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Bracing Help and starting to realize leaving the cab alone might be best


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Yes I'm still here asking crazy questions about topics that have been discussed. Problem is, your posts from 20 years ago don't have pictures. 

 

Braced one Tangent 500 to compare with stock and I am not happy at all. Less dynamics, and worst of all, less bass. Passive radiator isn't even close to as loud as stock, nor the woofer.

So either bracing is all wrong or this technique does not hold water in this situation. I guarantee I did it wrong, so am willing to give it one more try. 

 

Pictures will be at the bottom, notice how I have braced them first of all. 1x2 oak, 2 runs front to back and 2 runs for sidewalls and "tied" all 4 pieces together with a bit of glue. Went just under the active woofer and above the passive rad. First picture I think clearly shows that maybe the brace is preventing the woofer from fully performing. 

I did the same on the bottom of the cab underneath the radiator. Same on top of cab but had to remove one brace from the side to side due to the squawker touching it. 

The foam you see is the stock foam that the t-500 comes with. From factory it is loose one on the left one on the right. A rectangle that extends from bottom of cab up to active sub. 

With the bracing, I cut a few slits in the foam so it could pass through the bracing. Not loose anymore, tight against the sides.

 

A member from another forum wanted some pictures of what I did and for the heck of it removed the foam just to see. Certainly isn't any better.

I planned to experiment with damping but refuse to go any further untill I can prove bracing is effective with these speakers.

The stock speaker sounds beautiful compared to the braced cab, Bass is louder and sounds good (rock, hard rock, classic rock).

Braced cab may have a tighter mid end, that's about it. Non braced mid is harsher up close but sounds fantastic from my couch. The cab vibrating with the music, to my ears, is coloring the sound well. 

So what did I do wrong? Or is bracing snake oil in this situation?

Hope the people who have done this with a T-500 come forward with some information and preferably a picture so I can understand what to do. 

This is why I only did one so I have reference to the original and don't "convince" myself later that braced is better. 

 

Pics

https://ibb.co/PDb0mPd
https://ibb.co/GH5qJ9C
https://ibb.co/YhFR3c2
https://ibb.co/xLKvCMm
https://ibb.co/Mkp3GG1
https://ibb.co/zbTvgF1

 

 

 

 

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11 hours ago, ummagumma-89 said:

The stock speaker sounds beautiful compared to the braced cab, Bass is louder and sounds good (rock, hard rock, classic rock).  Braced cab may have a tighter mid end, that's about it. Non braced mid is harsher up close but sounds fantastic from my couch.  The cab vibrating with the music, to my ears, is coloring the sound well.

So what did I do wrong? Or is bracing snake oil in this situation?

 

The notion that just bracing the cabinet is the solution is I think the better part of the problem.  When you brace the cabinet walls, you change the resonant frequencies of them.  Below you will see a FEA simulation of a KEF loudspeaker box with (red trace) and without (blue trace) extra bracing (from this paper).  All you're really doing is moving the resonant frequencies upward, but you're moving those resonances into higher frequency bands that will be more audible, but not materially reducing the amplitude of those resonances:

 

image.thumb.png.37f6290adf7960de64ddc64e61f701ce.png

 

The objective (I would think) is to reduce the amplitude of the resonances that you've got. The old Wharfedale sand-filled panels is one effective way to deal with the problem:

 

6nlqd6900wv41.png?width=640&crop=smart&a

 

You can also encase the sides and back of the cabinet with a solid piece of MDF or wood, then join the inner (original) and outer (new) walls with some sort of sticky damping material ("constrained layer damping") would be an effective way to reduce the effects of those resonances. You could also fill the intervening space with sand (thus making everything much heavier, but also much deader acoustically). 

 

You could also place a lot of acoustically absorbent material around the outside of the cabinet to capture any re-radiating sound from the cabinet walls. 

 

All the above methods wouldn't affect the parasitic effect of the resonances (which is minimal), but would catch the re-radiated acoustic energy being broadcast into your room.  I recommend trying the absorption-on-the-outside trick, then listening carefully.  This will tend to tighten up the decays of the loudspeaker to transients (like bass drum impulses and midrange percussion effects), which is where you're going to most hear those cabinet wall resonances.

 

Chris

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I liked my 500's as they were stock.

Been coming to the conclusion that I must like the resonance of cabinets.

Not to dissuade others but have decided rightly or not, this is a sound that is preferred. That said, the Tangent could probably use another layer of skin.

Enjoy your discoveries...

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Appreciate the data, love seeing actual proof.

However, my cabinet,atleast to my ears untreated, has no serious resonating issues. Im only running 100w to them. I think my best option is to back off. Its not like they are falling apart and the vibration is minimul. I agree though if anything I should experiment with a bit of dampening for now and if it aint broken dont fix it

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In an ideal world, you make a bass enclosure stiff enough so that its resonances are all above the frequency band of the bass driver. Similarly, you make a midrange enclosure "floppy" enough so that its resonances are all below the frequency band of the midrange driver. Tweeters usually take care of themselves.

 

That's an ideal world. I'm still looking for an ideal world.

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12 minutes ago, Edgar said:

In an ideal world, you make a bass enclosure stiff enough so that its resonances are all above the frequency band of the bass driver.

...and only if you don't have woofer harmonic distortion, which is another "reality" that is there and can easily be seen in measurements and especially heard at higher SPL (i.e., nonlinear distortion).

 

Same thing for the modulation distortion sidebands--mostly AM distortion on woofer frequency harmonics. 

 

Horn loading of the woofer is the most effective way to eliminate modulation distortion sideband issues...which I find is the most audibly annoying distortion that's heard.

 

In any case, correlating what you hear with what you're measuring (in terms of distortion and secondary resonances from the cabinet and internal reflections inside drivers and from the box refections) is always an eye-opening experience, in A-B fashion.

 

Chris

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1 minute ago, Chris A said:

...and only if you don't have woofer harmonic distortion, which is another "reality" that is there and can easily be seen in measurements and especially heard at higher SPL (i.e., nonlinear distortion).

 

Same thing for the modulation distortion sidebands--mostly AM distortion on woofer frequency harmonics. 

 

There's that "ideal world" coming back to haunt us again!

 

In the real world, you can't escape all resonances, so you have to minimize their effects. That usually means making them low-amplitude and low-Q. ("Q" is related to the bandwidth of a resonance -- the higher the Q, the narrower the bandwidth.) Low-amplitude is usually accomplished by making the enclosure walls thick and sturdy (complex interplay here between stiffness and mass), while low-Q is accomplished by damping and/or absorption (difficult to do at low frequencies).

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10 hours ago, billybob said:

I liked my 500's as they were stock.

Been coming to the conclusion that I must like the resonance of cabinets.

Beware the person who jumps on this statement and says, "Your cabinets are COLORING the sound!! How can you LIKE this?!?!?" I've seen those comments. Most cabinets vibrate (I'm sure someone has sand-filled walls with viscoelastic dampers.) The vibration may be audible. But the designer liked the sound of the drivers in that cabinet. Just slaying the vibrations after the fact might have other effects that de-optimize the system. Taking your drivers out and putting them in a 3" thick graphite-composite cabinet with 6 inches of lead shot around it assumes that the drivers will behave exactly the same and the only effect is that some parasitic/audible vibrations will disappear. Maybe. But maybe the drivers and crossover were chosen with the cabinet surrounding them and the system works.

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3 minutes ago, Pondoro said:

Beware the person who jumps on this statement and says, "Your cabinets are COLORING the sound!! How can you LIKE this?!?!?" I've seen those comments. Most cabinets vibrate (I'm sure someone has sand-filled walls with viscoelastic dampers.) The vibration may be audible. But the designer liked the sound of the drivers in that cabinet. Just slaying the vibrations after the fact might have other effects that de-optimize the system. Taking your drivers out and putting them in a 3" thick graphite-composite cabinet with 6 inches of lead shot around it assumes that the drivers will behave exactly the same and the only effect is that some parasitic/audible vibrations will disappear. Maybe. But maybe the drivers and crossover were chosen with the cabinet surrounding them and the system works.

 

Thanks for your thoughts. Consider that the models do not sound as good as they do to me by chance or happenstance or the all too elusive, luck.

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And I will confess to bracing the backs of my Heresy One's. Tapping the backs revealed them to be much more resonant than the sides. Two 3/4"x1" diagonals were free from my scrap bin and the backs were off anyway as I was installing banana jacks. They stiffened the backs a lot based on tap testing. I could not hear a difference but left them in.

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Bracing is kinda like sushi: some love it, some hate it 😃

 

We all hear sounds differently, so I say "to each, their own" (no completely right or wrong answer) It's VERY subjective based on how YOU percieve sounds. 

 

I also think in some Klipsch models it's unnecessary, & may even be a "negative". But, in other models it may be an improvement. All I know is moderate bracing made a noticable difference (a good one) in my 1st pair of Chorus 1's & I liked it so much I'm doing it over again on my 2nd pair. 

 

I only post build threads & info for the curious, but would never try to sell everyone on the idea of "it's gotta be done". 

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If you add too much bracing like I've seen some pictures of here lately you can drastically reduce the internal air space and change the tuning of the cabinet, which in a lot of cases will reduce output of the bass. 

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All i know is that I lost dynamics. Whatever that means to any individual opinion. 

I care not what the meter says! 'Tis my ear that matters and bracing the cabinet (or taking it a step further) has diminished the sound in my opinion.

For he heck of it, was bored at work, opened up a sub I got for free (Jl-audio 83v3 with small ported box) and seen polyfil everywhere and mini bracing. 

Had a bunch of insulation I got for free and re-stuffed it - leaving the port area open. For some reason the factory blocked the wave port area. The volume and tone exploded. It blew me away the difference and what an enclosure that size is capable of.

So in my uneducated opinion, this type of stuff does improve a cabinets sound under certain circumstances. Maybe I am lucky and my cab sounds good in my environment.

Losing what I hear coming out of the stock t-500 on one side vs. the braced version with the stock foam in or out is absolutely not worth it. 

I answered my own question, but continue to share YOUR experiences please and thank-you

Edited by ummagumma-89
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6 hours ago, ummagumma-89 said:

I answered my own question, but continue to share YOUR experiences please and thank-you

I've never actually added any bracing to factory Klipsch cabinets but i recently threw together a pair of slightly modified Chorus style cabinets and after seeing what people have suggested and done here i decided that a single window frame type brace just above the woofer would be enough considering all of the Chorus models I've owned and really enjoyed never had anything.

 

 

20210317_190006 (452x640).jpg

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  • 1 year later...

Constrained layer Damping is something I’m currently adding to my K402 MEH cabinets. Bracing pushed the frequency of resonance up in Hz, but does not diminish amplitude, (as @ChrisA said).  My understanding suggest that higher frequency resonance is easier to reduce with a constrained layer. 
Im adding a layer of 1/2” particle board over my existing 3/4” mdf, with a layer of Green Glue in between.

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RANT:
I don't know why this stuff is always so hard for people. 

 

1) Panel resonances.  Vibrating panels radiate sound into a room.  They are sources.  
2) Vibrating panels are loss.  You put energy into your terminals and somewhere acoustic power comes out.  Exciting panels may/not help, but "warmth" & balance change when panel vibration changes.  If you stiffen a cabinet, both your head and the speaker need rebalancing.  
3) Standing waves.  Parallel walls, in our current universe, produce them.  Braces/filling/lined braces can alter them.  Where drivers/ports/PR's etc are located with respect to nodes/antinodes is part of the "soup".  
4) Rear-radiation from drivers relects around inside the box and comes out through the cone and cabinet walls again.  Changing lining/bracing/filling changes this bit of the "soup".
5) Damping (as in driver) is affected by all the preceding in addition to everything we're not even talking-about.  
 

Yes, designers listen to the products they toiled on and Somebody made the final call (prod mgt, eng, team blah) and called it Good.  However it shipped--it was a package not to be altered (or it would've had different pricing/configuration).  That doesn't mean you can't change it, it just means it's your speaker and not theirs. 

 

Anyone can perform some reversible experiments to convince yourself.  You want to know about cabinets, build an OB setup.  You want to hear what comes out through a cone, toss a portable audio source (phone/radio/etc) inside your (non-running) speaker and listen.  You want to know about bracing--add external clamps, listen for a week, and take the clamps off and listen.  You want to know about panel vibration--knock at a cabinet corner and knock anywhere else--do they sound the same?  How stiff a cabinet of what construction would it take for every spot to sound like a corner?  You want to see standing waves, watch some here: https://www.youtube.com/watch?v=VrgyKFBPQW4

 

Once you hear this stuff you can't Unhear it.  Ever.  Convince yourselves.  Measure if you can/seek to.  Nothing is any different than it ever was but people still think this is all voodoo and a crapshoot.  It's not voodoo, it's just inter-dependent and non-trivial to analyze.  Ask non-audio people which sounds cleaner or better or whatever it is you seek to improve.  If just curious, diy some test mules for the purpose and burn them when you are done--if your ears work and you repeatedly try 2 types of material (large soundbodies like cellos/pianos as one, heavy percussion as the other), you can hear night and day changes when altering filling/lining/bracing in about any "normal" cabinet larger than a couple breadboxes) as you change things. 

END RANT. (And stay off my lawn)

 

To the OP:  Applaud your curiosity and open-mindedness.  It may well be that the way it is is the easiest thing and if you are happy, then you have Succeeded--they are Your speakers and all that matters is that you like them. 

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I spent two years trying to figure out if I should, and how I should brace my three Cornwall pairs ('68, '74, '76). The '68 and '74s are super solid cabs in the original state, and I arrived at the conclusion that it was better just left alone as opposed to getting it wrong and just moving the "sonic anomaly" somewhere else on the spectrum. 

 

The 76 decorator cabs make the best case for bracing, but as they are surround speakers, and boast some of the most beautiful woodgrain faces you'll ever see on a speaker, I decided to leave those alone as well. 

 

I got tons of sonic mileage double dynamatting the horns and woofer baskets, actually did A/B tests here and it's pretty clear. I could do these by way of taking my time to get that right. In the case of bracing I didn't trust my ability to get them in there properly, such that I didn't damage the cabs or fail to lock the braces in solid enough to end up "Pillsbury doughboying" the the situation by just moving the problem somewhere else, and risk cosmetic or worse damage to the 50+ year old cabs.

 

I spent just over 2K per Cornwall pair in network and total parts replacement and the results don't have me regretting the "non brace" one bit. We had our own little "Axpona" over here and blew a few minds this weekend. Soiled underwear are back in fashion again. The only braces we needed were the ones protecting the listeners' jaw from hitting the floor. And these are people who own Heritage speakers, and know them pretty well.

 

So - 

 

If you don't feel comfortable modding those braces in - that's OK. And if you can't afford the extra 4K for Cornwall IV (bracing problem solved) it's not the HUGE deal people want to tell you it is, especially in '75 and prior Cornwall cabs. It IS an improvement in that specific area if done right (that's a big if). I notice this on Belle Klipsch and OG LaScala more than I do the Corns, but in the end I decided it was not worth the expense to attempt to solve that vs other improvements I could do on my own or in the case of networks just hire it done.

 

Later cabs might differ but those "sweet spot" late 60's/early 70s cabs are pretty solid, especially the Cornwalls. I expect that if I did this with some of the 80's versions I might get differing results too.

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