A7 Cabinet Resonances?

[tomdae]

Hi all
In my opinion the a7 cabinet reconances are somehow inherent to this system. The big box allows the air to resonate in various fequencies, to make the box out of stone would not help this. The compromise to let the A7 act as half bass reflex and half backloaded horn is the trick to make the A7 as eficient as it is down to about 40Hz. The drawback are these bothering resonances. I was not able to ignore them, so I sold my pair of A7's. I prefer the 9846-8A studio monitors. The resonances I'm talking about in the A7 cabinet could be stopped with a lot of damping material, but the bass power would then be lost too! To make two chambers in the A7 and add a sub in the lower part is an often discussed way to solve this problem. I tried that with adding a 411-8A to the lower part of the A7. Sounds ok, but the sound is not as nice as it is if 40 Hz to 500 Hz is done with one speaker alone. And it is complicated too, the 411-8A cannot keep up with the efficiency of a 515 or 416 speaker, so it needs biamping& electronic xover. But actually still.. I miss the bright mids of the A7. In switzerland they say "you can't have both the penny and the bun!"

[ngccglp]

Great info. For the past few weeks I've been bothered by certain resonance (sounds like buzzing) but just can't locate the exact location. Fortunately it only occurs when I play bass-heavy materials and loud!!!.

Think I'll just sit back and enjoy the music.

[Jack6428-2]

Hello,

If I were to use kitty litter, should I use the standard kind or the clumping kind?

Other than maybe a little less weight, what attributes may kitty litter have over sand?

Would pea gravel be worth considering since, if rinsed well, it would have less very small particles and be less likely to get into woofer voice coil gaps if the seal is broken (or would this be making a giant castanet!)?

NG

[bfish]

Don't think anyone's solutions yet have topped this devoted Altec fan's engraved granite A7....talk about a dead cabinet!

http://www.leesound.com/bw_photos/page4.htm

[dread64]

That "Plane wave tube" contraption has me reeling. What in the world was that used for?
Must have been some kind of sinister military use.

Dave

[Steve Mac]

Originally posted by bfish:
Don't think anyone's solutions yet have topped this devoted Altec fan's engraved granite A7....talk about a dead cabinet!

http://www.leesound.com/bw_photos/page4.htm

<font size="2" face="Verdana, Helvetica, sans-serif">Kitty litter...why?
If it's lighter than sand it is worse than sand.

[Steve Mac]

Originally posted by ngccglp:
Great info. For the past few weeks I've been bothered by certain resonance (sounds like buzzing) but just can't locate the exact location. Fortunately it only occurs when I play bass-heavy materials and loud!!!.

Think I'll just sit back and enjoy the music.

<font size="2" face="Verdana, Helvetica, sans-serif">This could be due to a bad glue joint.
This also could be due to a void in the plywood, if that is what the cabinet is constructed from.
I've also heard woofers that vibrate and make noise because of rips or holes in the speakers and the voice coil overheating, causing internal rubbing.
Wires, connectors, grille cloth frame...are all candidates.

[Steve Mac]

Originally posted by NebraskaGuy:
Hello,

If I were to use kitty litter, should I use the standard kind or the clumping kind?

Other than maybe a little less weight, what attributes may kitty litter have over sand?

Would pea gravel be worth considering since, if rinsed well, it would have less very small particles and be less likely to get into woofer voice coil gaps if the seal is broken (or would this be making a giant castanet!)?

NG

<font size="2" face="Verdana, Helvetica, sans-serif">Sorry, but I replied to the wrong post...this is the post I meant to reply to.

Kitty litter...why?
If it's lighter than sand it is worse than sand.
Pea gravel might work, but if some get loose somewhere you might hear a maraca. But again, sand is king.

[Steve Mac]

Originally posted by tomdee:
Hi all
In my opinion the a7 cabinet reconances are somehow inherent to this system. The big box allows the air to resonate in various fequencies, to make the box out of stone would not help this. The compromise to let the A7 act as half bass reflex and half backloaded horn is the trick to make the A7 as eficient as it is down to about 40Hz. The drawback are these bothering resonances.

<font size="2" face="Verdana, Helvetica, sans-serif">It may be your opinion, but you won't find a speaker cabinet designer who agrees with this statement.

[ngccglp]

Hi Steve,

You may be right, I always suspect its the 4 wooden strips that accept the screws of the back panel. But don't know how to solve it without making it worse. Think I'll just apply white glue all round when I have the time.

Thanks.