Great papers, thank you - why sealed subs are not more popular escapes me! Their simplicity and relative lack of acoustic problems makes them a winner, especially with cheap high power amplifiers available to offset their low efficiency. I use 6 x 18" drivers in my sealed PA subs and now find most ported and horn-loaded designs painful to listen to.
One thing I would like to add is to beware of trying to push too much excursion into a small enclosure, although this is often impossible! The little data available suggests that the displacement volume of the driver should not exceed 5% of the enclosure volume if non-linearity is not to be a problem. Further, mounting the speaker 'backwards', with the magnet outside the enclosure makes for an awkward package, but hugely reduces thermal power compression.
One thing I would like to add is to beware of trying to push too much excursion into a small enclosure, although this is often impossible! The little data available suggests that the displacement volume of the driver should not exceed 5% of the enclosure volume if non-linearity is not to be a problem. Further, mounting the speaker 'backwards', with the magnet outside the enclosure makes for an awkward package, but hugely reduces thermal power compression.
I personally also prefer sealed speakers in general, including subs. But it's not easy to find the right driver for it and they are expensive mostly (at least those that go low and loud enough). Especially if you don't use active crossovers or plate amps. And yes, that has advantages in some cases.
And my sealed sub is big, a Scanspeak 26W/8534G00 in a 77L sealed cabinet, used with a passive crossover to FR tops and amped with a tube amp of 32w. And it does th job for me.
And my sealed sub is big, a Scanspeak 26W/8534G00 in a 77L sealed cabinet, used with a passive crossover to FR tops and amped with a tube amp of 32w. And it does th job for me.
A device to allow the use of many more drivers in a closed box
I refer in my OP to this device (in construction)
I refer in my OP to this device (in construction)
Boring, distortion, and inefficient.
If a speaker moves, it distorts. ALL other enclosures make the speaker move less than SEALED in the passband per a given voltage.
I prefer BP4/BP6's. I hated the 2 SEALED 15's in my F150. I LOVE the single BP4 12" in my Solara and T-TQWT 15" in my HTS.
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ported boxes can give over excursion problems at low frequencies.
any i have built never seemed to boost low end much anyway.
any i have built never seemed to boost low end much anyway.
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dave
diyAudio moderation team
I've built a number of sealed cylinder subs and never really been thrilled with the results.
Same goes for ported (and some of those I've owned have been commerical units) but the transmission line pipe sub I now have is in a different league compared with the others. Goes lower for sure, sounds cleaner too.
And in each case I've used the same Dayton RSS drivers. Thanks to the members of DIY audio for the direction and sims on these. Much appreciated.
As always, however, YMMV (wrt ported and sealed, not help from members!).
Same goes for ported (and some of those I've owned have been commerical units) but the transmission line pipe sub I now have is in a different league compared with the others. Goes lower for sure, sounds cleaner too.
And in each case I've used the same Dayton RSS drivers. Thanks to the members of DIY audio for the direction and sims on these. Much appreciated.
As always, however, YMMV (wrt ported and sealed, not help from members!).
Right, comparing max flat alignments, they can only add ~ a 1/2 octave over sealed, but an extended bass shelf [EBS] alignment, which can have even better transient response than sealed, can be extended further down into the room's gain for significantly more gain BW than sealed.
In short, it's more about using the right alignment for the app than box type per se as luigi has learned. 😉
GM
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I thought the matter was settled in 1955 when Vilchur produced the sealed AR-1. Any progress since then?
BTW, I thought a pin-hole leak (not hermetically sealed) was necessary in sealed boxes to address air expanding? Some use a metal plate with a tiny hole which has no effect on the acoustic sealing.
Very nice papers, but why are authorities forever touting flat bass when some boost at the bottom sounds better to almost anyone who has posted their opinion?
B.
BTW, I thought a pin-hole leak (not hermetically sealed) was necessary in sealed boxes to address air expanding? Some use a metal plate with a tiny hole which has no effect on the acoustic sealing.
Very nice papers, but why are authorities forever touting flat bass when some boost at the bottom sounds better to almost anyone who has posted their opinion?
B.
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Yes or many more reasons (such as microphones don't capture sound in a room suitably or resembling how an ear would or recording engineers.....).
Whatever the reasons, seems fallacious to aim to create a flat speaker output when you don't want a flat output.
B.
Whatever the reasons, seems fallacious to aim to create a flat speaker output when you don't want a flat output.
B.
Off-topic and my personal guess for what a classical music listener at ordinary loudness might prefer.
In practice, really depends on what you have to work with, given the sub and the room. Anybody who has done much indoor speaker testing knows what I am talking about.
But I'd say good starting to ramp up below 80 Hz at maybe 5dB/8ave. Toole has a curve with treble and bass departure from flat - always a wise advisor.
With all the three-decimal-place sims, easy to forget how much art goes into crafting a driver, cab, and room in the first place. Lots of compromises hidden in the T/S world.
B.