hgcjr@utastro.UUCP (08/02/83)
Does anyone on the net have experience, negative or positive, with
subwoofers?
My current speakers are Infinity IRS III's, VERY pleasing indeed above
50-60 Hz. They are in a rather bright large living room (16x22). Because
of domestic considerations (ahem!) there is no possibility of redoing the room.
Ditto speaker placement -- they are at one end about 12-15 inches in front of
curtained windows, roughly three feet from the side walls: not at all ideal,
but there it is.
The speakers are capable of reproducing 40 Hz tones, but satisfactory
bass in music (classical orchestral) is generally lacking. I'm considering a
subwoofer as a possible solution, but have had no experience with them. I am
not even sure that a much cheaper and just as satisfactory(?) solution may not
be available (judicious use of Sonex here or there? much heavier curtains?)
Any ideas, recommendations, opinions, warnings, etc would be welcome.
Oh, yes -- a general price limit of $600 - 700 applies. (Again, "domestic
considerations".)
With thanks,
Harold Corwin
Astronomy Department
Univ. of Texas, Austin
(utastro!hgcjr)jeff@tesla.UUCP (Jeff Frey) (11/07/83)
Doesn`t anybody know anything about subwoofers? I`ve received no response yet to my earlier question about them. Jeff
rmd@hpcnoa.UUCP (11/13/83)
#R:tesla:-22900:hpcnoa:3500009:000:106 hpcnoa!rmd Nov 11 18:44:00 1983 We don't have your original note on our system. Would you mind repeating it? -Rick Dow hpfcla!rmd
mcm@ncsu.UUCP (Mike Mitchell) (02/23/84)
About a year ago I got a pair of used Quad ESL speakers. Mine are the older speakers, built circa 1960. They have fantastic mid-range response, but the low end is lacking. I've been thinking about a sub-woofer, but I don't know what kind will match the electrostatics. I'd also like to pick up an active crossover. Does anyone have one they'd sell cheep? Mike Mitchell decvax!mcnc!ncsu!mcm
gvcormack@watmum.UUCP (Gordon V. Cormack) (10/26/85)
> Ahem...the audio-pro B2-50 subwoofer uses (2) 5-1/4" drivers and I > believe it is fairly flat down to 20Hz. > ... other testimonial evidence I have a couple of comments. First, speaker manufactures LIE about their low-end frequency response (and accuracy, for that matter). I don't know about audio-pro, but look for independent test results to verify any manufactures claims. Polk, for example, claims the monitor 10b is 22Hz - 22Khz +- 2db. Tests in SOUND revealed it was pretty flat down to 40, but was down >10 db at 30. That still makes it a pretty decent speaker, but not as fantastic as claimed. Second, it isn't hard to make small speakers have excellent low-frequency response AT LOW OVERALL SOUND LEVELS. But in order to get a decent sound pressure level out of them, small speakers would have to have a cone excursion of several inches. This is nearly impossible to accomplish, and were it accomplished I doubt that the suspension would be very linear. Even if a linear ultra-long-throw suspension were developed, there would still be doppler distortion of the higher frequencies (maybe this wouldn't be a problem in a subwoofer). So, when you talk "frequency response", make sure you find out at what Sound Pressure Level. Here are some test pieces to use when checking out the bass response of a speaker system (see if you can play them at a realistic level). Time Warp (Telarc cd-80106) 1st and 2nd cut. 1812 Overture (Telarc cd-80041) 12:00-15:20 in particular Bach Toccata (Archiv 410 999-2) Pink Floyd - The Wall (CBS C2K-36183) "Don't Leave me now" -- has some very low synthesizer tones, but they are not all that loud.
rdp@teddy.UUCP (10/29/85)
In article <303@watmum.UUCP> gvcormack@watmum.UUCP (Gordon V. Cormack) writes: >> Ahem...the audio-pro B2-50 subwoofer uses (2) 5-1/4" drivers and I >> believe it is fairly flat down to 20Hz. > >> ... other testimonial evidence > >I have a couple of comments. First, speaker manufactures LIE about >their low-end frequency response (and accuracy, for that matter). >I don't know about audio-pro, but look for independent test results >to verify any manufactures claims. Polk, for example, claims the >monitor 10b is 22Hz - 22Khz +- 2db. Tests in SOUND revealed it >was pretty flat down to 40, but was down >10 db at 30. That still >makes it a pretty decent speaker, but not as fantastic as claimed. > First of all, the statement should be qualified to read: "SOME speaker manufacturers LIE about their <so-on and so-on>." Some don't. Secondly, I am sitting here looking at a copy "High Fidelity's 1986 Audio and Video Buying Guide". Without first refering to the caveats section usually present in such journals, one first notices that EVERY speaker measurement shows nearly the same set of gross anomolies below 500 Hz. Well, some of the reviews go on to explain about 315 Hz dips caused by room reflections and so forth. The point is that many of these reviews' measurements are as flawed and misleading as some manufacturers' data. It seems that, despite their assurances to the contrary, their measurement technique causes common biases in the results, often swamping meaningful differences that might be had otherwise. Also, the insistance on 1/3 octave measurement techniques as the only response measurement results in to little response information being made available. Some pretty gross (and quite audible) narrow-band effects can be completely missed using this technique. A classic example being the Bose 901. On 1/3 octave measurements, the 901's, while not measuring terribly well, do not exhibit the very gross anomolies that are apparent using other techniques, for instance, a 6 db peak 1/20 octave wide where ALL the cones have decided to go into their 1st mode rim resonance. >Second, it isn't hard to make small speakers have excellent low-frequency >response AT LOW OVERALL SOUND LEVELS. But in order to get >a decent sound pressure level out of them, small speakers would have >to have a cone excursion of several inches. This is nearly impossible >to accomplish, and were it accomplished I doubt that the suspension >would be very linear. In general I agree, but the number may be be a bit exaggerated. For example, 2 5 1/4" woofers have about 1/2 the radiating area of a single 12" woofer (2 x .012 sq m vs. .05 sq m). Therefore, for a given sound pressure level at a given frequency (requiring a certain volume-velocity), the tandem pair of 5" woofers would have only to excurse twice the distance of the 12" woofer. I know of no 12" woofers having a real inch of linear excursion, much less that much voice coil/magnet. So, reversing the argument for the moment, if all other things were equal, then a similarly based dual 5 1/4" system might be capable of attaining levels only 3 to 6 db less than the twelve inch based system. Which is not to say that such systems are practical. I once (as an excersize) built a transmission line system around the KEF B-110 woofer/midrange. It's anechoic response was remarkably linear (within 2 db or so) down to 29 Hz, below which it dropped like the proverbial stone (12db/oct due to compliance controlled operation, like normal systems, and another 6 db/octave due to line cancellation, plus another 18 db/oct for offending some engineering god's sensibilities!). The speaker, at low levels with quite disks sounded great! However, the presence of any warp, very low frequency disturbances, tone-arm resonance, whatever, all conspired to cause this poor little woofer to unmercifully beat its brains out banging against the back of the magnet. The inclusion of a 15 Hz sharp high-pass filter improved things greatly, and effectively raised its power handling by as much as 10 dB!. > Even if a linear ultra-long-throw suspension >were developed, there would still be doppler distortion of the higher >frequencies (maybe this wouldn't be a problem in a subwoofer). OH GOD! DOPPLER DISTORTION!!! (I think Paul Klipsch is probably old enough to have been present at Herr Doppler's original experiment). :-) >So, when you talk "frequency response", make sure you find out at >what Sound Pressure Level. And what measurement technique, and room conditions, and so on and so on. > >Here are some test pieces to use when checking out the bass response >of a speaker system (see if you can play them at a realistic level). > > Time Warp (Telarc cd-80106) 1st and 2nd cut. > 1812 Overture (Telarc cd-80041) 12:00-15:20 in particular > Bach Toccata (Archiv 410 999-2) > Pink Floyd - The Wall (CBS C2K-36183) "Don't Leave me now" -- > has some very low synthesizer tones, but they are not > all that loud. OK, What is a realistic level for synthesizer tones? What sort of SPL does whatever organ playing whatever random Bach Toccata produce? How loud was the orchestra playing in the 1812 overture? That sort of recommendation has it's own set of flaws. One experiment I performed years ago was measuring actual performance levels of the BSO and other orchestras, then asking people to play recordings of these performances at "realistic" levels on stereo systems. Invariably, people played them significantly louder in their homes than what was measured their favorite seat in the hall. Also, the longer it had been since they had heard the original concert, the louder their impression of "realistic" was, reaching a plateau averaging as much as 10 db above the actual levels measured. Another interesting effect: If the concert was simulcast, the presence of the visual cues caused people to lower what the expected as "realistic" levels! What is a far better recommendation is to listen to favorite recordings at LEVELS THAT YOU FIND SATISFACTORY AND NORMAL. Your judge of what constitutes realistics may differ greatly from this persons, my own, or anyone elses. You will not be listening at the levels I like, you will be listening at levels that YOU like. Dick Pierce
rcd@opus.UUCP (Dick Dunn) (10/30/85)
> >Before everyone runs off and builds subwoofers with two 8" drivers, > >I'd like to point out that this isn't going to be much of a subwoofer. > > Ahem...the audio-pro B2-50 subwoofer uses (2) 5-1/4" drivers and I > believe it is fairly flat down to 20Hz. > > A friend of mine designed a subwoofer based on the audio-pro idea. He used > 2-6" phillips drivers in acoustically isolated, ported, cabinets... Could someone explain what sort of magic is used to make this work? I assume that if these small subwoofers are not only flat down to the bottom end of the spectrum but can actually produce reasonable sound levels down there, there's some form of mechanical transformer effect due to enclosure and/or placement. Reason: If you've got tiny little speakers like those mentioned and they're just flapping around in the open air, you end up having to move the cone an inch or two to slosh enough air around to make any usable noise. Even if you could get that much cone travel, you'd manage to have some interesting distortion problems. You can presumably get around the problem by something with enclosure and/or driver placement which presents enough load on the driver to reduce cone travel--trading volume of air moved at the driver for pressure. SO, could someone who knows explain how they work? Oh, while I'm at it, could two or three people who know nothing about the matter flame me after reading only half of my question, or agree with me completely and flame the people who think small-driver subwoofers can work? (No, I really don't WANT this--but you can sometimes get what you ask for by asking for what you know you're going to get.:-):-) -- Dick Dunn {hao,ucbvax,allegra}!nbires!rcd (303)444-5710 x3086 ...At last it's the real thing...or close enough to pretend.