layman question about in box speaker crossovers

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kyrill

layman question about in box speaker crossovers
« on: 10 Mar 2008, 11:43 am »
What is a sound reason for crossovers to be inside the speaker box?
I mean sound is good sounding, i don't mean economical reasons.

To avoid as much as possible resonances and vibrations would'nt it be much better to have the
filter in a neat wooden box apart from the speakers?
the extra wire resistance can be incorporated in the filter design.
If you use real fine silver(plated) connections and so on?

Big Red Machine

Re: layman question about in box speaker crossovers
« Reply #1 on: 10 Mar 2008, 12:16 pm »
Don't know I could hear a difference, but I like the idea of getting the xover away from the resonating box.  B&W 800 series have their's in the plinth underneath the speaker.

AKSA

Re: layman question about in box speaker crossovers
« Reply #2 on: 10 Mar 2008, 12:19 pm »
This is interesting.  We did some work on this, Laurie and I, and found that if we located the crossover behind the driver the added microphonics seemed somehow to improve the sonics.  It was extraordinary.

I have seen this observation elsewhere, forget where.  Someone else noticed it too.  I suspect it depends on cap type and crossover configuration, probably order.

Cheers,

Hugh

Tliner

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Re: layman question about in box speaker crossovers
« Reply #3 on: 10 Mar 2008, 12:55 pm »
HI All,

The xover in the new Aspen VSonics is mounted above the bottom plynth. See the ASPEN web site for the details of the new VSonics.  When experimenting with xover placement with Hugh one day, we found that when on one of the prototypes for the VSonics the xover was mounted directly behind the drivers. We ran out of hook up wire. Orientation of the xover did make a difference to the sound. One direction the imaging went off and when the xover was turned turned 90 degrees the sound was excellent. Obviously the EMF from the magnets aligned with the inductors in the sweet position. But for this reason xovers are mounted as far away from the drivers as possible. There is no benefit to have the xovers in separate boxes. More junk to trip over!.

Cheers,

Laurie

kyrill

Re: layman question about in box speaker crossovers
« Reply #4 on: 10 Mar 2008, 03:03 pm »
Hi Laurie

I dont mean separate boxes for the sake of separate boxes, but outside the whole speaker cabinet
also to completely remove mechanical vibrations. the extra links "only" have to carry high voltage high ampere swings relative to signals from source from dac to pre-amps/amps and so on, so much less prone to all the other things normal interconnects hinder for good sound.
I understand that specific placement/alighnment  in the box will sound better than other placements

Martyn

Re: layman question about in box speaker crossovers
« Reply #5 on: 10 Mar 2008, 07:50 pm »
If you like tweaking crossovers or trying different topologies, having them outside makes it much easier.

Tliner

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Re: layman question about in box speaker crossovers
« Reply #6 on: 10 Mar 2008, 10:28 pm »
HI Kryill,

I have built xovers which have been mounted on sound absorbing stand-off posts so minimal vibes are transmitted into them. Well made xovers should have all the components soldered down as tightly as possible. The larger components eg caps and in particular inductors should be held in position by strapping as well as by double sided tape or heat melt glue. If all this is done one might hear the natural resonance noise of the PCB when tapped. If anything else makes a noise the source has to be located and fixed.  You would have to be playing the speaker so loud you could not hear any vibes from the xover, they would be drowned out. Cabling has to be well sorted and of good quality as it can be the source of all sorts of odd noises.
Over the years I have conducted many A/B tests with the placement of xovers and basically if they are not too close to the drivers there is little difference if at all.
Actually I had a customer who wanted his xovers potted to eliminate the possibility of all vibes ultimately influencing the sound. The xovers were potted in a soft PU with cut-outs around the inductors for cooling. The client rarely if ever played loud music and the xovers probably would never have become even warm.

It all depends what one percieves as the "best". That is what keeps us all going!

Cheers,

Laurie


kyrill

Re: layman question about in box speaker crossovers
« Reply #7 on: 10 Mar 2008, 11:35 pm »
thx ppl
for yr response

I dont understand "potted". It will in a way dampen some sound but mechanically induced vibrations will easily go thru the "pot" by heavily vibrating the pot as well

It all depends on how "transparent" the rest of the setup is
but now when CDP and CD transport are "yesteryears" technology and music on memory chips will be the source of the very nearby future no jitter because of moving "objects" (still jitter because of other reasons, S/PDIF,  clock no stable pws and so on) people will more easily hear the benefits of transparent designs. I still think to have crossovers in the very heart of vibrations ( the speaker) is an odd thing

Some designers even put their amps inside the speakers. And i don't mean subs

Related to this is to have the mid and tweeters vibrate with the woofer. Would.nt it be better to mechanically  de-couple tweeter from  mid and  woofer and mid from woofer??

Bill Baker

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Re: layman question about in box speaker crossovers
« Reply #8 on: 11 Mar 2008, 02:22 am »
Interesting topic. It has been discussed for many years and I have experimented with different variations as well.

 Potted crossovers do effect effect the character of any given speaker. When using potting methods for crossovers, it has to be taken into account when designing the speaker and circuit. The crossover has to be laid out and assembled in a way that the potting will have minimal effect. The different types of potting used all have different effects. I learned this the hard way many years ago. There is no going back once the crossover is potted. Potting is a last resort IMHO and some companies (Wilson Audio for example) do this to protect their proprietary circuit designs as well as control resonance. I can assure you they did a lot of R&D before the final recipe was chosen.

 I can assure you if you take any given speaker that you are very familiar with and pot the crossover, it will sound different. For better or worse? Who knows but if it's for the worse, you're buying a new crossover. I know because I have thrown a few crossovers in the trash.

 Having the x-over outside the speaker cabinet itself presents many advantages but this too differs depending on the speaker design. As Kyrill mentioned, there is some added resistance with the additional wiring used to mount a x-over externally not to mention weather or not you use connectors, the type of connectors or simply wire straight through. Then there is the type and AWG of wiring you use. But also as mentioned, all this can be taken into account during tweaking of the x-over.

 X-overs mounted inside the cabinet can also be free of ill effects, even without potting,  as long as it is done properly.

 In the end, a good design is more than simply mounting the crossover components on a board and sticking them on the floor behind the speaker.

kyrill

Re: layman question about in box speaker crossovers
« Reply #9 on: 11 Mar 2008, 09:28 am »
aa
all yr answers are somehow diplomatically
my original questions was
are there sound beneficial reasons for having the crossovers inside the speaker box, which are not based on economics?

Or preciser
If you add up pro's and cons is it better (knowledge based)   for the
sound to have crossovers inside or outside the speaker box?

rabbitz

Re: layman question about in box speaker crossovers
« Reply #10 on: 11 Mar 2008, 12:00 pm »
All my speakers are fine tuned with the xo outside the box and not once has the sound degraded when the final xo was installed in the box. It's more important to get the values right and locate the inductors correctly.

I have read somewhere that the preferred location of the xo is behind the woofer but can't remember the reason. Easy access and installation are reasons but there was something about the magnet.

kyrill

Re: layman question about in box speaker crossovers
« Reply #11 on: 11 Mar 2008, 12:37 pm »
i suppose the differences with the xover in the box or outside are,  if any,
subtle and highly depending on how transparent the whole setup is
maybe the tweeters and midrange which vibrate/resonate heavily with the wooden enclosure
mask these subtle differences
the more midrange and tweeter are structurally decoupled from the other drivers and each other,   will make it maybe easier to discern a silent from a vibrating Xover.
Just an idea

I am experimenting now with my open baffle ( well at least the upperbas/midrange) speakers to isolate the drivers from each other. But is is a hard job

Tliner

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Re: layman question about in box speaker crossovers
« Reply #12 on: 12 Mar 2008, 10:45 pm »
Hi Kyrill,

I don't think that there is any preference for the placement of covers except positioned too close to the magnets. You know when a xo vibrates, they buzz and rattle but even those noises appear to have little affect on the quality of the sound through the drivers. Vibrating xovers sound like a cabinet rattle and are often overlooked in the noise hunt. Often internal speaker wiring vibrating somewhere can cause a real problem too.

I have heard well built systems (with no cheap components in the first place) that have every percieced "upgrade". After all the $$$ and hours of work some systems may have improved slightly. That said, you should know your system better than anyone else and often you alone may appreciate an improvement.
Cheers,

Laurie

stvnharr

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Re: layman question about in box speaker crossovers
« Reply #13 on: 12 Mar 2008, 11:02 pm »
Hi Kyrill,

I don't think that there is any preference for the placement of covers except positioned too close to the magnets. You know when a xo vibrates, they buzz and rattle but even those noises appear to have little affect on the quality of the sound through the drivers. Vibrating xovers sound like a cabinet rattle and are often overlooked in the noise hunt. Often internal speaker wiring vibrating somewhere can cause a real problem too.

I have heard well built systems (with no cheap components in the first place) that have every percieced "upgrade". After all the $$$ and hours of work some systems may have improved slightly. That said, you should know your system better than anyone else and often you alone may appreciate an improvement.
Cheers,

Laurie

Excuse my ignorance please, but what would cause an XO or wire to vibrate, other than unsound construction, as in loose fitting of an inductor to the board or the crossover board to the cabinet.

netaron

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Re: layman question about in box speaker crossovers
« Reply #14 on: 13 Mar 2008, 06:09 am »
My 2 cents worth:

Vented speakers-cross over placed outside of box=better sound
Sealed speakers-cross over inside or outside of box=no difference

Just from my own experience.

But again, as much as I tweak cross overs, the extra sound benefit isn't worth the hassle of placing the cross over inside the cabinet. The screwdriver has slipped and I have managed to put holes in a few drivers.

Haron

Tliner

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Re: layman question about in box speaker crossovers
« Reply #15 on: 13 Mar 2008, 06:53 am »
HI Stvnharr & All,

This is a flat statement. Virtually everything has a harmonic point to which it will resonate (vibrate). Guitar, piano strings, drum skins, water pipe and all kinds things resonate when excited by hitting, scraping, donging etc. Therefore it can be extrapolated that all objects have a point at which they resonate. In xovers, caps, resistors and inductors all have wire tails at some length or other. This length of wire will have a resonant point at which it becomes excited. And if the stimulation is great enough the piece of wire no matter how long will vibrate. Now a small piece of basically soft wire well soldered to a PCB is not going to vibrate much at all, but it will vibrate usually not enough to he heard. Now any perceived form of likely vibration gives some audiophiles an attack of the terrors. The same can be said if their system is not sorted out to the Nth degree, they are always worried that something is wrong.

IMHO I don't think that vibrations in a well made xover am mount to anything much. Certainally not enough to put me off my favourite piece of music and my beer to go mysteriously flat.


Cheers,

Laurie

Jens

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Re: layman question about in box speaker crossovers
« Reply #16 on: 13 Mar 2008, 10:29 am »
I agree with Laurie. If the xover is well built, i.e. components well soldered and tied properly down, and perhaps even glued onto the board, any vibration in the xover will be neglible. Meticulous construction of the xover and careful selection of the components - like in the VSonics - are so vastly more important than the actual placement of the xover that any sensible placement of the xover within the enclosure (except directly onto a driver magnet, which will affect coil values) can be chosen.

If you're still worried, then create a separate compartment for the xover within the speaker enclosure. When you build your own enclosures, this will be very easy to incorporate (but remember to keep the volume of air for the drivers at the same size!), e.g. by adding a double bottom. And then - if you're really, really worried - put the xover in a heavy duty plastic bag before you put it into the compartment, and fill the compartment with sand! :green: I don't really believe this is worthwhile, though ....

Bill Baker

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Re: layman question about in box speaker crossovers
« Reply #17 on: 13 Mar 2008, 02:06 pm »
Quote
I agree with Laurie. If the xover is well built, i.e. components well soldered and tied properly down, and perhaps even glued onto the board, any vibration in the xover will be neglible.

 Agreed, as long as you properly lay out the crossovers (orientation of inductors is critical), maintain shortest possible leads and secure them to the substrate and secure the assembly tightly to the cabinet, you will be fine. Don't "over think" things as this takes the fun out of it.

 The one good thing about an outboard crossover, especially for tweakers, is the ability to more easily access it for tweaking.

Jens

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Re: layman question about in box speaker crossovers
« Reply #18 on: 13 Mar 2008, 03:06 pm »
Quote
I agree with Laurie. If the xover is well built, i.e. components well soldered and tied properly down, and perhaps even glued onto the board, any vibration in the xover will be neglible.

Agreed, as long as you properly lay out the crossovers (orientation of inductors is critical), maintain shortest possible leads and secure them to the substrate and secure the assembly tightly to the cabinet, you will be fine. Don't "over think" things as this takes the fun out of it.

Sure thing! Incorrect orientation of inductors is as bad (or worse) as mounting them close to driver magnet. In both cases, the magnetic fields will play havoc with the inductor values and the xover will not work as intended.

Quote
The one good thing about an outboard crossover, especially for tweakers, is the ability to more easily access it for tweaking.

Very true. I've had outboard xovers, too, because I wanted to experiment. In fact, I always start out with an outboard xover when working on a new speaker and usually move it inside once the final adjustments have been made. Again, if xovers are well made, there's no detrimental effect on sound by having them outside :wink:

kyrill

Re: layman question about in box speaker crossovers
« Reply #19 on: 13 Mar 2008, 04:06 pm »
hi
Ok we have covered vibrations
But everybody hears the big effect of damping source, preamps and even amps.
you can buy feet costing hundreds of dollars per piece and you need a minimum of 3.
That is not stopping them from vibrating in the sense stop them from   rattle or making noises by them selves. but to dampen the very minute "little vibrations" on a microscopic scale as these do influnece the sound. the more on source, a bit less on preamp and so on.

So in that sense these vibrations on the Xover wil have the least effect, BUT the vibrations are a million times more strong than over the air to platforms where yr setup rests