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Vandersteen Sub woofers v Rythmik Subs

I really love the idea of the Vandersteen Subs where they are connected with the mains via extra speaker cable off right and left channels off the main amplifier, which is supposed to provide better bass transition from the mains while keeping the signature from the main amplifier. My question is with Vandersteen coming out with the SUB THREE and the price going significantly higher, I was wondering if there are other subs for less that you could integrate in the same way. (Most subs seem to rely on the line level input which is just a sub-woofer RCA going from the pre-amp to the amp on the sub). Can this same Vandersteen set-up be achieved with other subs?
I picked Rythmik since they are known (in the home theater community anyway) for being one of the best bang for the buck subs and the most "musical" of the bunch. (between Hsu, SVS, PSA).
And could I possibly achieve even greater sub-woofer nirvana since I could get an 18" for around $1500? Vandies only have 3 eight inchers.

I am a Vandersteen fanboy and I would like to support RV whenever I can, but don’t know much about my other sub-woofer options so looking for some feedback. Doesn’t even have to be related to Rythmik necessarily. If you know of other subs that can integrate the same way I want to know about it!

Thanks
bstatmeister

Showing 4 responses by ieales

ieales's avatar
ieales
1,201 posts
 
The sub farm is an interesting concept, but I suspect phase coherence may leave a lot to be desired.

Phase coherence will determine the quality of the bass. The farm concept will definitely smooth out the level or quantity, but at the expense of phase or quality. DSP would be mandatory.

Vandersteen makes excellent products, but some of the sub parameter choices seem odd.

First rolling the bass off before sending to the sub requires additional EQ in the sub and EQ means more phase shift.

Since there is no phase control, physical positioning is critical. IMO, both a phase control AND a phase invert are mandatory.

The XO is limited in frequency selection and will have a rather large range. eg, a 55k input will xo @ 132Hz and a 100k input will xo @ 73Hz, almost an octave! IMO, step size should be about 10Hz for subs.

A bunch of dip switches in the circuit are a very bad idea. NO connector is inaudible.

It appears the filters are 1st order which sum in theory, but may not so well in practice.

For a saga on sub integration see http://www.ielogical.com/Audio/SubTerrBlues.php/ and http://www.ielogical.com/Audio/#SmallestThings for my passive XO design. C = 1 / ( 2 * π * f * R )

ieales's avatar
ieales
1,201 posts
 
Bass room gain?? Bass is all over the map in any room but an anechoic. ±30db is not a typical.

A multi-sub system may smooth out level, but it will be a phase nightmare. Imagine a rectangular box filled with water. Drop in a pebble. The wave will bounce around dependent on wall reflectivity. Add additional pebbles and interference patterns develop in the primary wave.

Subs that connect to speaker terminals do not 'take on' the main amp character. They add their character to the main amp.

ieales's avatar
ieales
1,201 posts
 
No need. I can do the math.
ieales's avatar
ieales
1,201 posts
 
@hifiman5 
Only a proselyte would believe that it is possible for a dumb amplifier to change characteristics based on it's driving source. If that were possible, changing any of the 'perfect' electronics in our systems would hopelessly dependent on its upstream device.

In the Vandersteen 2ce II, the impedance doubles from 4Ω to 8Ω between 35 and 75Hz, dropping to a nominal 6Ω @ 200Hz.

The output of a tube amp transformer will be a non-linear voltage driving such a load  as can been see on any Stereophile tube amp review.

The Vandersteen sub amp is a voltage driven device, as are most amps. When the voltage rises the output of the sub will also rise. What results is a doubling of the bass output @ 35Hz vs 75Hz. This would not occur with a tube amp driving a loudspeaker.

Another issue I never considered a good design was the passive XO with limited adjustment. In all but a limited number of amp input impedances, the frequency will be sub optimum possibly varying by as much as half an octave. It's been my experience that as little as 10Hz can have a significant effect when tuning a sub into room. A fixed frequency sub may work well in the lab, but may not elsewhere.

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