almost none).

Dave

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Re: Boomy bass response

Dave

Thanks

The equipment is as follows

Quad CDP-2, pre 99, 909 power
Quad 22L2 speakers
Rega Planar 3, Dynavector VX20 High output

The equipment is placed on a large sideboard between the speakers, there is no special isolation plinths etc.
The speakers are on the long wall approx 8-9 ft apart, and 10 ft from the listening position which is actually the Bed !! ( I know its not normal but it works for me ). The room is painted dry wall with thick carpet and a bed. One of the speakers is in the corner and this does appear to be causing that sepeaker to be the dominant channel.

For some reason the T/T is especially prone to the problem.

The issue again is that I get bass but its just very boomy, muddy and slow.

Alan

tom collins
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Re: Boomy bass response

look up ethan winer on this forum and read his treatises on the subject of room treatments, specifically bass treatment. it is illuminating. he owns a company that produces products to fix your problem, but his writing explains the concepts well while not particularly hocking his products. i don't have his products, but i have sent him a few questions about my situation and he has always graciously answered them. with that said, beware - it is a major subject and can really fry your brain.
in fact, in the next column down for dealers is the Real Traps Intro - you can start there and there will be links. i have been working slowly on this problem myself in my room and if anyone tells you they have a room that does not need treatment, they are mistaken. i don't think you can really know what your equipment really sounds like until you fix your room. many people have probably spent thousands of dollars unnecesarily thinking they needed new gear, when it was really the room.
tom

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Re: Boomy bass response

As you suspect, a speaker in the corner can be problematic. Unfortunately, because beds take up so much room, it's hard to properly place speakers in a bedroom. If it's possible to try this, pull the speakers out 6-ft from the back wall and side walls to see if that doesn't clean things up. It probably will, but then they'll be in the way of walking around the room.

Still, if that sounds good, then you've confirmed that it's a placement problem and not an equipment problem. Next try moving the speaker out from that corner. Bass nodes are very sensitive to placement and moving a few inches will unexcite a node. The relationship to the rear wall is also critical, so experiment with moving the speakers in and out just a few inches. Lastly, apply room treatment to the extent that you don't have room to fix placement.

Dave

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Re: Boomy bass response


Quote:
The equipment is placed on a large sideboard between the speakers, there is no special isolation plinths etc.


That's okay.


Quote:
The speakers are on the long wall


Not so good. The main issue is you want the wall behind you as far back as possible.


Quote:
The issue again is that I get bass but its just very boomy, muddy and slow.


The solution is bass traps. All domestic size rooms are riddled with bass peaks and nulls, and ringing. It's the peaks and their ringing that makes bass sound boomy. It's impossible to make any room perfectly flat, but the more bass traps you have, the closer you'll get. It's pretty much that simple.

--Ethan

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Re: Boomy bass response

Regarding your statement that the turntable is "especially prone to the problem," perhaps the 'table itself is actually in a peak node. Put your ear next to the 'table while the music is playing. If it sounds even more "boomy" try moving the 'table a bit. Also, how sturdy is the surface the 'table sits on? I'm sorry, I don't know exactly what a sideboard is, but can you feel it vibrate when the music is playing? Better isolation may be needed.

tom collins
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Re: Boomy bass response

i was just at my dealer picking up a new power cord. he has a room set up with a set of large Thiel 2.4 speakers driven by mid level Naim gear. the room is on the small side for such major gear. the last time i was in this room, the bass was all over the place and it did not sound worthy of the investment. today, he had 3 upright helmholtz resonators in place. the difference was huge, everything was much more under control. placement is important, but its usually the room.
good luck.

tom

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Re: Boomy bass response

yes, if the TT is especially prone to the problem, then that may be what you should address first. TT/arm/cartridge are more susceptible to acoustic feedback than other components. If you want a no-cost tweak - or just consider it a test - put something flat and heavy - like a patio paving stone - on the sideboard, for the TT to sit on. If things are better, than you have identified a vibration related problem on your sideboard.

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Re: Boomy bass response

Tom and Ethan are so right. Boomy is gonna happen till the room treated. Moving things around will minimize it, but bass traps will eliminate it, whatever kind you get.

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Re: Boomy bass response

Room treatment is the right answer, but the claims that "bass traps will solve all of your problems, it's that simple" are wishfull thinking. Bass traps are fairly narrow in their bandwidth of absorbsion about their center frequency. Their center frequency and bandwidth may or may not solve your problem. Bass traps can do wonders, but are not always the final answer. Speaker position, listener position, room dimensions and room furnishings also play a major influence.

tom collins
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Re: Boomy bass response

i solved a great deal of my bass bloat problem yesterday in a very unexpected way. i replaced the stock power cord on my cd player with a nordost. all of a sudden, bass notes are distinct and deeper. i have been working on room treatments and will continue to do so, but i never expected this from a power cord. i guess part of the problem was that the unit was not resolving the lower register cleanly. i am not saying run out and buy a cord, but just my experience.

tom

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Re: Boomy bass response

One of the speakers is in the corner and this does appear to be causing that speaker to be the dominant channel.

You most definitely have to get that speaker out of the corner.

It was not designed to be corner loaded like that,and you will get an unrealistic and emphasized mid-bass and bass.

You also have to align the subwoofer and speakers acoustically with one another, so they have equal length paths with regards to distance from your ears. Did you get the matching sub you where speaking about in the other thread?

At the same time consider the movement of the turntable after (or during the same time, but it's best to try it after) these other things have been done.

You head against the wall while being on the bed is causing the absorption of a fair amount of lower midrange and then up (the bed itself, combined with your proximity) ....and your head's proximity to the back wall is helping cause bass emphasis.

Between the bunch of issues, they combine to be the overall cause of your situation.

By the sounds of it, this room does not have big windows. Big windows are like a giant bass sink/trap, the energy gets out through them.

OK. 16x14. If the height is the standard 7.5 feet, then there's a large part of your problem. The room's overall bass loading re-enforcement nodes all overlap with one another.

This means that positioning of gear in the room, both the turntable and the speakers is CRITICAL..to avoid exiting those resonances.

You will have to play with it.

Start by placing the speakers on exact thirds along the long wall. This should bring tremendous effect, in the direction you desire.

Placing the speaker in the corner fires up all three 'bad news energy nodes' , the height of the room, the length and the width all become fired up when you place it in the corner.

On the 16 foot wall, place the speaker's woofer port so it is 5.3333 feet from the wall...and then the other speaker at the same distance from it's wall. This means they will be 5.333 feet apart.

The ports should be 2.333 feet from the wall that backs them (the 14 foot distance)

If that lowers the level of your problems tremendously, (as an experiment) then you will know that placement of speakers in that room is CRITICAL. I expect this to be the result.

Try centering the positions on 1/3rd's and 1/6th's in the room. This is what I've done with respects to the 14 foot distance and the 16 foot distance, if you think about it for a few seconds.

For example, the turntable cannot be exactly half way across the room, that would put it in a positive pressure node that is a re-enforcement node at the primary low excitation frequency for that room size.

I just looked at those speakers on the internet. You definitely do --NOT-- require a subwoofer with those speakers, in that size room. All a sub will do is ruin what the speakers are trying to deliver, with respects to tuneful bass. They've got lots of woofer for that room size already, you don't need more.

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Re: Boomy bass response


Quote:
Bass traps are fairly narrow in their bandwidth of absorbsion about their center frequency.


That's not necessarily true. There are two basic types of traps - tuned and broadband. Tuned absorbers like Helmholtz resonators and wood panel traps do have a center frequency where absorption is greatest. But that type of trap is old school, and not appropriate for most domestic size rooms. More modern thinking uses broadband bass traps because we now know that peaks and nulls happen at all frequencies, not just those related to the room dimensions. (Though ringing happens only at a room's resonant frequencies.) More on that here:

Small room treatment


Quote:
Speaker position, listener position, room dimensions and room furnishings also play a major influence.


Yes, and those should always be optimized first. More on that here:

How to set up a room

--Ethan

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Re: Boomy bass response

I have followed this discussion with great interest, as I also have a pair of Quad 22Ls, and also have problems with a sort of muddy bass/lower mid range, which is especially noticeable with dialog in movies and TV (I use the system for both stereo listening and HT). I know the problem goes away if I move the Quads 4 or 5 feet into the room, but the system is set up in my living room, so I can't really leave speakers that far into the room.

But after reading the suggestion about the placing the speakers a third of the way across the wall - well, much to my surprise, this almost completely solved my problem, making dialog more clear and understandable, without changing the character of the Quads. Thanks for the suggestion!

In some ways this 'rule of thirds' is counterintuitive, as the speakers are now much closer together than I had been inclined to place them - I went from about 9 feet apart, to exactly 6.33 feet apart. Unfortunately, because this is a living room, there is no way to bring the speakers 8.33 feet into the room as the rule of thirds would dictate, about 3 feet is the best I can do. But even following the "rules" in one direction has had a definite effect.

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Re: Boomy bass response

Hi

Thanks for all the input.

There is a lot of information to absorb and a few more bits that I can add. The first thing being that my last speakers were Von Schweikert VR3's which are pretty large, they were in exacty the same spot and didnt cause any of these bass issues, they also didnt have spikes. This got me thinking and just for the fun of it I placed each of the Quads on a granite tile and it has definetly improved things, it superficially looks as if the room is very live acoustically and physically linking the speakers to the room via the spikes is a bad idea.

I appreciate the opinion that I dont need a sub with these speakers, the issue is that i love a lot of different music styles and one of the main ones is heavy rock, you need the sub to act almost like a sound reinforcement device to really give the music that drive and enegry that rock needs to sound live.

So although moving the speakers and some isolation is making small improvements the main thing seems to be the "live " nature of the room at low frequencies. Is there a cheap way to prove this ? using blankets or similar on the walls to act as bass traps ? I dont mind purchasing asoustic treatments as long term solution but id love to find out prior to the investment that I was on the right track.

Thanks

Alan

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Re: Boomy bass response

It sounds like getting some good corner traps will go along way to fixing the issues. I have a preference for ASC products when it comes to corner traps or 'full rounds', but have no idea what is available to you where you are at. Corner traps can be built at a fairly reasonable cost, but it takes some expertise with woodworking equipment and such. Ethan's corner traps may work as well, or better, or worse than the ASC products, it's truly difficult to tell until both are tried. The measurements and numbers are nice and all, but it's the actual trying that makes the hearing work or not work.

The reality is that that there are 4 different dimensional aspects that are near complimentary in that room, with regards to re-enforcing and overlapping one another.

Please--move the speakers a few feet, and see if it improves the sonics. That's the first step. Having the speaker directly in the corner is a very real issue, and it is a very real source of bass issues. Traps will alleviate the issue to a good extent but the best situation is to never have an issue in the first place - and that involves placing those speakers correctly in the room.

I just looked, the VR3' are aperiodically ported in the back. The quads are apparently ported in the back. Move the quads so they have their ports at the same location as the VR3's did. Likely half of the problem will go away. The Quad, with the port out the back..in this specific case..is like screaming bass notes into a giant barrel. The whole room fires up like when you blow air across the top of a coke bottle..and make the whole bottle 'honk'.

Aperiodic porting is quite different than standard porting, so the Quads will suffer in a room with bass loading issues, which you seem to have.

For example, one single ASC 9" round, in the corner, behind the one corner loaded Quad speaker, may make a large part of your issues go away.

http://www.asc-hifi.com/tower-trap.htm

or:

http://www.asc-hifi.com/tube-trap-image-2.htm

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Re: Boomy bass response


Quote:
using blankets or similar on the walls to act as bass traps ?


Alan, blankets do nothing at bass frequencies. Maybe if you layered 20 of them to be a few feet thick.


Quote:
I dont mind purchasing asoustic treatments as long term solution but id love to find out prior to the investment that I was on the right track.


Buy four bales of fiberglass at the hardware store and stack one in each corner vertically resting on the floor. (Leave the fiberglass in the plastic bags.) It looks like hell, and is not as good as better commercial products, but for $50 or whatever it will prove to you that bass trapping is the answer. Then you can get "real" bass traps.

--Ethan

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Re: Boomy bass response

Quad says that your speakers should be 322mm from the rear wall. I suspect that includes the corner. Have you checked that? Obviously, it's designed to work with a certain relationship to the wall.

Dave

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Re: Boomy bass response

Hi

I originally had the speakers toe'd in a little, i moved them to be square as the VR'3 were and it did improve things.

Ethan when you say a bag of fibreglass what exactly do u mean ? dont want to sound stupid but where would u get a bag of fibreglass ? soes teh fibreglass absorb the sound ? would it matter what type of bag/sack it was in ?

Thanks for everyones input

Alan

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Re: Boomy bass response


Quote:
Hi

I originally had the speakers toe'd in a little, i moved them to be square as the VR'3 were and it did improve things.

Ethan when you say a bag of fibreglass what exactly do u mean ? dont want to sound stupid but where would u get a bag of fibreglass ? soes teh fibreglass absorb the sound ? would it matter what type of bag/sack it was in ?

Thanks for everyones input

Alan

He's talking about the 'batting' that is used in walls between the studs. Buy a few packs of those and place them in the corners in their sealed bags. This will tell you, to some extent, how well your room will respond to acoustical treatment in the bass range, by placing something that does have a minimum effect-in those said corners.

The bag of fiberglass material will have an effect, but not the best kind of effect, not by a long shot..but a noticeable effect.

This kind of bag:

http://www.oldershaws.com/images/mrpink2.jpeg

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Re: Boomy bass response


Quote:
This kind of bag:

http://www.oldershaws.com/images/mrpink2.jpeg


Exactly.

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Re: Boomy bass response

Hi

I tried one large bag in the offending corner and there was a bit best a very minor improvement, do i need to do the whole room or just the corner where the speaker is located ?

My CD player wone play MP3's etc is there any way to create a series of test tones that I can play and do a simple Hz/dB graph to see what the specific issues are ?

Alan

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Re: Boomy bass response


Quote:
do i need to do the whole room or just the corner where the speaker is located ?


Your room likely has hundreds of square feet of reflecting surface, and you need to cover some reasonable proportion to make a dent in the problem. Corners are efficient, but you need to treat at least two of them. That's why I suggested four bales. Either two in each front corner, one above the other, or one each in all four wall-wall corners.


Quote:
is there any way to create a series of test tones that I can play and do a simple Hz/dB graph to see what the specific issues are ?


If you have a computer with CD burner, this is what you want:

RealTraps Test Tone CD

--Ethan

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Re: Boomy bass response

Hopefully folks saw my May As We See It in which I talk about speaker placement. Since writing that, a pretty amazing thing has happened. When installing a new set of speakers here for review, I was unhappy with the bass response. I ended up moving them far closer to the front wall (the wall behind them) - less than 3' - than I'd ever done with any set of speakers. The bass not only got deeper, but also much tighter.

Then I tried placing my old Talon X Mk. IVs, whose two 10" woofers in isobaric configuration have always produced uncontrollable bass despite numerous upgrades, in the same position. An AMAZING improvement. It's like having a different set of speakers. My soundstage isn't as deep - I'm working on it, slowly given multiple writing deadlines - but the bass response has me blown away. Who woulda thunk?

Moral of the story. Every room behaves differently. In my case, no side walls for miles, lots of space in front (over 21 feet from the front of the speakers to the rear wall), and a big entry into the dining room, all of which play havoc with the bass.

Now, I'm sure that lots more room treatment would also improve the situation. But this is my living room, and I have a spouse. It ain't gonna happen. How I've managed to keep the Shakti Hallographs in the middle of the room without him strangling me still has me dumbfounded. But any day now, I could come home to discover them moved to another spot, as has happened before. Many of us walk the audiophile tightrope...

jason victor serinus

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Re: Boomy bass response


Quote:
I ended up moving them far closer to the front wall (the wall behind them) - less than 3' - than I'd ever done with any set of speakers. The bass not only got deeper, but also much tighter.


This does not surprise me. The "audiophile" approach of putting speakers very far into the room is not necessarily a good placement. The key to all loudspeaker (and listener) placement optimizing is to measure the LF response at high resolution as you experiment. Anything else is just guessing. And trying to do this by ear while listening to music is not recommended.

One problem with using music instead of test ear is any given tune is in a particular key and so has some, but not all, low frequencies present. A placement that's reasonably flat for the key of A may be terrible for the key of C, for example. Measuring with software tests all frequencies, so you can see what happens and optimize the placements for all low frequencies.

Another problem with "by ear" is some frequencies simply sound better than others. The range from 200 to 300 Hz sounds boomy and boxy, so a placement that reduces those frequencies may sound more pleasant but will not be accurate. Likewise, a placement that emphasizes the fullness range around 80 to 120 Hz may seem to have more weight, but again will be less accurate.


Quote:
My soundstage isn't as deep - I'm working on it


Do you have absorption at the reflections points on the side walls and ceiling? If not, that's the most direct route to excellent imaging and depth.

--Ethan

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Re: Boomy bass response

Hi Ethan,

A few questions.
1. What is/are your preferred test CD(s) for evaluating bass response?
2. What's your favorite meter? (Others are invited to chime in here). I've got the Shack's, but I know from a rap that accompanied the AV123 subwoofer I once received that the Radio Shack meter is notoriously inaccurate at the bottom of the spectrum, and requires a lot of compensation. Is there an affordable one - hey, I'm a freelancer - that you recommend?

If I were to put sound absorption panels on the ceiling, they would have to absorb my head, which would be sent aloft as soon as the husband saw them. I do have stuff on the side walls midway between speakers and listening area. If you look at the photo in my Stereophile Gallery that shows a side view of part of the listening area, what you don't see behind the hanging bird tapestry is (dare I say it) the Echo Buster double buster or something like that that a friend sold me for $10 when he was leaving town. There's a thick tapestry in a similar spot on the other side of the room. And that's a long distance away. This is also an old photo, with the Eggleston Works speakers here for review farther into the room than the Talons are now.

Thanks so much,
jason


Quote:

Quote:
I ended up moving them far closer to the front wall (the wall behind them) - less than 3' - than I'd ever done with any set of speakers. The bass not only got deeper, but also much tighter.


This does not surprise me. The "audiophile" approach of putting speakers very far into the room is not necessarily a good placement. The key to all loudspeaker (and listener) placement optimizing is to measure the LF response at high resolution as you experiment. Anything else is just guessing. And trying to do this by ear while listening to music is not recommended.

One problem with using music instead of test ear is any given tune is in a particular key and so has some, but not all, low frequencies present. A placement that's reasonably flat for the key of A may be terrible for the key of C, for example. Measuring with software tests all frequencies, so you can see what happens and optimize the placements for all low frequencies.

Another problem with "by ear" is some frequencies simply sound better than others. The range from 200 to 300 Hz sounds boomy and boxy, so a placement that reduces those frequencies may sound more pleasant but will not be accurate. Likewise, a placement that emphasizes the fullness range around 80 to 120 Hz may seem to have more weight, but again will be less accurate.


Quote:
My soundstage isn't as deep - I'm working on it


Do you have absorption at the reflections points on the side walls and ceiling? If not, that's the most direct route to excellent imaging and depth.

--Ethan

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Re: Boomy bass response

I believe that you must place speakers "by ear" first and then move to instruments and treatments last, to deal with room problems that can't be solved with placement.

I used the Sumiko Master Set to place my Vienna Acoustic Baby Grands in my 15x36x9 room, which also has several large openings. Turns out that the room doesn't need any treatment, with the speakers amazingly flat from 40Hz to 200Hz and with a 4dB roll off at 31Hz and 10+ at 20Hz. I'm lucky, largely due to the large size of the room.

Anyway, my point is that few rooms are simetrical enough to calculate placement geometrically. Integrating the bass and mids via careful placement relative to the rear wall and corners is the starting point. Next the drivers need to be firing together (distance-wise and in rake angle) so that intermodulation distortion is minimized. When you get it right, the "apparent loudness" goes down several dB and the "shout" is taken out of the mids and the imaging is optimized.

If problems remain, then treatment may be required, but you do this last.

Dave

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Re: Boomy bass response


Quote:
Hi Ethan,

A few questions.
1. What is/are your preferred test CD(s) for evaluating bass response?

Not Ethan, but Sumiko uses the "Ballad of the Runaway Horse" from Rob Wasserman's "Duets" CD. It features Rob on bass and Jennifer Warnes on vocal and not much else, so it's great for get the integration of the mids and lows correct.

Jeffnifer Warnes own "Amazing Blue Raincoat" has synth on the "If It Be Your Will" track that often surpass the abilities of many speakers costing over $5000, rendering it without overtones or color.

"A Twist of Motown" has synth mixed with electric bass on a few cuts. My favorite is "Papa Was a Rolling Stone" which is well beyond the capacity of many pretty large speakers. Many render it one-note and have no texture and richness.

These extreme low notes should not interfere with the mids and shouldn't stick out obtrusively.

Dave

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Re: Boomy bass response

"If I were to put sound absorption panels on the ceiling, they would have to absorb my head..."
LOL!

Be careful listening to a recording to find the best bass. Ethan is correct, the key of the piece will dictate where the speakers sound best - but change the key and all bets are off.

Thus, I put together a CD of lots of different pieces of music of different keys and "density" (some just a few instruments, others with lots going on). At a given placement, typically some tracks will sound great with others bad.

I happen to have a Velodyne SMS-1 so I use this to start (graphing the measurement in real time to a screen). I look for a spot that measures the flattest, then I put on my CD of mixed stuff. If everything sounds good I am done.

What do others think of putting a subwoofer at the listening spot and then moving around the room to find the best sound?

ethanwiner
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Re: Boomy bass response


Quote:
1. What is/are your preferred test CD(s) for evaluating bass response?


Again, I always do this by measuring rather than by ear, for all the reasons stated. Of course, it's a good idea to also play several different music tracks afterward to be sure you didn't overlook something obvious.

Measuring can be done two ways - the simple (though time-consuming) method is to play a test tone CD and chart the level at every Hz. There's a Test Tone CD you can download for free at my company's site. Because it tests every 1 Hz the resolution is very high, which is needed. But that also means it takes half an hour to run each test. That gets old very quickly if you're experimenting with placement. So I prefer software that does the same thing in just a few seconds. But test tones are the okay for people who have no way to connect a computer to their systems. More on room measuring software here:

Using ETF


Quote:
2. What's your favorite meter? ... the Radio Shack meter is notoriously inaccurate at the bottom of the spectrum, and requires a lot of compensation. Is there an affordable one


This comes up very often, so in a few weeks I'm going to test a dozen different microphones and publish the comparison on the RealTraps site. Unless John would like me to publish it in Stereophile.

I have a Radio Shack SPL meter, plus two very expensive microphones. I have three other inexpensive popular microphones on order for this test, plus several more of varying price that friends are bringing.

In the mean time I can tell you that the RS meter is not bad at low frequencies, which is what most people need to measure. A few years ago I compared mine to a expensive calibrated microphone, and they tracked within 1 dB up to 800 Hz, then deviated above that. Graphs of the LF and HF response from that comparison are shown here:

SPL Meters

--Ethan

bertdw
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Joined: Sep 18 2007 - 5:41am
Re: Boomy bass response

Test Tone CD link is bad, Ethan. Here you go:

http://www.realtraps.com/test-cd.htm

ethanwiner
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Joined: Sep 1 2005 - 2:26pm
Re: Boomy bass response

D'oh!

Thanks Bert.

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