Subwoofer Decision

The notion that an 8" woofer will automatically be "quicker" than a 12" or 15" one seems logical, but is actually an over-simplification. The size of the cone is only one factor in a woofer’s performance capability. A woofer’s moving mass vs. it’s motor (magnet) strength is a better way to predict it’s performance capabilities, but again, there is more to it than that simple relationship. The Rythmik website has very technical design information available for those interested (some of it WAAAY over my head. Brian Ding is an engineer with an advanced technical education, having a PhD in the field).

Rythmik offers subs with one or two 8" woofers, but Rythmik designer/owner Brian Ding advises that his 8" woofer is no "faster" than his 12", or 15" and 18" (!), for that matter. But the maximum output capability of the 8" is less than the 12", and the 12" less than the 15", the 15" less than the 18". Three 8" woofers will NOT reproduce to a lower frequency than a single, but will have less low end roll-off as it approaches the lowest frequencies it reproduces, and may therefore sound as if it does. However, three 8" woofers will, of course, have higher maximum output capability than a single. I have heard the Vandersteen subs at Brooks Berdan’s shop (Brooks was one of Richards first dealers), and they are excellent.

tomic601, the Vandersteen sub uses the output of the power amp as it’s signal, rather than a line level signal from a pre-amp. I’m not sure, but Richard may have pioneered that approach. But to repeat, both Rythmik and REL subs offer the exact same facility---it is not exclusive to Vandersteen. The Rythmik PEQ model plate amps provide both a high level input on speaker binding posts (from a power amp, in exactly the same fashion as Vandersteen), as well as a line level input on RCA jacks (from a pre-amp, etc.). There is nothing proprietary about the Vandersteen high level input design; the power amp is connected to the sub via a speaker cable that goes onto the sub’s input binding posts. That high level signal then goes into a circuit that converts the watts into volts (via impedance conversion, I believe). That voltage is then used as the signal for the sub.

My questioning of the logic of the idea is a separate issue, having to do with the wisdom of having the sub’s input signal go through an extra stage of amplification (the power amp) as part of the effort to get the sub to have the same sound characteristics as the speaker the sub is partnered with. The idea is that both the speaker and the sub get their input signal from the same exact source---the power amp, and the sub will therefore be more likely to sound "as one" with the speaker as it would if the sub got it’s signal from a different source---the pre-amp.

@bdp24, this has been an interesting and timely thread. I’m encouraged to read that ESL speakers respond so well with Rythmik subs.

My dedicated music room is pretty much finished sans subwoofer support. I use JansZen’s hybrid Valentina ESL speakers driven by Linear Tube Audio’s ZOTL40 amp and MZ2 preamp, both license David Berning designs. I’m also a vinyl junkie just recently adding the new Technics SL-1200G turntable.

This mix provides a very well balanced and revealing system. Bass with the JansZens is flat to about 30Hz, but I know something is missing and I would classify my bass as super clean, accurate, but polite. I’m not a bass freak, but even David Janszen has told a few of us customers that bass has a ton of ambient information that lives well below what the speakers can produce that only good subwoofers will bring forward. He uses explanations that clip my understand, but in the end he puts it that bass can be great with the right support. A few of us do use subs and I think I’m next. Everyone says use 2 subs. My room is modest size.

My independent research has somewhat narrowed the search to JL Audio and SVS sealed subs and to the servo controlled Rythmik F12G. I have had a 15" Velodyne servo sub in my HT for years and I like what the servo approach does for control. I really like reading what the Rythmik approach does. I also like that the F12G is more affordable than the JL Audio e-series subs. All the other sub brands I’ve researched seem like me-too designs. SVS has stood out simply due to great pricing and amazing customer support. I do know of one friend who uses Vandersteen subs but I know those are priced higher than I care to spend, given that I’m already sold on the idea that I’ll want two.

One nice feature of my LTA amp is it has a pre-amp pass through ability for single ended connections. My amp is between my speakers on a floor rack so bridging interconnects to a couple of subs placed by each speaker should be an easy setup.