Subwoofer Crossovers

Originally posted by SteveC
... I have a problematic room resonance broadly around 90Hz, and for whatever reason the current set-up cleans up this area considerably. The sub is just to the left of the left Espek, in a corner.

Re directionality, if I turn off the other speakers I can clearly hear where the bass is coming from on a frequency sweep, but with the full range on, characteristics like the thwack attack of a drum localise the sound where it should be. Even so, I would like to run stereo subs, and gain the extra power for things like the film Master and Commander, where cannons feature.
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With the extra flexibility of placement, separating the deep bass from the main speakers, the system should be easier to set up to integrate into your listening room, not more difficult. That's one reason why I designed the Nonsuch system in this way (the other reason was that I think it makes a more attractive overall package).

Re directionality, the crucial thing here is to have subs that don't have much vibration or distortion in the directional frequency range, as these can be dead-giveaways for detecting the position. Other than that, room size is also crucial in this regard. In a smaller room (or car) you won't detect the position as easily as in a large room. If you set up the speakers in a large hall, you could detect the direction down to very low frequencies.
 
Originally posted by 7_V
Therefore, if there's a problem with control of the bass, it's nothing to do with the 'principal' of subwoofers.
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I agree - that wasn't what I was trying to imply :) .

<pedant> the word you want is principle not principal </pedant> ;)

Michael.
 
Originally posted by wadia-miester
I must be a lucky guy, all this talk of subs, and I don't require one, think of the money saved and time spent having fun. Thanks Guys :)
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Bless the ignorant... :p
 
Originally posted by lowrider
Bless the ignorant... :p
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Originally posted by merlin
Tish! Just think what you are missing below 32hz:D
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Oh come on guys. Not every recording contains many notes with their fundamental frequencies between 16 and 32 Hz.

As long as Tone sticks to the other recordings, I'm sure he can get quite adequate bass reproduction. Some of the live recordings may be lacking in a little deep bass ambience but that's no big deal.

:duck:
 
Fair point Steve.

I'm sure for most of the stuff Tony listens to, the bass he gets is acceptable, if missing that last half octave for the grander stuff.

I'd agree that distortion plays a significant part in giving away poorly designed subs. What I have found in nearly all setups that employ a low crossover point is that it always sounds like a pair of whatever with one or two subs tacked on the bottom. Sure there is no giveaway directionality (although the satellites can fail to disapear as the distortion increases below resonance), there's no lumpiness, but they do sound like two different speakers with individual characteristics that somehow destroy the illusion.

Just my experience and I certainly haven't heard many of the better subs from Velodyne, B&W, and Audio Physics. The Martin Logan was impressive, but again, all these subs offer very low distortion figures down to 20hz. Sadly a lot of well regarded subwoofers don't in reality.
 
Antonio,
I really don't need to have a sub, my neighbours get a hard enough time as it is.
I wan't to listen to gut wrenching rumble, I don't have to travel to far either, but thanks for the offer :)
 
Sorry guys for my intrusion, I just want to answer the first question of this thread. :duck:

Low pass at 250Hz (passive); 18 db/octave (3rd order)
 
so here is the other half:
two Nestorovic Type 8 Reference in closed boxed 56 x 66 x 66 cm (HxWxD).
In each there are two woofers with different mass and compliance to work properly (diameter 12")

sub.jpg
 
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Originally posted by titian
... two Nestorovic Type 8 Reference in closed boxed 56 x 66 x 66 cm (HxWxD).
In each there are two woofers with different mass and compliance to work properly (diameter 12")
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Very interesting. I don't know much about these subs. From the information that you've given, it seems that the drivers must be operating below their resonant frequencies (the box seems too small for two 12" drivers operating conventionally). I would guess that the system needs quite some equalization and very powerful amplifiers. Am I right or do I have to give back my speaker designer's diploma? :shame:

I like the concept of the two woofers tuned differently. It reminds me of stories of the early car suspension system, before modern dampers were invented, when they often used two springs tuned to different resonances. One would damp the other.

How do you find the sub, in practice (and don't say "I just go into my listening room and there it is.")? :rolleyes:
 
The drivers do operate under the resonant frequencies.
Everything, also the drivers are made by Nestorovic except for (perhaps) the magnet which is 1.71 Kg in barium ferrite (BI product is 21 tesla-meters).

The subwoofers work in a special way (I bet there is a patent on it) designed by Nestorovic.
It is recomended to use a 150 W power amplifier for it but they are safe up to 350 W.

How do I find the sub?
Once you have them you might believe that the rest is crab.
Honestly speaking if there is a weak point in his system 16 or 12 (the ones with the two subs) then that is not the subwoofers.
They integrate perfectly with the satellite like I supose every one would say his do. :SLEEP:
I prefer that other people comment on my system because I could be to subjective. And anyway the best way to get the answer is hearing them yourself (as for everything else). :D
 
Originally posted by 7_V
I would guess that the system needs quite some equalization and very powerful amplifiers.
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Are you trying to say something behind the lines?
Wondering that it cannot be better than without equalization/crossover...? :D
 
Originally posted by titian
Are you trying to say something behind the lines?
Wondering that it cannot be better than without equalization/crossover...? :D
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No, it's just that if the drivers are being operated below resonance, they will need boosting as the frequency goes down (by 12dB/octave). They certainly could not work without equalization or a crossover.

I even use a filter on my subs and I'm very opposed to them generally (although in this application, I don't think that a well designed Xover causes any problems). I did look at various design possibilities which would not require filtering and I even built a prototype of one method - it's in my garage with the TTs. :) I didn't like it though.

I'm surprised that your subs' power amplifier is as small as it is, in view of the equalization.

I look forward to listening to your system in the near future. How far are you from Klagenfurt, Austria?
 
Nestorovic recomendationis to use a 150W amplifier for the subs but I am using a 300 W Krell.
Klagenfurt is over 600km from my place.
The best and cheapest way is to take a flight to Zürich. They are cheap ones if booked a few months in advanced.

The idea of building speakers without filters isn't new. Up to now, though, IMO they all have a main problem in reproducing complex music.
While for music with few intruments they sound good, when reproducing big orchestral music they are messy.
 

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