What flat-sounding speakers to buy for sound therapy?

[quick_frog]

Hi!

I need a pair of speakers for sound therapy (for oversensitive hearing). I am looking for a flat or near-flat frequency response curve or something that I can equalize out. The other acoustic properties, like transient response don't matter since there will be continuous noise played back.

Durability: I need it to last about 3-5 years with 6 hour daily use. The sound level will be similar to the background noise which is traffic noise through a window, and it will be raised slowly about 34 decibels from there.

Budget: You tell me... Suggest speakers from multiple price ranges if you think it is appropriate.

My listening opportunities are limited. I would prefer buying mainly based on measurements.

What speakers do you suggest?


Thank you.

 

[zieglj01]

Philharmonic AA speakers
http://www.philharmonicaudio.com/aa.html

Philharmonic New Philharmonitor
http://www.philharmonicaudio.com/New Philharmonitor.html

 

[shadyJ]

In that criteria I would be looking at something with a wide dispersion. Anything from Revel would work well. I think anything from Ascend Acoustics would do well. The aforementioned Philharmonic speakers should do well. Those are by no means the only good manufacturers of these type of speakers, they are just a few solid choices.

By the way, 34 dB on top of traffic can be pretty loud- probably louder than you would want for any Therapy. Faint traffic would be about 60 dB C-weighted. Near traffic would probably be 70 to 75 dB. Even at 60 dB, 60 + 34 = 94 dB. 94 dB is quite loud to listen to anything continuously. You don't make it sound as if you will be doing some head-banging either.

 

[theJman]

Are you looking for powered or passive?

 

[rojo]

Are you looking for powered or passive?

Great question. And another few for @quick_frog, do you need full enough range to reproduce the fundamentals of diesel delivery trucks? Do you prefer not to add a subwoofer? Will the listener remain a static distance from the speakers, or would more consistent SPL over varying distance be beneficial?

 

[j_garcia]

IMO, the Ascend CMB-170SE is very neutral in tone. Honestly though, I'd look at studio monitors probably, as they will tend to be flatter than most and they normally come in powered (active) or passive. Mackie, KRK, Behringer, etc... should be a range of budget options too.

 

[theJman]

Honestly though, I'd look at studio monitors probably, as they will tend to be flatter than most and they normally come in powered (active) or passive. Mackie, KRK, Behringer, etc... should be a range of budget options too.

That's exactly where I was going with that, studio monitors. A large percentage of them are powered, but in general they tend to have the most neutral output response.

 

[sholling]

Honestly though, I'd look at studio monitors probably, as they will tend to be flatter than most and they normally come in powered (active) or passive. Mackie, KRK, Behringer, etc... should be a range of budget options too.

I was thinking the exact same thing. Add in JBL LSR305 with some adapter cables to your list. I auditioned KRK's Rokit 5 and the JBLs recently and to my ears the JBLs are worth auditioning. I've been wanting to audition Presonus's E5 (so far I can't find a set locally) but I'm hearing rumors of a hiss problem.

 

[OscarJr]

The room will wreak havoc with any speaker and generate a final non-flat frequency response. You will need EQ/RTA if you truly want flat at the listening position.

The renown Legacy Studio HD's, before & after EQ'ing via Dayton OmniMic V2 and a dbx Driverack PA².

 

[Dennis Murphy]

The room will wreak havoc with any speaker and generate a final non-flat frequency response. You will need EQ/RTA if you truly want flat at the listening position.

The renown Legacy Studio HD's, before & after EQ'ing via Dayton OmniMic V2 and a dbx Driverack PA².

What measuring mode do you have your omni mic in, and how far away are you measuring?

 

[OscarJr]

What measuring mode do you have your omni mic in, and how far away are you measuring?

I'm using the monophonic short sine sweep, and I am measuring at the listening position, which isn't too far away since it is a very near-field setup.

 

[Irvrobinson]

I'm using the monophonic short sine sweep, and I am measuring at the listening position, which isn't too far away since it is a very near-field setup.

Pretty good results, considering how small the room is. Did you also make a plot with 1/12th octave smoothing?

Comparing to live sounds recorded in the same room, I find that a smoothly rising bass (to about +3db at 30-40Hz) combined with a roll-off that is at least -3db at 10Khz results in playback that seems to most resemble the live source. Of course, I've only done those tests in two listening rooms (my own, in two different houses), and both were much larger than the room being discussed here. I'm guessing even more HF roll-off would be necessary in your room, unless the walls are pretty much non-reflective.

 

[Dennis Murphy]

I'm using the monophonic short sine sweep, and I am measuring at the listening position, which isn't too far away since it is a very near-field setup.

So it's really anechoic above 250 Hz. (I use the omnimic for a lot of my work). Those irregularities are apparently inherent to the speaker, and not room effects except for the range below 250 Hz where OmniMic automatically widens the sampling window to get greater resolution for the longer bass waves, and with it room effects. I'm very surprised to see such non-linear results for what I'm assuming is a high quality speaker, particularly with such aggressive smoothing (6 dB/octave). I think something may be off. Have you tried using the "All" function, which shows all of the sound reaching the mic, which will include room reflections. The graph will be a jumble of lines, but it would be interesting to see whether the general pattern is following the anechoic results.

 

[OscarJr]

Pretty good results, considering how small the room is. Did you also make a plot with 1/12th octave smoothing?

Comparing to live sounds recorded in the same room, I find that a smoothly rising bass (to about +3db at 30-40Hz) combined with a roll-off that is at least -3db at 10Khz results in playback that seems to most resemble the live source. Of course, I've only done those tests in two listening rooms (my own, in two different houses), and both were much larger than the room being discussed here. I'm guessing even more HF roll-off would be necessary in your room, unless the walls are pretty much non-reflective.

I agree that is is somewhat bright (but not unbearable by any definition), and the low-end is thin if I leave it flat. I'll still playing around with tuning a little bit more here-and-there, as there are so many possible combinations to try out.

I'm going to put foam acoustic panels on the walls to try and cut down on high-frequency reflections and corner bass traps very soon. Then comes some more fun (tuning).

 

[OscarJr]

So it's really anechoic above 250 Hz. (I use the omnimic for a lot of my work). Those irregularities are apparently inherent to the speaker, and not room effects except for the range below 250 Hz where OmniMic automatically widens the sampling window to get greater resolution for the longer bass waves, and with it room effects. I'm very surprised to see such non-linear results for what I'm assuming is a high quality speaker, particularly with such aggressive smoothing (6 dB/octave). I think something may be off. Have you tried using the "All" function, which shows all of the sound reaching the mic, which will include room reflections. The graph will be a jumble of lines, but it would be interesting to see whether the general pattern is following the anechoic results.

I'm not sure what you mean by "it's really anechoic above 250Hz". Echoes/reflections are not addressed in any physical way in this room, so how can it be anechoic? All surfaces are highly reflective (tile floor, hard walls, no soft furnishings)

That plot is with the "All" function already enabled, capturing the room reflections, in order to capture the "reality" of the situation.

 

[Dennis Murphy]

I'm not sure what you mean by "it's really anechoic above 250Hz". Echoes/reflections are not addressed in any physical way in this room, so how can it be anechoic? All surfaces are highly reflective (tile floor, hard walls, no soft furnishings)

That plot is with the "All" function already enabled, capturing the room reflections, in order to capture the "reality" of the situation.

That's why I asked what mode you were using. If you just invoke the frequency response button with the monophonic short sine sweep signal without enabling the "all" function, you get an anechoic response response above about 250 Hz. It has nothing to do with the room you're measuring in. The sampling window above about 250 Hz is very short and doesn't capture room reflections. So you're just measuring the inherent response of the speaker. Even without the "all" function, omnimic shows you the room response below 250 Hz because the sampling window is widened to capture reflections. When you press the "all" button with 1/6th octave smoothing invoked (which is the default setting), you will get some smoothed room effects, but the impact is very minor, because most room effects are below 250 Hz. The exact difference with and without "all" depends on the room and the off-axis response of the speaker, but I just measured a speaker I'm working on with the "all" function working, and there was very little difference with and without it. Either curve fit easily within a +/- 2.5 dB window. I guess the difference is that you're measuring both speakers? The mic is in between them at the listening position with both speakers running? If so, what you may be getting is interference effects between the speakers, and those will change with small shifts in the mic position. Equalizing the measured response might give you strange results overall.

 

[OscarJr]

Yes, you are correct that the mic is in the listening position, equidistant from both speakers playing the monophonic sine sweep, just as in the picture in the Legacy Studio HD thread. I played both speakers to capture the frequency response because, well, that's how they'll be playing when playing music--both at the same time. I'm not sure if you're suggesting only capturing the FR of each speaker, one at a time? It almost sounds like it, but I can't tell.

I understand what you are explaining with regards to how the OmniMic is capturing the sounds. I guess what I'm not understanding is exactly what "non linear results" and "irregularities" are you referring to? The two peaks @ 50Hz and 100Hz? Something else? Also keep in mind, that FR graph is with the subwoofer active as well. All the details are in the Legacy Studio HD thread, and the screenshots all show the "all" function enabled at all times.

 

[Dennis Murphy]

Yes, you are correct that the mic is in the listening position, equidistant from both speakers playing the monophonic sine sweep, just as in the picture in the Legacy Studio HD thread. I played both speakers to capture the frequency response because, well, that's how they'll be playing when playing music--both at the same time. I'm not sure if you're suggesting only capturing the FR of each speaker, one at a time? It almost sounds like it, but I can't tell.

I understand what you are explaining with regards to how the OmniMic is capturing the sounds. I guess what I'm not understanding is exactly what "non linear results" and "irregularities" are you referring to? The two peaks @ 50Hz and 100Hz? Something else? Also keep in mind, that FR graph is with the subwoofer active as well. All the details are in the Legacy Studio HD thread, and the screenshots all show the "all" function enabled at all times.

This technical discussion is probably only of interest to me, but it's actually a very important issue. The non-linear response I'm concerned about is between 500 Hz and 20 kHz, although mainly between 500 Hz and 10 kHz. The disparity in response between 500 Hz and 2.2 kHz is almost 15 dB. That's HUGE, and results in fairly drastic EQ'ing. If the speaker response really is that ragged (and I find it very difficult to believe a trusted manufacturer like this would produce a speaker like that), then I guess the equalization is called for. But if the the swings in amplitude are simply interaction effects between the speakers at the particular mic position, and the inherent response of the speaker is much smoother than that, then room equalization efforts like this are likely to produce very unreliable results. I always tell purchasers of my speakers to limit equalization to the bass region, where room effects really are important. Speaker designers don't measure two speakers at a time for this reason. If a single speaker measures well above the bass region (and I'm not just talking about on-axis response), then the speaker will sound accurate in the room, assuming there aren't gross problems. Bass room response is another story, of course. If you could humor me, I would be very interested to see how one of these speakers measures at the standard 1 meter distance. You don't have to show the graph, and you can just let me know privately what the results are. As a speaker designer interested in producing speaker that will sound right in most rooms, I really would like to know exactly what is going on in the graph you've show. Thanks!

 

[zieglj01]

This technical discussion is probably only of interest to me, but it's actually a very important issue.

Well, some of us may be interested -- like me.

 

[OscarJr]

This technical discussion is probably only of interest to me, but it's actually a very important issue. The non-linear response I'm concerned about is between 500 Hz and 20 kHz, although mainly between 500 Hz and 10 kHz. The disparity in response between 500 Hz and 2.2 kHz is almost 15 dB. That's HUGE, and results in fairly drastic EQ'ing. If the speaker response really is that ragged (and I find it very difficult to believe a trusted manufacturer like this would produce a speaker like that), then I guess the equalization is called for. But if the the swings in amplitude are simply interaction effects between the speakers at the particular mic position, and the inherent response of the speaker is much smoother than that, then room equalization efforts like this are likely to produce very unreliable results. I always tell purchasers of my speakers to limit equalization to the bass region, where room effects really are important. Speaker designers don't measure two speakers at a time for this reason. If a single speaker measures well above the bass region (and I'm not just talking about on-axis response), then the speaker will sound accurate in the room, assuming there aren't gross problems. Bass room response is another story, of course. If you could humor me, I would be very interested to see how one of these speakers measures at the standard 1 meter distance. You don't have to show the graph, and you can just let me know privately what the results are. As a speaker designer interested in producing speaker that will sound right in most rooms, I really would like to know exactly what is going on in the graph you've show. Thanks!

Sure thing, I can do that. The only thing I can't change (for now) is the room, since these are in my office at work. Another thing I can't (shouldn't?) change is that the mic ends up being butted up against the rear wall. I mean, of course I can move it around, but then it wouldn't represent what I'd actually be hearing, since that is where I sit at my desk in my tiny office.

Eventually in about 2 weeks, all of this will be for naught since they will be coming back home when they get replaced by Legacy Calibre's. But in the meantime, I can take any measurements you like, in exchange for more tips like those that you are mentioning. When they do come home, I can take more measurements of course.