Vandersteen Sub woofers v Rythmik Subs

I guess I'm on my way to a distributed bass system.

I started with a single REL Storm sub and really enjoyed it.
Later I built two very heavy cabs for a couple Rythmik 12" kits connected at speaker level and it was a significant improvement over the Rel. I experimented several locations and setups also using measurent help and ended using them in stereo taking line in from my pre. While the xo wasn't 100% transparent it relieved my tube amp and speakers from attempting to reproduce up to 80Hz which was worth the tradeoff. This was another significant step up in sound.

Later I experimented with a multiway DAC and created digital xo to drive the subs and main amp directly from the DAC. Now my system is fully active with digital linear phase xo and room correction. No going back!

And I'm considering adding a couple additional Rythmiks. Rythmik kits allow for custom cabinets that make it easier to disguise or integrate into the decor.

FWIW, in his approach Geddes recommends one of the subs to be elevated from the floor so not all subs are exciting vertical modes from the same position (the floor). For this either a small sub or a custom installation is ideal (no way to raise my 50kg subs 2 meters off the floor!!).

Glad to see this approach discussed here.

bondmanp- Yes no filter in the signal path would be ideal but as you say the M5hp is very transparent. So much that I can not tell the difference. All I know is that the whole system sounds much better with the subs and filters than without. In fact I just tried a comparison with and without a week ago and its a dramatic improvment in the upper bass and midrange clarity. It removed a bit of boxiness in the 3a sig's upper bass. I can certainly live with the filters in place.
 Also I really like the adjustable q on the subs. It really helps with taming the room response. I also position the subs next to the mains well away from the walls and corners. I have found that I don't like subs in corners. It just makes them boomy.  I feel I get better time blending with mains as well with the subs in or even forward of the plane of the loudspeakers. These speakers and subs are time and phase correct top to bottom. Makes for great imaging. Very holographic.

lewinskih01- Funny you should mention elevating the subs as I have just begun experimenting with that concept. Trying to come up with something put under them. Tried milk crates about 10 inches high. Did seem to slighly reduce a bit of boominess in my room. I do want to keep trying different positions. I will also try raising just one.

Would be interesting to try the swarm idea with the Vandersteen subs and crossover implementation. All the subs would maintain the sonic signature of the main amp that way.

The Audiokinesis Swarm review by The Absolute Sound refers to Geddes.  Earl Geddes published his approach:  https://mehlau.net/audio/multisub_geddes/

For the brief time I had the Rythmik and Rel together I tried his approach and got close to what he described. He calls for summing up sub frequencies and all subs playing the same mono signal, and also some location guidelines and says 3 subs should suffice. My listening area is in my living room so aesthetics are an important consideration and Geddes location guidelines didn't fit into the aesthetics (in my room). Since I can't maximize the potential from 3 subs in mono I'm hoping 4 subs in stereo will be enough to achieve similar results. Worst case I could go to 6 subs! 😨

BTW, note Geddes says he needs little output from the third sub. So a much smaller sub would work, making it easier to conceal in the decor.

Another implication of Geddes approach: if you allow you main speakers and subs to play the low bass in parallel you effectively have 2 additional sources of bass (the main speakers) so it would help achieve those goals. Whether your system sounds better like this vs relieving the mains and amp from reproducing low bass is for each to decide.

Cheers!

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 )