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How to treat Cornwall 3 cabinets for better bass?


Boomzilla

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I believe the front and back panels are set into a groove/dado cut into top/bottom and sides.

I think you're right about the motorboard being set into a dado, but the rear appears to be a removable, screw-in panel.

I don't think they are screwed in. If you look at the back, you can see how the panel is beveled on the edge. It goes over to fit in the grooves in the top/bottom and sides.

Bruce

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Those 2x4 braces should go a long way in stiffening the front to the rear, but unless there are screws on the back at that position, I would assume they are glued in place.

I am sure they are glued... and screwed.

Bruce

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If you look at the inside of the cab on this pic, you will see there are no strips to put screws into.btw, these are pics taken of the CW IIIs under construction that DTEL and Christie won at theHope pilgrimage.

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"Bass reflex boxes" are too diverse to be thrown into a single category, IMHO. I've heard ported boxes (some with just ports, others with passive radiators in place of ports) NONE of which sounded like the Cornwalls.

Because some of the other vented boxes that I've used in my room DID provide taut and pitch-accurate bass, I think that one of two things may be preventing the Cornwalls from doing so as well:

Either the design is optimized for high efficiency at the expense of bass accuracy (possible) or the economies taken in the manufacturing process have resulted in insufficient cabinet rigidity and allowed the cabinet to vibrate along with the signal (likely).

I'd like to know (hear with my own ears) what your idea of "pitch-accurate bass" is. Since the frequency response of the bass range, regardless of speaker design, is influenced primarily by the speaker's interaction with the room, that tells me you don't really know what "taut and pitch-accurate" bass, bass accuracy is. And since Klipsch design puts first priority on low-distortion at adequate (live-realistic) acoustic power output which goes hand in hand with high efficiency (if you disagree please mathematically prove right here for all to see), third in importance polar pattern, and lastly the effective frequency response, I suggest you go back to whatever it was you were using before. Nothing to be ashamed of. Some people just like more distortion. It's your right. Exercise it.

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I'd like to know (hear with my own ears) what your idea of "pitch-accurate bass" is. Since the frequency response of the bass range, regardless of speaker design, is influenced primarily by the speaker's interaction with the room, that tells me you don't really know what "taut and pitch-accurate" bass...is.

Well, I guess that puts me in my place, artto. Since I've already said that I've heard "pitch-accurate" bass from other speakers in the SAME room and in the SAME locations as the Cornwalls, then it stands to reason that I don't know what I hear.

...I suggest you go back to whatever it was you were using before. Nothing to be ashamed of. Some people just like more distortion. It's your right. Exercise it.

No further comment, thanks.

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If you look at the inside of the cab on this pic, you will see there are no strips to put screws into.btw, these are pics taken of the CW IIIs under construction that DTEL and Christie won at theHope pilgrimage.

I see the braces above the woofer, but it appears that there is no lower shelf below the woofer. I thought that lower shelf had a lot to do with the particular tuned alignment of the Cornwall cabinet?

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I agree here. The two 2x4 stringers are an ok start and are much better than nothing but this is still a very much under braced and stiffened cabinet as far as I am concerned. The baffle isstill weak and all the other panels require braces and stringers to tie them all together. If you take a look at the pictures in the link you will see a retro brace job on a pair of Heresy 3 which like the CW3 have both front and back baffles locked into the sides of the cabinet. In the case of the H3 the baffles were all lose dry joints which had to be repaired. All work was done through the woofer opening. The material used was solid white oak for its stiffness and strength. I would consider an approach like this (with larger dimensioned brace material) a decent quality job. If you were to build a larger cabinet from the ground up you could of course utilize more significant brace and stiffening materials. My two cents this is the way I do it, of course there are other ways. Best regards Moray James.

http://www.audiokarma.org/forums/showthread.php?t=438234 Heresy3 brace work

http://www.audiokarma.org/forums/showthread.php?t=372783&highlight=klf20 pictures of a brace job on a Quartet and a fast and dirty job on a pair of KLF20

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Thank you, Moray -

I've sent you a PM for other ideas on the Cornwalls. I'm also getting to the point where I must ask the question: Should I abandon the Cornwalls and select another pair of speakers? It seems that almost a full "re-engineering" of the Cornwall will be required before it will do what I want. Would it be easier, cheaper, and more effective just to select other speakers?

Boomzilla

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Got your PM and have responded. I does seem daunting at times with respect ot rebuilding speakers but there is really no option other than building from the ground up yourself. It is not as bad as it seems and the rewards are there. Take a look at the recent CF3 thread. Whild not exactly as I would have done the job it is close and the owner has and is extremely pleased with his efforts. The twas a retro job an as such slall the work has to be done through driver openings. The time frame does not have to be unreasonable if you plan things out. Tothe speaker which I would see (personally) as more interesting than the CW are the Chorus ll the KLF20/30 the CF3/4. Best regards Moray James.

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If you look at the inside of the cab on this pic, you will see there are no strips to put screws into.btw, these are pics taken of the CW IIIs under construction that DTEL and Christie won at theHope pilgrimage.

I see the braces above the woofer, but it appears that there is no lower shelf below the woofer. I thought that lower shelf had a lot to do with the particular tuned alignment of the Cornwall cabinet?

Mike, That shelf only goes back about 9.5 inches and is not quite 4 inches tal. I think you just aren't seeing it through the woofer opening, as you don't see the back where it meets the bottom either. Don't forget, the woofer opening is also a lot higher than the CW and CWII.

Bruce

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If you look at the inside of the cab on this pic, you will see there are no strips to put screws into.btw, these are pics taken of the CW IIIs under construction that DTEL and Christie won at theHope pilgrimage.

I see the braces above the woofer, but it appears that there is no lower shelf below the woofer. I thought that lower shelf had a lot to do with the particular tuned alignment of the Cornwall cabinet?

Mike, That shelf only goes back about 9.5 inches and is not quite 4 inches tal. I think you just aren't seeing it through the woofer opening, as you don't see the back where it meets the bottom either. Don't forget, the woofer opening is also a lot higher than the CW and CWII.

Bruce

Ok. I couldn't imagine not using that shelf.

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Does everyone here think that bracing the cabinet or stiffining it will change the sound of the speaker..........because I definitely don't. It MAY produce a TINY bit more energy that was getting lost. I bet you couldn't hear the difference. I just don't think it would do anything in my opinion to solve a "bloating" issue, and I would not waste a moment changing the engineering of the cabinet. It will just devalue a beautiful pair of speakers.

Since the original poster is well aqcuainted with the room and placement I would consider using a mic and an RTA (software program) to make an in-room curve of the woofer response and see if arrangements could be made to have an older CW brought in to do the same. See what changed! The CW-III obviously has a different FR.

In other words I would actually try to figure out the problem rather than throwing solutions blindly at it and making a radical change.

You could easily use a graphical EQ to replicate one or the other to get them to sound nearly identical.

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...Since the original poster is well aqcuainted with the room and placement I would consider use a mic and an RTA (software program) to make an in-room curve...

Thanks - a very reasonable suggestion. Unfortunately a "static" room response at different frequencies won't necessarily catch retained energy output from cabinet resonances, will it? If so, then where do I find a calibrated microphone and software for Mac OS-X? If not, then is a FFT mapping software required? A tape-on contact microphone to show cabinet wall resonance? How do I get where I need to go from here?

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What I suggested is really easy stuff to do, and a lot of folks on this forum use an RTA (real time analyzer). It presents a visual image of what you hear. You would use "pink noise" not music. You could disconnect the MF and HF drivers to get a curve........but not really required.

I highly doubt what you are hearing is a cabinet vibration. That would be a remote possibility on such a new design with all the modeling capability Klipsch has, really. A gross vibration would not get caught by Kipsch? Do you think you got 2 defective speakers, or just one? Do they both do the same thing as one another? Then..........every CW-III built is defective? No way. It's something else.

The new and old are a completely different cabinet design, the new uses different electronics, and are designed for a different frequency response performance than the old ones. They are different.

It would be simple to find out where you have a "bump" or difference in the FR and EQ it so the curve of the CW-III lands exactly on top of the old CW curve. You will not ever get exact sound between the two because of the design and part differences, but it will more than likely be so close you will be happy. really, the CW-III shoudl sound a lot better.

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Does everyone here think that bracing the cabinet or stiffining it will change the sound of the speaker..........because I definitely don't. It MAY produce a TINY bit more energy that was getting lost. I bet you couldn't hear the difference. I just don't think it would do anything in my opinion to solve a "bloating" issue, and I would not waste a moment changing the engineering of the cabinet. It will just devalue a beautiful pair of speakers. ........

cabinet

I agree with Mark on this one. Unless the cabinet had some inherent flaw, I doubt you are going to get a substantial difference from bracing. In my limited experience and unless there is a problem with the design of the speaker, "bloating" is best addressed by looking at how the speaker is interacting with the room. Mark has given a good direction on how to tackle this problem.

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...I agree with Mark on this one. Unless the cabinet had some inherent flaw, I doubt you are going to get a substantial difference from bracing...

OK - makes sense to me. Assuming that what I'm hearing is NOT the cabinet, but rather the speaker-room interaction, why don't I hear this "bloat" with other speakers that I've used in the same room, in the same locations, and with the same electronics? Is there something radically different about how a Cornwall interacts in a room than with how a Thiel, say, interacts with the same room?

This is not a trivial question! Unless there is some logical explanation for these differences, then, despite your "no inherent flaw" hypothesis, the Cornwall cabinets ARE the problem. To paraphrase Sherlock Holmes, what remains after all other explanations are proven false must then be the truth.

Assuming that there IS some logical explanation for why the Cornwalls sound radically different in the bass than all other speakers used in the room, then let's further assume that I want to use some "electronic magic" to tame the speaker-room interface. Am I better off using an AV front-end that has built-in Audissey or TACT? If not using an AV front end, then what exactly do I need to analyze the room? Will the "bass only" analyzers such as the DSPeaker Anti-Mode 8033 work with full range speakers, or are they intended for subwoofers only?

I'm not asking to aggravate, but because I'd truly like to know

Thanks - Boomzilla

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A sub can sound great in one spot but if you put a different sub in the same spot it can be not so great. Bass is tricky from one speaker to another. Some speakers need a corner some dont depending on the room and the speaker.

Sounds like the cw3 dont work well in the spot you want them from all the reviews you have done on them so far.

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It sounds like you have a particular part of the frequency spectrum being overdriven......so you are getting too much of something somewhere. The easiet way to solve it.............or try to identify what it may be is to measure what you hear. Play the problem. Record the problem so you have a visual picture, and turn it down where it hurts. It's not very hard. That's why they made EQs.

So why does this happen when all you did was change cornwall for cornwall? Maybe the CW-III just puts out a little more energy in certain parts of the spectrum. Maybe a hair more efficient in some spots.

I wish I was there because I bet we could fix it to your satisfaction in less than 30 minutes with an RTA and a little EQ, or at least I could demo a fix. Some folks on this board curse out equalization and tone controls. Those are the guys that fix something like this with a cabinet project, network tweaks, a room full of symmetrically placed treatments that appear to have been engineered, and $689.00 worth of new tubes from Brent Jessie. [8-)] Then the problem is gone. The truth is they never really identified it in the first place.

This is just MHO, but in 30+ years in audio the single most difficult thing FOR ME has been treating a room. I try never to do it. If it comes down to that, I can recommend someone with the proper tools and know how.

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Using the RTA is the only way to truly know what is happening in the room. Bass is a tricky creature.

Agreed - I've asked thrice about RTA packages for the Mac and received zero suggestions. Googling it, I find a plethora of software, most of it intended for pro-audio applications.

I'm willing to spend the $$$ and the time to master a RTA program, but don't know which to choose. I'm overwhelmed. I may just give up and get an AV preamp with its own calibrated microphone and "dummy-proof" calibration built in.

In the mean time, the Cornwalls come down. My Heresy speakers go back up. A small subwoofer comes in to supplement the bass. I know that this combo works!

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