Re: OT:For Howard

ScottW wrote:

My Legacy Focus aren't flat to 20 in spite of their 18 Hz spec
but they can do low 20's...and when they did it wasn't
pretty. Pictures hanging on the walls is a bad idea
for a 20 Hz listening room :).

Yes, it can be disconcerting. My Velodyne F1800RII (used for the center, surround, and LFE bass in my main room) has a lamp sitting on it and even a foam pad underneath does not keep the shade from buzzing sometimes. Most of the pictures in the room have foam or felt pads behind the frame edges, and all of the trinkets sitting on bookshelves also have pads on the bottoms.

The biggest rattlers are the sheet-wood panel backs on all of the bookcases. I spent some time securing those items a while back. Even the rather heavy surround speakers hanging on the walls buzz a bit with strong, clean low-bass from the subs, and they also have foam pads behind them. Sometimes, after watching a really explosive movie, I have to slightly re-level several of the pictures hanging on the walls.

However, there is more to deep bass than musical performance. Often, classical recordings include the "sound" of the hall itself, and that sound is often very low in frequency. If a system can reproduce really down into the low-bass range it will reproduce that "sound" and that adds spacious hall realism to program source material that may not go all that deep musically.

I know what you mean by the Hall sound but more often than
not, I found that low hall sound to be a bloom that I ultimately
determine isn't acoustically desirable and eventually becomes
annoying as it imposes itself on the music.
A hall shouldn't resonate without in band stimulus and ones
that do continuously aren't to my liking.

Yes, hall-space noise can be a problem. I have a number of organ recordings (many done on the defunct Gothic label) that allow one to hear low-frequency truck and automotive traffic outside of the church. (Churches, while acoustically often very nice, are not as well exterior-sound protected as good concert halls and studios.) In addition, it is not unusual at all to hear heat/AC operations going on even in supposedly quiet concert halls.

I think when you are on site in such places you tend to ignore the noise, particularly because there will also be an audience on hand generating its own noise that directs attention away from hall-space noise. However, in a home-listening environment hall-space noise becomes more apparent.

I remember auditioning one recording (as part of my work as a record reviewer some time back) where I thought a large truck was idling its engine out in front of my house. When I went to look there was no truck there, but when I returned to the listening room in the back and hit the pause button the rumbling disappeared.

However, if the hall is a good one the "sound" of the large space can add a degree of three-dimensional spaciousness to the sound that may enhance the sense of "being-there" space. It may be annoying at times, but at other times, particularly when DSP surround circuitry is also being employed to channel mid- and high-frequency surround ambiance to a group of surround speakers, the effect is enjoyable.

Perhaps one problem people have when all they employ is a pair of stereo speakers, is that the lack of mid- and high-frequency surround ambiance just screws up the spacious balance. When you have surround sound added in the room-ambiance sound blends in nicely with the very low frequency hall-space sound.


Ok...now I have a question. My Hsu VTF-2 is hooked up
via the speaker level inputs to my Qauds in parallel with
the speaker terminals driven by my Krell KSA-150.
I'd also like to hook it up to the LFE out (line level)
on my surround receiver.
No mention of this dual hookup option in the Hsu manual.
What kind of isolation is there between line level in
and speaker level?

From what I gather, one cannot simultaneously hook up the speaker-level and line-level inputs on a subwoofer. Why not just configure both packages to use line-level inputs for everything? Yes, with that kind of arrangement you would have to use some kind line-level switch box, and you would need a line-level crossover network for the Quad/Hsu part of the package.

A good full-feature crossover network like the Paradigm X-30 would be ideal for that. It cannot handle inputs from two different amp systems, but it does at least offer the user the option of selecting variable low-pass filtering and three different high-pass frequencies.

Incidentally, that hookup you mention indicates that the Quads are not high-pass filtered at all. The Hsu basically "augments" the Quad's low-range performance, with the latter just rolling off naturally at the bottom. The problem with that is that any low-bass distortion artifacts the Quads might generate will add some colorations that a "subwoofer only for low-bass" hookup (with high-pass filtering for the Quads) would eliminate. In addition, running the satellites full range down into the low-bass range compromises their power handling. If they are high-pass filtered their headroom will increase considerably during spirited listening that involves source materials with a lot of low bass.

Frankly, to reduce the complexity of your situation I recommend simply getting an additional subwoofer for use with your other (receiver controlled) system. Hsu's new STF-1 sub only costs $300, and it astonishingly can just about match the VTF-2 down to 30 Hz. (I own both subs, by the way, and use them for reference work when doing subwoofer analyses.)

If you want to pull out all the stops consider Hsu's new VTF-3 MK3 model. I recently reviewed that for The Sensible Sound (I also reviewed those other Hsu models mentioned above, but some time ago), and it is a terrific performer that can get to 20 Hz with ease. With its optional "turbo" boost add-on device (admittedly, that is ugly), the sub becomes a real wall shaker.

Yeah, I also have it on hand with my second system, where it works along with a Hsu TN1220. Each has separate duties, with one handling the center and surround bass and the other handling the LFE. The main-channel bass in that system is handled by the woofers in the main-channel Dunlavy Cantata speakers. Since I always employ the center channel, the Cantatas share duties with one of the subs down really low.

My main system, in addition to the Velodyne F1800 mentioned previously, also employs a large, modified (by me) SVS 16-46 subwoofer to handle the main-channel bass. I cross it over from my Allison IC-20 units (using a Paradigm X-30 crossover network) at a low 50 Hz.

I suspect the speaker ins are just resister divided down
to line level but I'm not sure.

Yes, and the signals are then sent to the low-pass network. The input may also employ large, non-polarized capacitors to filter out the low frequencies that would normally go to the speaker-out jacks. (My guess is that a Quad owner would NOT want to use that high-pass filtering option. I have not pulled that amp to check that out, but the larger Hsu subs have used the approach in the past. You might phone Hsu to get his take on your idea. He, or one of his helpers, are pretty good at sorting out various approaches to hooking up his subwoofers.

As for room rattling, put some foam pads under various articles in the room, as well as behind pictures hanging on the walls. Find those rattles and quash them.

My rooms good to 30 with VTF-2. I'm happy with that for
now but if I hook it up to the LFE...I might have to
do a little rattle tracking.

For me, the VTF-2 remains a reference standard for moderately priced subwoofers. However, Hsu's own, newer STF-1 sub, which costs even less, and is even smaller, can give it a shocking run for the money.

Howard Ferstler

.

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