Taming a bright room

[Cassel5995]

I've been involved with audio for 25 years, from tubes to class D. I've read all the magazines and, visited the salons and attended a number of shows. I became aware of Audio Ameture, speaker builder and audio electronics years ago, and was off to the races. Built several speaker projects, anyone familiar with Marc Bacon? Canadian engineer who designed an open baffle MTM with a vented 10" woofer on bottom called the Danielle? I now own a pair of Talon Firebirds, driven by a NAD32. Source is my Microsoft laptop through a cheapie USB using Tidal and Qobuz. My room is hard, lots of reflective surfaces, and would like to try some kind of software based equalization, DSP? The problem is in the upper midrange to lower treble. Surprisingly good in the lower mids to bass. I know nothing of this, except from what I've read on the forum. Seems that some speaker reviews have comments on how to fix frequency response by means of DSP- active equalization. Any help would be greatly appreciated. 1st time posting, greatly appreciate the wealth of knowledge, and the generosity of those who are more knowledgeable. Like to thank Amir for his tireless pursuit of sifting through the bullshit, snake oil salesmen and golden eared turds.

 

[kemmler3D]

Welcome to ASR!

Unfortunately I have bad news about the prospects for DSP in the upper frequencies. The reason that sound bouncing off hard surfaces is bad is that the sound waves interfere with themselves and each other, leading to peaks and nulls that vary wildly depending on where in the room you are.

This variation in sound depending on position is essentially a property of the room, not the speaker* or electronics. As such you can only correct very wide-in-frequency problems in the room. The narrower the peak or valley in your measured response, the less advisable it is to attempt to fix with EQ.

To make it clear why this is: Suppose you have a null at some position in the room of zero amplitude, at 5Khz. The sound waves at that frequency and location in the room are bouncing back and cancelling themselves out completely. You cannot correct this null with EQ, you can only make things worse. 10dB - 10dB = 0. 100dB - 100dB = 0. 3dB - 3dB = 0. However, somewhere else in the room, you do hear the effect of EQ and it's probably not helping.

Peaks are correctable, but you're still causing issues in one spot when you fix them at another spot.

You CAN fix the sound using EQ - but only in a small spot corresponding to the highest frequency you're correcting. If you want to be able to move your head more than (say) 10" while listening, you're basically looking at 500hz or lower. What you do is place a microphone in that spot, measure the curve, and then apply EQ to flatten said curve. The problem is that curve is going to look very different 3 feet from that spot in any direction. So what sounds good at the main listening position might sound incredibly bad everywhere else.

The good news is that high frequencies are the easiest to control with acoustic treatment, and you have the most affordable options. If your low frequencies are under control, you're basically starting in the best situation one can hope for, because controlling low frequencies is really difficult and expensive.

I would recommend looking at some rockwool or PET felt panels.

You can also get a UMIK-1 and a copy of REW to measure your room and see exactly what needs fixing. There are plenty of threads on both subjects here.

Best of luck!

*as you probably know speaker directivity affects this, but you know what I mean.

 

[Cassel5995]

Not exactly the answer I wanted, but comes at no surprise. Apart from WAF,some acoustic treatments are probably my best hope. I'm thinking just putting an area rug on the tile floor, and moving the glass coffee table away from in front of my seating position would help to start. Do you think pulling the listening seat out from back wall would help? Slap echo I think its called. Acoustic panels behind speakers?

 

[HarmonicTHD]

Not exactly the answer I wanted, but comes at no surprise. Apart from WAF,some acoustic treatments are probably my best hope. I'm thinking just putting an area rug on the tile floor, and moving the glass coffee table away from in front of my seating position would help to start. Do you think pulling the listening seat out from back wall would help? Slap echo I think its called. Acoustic panels behind speakers?

For PC, APOEQ is the most commonly used together with the Peace User interface gives you DSP and all for free. If not in the upper, certainly for tackling the lower frequency room modes. But you need REW (free ) and a UMIK1 (100bucks) to determine which filters to put into APOEQ.

 

[Cassel5995]

Thankyou for your response, as I said in my post I don't know much about it, so if you wouldn't mind explaining it in more detail, would be great. I've heard my speakers in other rooms and sound glorious. The upper mid sometimes has a cupped hand sound, and the highs can be over analytical, shrill. On bad recordings, ouch, on good ones less than bliss.

 

[Killingbeans]

Apart from WAF,some acoustic treatments are probably my best hope.

The one good thing is that higher frequencies require less intrusive treatment to get effective absorption.

 

[kiwifi]

You can use quasi anechoic measurements in REW, which gate out the room reflections, to flatten the frequency response of your speakers.

To control the in room response above the Schroeder frequency you will need room treatment. You should aim for 15 percent of the room's total surface area being absorbsion plus another 15 percent dispersion, starting with the primary reflection points. You should be able to clap your hands in the room without hearing ringing, but it should not feel "dead" either.

DSP can be effective below the Schroeder frequency and is more practical than large bass traps, as are multiple subwoofers.

 

[Recluse-Animator]

Acoustic treatment. Comes in many shapes and colors.

If WAF isn't an issue.

 

[tuga]

First I would measure the anechoic on-axis response to make sure the speaker response is flat in the upper-mids/lower treble.
If it isn't flat, EQ may help.

WIde directivity and/or a peak in the upper-mids/lower treble might be another cause, in which case you should consider treating early reflection zones on side walls (online calculator here). Try to achieve some degree of symmetry.

You can also try a long wall setup if that is not your current layout, and to listen closer to the speakers (reduce the length of side on the speakers/listener triangle).

 

[Mart68]

Not exactly the answer I wanted, but comes at no surprise. Apart from WAF,some acoustic treatments are probably my best hope. I'm thinking just putting an area rug on the tile floor, and moving the glass coffee table away from in front of my seating position would help to start. Do you think pulling the listening seat out from back wall would help? Slap echo I think its called. Acoustic panels behind speakers?

I'd do all those things, plus diffusion on the wall behind the speakers, absorption on the wall behind your listening position.

 

[LTig]

I'm thinking just putting an area rug on the tile floor, and moving the glass coffee table away from in front of my seating position would help to start.

This will cancel dips and peaks from the floor / desktop which is very good (my main system sounds horrible without the rug) but it will not tame the treble. For this I would just use tone controls or (when a UMIK 1 is at hand) a high shelf filter.

Do you think pulling the listening seat out from back wall would help? Slap echo I think its called. Acoustic panels behind speakers?

Panels behind the listener are in my opinion more helpful. Or install book shelves half filled with books or other stuff.

 

[Cassel5995]

Thanks to all that took the time to offer help. 1st order is a thick area rug to handle floor reflection. Coffee table in front of listening seat gone. Absorption- reflective panels behind speakers and listening position. How effective is correction above 5-600 hz? These speakers really sing in previous room, so it came as a total surprise to me the problem I've encountered. Those who don't know about the Talon firebird, it's designed around the acuton 3/4" diamond tweeter, acuton 5" midrange and an 11" focal audiom woofer. All this in a 325lb enclosure with faceted front baffle. When set up properly in a decent room, using my NAD M32 it plays with astonishing impact, incredibly large Soundstage with pinpoint accuracy. Easy to dive, 8ohm nominal impedence, never dropping below 6.5 ohms. Not getting what I know is there is quite troubling. All suggestions are welcome. To my ear it's upper mids can sound recessed, cupped hand effect and lower treble tizzy, harsh. Although on well recorded media, you can still hear the fine attributes I love.

 

[Recluse-Animator]

Absorption or diffusion behind speakers is the last place you should treat. Start with first reflection points on walls and ceiling and flutter echo ( echo in the room ) Some people recommend absorption and others diffusers at first reflection points. For flutter echo just place absorption or diffusers anywhere you can.

I hope your listening position isn't against or close to the back wall?

 

[kemmler3D]

What you're describing, 'cupped', 'tizzy', recessed, sounds like crappy treble acoustics. Since you liked the speakers in a different room, and you've described a problem room to a T, I don't think the speakers are a problem.

I think you should find some high-WAF absorption materials and see how far that gets you. Take a REW measurement at LP every time you add some treatment to know when to stop. (also use your ears.) There is such a thing as acoustic panels with custom printed artwork on them, so that gives you an opportunity to wreck the decor a bit less.

The advice about moving your stuff is also good. If you have any flexibility on moving the speakers and seating, that can pay off bigtime.

 

[abdo123]

Guys it is misinformation to spread that we're hearing the tiny very high Q nulls above 1KHz, I would focus my efforts completely below 1KHz just for that reason.

 

[kemmler3D]

Guys it is misinformation to spread that we're hearing the tiny very high Q nulls above 1KHz, I would focus my efforts completely below 1KHz just for that reason.

Hmm, really? You can easily hear nulls in a bad room if you play a test tone at (say) 2khz and move your head around. The effect in a highly reflective room is not subtle.

What we don't hear easily are small treble nulls in a speaker or headphone frequency response. Those tend to get obscured by harmonically rich content etc etc.

Either way I would advise OP to take some measurements.

 

[NTK]

Hmm, really? You can easily hear nulls in a bad room if you play a test tone at (say) 2khz and move your head around. The effect in a highly reflective room is not subtle.

What we don't hear easily are small treble nulls in a speaker or headphone frequency response. Those tend to get obscured by harmonically rich content etc etc.

Either way I would advise OP to take some measurements.

Room modes are irrelevant above Schroeder frequency. It is, after all, the definition of Schroeder frequency, above which, the room modes are so many and the modal frequencies are so close that they all blend together.

What you described is comb filtering. Quoting Dr. Toole:

Comb filtering is often mentioned in the context of these side wall reflections. It is indeed true that one measures what looks like a comb filter. However, two ears and a brain process sounds in a manner that distinguishes between sounds based on the angle of incidence, a microphone does not. When the direct and reflected sounds arrive from different directions, the perception is normally of a small spatial effect not destructive timbral distortion. Figure 7.3 (p. 164) and the associated discussion are relevant.​

​

An interesting fact is that when we are moving we can hear things that we don’t when we are stationary. I have witnessed an acoustical consultant playing pink noise and demonstrating that acoustical interference, which was called “phasiness,” was audible when swaying the head from side to side. However, the same phenomenon that was audible in the dynamic situation with pink noise, a highly revealing signal, becomes inaudible if a listener simply walks in, sits down, and listens to music or movies. Such reflections, and there are many of them, fall into the context of “room sound,” which human listeners are known to readily adapt to. To a very substantial extent, we are able to “listen through” rooms. It is what happens in live, unamplified music performances, and everyday conversation. In terms of speech intelligibility, most small room early reflections are desirable (pp. 200–201).​

 

[Cassel5995]

Absorption or diffusion behind speakers is the last place you should treat. Start with first reflection points on walls and ceiling and flutter echo ( echo in the room ) Some people recommend absorption and others diffusers at first reflection points. For flutter echo just place absorption or diffusers anywhere you can.

I hope your listening position isn't against or close to the back wall?

Yes, your correct about my listening position being against the back wall. Knew it was a problem theoretically, didn't think it would have the effect it has along with the room having a distinct echo. I have now negotiated a new room for music with the wife, don't ask what I had to give to get lol. New room allows me to have speakers 3' from rear wall, 3' from sides with 8' between, 10' from speakers to listening position and 6' to rear wall. The room is better damped and acoustic treatments are not a problem being its now my room, sans WAF. Will update once I move the behemoths in. 325lbs each, not for the weak or faint of heart.

 

[Recluse-Animator]

Yes, your correct about my listening position being against the back wall. Knew it was a problem theoretically, didn't think it would have the effect it has along with the room having a distinct echo. I have now negotiated a new room for music with the wife, don't ask what I had to give to get lol. New room allows me to have speakers 3' from rear wall, 3' from sides with 8' between, 10' from speakers to listening position and 6' to rear wall. The room is better damped and acoustic treatments are not a problem being its now my room, sans WAF. Will update once I move the behemoths in. 325lbs each, not for the weak or faint of heart.

Good. If you're not gonna use any acoustic treatment in that room I recommend experimenting with your listening position.
Looking at the Talon Firebirds I assume they have quite a wide dispersion which not only is gonna cause first reflection, but also secondary reflections when listening further away.
99% of the time the middle of the room is gonna have the worst bass response so try get your listening position on the same half of the room as the speakers. This would also reduce rear wall reflection.
The problem with your speakers is that the tweeter and mid drivers are unusually far a part so you can't sit too close to them.

 

[Cassel5995]

Good. If you're not gonna use any acoustic treatment in that room I recommend experimenting with your listening position.
Looking at the Talon Firebirds I assume they have quite a wide dispersion which not only is gonna cause first reflection, but also secondary reflections when listening further away.
99% of the time the middle of the room is gonna have the worst bass response so try get your listening position on the same half of the room as the speakers. This would also reduce rear wall reflection.
The problem with your speakers is that the tweeter and mid drivers are unusually far a part so you can't sit too close to them. None the less my listening position isno closer then 10'. Seating position close to rear boundaries will have a more profound effect, IMHO. Therefore changing rooms will help considerably, allowing me to have at least 6' behind.

Thanks for your reply, tweeter to mid distance center to center is 6"", the crossover point will dictate the spacing. I honestly don't think that is unusually far apart.