Why no high efficiency bass drivers for sealed bass channel?

[bbggg]

The OP might want to take a look at woofers by Eighteen Sound, a pro manufacturer from Italy.
Some of their bigger models feature 16 and 8 Ohm versions, neo magnets, double or triple spiders, and goodly efficiency.
Some woofers by Precision Devices may also fit the bill, but they are expensive, so they actually might not.

[Helmuth]

selenium high q required for closed box. Selenium has that only watch out for the limited xmax. works fine for hifi medium power.

simulation series resistance 0,4 ohm of filter is calculated.

http://www.selenium.com.br/site/asse..._pdfManual.pdf

[Kjeldsen]

Originally Posted by Helmuth

selenium high q required for closed box. Selenium has that only watch out for the limited xmax. works fine for hifi medium power.

simulation series resistance 0,4 ohm of filter is calculated.

http://www.selenium.com.br/site/asse..._pdfManual.pdf

It's 5 dB down at 60 Hz. Even with room contribution, the low end will be suffering. eq'ing the response just gets the overall sensitivity down, to a normalt 15" hifi woofer, with natural linearity in the low end (not the high mass moderne woofers - try look at the Peerless i'm linking)

[hasselbaink]

Originally Posted by sumaudioguy

By the way,- we all here prefer to use low Q in box, 0.5 or less, and EQ to end up with flat bass in a calibrated system. Never have been in a room that did not have problems in the bass so EQ has always been used.

I prefer a Q around 0.6. Much lower than that and you get what I call "market-place-bass" - it sounds like bass in a very large outdoor setting. I know a guy with a closed box speaker with a Q of 0.3 and it sounds remarkably bad.

Best
Kris

[hasselbaink]

Originally Posted by bbggg

The OP might want to take a look at woofers by Eighteen Sound, a pro manufacturer from Italy.
Some of their bigger models feature 16 and 8 Ohm versions, neo magnets, double or triple spiders, and goodly efficiency.
Some woofers by Precision Devices may also fit the bill, but they are expensive, so they actually might not.

I know 18Sound fairly well and their woofers are made for sound reinforcement which means ported enclosures.
I specifically asked about woofers for closed box.

Kris

[thoriated]

My best attempt so far is a ported box that 'sounds' like a closed box (basically an overdamped response) with a low port tuning (~32hz). Doing that and using activated charcoal to increase box compliance by an estimated 50% and playing some (passive) xover tricks to fill in the otherwise saddle shaped LF response allows me to get 90db + at 40hz trending to 100db/w/m above 60hz in half space in a 100 liter enclosure using a JBL 2220A. Part of the xover is 600uF of polypropylene input coupling capacitance which limits excursion below the passband and give an extra db or two response in the 30-40hz range. This capacitance value would seem a bit low, but this is actually a true 16 ohm system (that I allow to dip to 12 below 40 hz to scoop up a db or two more sensitivity in that range), even though it uses an '8 ohm' bass driver partly due to a custom wound air core transformer in the xover which almost completely flattens the upper BR impedance peak, turning it into into more sensitivity in the 50-80 hz range. I call it the Iron Lawbreaker.

I have considered making a super low moving mass high efficiency 15" driver that might work in a closed box for good bass extension but have not found the time yet.

[Antripodean]

It may not be low enough but I am running two Acoustic Elegance TD15S to achieve a good response sealed to ~45Hz. As I say, not sure if this is low enough but you could run them in series for 16 Ohms. It requires a big box!

[CLS]

This should be ideal, I should've thought about it earlier:

400 EXC SUPRAVOX

High efficiency, low fs, light cone, adjustable motor strength (Q), how adorable!!

[doug20]

He needs LARGE drivers do this and still have sensitivity.

TD18H from AEspeakers.com is a SICK woofer.

Depending on what he considers efficient, I Would even say the AV15H is another incredible woofer. Its actually a subwoofer but its sensitivity is the highest for that class of designs I have ever seen and it digs deep!!

[CLS]

Er.... any limit to the 'box' size? If no, how about this

AE TD15M (what?), used in IB (or you can build a box of 1000 liter), and got this: 90dB/w at 32Hz. BUT, driven by an amp with 10 Ohm output impedance.