sealed vs vented subwoofers

Duke,

I am confused now because you say group delay is worse on sealed? You can clearly see on the links I gave how blocking the port reduces group delay - so how do you explain that? (My understanding is that the port radiates one full cycle out of phase at the tuned frequency - inevitably this implies poor group delay at the tuned frequency and can be seen on most plots on HT SHack website)

My guess is that kick drum sounds better on a sealed sub is probably again the higher group delay and possibly port ringing effects. (Port ringing may even affect mid bass quality)

Stan,

I agree with you that measurements are not everything. However I approach things differently from most - I try to start with good measurements to begin with and then listen for what sounds best to my tastes. It kind of weeds out stuff which simply sounds good but is actually adding coloration.

Have you ever had a pair of RELs in your house or did you dismiss them on the basis of some specification?

No. However I did not dismiss them - if you did go to the HT Shack website you will notice they have EXCELLENT extremely low group delay. Lord appears to design these deliberately with a very low Q and therefore they are not as efficient (play as loud with low distortion) as others but are probably much more musical sounding than many of the subs that were tested - especially on a kick drum. I suspect the REL's would work well with low Q speakers like ATC but I have not tried myself - so this is simply speculation based on the measurements. They also use Volt drivers that have a good reputation. I did not dismiss REL.

Um, I've sold just about every kind of sub on the market over the years, and owned a variety of both. I'd say that, overall, the more musically accurate subs I've come across where "sealed" designs. But then I've had some excellent ported designs.
I would say it depends, and that you can get excellent perfomers on both sides. Sealed usually offeres a tighter more accurate response, seams like, while efficiency and output definitely seem to go to "the port". Still, I've found I can get good results with both. But, if I had to, in a music system, I'd likely lean to sealed. In an HT system, where all out output mattered, or in an undersized application in a larger room, I'd look at ported. Depends.
My favorite music/ht sub thus far has been the Paradigm Servo 15, hands down, in the past. But, I've had some very expensive sealed MTS infinity subs that were stellar as well. So, a lot has to do with design considerations, I'm sure.
I'm no expert speaker builder though...just an observer - lol.
Um, does this help? I can't tell.

Shadorne - my bad! You are absolutely right; sealed boxes have LESS group delay than vented boxes. I was thinking that, but carelessly typed the exact opposite.

That first sentence should read:

"A sealed box will have less group delay than a vented box..."

My compliments on your restraint in not calling me the idiot I certainly appeared to be.

Duke

I got around to looking on the HT Shack site. I had somehow supposed this to be connected to Radio Shack. I find that it is run by Home Theater Mag. , to which I subscribe but seldom read. I had always thought it axiomatic that the requirements for home theater bass were different from, and less stringent than , music reproduction. Sub reviews by mags like Hi Fi News and Hi Fi Plus state this explicitly. I will be glad to provide citations. I was surprised to see subs apparently being tested in the middle of a parking lot. At first I thought they might be preparing an article on Hi Fi for the Homeless but then surmised that they were doing free air testing of the woofers. This mirrors the testing procedures of 30 years ago when anechoic chambers were used to test speakers. I have not seen this done in years as it became apparent that to take a speaker out of a room was to take away most of the value of the measurement. Since the REL are explicitly designed to be placed close to a wall I cannot see what their performance in a boundary less environment can tell us. The room is the most important component in any system, removing a speaker from a room does not provide an equal playing field; it will favor those designed to be placed well out into a room. In a good test of a component the measurement is done AFTER the listening test in order to explain what the panel has heard. As often as not the measurements contradict what the panel has determined, i.e., the product with the least distortion or greatest frequency range is seldom the best. This does not mean some mystic power is at work but that we have NEVER succeeded in constructing a set of rules which will tell us what makes a component sound good. Stan Curtis, who has spent a lifetime designing amps, is currently writing a series of articles about his career ,describing much of it a process of forgetting theory and trusting experience. For example, that point to point wiring is better than circuit boards and that higher quality parts make a sonic difference even when the measurement of their performance is the same. Peter Walker often remarked that he could design an amp that would look good on every measurement but which would render familiar tunes unrecognizable. 40 years ago I had memorized the Stereo Review and High Fidelity performance graphs of about every amp on the market [not hard in those days]. It was a total waste of time. A friend recently chided me for not paying enough attention to the theory behind a product we both use and like. I told him I didn't care if it worked by channeling Angels from heaven if it sounded good. The only way to determine if you will like the sound of a component is either to listen to it in your own home [by far the best] or read a test by a person or group whose ears you trust of the item in question actually in use in a home environment. NO measurement or design principal has ever been shown to give a close correlation with sound quality.

NO measurement or design principal has ever been
shown to give a close correlation with sound quality.

I agree in the sense that no single measurement does - it is usually a
combination of measurements and design principals that correlate to sound
quality. Often there is more than one way to skin a cat.

BTW - The student who ran these subwoofer tests in a parking lot has been
hired by Genelec - to
work in their R&D department. He will have access to anechoic chambers
now. I suspect the parking lot is just a way to get raw baseline comparable
measurements under controlled conditions - for sure these need to be
interpreted carefully. As Duke points out - a roll off is probably more
desirable than a flat response to 20 Hz - due to the in room wall boundary
boost effect.

Genelec is not well known to audio consumers but they have a strong
following in the music recording business.