Acoustic suspension

[dan stanton]

Even though I am new here, I can't help but wonder why people keep using acoustic suspension speakers in open,or infinite baffle designs. They are made to be in enclosed cabinets. The Thiele(sp)/ Small parameters are for sealed speakers. What am i missing here?

[PeteMcK]

Because the parameters of those drivers suit Open Baffle or Infinite Baffle designs even better than closed boxes, which are usually compromised in some way...

[dan stanton]

Pete, please explain.

[indianajo]

Pardon me for stupidity, but what vendor gives you a choice of Acoustic suspension versus ? bass reflex? The only speaker selector I have found is Mouser Elec, and in the 3" 8 ohm size, they only have one obsolete entry that has a top frequency of 5000 and top watts of 1.5. I would like to buy an acoustic suspension speaker of that dimension that goes to 20000 like my KLH 23 had.

[dan stanton]

Is that Indiana jo? Grew up in Merrillville.

[indianajo]

Yeah, I live in Jeffersonville instead of near Indianapolis. The first forum I got on required 8 character names, so I was indianaj. My real name is much weirder than Joe. I don't wear a hat, but do vacation in slighly adventurous places.I grew up in Houston, Spring Branch Elementary, SB Junior High, SB High School, Rice, U of H. Traffic got too much for me, I was rear ended 7 times. Where are you buying in the US speakers designed for Acoustic Suspension? Mouser was reccomended on another website, but they don't do 3" tweeters. I just retired and am spending the snow months activating some of the cool junk I have in the attic, also increasing my electronics knowledge. I bought the LWE speakers at Home Entertainment on Kirby, are they still a big deal? I used to buy electronic parts from Sterling on SW freeway and Electrotex on Westheimer, are they still the TV repair homebase?

[MJL21193]

Originally Posted by indianajo

Where are you buying in the US speakers designed for Acoustic Suspension? Mouser was reccomended on another website, but they don't do 3" tweeters.

Popular in the US is Parts-Express.com - Speakers, Speaker Building, Home Audio and Video, Pro Audio, Electronic Parts & Accessories PARTS EXPRESS, Speakers, Speaker Parts, Guitar speakers, Bass speakers, Woofers, Drivers, speaker upgrades and replacement speakers. Emine

Acoustic suspension is different from an ordinary sealed box - the box has a lot smaller volume and the driver needs to have the correct T/S specs to work well in it. The T/S specs that are good for acoustic suspension (in particular high Qes) happen to be ok for open box or infinite baffle.

[PeteMcK]

Usually these drivers have a high Q & high Vas, which means they need a huge box. A sealed box is the best compromise for a reasonable size, but if you sim a High Q driver with a small box in Winisd or Unibox, you will see that the the frequency response usually has a hump at the low end then falls off. To get a flat response you need a very large box, which is what infinite baffle or open baffle apears to be to the driver. With Open baffle you have the added complication that cancellation occurs depending on baffle width, & needs to be equalised somehow.

[indianajo]

Okay,thank you. My 1974 KLH's were built right at the end of the acoustic suspension craze. I just read Wikipedia on speaker enclosure. What T/S numbers are suitable for acoustic suspension? Wikipedia didn't cover that. Is this just for woofers or is it also for tweeters? What numbers are suitable for sealed box? I'm quite sure the 23's are sealed, whether they are acoustic suspension apparently has to do with whether there is an interior smaller box. The woofers go almost an inch when playing low frequencies loud, I think that means acoustic suspension.

[MJL21193]

Originally Posted by PeteMcK

To get a flat response you need a very large box, which is what infinite baffle or open baffle apears to be to the driver. With Open baffle you have the added complication that cancellation occurs depending on baffle width, & needs to be equalised somehow.

Hi Pete,
That response peak is usually 2 to 4db in a well designed acoustic suspension box and can factor in well for baffle step compensation in a three-way.
Also worth considering is Xmax and how the ideal acoustic suspension driver may run out of linear excursion if used in an OB/IB, particularly if EQed.