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Subwoofer advice please

I'm hoping to find a little bit of clarity with your help.

I've got the itch to buy a pair of modestly priced subs, (SVS SB13 Ultra or REL S/3 SHO).

Here is my dilemma; I use a PrimaLuna Dialogue Premium HP driving a pair of rebuilt and completely upgraded Quad 2805 speakers.

The PrimaLuna has one subwoofer out. Okay, great I think.

My dilemma is when I research proper subwoofer integration almost all posts and articles state that an external crossover is needed to really dial in the sound.

Obviously I can't do that with the PrimaLuna.

It would be less expensive to sell the Quads and upgrade, (a topic I'd love to talk about) than to buy a new front end and hope that the subs worked out for me.

Any help or advice is greatly appreciated and if you're ever in SE Washington state I would repay your kind advice with world class bbq and cool, refreshing beverages.

Thank you in advance,

Bob
jzzmusician
bdp24's avatar
bdp24
9,451 posts
 

willem, it is very true that part of the reason most subs don’t mesh well with ESL’s and other planar speakers is the dipole nature of their radiation pattern, which excites fewer room modes than non-dipole speakers and subs. Their null to each side prevents the side wall-to-sidewall mode from being energized.

It is for that reason that dipole subs are embraced by a small segment of the dipole speaker fraternity, and why there are companies offering dipole subs to that group. DSPeaker themselves developed and manufactured dipole subs for both the Quad 63, and the original ("57").

But the really interesting and high-performance dipole sub is the one co-designed by Danny Richie of GR Research and Brian Ding of Rythmik Audio. It consists of two 12" woofers per sub, mounted on an open baffle H-frame, along with a plate amp containing a shelving circuit to compensate for the inherent dipole-cancellation roll-off as frequency descends. If interested, check it out on both company’s websites, and read discussions about it on the GR Research AudioCircle Forum.

willemj
1,036 posts
 
Yes, I know there are (a very small number of) dipole subs. It was Gradient in Finland (not DSpeaker) who made them. However, they were huge and not particularly cheap. I am in Europe, so the GR Research offerings were not really an option. But yes indeed, if you are in North America and have a bit of space, they are interesting.
shadorne's avatar
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shadorne
7,467 posts
 
@willemj

Subwoofers are hard to do well and 8 inch woofers are rather small for that application. Room modes are certainly part of the usual problem. If you have a chance - try a JL subwoofer before buying another PV1D - you may find it integrates better. B&W make superb products but they are often bass heavy and resonant. An important factor in subwoofer design for audiophile high fidelity quality is group delay - hardly anyone measures or quotes this but I have seen measurements for JL and they are superb - measurements for many other subs I have seen tested were terrible (primarily because higher output is achievable at the expense of high group delay)
willemj
1,036 posts
 
Thanks for the comment Shadorne. I agree 8 inch is small for a subwoofer driver, but the PV1d has two of them, in opposition to each other. As for alternatives, subwoofers are rather less common in the EU than in the US because our living rooms tend to be a lot smaller, so the choice in the market is more restricted. A home demo of my shortlist was impossible. However, after my initial disappointment, and once I got the PV1d equalized by the Antimode, the sound was in no way bloated. You push the sub into the corner for maximum reinforcement, but the Antimode then flattens the response. The result has been that the bass really seems to come out of the stats, and has the same kind of clarity. It is important to cross them over pretty low: 33 Hz with the 4th order filter slope (and zero degree phase) is what I arrived at for minimum colouration and smearing.
The PV1d also looks very nice in our modern design interior.
bdp24's avatar
bdp24
9,451 posts
 

Right you are, willem, it was indeed Gradient. DSPeaker and Gradient are both Finnish companies, and there is some relationship between them, though I don’t recall exactly what it is.

The GR Research OB/Dipole Sub is offered as a kit, the H-frames into which it is installed needing to be made (or have made) by the user. So shipping shouldn't be too bad. The dimensions of the H-frame are about 16" wide, 14" deep, and 28" tall, not too bad.

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