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merkinman

Cornwall IV Bass Issues

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I've noticed what to me sounds like bass resonance from inside the speaker cabinet and it seems to vary to a large degree on the recording.  I have a bit of a challenging room...14' x 20' basement with concrete floors and front/side walls.  The speakers are positioned 1-2 feet from the front wall near the corners and toed in a bit on the short wall.  I've experimented with placement and it doesn't seem to help.  Are there any known issues with lack of bracing of the cabinet?  I don't have a lot of flexibility with speaker placement due to them being located in my home theater on either side of the screen, so I was thinking of getting a mini DSP or ACS tube bass traps for the corners to see if that would help in case it's the room.  Appreciate any advice.

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I heard what you describe with a pair of CW II and a pair of Cornscalas. I now own Cornwall IVs and hear nothing like that, nor have I heard anyone else mention it. The IV did improve on the internal bracing over the III. I would suspect a room issue and bass traps could help. I have a pair but actually removed them with these speakers, not necessary at all.

 

Shakey

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I would strongly recommend bass traps (more than one) and a fair amount of absorption material covering the walls, and carpet (thicker is better) on the floor. 

 

Most stereo setups rely on drywall flexure at low frequencies to absorb these hard-to-absorb frequencies, but concrete walls don't do that very well.  Cornwalls have a very well-controlled bass response, so what you're likely hearing is the lack of low frequency absorption. 

 

The miniDSP (all crossovers except the "2x4"--without the "HD"...this has too much noise/too little gain latitude) you mention could also be useful in re-EQing the bass frequencies to flat response, and also the rest of the midrange and treble bands--measuring one loudspeaker at a time--to get the overall response as flat as you can.  Don't use boosting EQ at low frequencies--just attenuating PEQs to flatten the peaking response areas, or you'll be chasing your tail pushing room modes around. 

 

I wouldn't try to use room EQ software (Audyssey, etc.) in a hard-walled room with so little absorption.  It's better to do it manually or you'll probably wind up dissatisfied by the results. 

 

You'll need something like a UMIK-1 (calibrated microphone) and Room EQ Wizard (REW) shareware to measure at your listening position(s) to do this effectively. 

 

Good luck.

 

Chris

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I believe it's the room and not the speakers.

 

As a test (and just a test; I'm not suggesting this as a solution), try placing the speakers in another room (as Chris A suggests, it could be the concrete walls, so you can try them in a wood-framed, drywalled room), or try placing them against the adjacent  wall in the concrete basement (90 degrees from the current wall).

 

The former would prove Chris A's theory of the concrete walls; the latter would eliminate the speaker position as the cause.

 

Updated thought: Try getting the Cornwalls off the floor, on stands or concrete blocks of some sort as another experiment.

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16 hours ago, Chris A said:

I would strongly recommend bass traps (more than one) and a fair amount of absorption material covering the walls, and carpet (thicker is better) on the floor. 

 

Most stereo setups rely on drywall flexure at low frequencies to absorb these hard-to-absorb frequencies, but concrete walls don't do that very well.  Cornwalls have a very well-controlled bass response, so what you're likely hearing is the lack of low frequency absorption. 

 

The miniDSP (all crossovers except the "2x4"--without the "HD"...this has too much noise/too little gain latitude) you mention could also be useful in re-EQing the bass frequencies to flat response, and also the rest of the midrange and treble bands--measuring one loudspeaker at a time--to get the overall response as flat as you can.  Don't use boosting EQ at low frequencies--just attenuating PEQs to flatten the peaking response areas, or you'll be chasing your tail pushing room modes around. 

 

I wouldn't try to use room EQ software (Audyssey, etc.) in a hard-walled room with so little absorption.  It's better to do it manually or you'll probably wind up dissatisfied by the results. 

 

You'll need something like a UMIK-1 (calibrated microphone) and Room EQ Wizard (REW) shareware to measure at your listening position(s) to do this effectively. 

 

Good luck.

 

Chris

Appreciate the advice.  I have a pretty well treated room.  3' tall 6" thick corner bass traps behind the speakers, carpet, and 2" thick panels at first reflection points.  A wall to wall bookshelf on the back wall.  I really think it's the concrete floor and walls.  I ordered the minDSP DDRC-22D and will see what that can do.  I would say the bass issues are only audible with 20% of the content, so it seems pretty isolated/specific.  Will report back.

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23 hours ago, merkinman said:

I've noticed what to me sounds like bass resonance from inside the speaker cabinet and it seems to vary

is the resonance equal in both speakers -    have you tried rotating the speakers to see if there is a difference -

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8 minutes ago, RandyH000 said:

is the resonance equal in both speakers -    have you tried rotating the speakers to see if there is a difference -

Haven't really noticed.  What are you thinking?

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2 hours ago, merkinman said:

Haven't really noticed.  What are you thinking?

 check if the resonance is only in 1 speaker or both  -

1st step - rotate the left and right  speakers   ,  if both speakers sound exactly  the same  and identical resonance ,  then the issue is not the speakers , 

 

 

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12 hours ago, Heritage_Head said:

Concretes the worst

Which is an interesting observation considering virtually all venues have as a minimum a concrete floor. And large concert halls/rock venues are concrete all around, and we tend to compare our listening experience to live music.

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1 hour ago, Peter P. said:

Which is an interesting observation considering virtually all venues have as a minimum a concrete floor. And large concert halls/rock venues are concrete all around, and we tend to compare our listening experience to live music.

This is true... But for bass in my experience in a home setting (with those rooms being much smaller then a venue). Bass IMO is humongous pain in the ***. The Cornwalls that I had on concrete (even in corners) compared to the living room 1 floor up on wood framed floors (not even in corners) was extremely different. 
 

Others can chime in but it would be my guess that a room in a home setting might have more acoustic overall affect than a large space like a venue where the walls, ceilings and floors are normally a large distance away from the speakers? 

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Home-sized rooms are not concert halls.  The difference is volume--dimension.  The reason for the "X" curve used in cinema (which itself isn't a correct curve to use, as it turns out) is due to the absorption of acoustic energy by the mass of air in these venues.

 

I think it's good to have these kind of conversations online, but you really need to read and understand the engineering/physics body of knowledge on the subject of interior acoustics for live performance (i.e., generally very large venues) vs. very small home-sized listening rooms. 

 

At the frequencies below the room's Schroeder frequency (which is dimensionally dependent on the linear dimensions of length, width, and height of the listening room, as well as the damping ratio of the sum of interior surfaces), the acoustic energy behaves like you're inside a chamber that is smaller in one or more dimensions than the wavelength of the acoustic waves, so the effects of toe-in, etc. have essentially no effects below the room's Schroeder frequency.  So worrying about which way the loudspeakers are pointed means nothing below the room's Schroeder frequency as it turns out, only the distance of the loudspeakers from the mouths of the horns or the face of the woofers to the room's boundaries count, and if that spacing is less than 1/4 wavelength, it means that the way that the bass bins are pointed has no effects.

 

However, at frequencies above the room's Schroeder frequency (generally around 200 Hz for most peoples' listening rooms), toe-in/pointing of the loudspeaker is very important.  So in general, the frequencies affected by toe-in and other aiming of the front baffle of the loudspeakers are the midrange and treble frequencies only--but not the bass frequencies well below ~200 Hz that the OP is talking about in this thread. 

 

Chris

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35 minutes ago, Chris A said:

Home-sized rooms are not concert halls.  The difference is volume--dimension.  The reason for the "X" curve used in cinema (which itself isn't a correct curve to use, as it turns out) is due to the absorption of acoustic energy by the mass of air in these venues.

 

I think it's good to have these kind of conversations online, but you really need to read and understand the engineering/physics body of knowledge on the subject of interior acoustics for live performance (i.e., generally very large venues) vs. very small home-sized listening rooms. 

 

At the frequencies below the room's Schroeder frequency (which is dimensionally dependent on the linear dimensions of length, width, and height of the listening room, as well as the damping ratio of the sum of interior surfaces), the acoustic energy behaves like you're inside a chamber that is smaller in one or more dimensions than the wavelength of the acoustic waves, so the effects of toe-in, etc. have essentially nothing to do with the toe-in of the speakers below the room's Schroeder frequency.  So worrying about which way the loudspeakers are pointed means nothing below the room's Schroeder frequency as it turns out, only the distance of the loudspeakers from the mouths of the horns or the face of the woofers to the room's boundaries count, and if that spacing is less than 1/4 wavelength, it means that the way that the bass bins are pointed has no effects.

 

However, at frequencies above the room's Schroeder frequency (generally around 200 Hz for most peoples' listening rooms), toe-in/pointing of the loudspeaker is very important.  So in general, the frequencies affected by tow-in and other aiming of the front baffle of the loudspeakers are the midrange and treble frequencies only--but not the bass frequencies well below ~200 Hz that the OP is talking about in this thread. 

 

Chris

Every time I read one of your posts Chris I learn a ton of stuff of course (thanks 👍).... And I’m also reminded of just how little I know (thanks 😉). 

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On 11/14/2020 at 5:11 AM, Chris A said:

I would strongly recommend bass traps (more than one) and a fair amount of absorption material covering the walls, and carpet (thicker is better) on the floor. 

 

Most stereo setups rely on drywall flexure at low frequencies to absorb these hard-to-absorb frequencies, but concrete walls don't do that very well.  Cornwalls have a very well-controlled bass response, so what you're likely hearing is the lack of low frequency absorption. 

 

The miniDSP (all crossovers except the "2x4"--without the "HD"...this has too much noise/too little gain latitude) you mention could also be useful in re-EQing the bass frequencies to flat response, and also the rest of the midrange and treble bands--measuring one loudspeaker at a time--to get the overall response as flat as you can.  Don't use boosting EQ at low frequencies--just attenuating PEQs to flatten the peaking response areas, or you'll be chasing your tail pushing room modes around. 

 

I wouldn't try to use room EQ software (Audyssey, etc.) in a hard-walled room with so little absorption.  It's better to do it manually or you'll probably wind up dissatisfied by the results. 

 

You'll need something like a UMIK-1 (calibrated microphone) and Room EQ Wizard (REW) shareware to measure at your listening position(s) to do this effectively. 

 

Good luck.

 

Chris

I'm looking forward to trying out the miniDSP.  Does the DSP correction degrade sound quality in a noticeable way?

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1 hour ago, merkinman said:

I'm looking forward to trying out the miniDSP.  Does the DSP correction degrade sound quality in a noticeable way?


Most here will say no. To my ears, any time you can remove something electronic from the chain it’s beneficial to do so. Simpler is often better in high end audio. That said, if it corrects issues that are otherwise impossible to live with, it’s worth it. But I would try to passively solve your issue first.

 

Shakey

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3 hours ago, merkinman said:

Does the DSP correction degrade sound quality in a noticeable way?

It improves the sound considerably, especially if you flatten the SPL response to ±1.5 dB (using psychoacoustic smoothing), not counting room nulls due to room modes, and flatten the phase response to within ±90 degrees from 20 kHz down to at least 100 Hz, then things get a LOT better.  Just ask any of the Jubilee/other DSP-crossed loudspeaker owners that I've helped dial in their systems (a few dozen of those guys that are around). 

 

I think what a lot of people are reacting to (and it's clearly a knee-jerk a reaction at best) is the bad old days of not-so-good analog EQ boxes that significantly degrade the sound due to numerous transfer function issues, as well as other added distortion. 

 

With good quality DSP units today, they are totally transparent (except for the desired response corrections you dial into them) in my experience. 

 

Go over the diyAudio.com and read the numbers of guys using DSP there in the multiway forum.  It's a high percentage with most saying that they would never go back to passives (which I agree with).  Passive crossovers are definitely becoming a dying breed there.  Those that most vocally oppose DSP crossovers are usually those that apparently lack to skills to dial in their DSP crossovers properly. 

 

Chris

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I’d try Aurelex subwoofer base. I out then under my subs and boominess is a thing of the past. 

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10 hours ago, Chris A said:

Home-sized rooms are not concert halls.  ...200 Hz that the OP is talking about in this thread. 

 

Chris

My head exploded. 😀

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