Speaker Cabinet Vibration and Measurements

Whist we are on this topic, has anyone experimented moving out crossovers from inside of speaker cabinets? Surely these electronics take some beating due to vibrations inside the speakers not to mention effects from drive unit magnets located in close proximity.
Most manufacturers take great care to isolate electronics from airborne and structural vibrations within the casings of cd players and amps and so do we the end user with the assembled equipment mounted on decoupled feet, acoustic slab, stands etc. So why aren't crossovers made as outboard modules as in car audio?
Cheers all.

jokiarch wrote:

bassraptor wrote:...
You know, I spent a weekend fine-tuning the position of my maggies to get it just where I felt it was just right. Then, when I thought I had done that, I pulled out the Apogee Centaurs and lined them up vs the Maggies. I wanted to cry when I heard the Centaurs then, even without optimum placement. Made my work with the Maggies seem so futile.
...

Now you are onto Apogee? And you want to cry? I want to congratulate you Bassraptor!! I love Apogee ultimately, and to a lesser extend, ESL-57 which I own but pending setting up. Welldone!!

I can appreciate your predicaments in spending tremendous hours in your set-up and only took a hugely compromised drop-in of another to knock it off! In the persuit of hifi, this is a good thing considering the rarity in finding "the right one" here.

Congrats again!
Jo Ki

Sujesh, I suppose now if I tell you there are people who actually used to own 3.5 pairs of Apogees (7 speakers in all), you won't be surprised at all right ?!! ALL of them are in use.

Wan Azami Hamzah wrote:Whist we are on this topic, has anyone experimented moving out crossovers from inside of speaker cabinets? Surely these electronics take some beating due to vibrations inside the speakers not to mention effects from drive unit magnets located in close proximity.
Most manufacturers take great care to isolate electronics from airborne and structural vibrations within the casings of cd players and amps and so do we the end user with the assembled equipment mounted on decoupled feet, acoustic slab, stands etc. So why aren't crossovers made as outboard modules as in car audio?
Cheers all.

Hi wan,

Sadly, this is still a consumer-driven world. So product packaging counts alot.
Who wants to buy a speaker that comes with an extra set of boxes housing the external crossovers if it can all be nicely fit into one handsome luxury packaged product? Glossy piano finishing, or Ebony+rosewood veneer as the finishing touch ? Consumers don't want to deal with added complexities more than its needed. Hooking up a simple hifi rig is quite painful for a sizable chunk of the human population already. Let alone an AV system as an even more extreme example.

That being said, there are always exceptions to the majority. Some Magneplanars have external crossovers (i think i remember seeing them lying around on the floor next to certain Maggies). Some Infinity IRS-series also have external X-over boxes if I'm not mistaken. Even Krell made aftermarket external X-over units for some particular model of B&W speakers.

The idea of a home-made modification of relocation loudspeakers' X-over units to an external box might be an interesting tweak that could yield great results. But alas, not so many speakers would be tweak-friendly to a X-over lobotomy. Imagine trying to do this one a pair of perfectly functioning vintage LS3/5a speakers! Ouch! Some things are better left untouched!


The car audio scene is an entirely different story. Car audio makers don't sell you an all encompassed speaker system. They just sell you the woofers and tweeters. Then its the resident woodworks/carpender dude at your favourite car accessory shop that goes about making the speaker cabinets with their amazing carpentry skills.
I would say (and i dare say it aloud) that no amount of well skilled car audio installer dude will ever build any decent mobile sound system that can even come close to the bare absolute honesty of a pair of LS3/5a bookshelves, for example.

Case in point: Home loudspeaker mfgs would invest in R&D to get the proper cabinet design, source for the appropriate OEM drivers (or in the case of Thiel or Magico, and others who make their own drivers in-house, etc) to make sure the speaker sounds "decent" and up their expectations of a final product. Contrast this with JL-Audio or Soundstream Tarantula drivers. They just sell you that big round thing, and then "hope" that your installer might know what to do with them, who would build you a speaker enclosure with the main objective of ensuring that you might still have space in the boot for at least 1 set of golf clubs, and still accommodate the spare tyre also. Speaker cabinet design for the sake of audio reproduction takes a back seat right from the start already. Different execution of priorities at work here.

Dave Wilson goes to great lenghts to design and make the speaker cabinets as rigid and inert as possible. But "Dave the car audio-installer" would just make sure that the aftermarket woodworks in place of your back seat and boot space won't crumble down when u go over speedbumps or take a fast corner... it's mission accomplished for him already.

Car audio may win in the decibel war (albeit in a totally disgusting manner to the purist audio aficionado) and this aspect alone seems to be the only thing going for insane car audio buffs (heck, they even have decibel level competitions among the industry!! To see who's boom-boom system on wheels can peak the highest on the dB scale!), but in terms god-honest audio reproduction, it can't be further away from the truth.
For example: Alpine's "IMPRINT (tm)" digital correction system is a good attempt at addressing such shortcomings. But as noble as it's intentions, its only a "good attempt". Nothing more.

How would i know ? From years and years of spending too much time in the car aftermkt industry, Jln Horsepower, Sunway for starters. And i doubt if any of the staff from Kenn-Kenn, Brother Peter, Brothers (this one is right out), KKLau or CV Mobile, or your neighbourhood Fat-Pete (with apologies to the person so referenced) car accessory guy could EVER be regarded as an authority on sound reproduction. IMO of course. But in the spirit of leaving doors open, if anyone here can point me the direction to a SERIOUS Car Audio setup that can rival a 2-channel home system in many an aspect of audio reproduction, I am all ears!

And no, even the complete Mark Levinson system in the Lexus LS460 doesn't quite come close to making the grade still.


Anyone is welcome to disagree on all the above of course.

And lets not get started on the fundamental flaws of audio reproduction in a typical car enviro. It's a different can of worms altogether.

I agree ... for years, I was a regular at Tehnichi, whose Simon Teh has a keen ear and passion for good sound - he'a a dedicated audiophile of the most committed type, a tweaker. But however good the car system sounded while being demo-ed or checked in the showroom, the moment you started the engine, and then hit the road, it was all down hill. If I'm going to get road/wind/tyre/engine noise with my music, I might as well stick with the standard system in the car.

High-end car audio would work for me if I could accept the above and effect a complete paradigm shift in my senses ... but I've found out after much time and effort that I can't ... I need my traditional staging and balance ....and I'm not into decibels or heavily DSP-ed modes ...

[/quote]by Wan Azami Hamzah Yesterday at 11:13 pm
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Whist we are on this topic, has anyone experimented moving out crossovers from inside of speaker cabinets? Surely these electronics take some beating due to vibrations inside the speakers not to mention effects from drive unit magnets located in close proximity.
Most manufacturers take great care to isolate electronics from airborne and structural vibrations within the casings of cd players and amps and so do we the end user with the assembled equipment mounted on decoupled feet, acoustic slab, stands etc. So why aren't crossovers made as outboard modules as in car audio?
Cheers all.[quote]

I have done the mod of removing the x-over of my SF Concerto. Actually, I HAD to remove the x-over as I did a capacitor change to the tweeter circuit and there wasn't enough space in the speaker enclosure to accommodate the modified x-over. So the best solution was to locate it outside the enclosure.

However, I did not totally isolate the x-over away from the speaker. I stuck it to the back of the speaker on a piece of wooden board.

Although this has eliminated the effect of sound waves (if any) on the x-over, it is still subjected to cabinet vibration as it is not physically isolated from the speaker cabinet. But being outside of the cabinet has given me the opportunity to make further mods in future, if I so desire.

I can't really confirm if isolating the x-over to the outside has any significant benefits, but the capacitor change did have a dramatic change for the better.

I was advised that isolating x-overs to the outside will have an effect. How significant? I can't confirm. But one will need to have longer wires to connect the speakers' terminals to the x-over, especially if it is isolated away from the speaker cabinets.

sph wrote:
I was advised that isolating x-overs to the outside will have an effect. How significant? I can't confirm. But one will need to have longer wires to connect the speakers' terminals to the x-over, especially if it is isolated away from the speaker cabinets.

Lets do a quick take:

Pros:
- X-overs not subjected to vibrations.
- can fit more exotic components due to no more space constraints

Cons:
- longer wires
- Ugly / more physical items to deal with
- s/hand value drops.

So it's a give & take. But my guess is that it should still have a net-positive effect in terms of sound quality especially for budget bookshelf speakers. Just a guess.

For full panel type speakers like Apogee and probably Magneplannar, Acoustat, etc, it is actually better to locate the cross over inside the speaker itself. These type of speakers treats the room as the 'enclosure'. In addition, ribbons are so light the speaker itself doesn't vibrate much. So there is actually more vibration outside the speaker than there are inside the speaker.

Higher end speakers tend to have extremely rigid enclosures so mounting the crossover inside the cabinet in a well isolated spot might be more 'peaceful' than outside. E.g., next time you have a chance to check out a Wilson speaker up close, when it is playing, put your hands on the cabinet. You won't feel anything. Then put your ears against the speaker. You actually hear complete silence from the cabinet, even when the speaker is playing very loud.

crossovers of some speakers are potted.

i used to own mission 782 3-way floorstanders. the crossover is inside the small compartment where the side-firiing woofer is and i discovered that the crossover had some potting compound over it.

it's not possible to change any of the components without digging out the potting compound or damaging the crossover.

Pros:
- X-overs not subjected to vibrations.
- can fit more exotic components due to no more space constraints

Cons:
- longer wires
- Ugly / more physical items to deal with
- s/hand value drops.

So it's a give & take. But my guess is that it should still have a net-positive effect in terms of sound quality especially for budget bookshelf speakers. Just a guess.

Mugen,
You are quite right.
But if no alterations are done to the x-over, it can easily be placed back into the speaker enclosure (if the other parts are not discarded). And everything will be the same as before.

I kept the parts I changed from the x-over circuit in case I decide to put everything back into the cabinet.



crossovers of some speakers are potted.

i used to own mission 782 3-way floorstanders. the crossover is inside the small compartment where the side-firiing woofer is and i discovered that the crossover had some potting compound over it.

it's not possible to change any of the components without digging out the potting compound or damaging the crossover.

sflam,

Yes, most components in the x-over are covered with a bitumen type of material or even common hot-melt glue. It is difficult to remove in it's original state. But these materials becomes soft when heated up with a hairdryer. It is then very easy to remove the components from the circuit board, just a matter of desoldering the components.

Yeah, the back of my speakers is kind of ugly but it's the sound that mattered. Overall, I'm quite happy with the modified x-over.

Recently, I installed heavy duty pad(use on cabinet leg)made from plastic with felt padding,size about 20sen coin,at 4 corner of my Klipsch Cornwall speakers box stand(floorstand) with the thought of isolate(decouple) from the floor. I thought, I'll get a more firm bass but the result is the bass become vibrating and less punchy. Does this mean the speaker become more unstable after the pad installation as compare to the orig box stand.
Klipsch Cornwall is quite a sizeable speaker with dimension 25.25"L x15.5"w x38"h(with 2" box stand) weigh 98lbs.
Anyone can help on this? or stay orig and be happy with it.

7810sam wrote:Recently, I installed heavy duty pad(use on cabinet leg)made from plastic with felt padding,size about 20sen coin,at 4 corner of my Klipsch Cornwall speakers box stand(floorstand) with the thought of isolate(decouple) from the floor. I thought, I'll get a more firm bass but the result is the bass become vibrating and less punchy. Does this mean the speaker become more unstable after the pad installation as compare to the orig box stand.
Klipsch Cornwall is quite a sizeable speaker with dimension 25.25"L x15.5"w x38"h(with 2" box stand) weigh 98lbs.
Anyone can help on this? or stay orig and be happy with it.

The theoretical ideal is for the woofers to do all the vibrations (to push the air), and the cabinet to have as no vibration whatsoever so the drivers can do their jobs as perfectly as possible.

Back to simple phsyics: From Newton's basic laws of motion, the speaker cabinet will always want to move in opposite direction against the woofer's action. (The law of action - reaction thingy , Prof. Newton's 3rd law.)

If you have decoupled the cabinets from the floor (with those fuzzy felt footers), this means you have allowed the cabinets to vibrate more than usual, and this mean the woofers won't give u as much slam and dynamics anymore. Bass, being the lower freq where the cone's physical excursions are more pronounced also would mean your Klipsch cabinets are doing the cha-cha dancing more than before.

7810sam,
Try to use some form of spikes instead. Don't the Klipsch have provisions for spikes at the bottom ? If not, is it possible to DIY spikes onto the speakers to sit them on ?

Mugen/wongKN many thanks.
Aiyoyo, with spike on my speakers will definately ruin my floor tile. Is there
anyway to do it without damaging the floor. Is the spikes really sharp?
Or use blunt spikes. There one guy suggest using fridge cememt block stand and I have not try it cos it will look dam ugly to my living hall.
My system is in living hall thus not ideal at all becos of T shape and can't have carpet cos my children allergy to it.
Will try all possible way including wooden chess and ask my friend to machine a set of spike. Is there any particular dimension for the spike?

In the first place, you need to confirm that there are threaded holes into which you can screw in the spikes. When you get your friend to make the spikes for you, also get him to make you a set of metal discs about 5mm thick on which to sit the spikes. That way the spikes sit on to the discs which sits on the floor and you avoid damaging your floor. Ideally he should drill a small indentation to secure sit the spikes into.

Ok, 5mm thick for the metal disc, how about the diameter?

no need to machine anything , just go to ATS shop at Amcop mall, they sell spikes and spike-cups in all shapes and sizes. Some brass, some stainless steel, some iron, etc etc ....

But if the Cornwall originally doesn't have threads to attach any spikes, i would not recommend to drill the base to add spikes to it. It will spoil the original design and kill any collectors value to those speakers as well.

Other things to try out would be also to go to ATS shop and maybe see if they have suitable platforms to place your speakers on. Then the platforms can be spiked to the floor (with spike-cups to protect the flooring). Or ask fellow forummer "jokiarch" on any tips to to go about getting platform slabs like granite or marble or some big chunk, which can then also be spiked & spike-cupped to the floor.

7810sam wrote:Mugen/wongKN many thanks.
Aiyoyo, with spike on my speakers will definately ruin my floor tile. Is there
anyway to do it without damaging the floor. Is the spikes really sharp?
Or use blunt spikes. There one guy suggest using fridge cememt block stand and I have not try it cos it will look dam ugly to my living hall.
My system is in living hall thus not ideal at all becos of T shape and can't have carpet cos my children allergy to it.
Will try all possible way including wooden chess and ask my friend to machine a set of spike. Is there any particular dimension for the spike?

In your circumstance, with the floor standers, you cannot use the chess as it is not "strong" enough to perform the job 'as is'. This is because the chess are usually a cross-cut grain ie. the direction of grain is in upright position when uses as interface.

Wood has good tension but poor in compression; using chess in heavy weight induce excessive compression which renders it not effective. However, if you are willing to destroy 3 pieces of a good chess set, hmm.. reluctantly, and I must say to you that this is not 'green' approach in the current environmental condition, you could splice the chess to half, equally right in the middle. This is not as easy as you thought because the grain would take its own direction of the splitting plan. Hence, you must select those that have good straight grain and avoid those with notch at all time.

After you have successfully split them half, preferrably ask your carpenter to machine cut it, sand down the cut edge well to a perfect flat surface, make sure that all 6 pieces of them are of equal size. The curved side forms as the spike, rounded and thus will not damaging your floor finishes, which is usually tiled or marble. Place them pointing down.

Depending on the weight of your speakers, drill a small hole right in the middle of the cut plan and monitor the depth of the hole (at this point, Bassraptor spring into mind... I wonder why???). The size and depth of the hole should have a co-relationship to the weight of the speakers it is supporting. So you have to trial and error from here.

You will know the entire chess set will be all used up after some times with different size and depth of holes.

Jo Ki

Thanks Mugen. I'll dropby ATS to have look.
Thanks alot Jokiarch, for trouble to elobrate the details of the tweats. I think it's not easy to do it but wil try it one day.