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Placing speakers on top of subwoofers

stunta

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#1
I am trying hard to win the "dumbest question on ASR" award, so here goes...

The seating I have is low enough that if I place my ATC SCM-19 on my REL Storm III subwoofer (I have just one now and looking for a 2nd), the tweeter should roughly be at my ear height. Would this be a bad idea and if so, why?

Thanks

 

DonH56

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#2
It really depends upon how much vibration the sub couples to the speakers sitting on it and whether it is audible. You can get a Doppler effect in addition to spurious tones from the speakers sitting on top but often they are not audible. A number of folk do it to save space, usually placing some sort of isolation mat between them (anything from a piece of felt, to stick-on feet, to fancy isolation pads sold for big $$$). I have not done it for years but the only thing I recall doing was getting a rubber no-slip mat because the speakers on the sub tended to walk across the surface.

To my mind a subwoofer cabinet is likely to be thicker and heavier, less likely to resonant, than most regular speakers. Placing the speakers on top of the sub is thus not really any worse than a full-range system with all the drivers in the same box, and in fact may be better since the sub and other drivers are in separate cabinets.

Short answer: Most likely no problem.

IMO - Don

Edit: I am quite sure that we can find numerous other, better, contenders for "dumbest post on ASR"...
 
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stunta

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#5
not really any worse than a full-range system with all the driver in the same box, and in fact may be better since the sub and other drivers are in separate cabinets.
That is a very interesting way to look at it.

The REL seems quite stable (inert?) and passes my highly scientific "place my hand on the cabinet while playing bass-heavy music" test. The ATC cabinet easily passes the knuckle-wrap test (hurts my knuckles though) and it is heavy as hell (around 35 lbs each).

I have some Auralex monitor foams lying around somewhere and will see if that works between the sub and speakers.

Now if I can just find another REL Storm III, I wouldn't have to go through the hassle of buying 2 new ones and selling this.

Thanks!
 

sergeauckland

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#7
I don't see it as a problem at all. In any event, what's the difference between a genuine large full-range loudspeaker and a small loudspeaker on top of a sub? There are benefits to using a sub, especially if the sub has filtering to remove the LF from the small 'speaker, as that will considerably increase the small loudspeaker's power handling and reduce distortion.

I don't say it's as good as a genuine three-way large loudspeaker, as the frequency range handled by the individual drivers won't be optimum, and the dispersion pattern for the small loudspeaker will be compromised by the larger size of the bass/mid unit, but as a way of improving a small two-way, I can't fault the idea.



S.
 

andreasmaaan

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#8
With the sub that close to the main, setting the sub-main crossover as high as possible is probably advisable (within reason).

the dispersion pattern for the small loudspeaker will be compromised by the larger size of the bass/mid unit
I'm not sure this is going to be a problem - at any practical crossover frequency, both the sub and the main woofer are likely to be omnidirectional.
 

sergeauckland

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#9
With the sub that close to the main, setting the sub-main crossover as high as possible is probably advisable (within reason).



I'm not sure this is going to be a problem - at any practical crossover frequency, both the sub and the main woofer are likely to be omnidirectional.
I was thinking of the mid to tweeter transition, which in most two-ways is somewhat compromised. To get decent bass, the bass/mid unit will be larger than needed for MF, so by the crossover to the tweeter will probably have started beaming somewhat. This can be avoided by a tweeter that goes down to a few hundred Hz, but those are rare beasts (Manger for example) and certainly that's not the case with the ATC's tweeter or any similar two-way. A three-way loudspeaker will have crossover frequencies at around 300Hz and 3kHz with an MF unit of perhaps 4-5".

Incidentally, that particular ATC loudspeaker has an unusual bass/mid driver as the 'dust cap' is almost the size of the whole cone so will have much less of the beaming issue than other two ways with more conventional drivers. This is an excellent example of cat-skinning, insofar as if one can't get the tweeter to go down low enough, make the bass/mid go high!

S.
 

andreasmaaan

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#10
I was thinking of the mid to tweeter transition, which in most two-ways is somewhat compromised. To get decent bass, the bass/mid unit will be larger than needed for MF, so by the crossover to the tweeter will probably have started beaming somewhat. This can be avoided by a tweeter that goes down to a few hundred Hz, but those are rare beasts (Manger for example) and certainly that's not the case with the ATC's tweeter or any similar two-way. A three-way loudspeaker will have crossover frequencies at around 300Hz and 3kHz with an MF unit of perhaps 4-5".

Incidentally, that particular ATC loudspeaker has an unusual bass/mid driver as the 'dust cap' is almost the size of the whole cone so will have much less of the beaming issue than other two ways with more conventional drivers. This is an excellent example of cat-skinning, insofar as if one can't get the tweeter to go down low enough, make the bass/mid go high!

S.
Totally agree. Had misunderstood your original point. This (and the reduced tweeter diaphragm displacement) is why I believe in horns/waveguides for two-way speakers, which cost little from a manufacturing perspective and whose benefits tend to greatly outweigh drawbacks.
 

Patrick1958

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#12
What might be experimenting worth is connecting the speakers in or out phase. This could have influence on how you hear/experience the bass presence. According to your listening position this could have an audible effect.

I use the Teufel Hybrid 6 in my living room. The towers are 3 way system, top is a passive two way d'appolito configuration and bottom woofer is an active sub. The sound their best when the top is out of phase connected. That way the sub seemingly integrates with the system as a whole. In phase i experience a gap between top and bottom. Top and bottom are separate driven by amplifier.
 

DonH56

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#13
One caveat: I would place the smaller speakers right at the front edge of the sub to avoid a diffraction (bounce) from the top of the sub.
 

svart-hvitt

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#14
Inspired by the speaker-on-sub idea, and @andreasmaaan 's remark that "horns/waveguides for two-way speakers, which cost little from a manufacturing perspective and whose benefits tend to greatly outweigh drawbacks", got me thinking about a new soundbar for my 75 inch TV (two new Genelec 7382 subs featuring three 15 inch woofers each, SPL @129 dB; plus three new S360 two-way speakers with compression driver and 10 inch woofer, SPL @118 dB):

snipped.jpg
 

andreasmaaan

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#15
Inspired by the speaker-on-sub idea, and @andreasmaaan 's remark that "horns/waveguides for two-way speakers, which cost little from a manufacturing perspective and whose benefits tend to greatly outweigh drawbacks", got me thinking about a new soundbar for my 75 inch TV (two new Genelec 7382 subs featuring three 15 inch woofers each, SPL @129 dB; plus three new S360 two-way speakers with compression driver and 10 inch woofer, SPL @118 dB):

View attachment 16613
Ahahaha :)

Crazier things have been done...
 

DonH56

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#17
To really impress people you should build Wilson-like mounts for the little speakers on top of the subs... Call it a prototype and wait for the awards.
 

restorer-john

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#18
Funny, I was just about to do the same in my room. I've got a few big PSB subs lying around unused and I am currently using a few pairs of small standmount speakers.

It wouldn't have a high WAF however (wife acceptance factor) and may look a bit awkward.
 

Wombat

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#19
Cheap and effective.

28'x48"

Similar but lighter duty material in rolls is available in many general merchandise and also hardware stores for around $5.

Use one or more layers to suit.
 

restorer-john

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#20
Cheap and effective.

28'x48"

Similar but lighter duty material in rolls is available in many general merchandise and also hardware stores for around $5.
Mate, that stuff is dangerous. It eats into plastic/perspex/paint and gloss surfaces over time and ruins them. Trust me. I've thrown out any and all of it from my place. You should see what it does to a perspex/acrylic turntable lid or the backs of remote controls in a drawer.

People use it to line drawers and tool boxes- don't do it. It must gas off goodness knows what.
 
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