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Re: A question about woofer dampening

October 22nd, 2020, 12:37 pm

My best description would be cleaner, and more natural sounding bass. No bloom or boom. My full range speakers and subwoofers are overstuffed (loosely) with natural wool fill. There is a loss of deeper bass (lower dbs) that normally comes from the ports/vents. Using the sub overcame that problem with the full range speakers, but the sub doesn't go quite as deep as no fill (as designed), but it sounds more natural. Probably only flat to 30hz, but no bloom or boom. Among the best (most natural) bass I've heard in a home system.

Re: A question about woofer dampening

October 22nd, 2020, 2:06 pm

Jim G wrote:My best description would be cleaner, and more natural sounding bass. No bloom or boom. My full range speakers and subwoofers are overstuffed (loosely) with natural wool fill. There is a loss of deeper bass (lower dbs) that normally comes from the ports/vents. Using the sub overcame that problem with the full range speakers, but the sub doesn't go quite as deep as no fill (as designed), but it sounds more natural. Probably only flat to 30hz, but no bloom or boom. Among the best (most natural) bass I've heard in a home system.


AMEN!

Re: A question about woofer dampening

October 22nd, 2020, 2:40 pm

so you are advocating adding dampening to tighten base at the expense of lower freq response. I can live with that.

Re: A question about woofer dampening

October 22nd, 2020, 3:00 pm

Pelliott321 wrote:so you are advocating adding dampening to tighten base at the expense of lower freq response. I can live with that.


In my case I didn't sacrifice anything. I kept screwing with it until i had a nice neutral mid-range along with extended bass. That's how I ended up with the quasi transmission line.

Stock -- the Altecs were flat to 50-Hz. then rolled from there at about 6-db/octave. Stock -- the bass seemed loose and thin. The vents really didn't behave like a port. Your Jazz speakers have a tuned port.

If you really want to have fun -- get a box of soda straws -- make a bundle that will fit in the port -- then cut them down in groups following the rules-of-logarithms. The longest straws should be the length of the port.

This is an old ProAc trick and I've done this trick on other speakers to great effect. An old slide rule can be of benefit to determine the lengths. Use the left-end scale staring with zero.
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Re: A question about woofer dampening

October 22nd, 2020, 3:28 pm

Pelliott321 wrote:so you are advocating adding dampening to tighten base at the expense of lower freq response. I can live with that.

Yes, in my case. I'm sure the technical side as Tom said is right, it's changing the woofer's parameters, but what's audible in my case is perhaps less resonance and reflection.(?) My speakers have 2- 15" woofers and 1- 18" woofer per side, all lightweight pulp/paper cones. Certainly, less time smear from the port/vent as the level is quite low. Perhaps, the damping is reducing overshoot also?

I added a pound at a time (large cabinets. 12 cubic feet for each full range and 8 cubic feet for each sub.) until I got the sound I was after. Picture shows how it's packaged and in the box. Kinda looks like cotton candy.
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Re: A question about woofer dampening

October 22nd, 2020, 6:23 pm

Jim G wrote:
Pelliott321 wrote:so you are advocating adding dampening to tighten base at the expense of lower freq response. I can live with that.

Yes, in my case. I'm sure the technical side as Tom said is right, it's changing the woofer's parameters, but what's audible in my case is perhaps less resonance and reflection.(?) My speakers have 2- 15" woofers and 1- 18" woofer per side, all lightweight pulp/paper cones. Certainly, less time smear from the port/vent as the level is quite low. Perhaps, the damping is reducing overshoot also?

I added a pound at a time (large cabinets. 12 cubic feet for each full range and 8 cubic feet for each sub.) until I got the sound I was after. Picture shows how it's packaged and in the box. Kinda looks like cotton candy.

A word about Jim's choice of fill. Wool (what Jim used) and fiberglass are the fill materials of choice. They are not reactive -- PERIOD! Polydacron fill and foam as used in bedding, is reactive, and works counter to the goal of damping.

There is course polydacron fill that can work -- but most of what is sold in fabric stores is the fine fluff -- the coarse polydacron is difficult to come by. One other fill material that I really like a lot is raw cotton -- right off the vine -- seeds and all.

I've used cotton fill in the past and liked the end result.

Re: A question about woofer dampening

October 22nd, 2020, 7:15 pm

True enough. My full range speakers came overstuffed with polyfill from the factory by design. 2 woofers sharing the same 12 cubic foot vented cabinet as a 2.5 way by design. The wool, (suggested by a friend) was an immediate (subjective) improvement.

Re: A question about woofer dampening

October 22nd, 2020, 11:16 pm

Jim G wrote:True enough. My full range speakers came overstuffed with polyfill from the factory by design. 2 woofers sharing the same 12 cubic foot vented cabinet as a 2.5 way by design. The wool, (suggested by a friend) was an immediate (subjective) improvement.

One final note -- a little goes a long way. I've upgraded four B&W 801s and 802s. The B&W speakers that have a separate mid-range enclosure sitting on top of the bass enclosure. The mid-range enclosures especially were stuffed to the point where you could not even push the fill in. The good news? Nice wool. The bad news? 80-grams of fill -- 40-grams got the job done with a mid-range that opened up where before it was dark with a strange "plastic coloration" and dead.

Same goes for the bass. The fill should fool the woofer so that it seems it is mounted in a bigger box than what it is (for the scientists in the group -- it is a function of adiabatic expansion). Go too far and the box volume "shrinks," which is counter to what needs to be accomplished.

Re: A question about woofer dampening

October 23rd, 2020, 8:11 am

Thanks guys
This has given me a lot to work with
I am work with a ported base box that has a 50-60 hz bump( some is due to room)
I want to smooth out. The builder likes this bump and he feels it makes this a great rock speaker. Maybe so. I am looking for a more smooth response

Re: A question about woofer dampening

October 23rd, 2020, 9:11 am

Pelliott321 wrote:Thanks guys
This has given me a lot to work with
I am work with a ported base box that has a 50-60 hz bump( some is due to room)
I want to smooth out. The builder likes this bump and he feels it makes this a great rock speaker. Maybe so. I am looking for a more smooth response

AHHHH! The manufacturer's hidden agenda finally revealed. ROCK & ROLL! Of course -- it may serve the Fender Bass -- but my view is that it will serve in a bad way.

Accurate speakers serve ALL genres of music.
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