extreme cone movement

[Einric]

I have recently built a pair of Dayton DA175 two way speakers.
They are BR in.9 cuft tuned to 33hz.
Even at relatively low volume the woofers move A LOT.
They still sound fine but it still concerns me.
What would cause this.
I am on a commercial HT amp with high pass @ 100hz.
Even when I set the High Pass to 200hz I still see great cone movement with explosions.
I have never noticed this with the other two sets of speakers I have attached to this receiver over the past 10 years.

I have heard great things about this woofer and I find it hard to believe that it is the woofers fault.
I am in the process of finding leaks in the boxes that might cause the box to be "Larger" than it is.
This woofer needs 1.9 cuft on the simulations.
Is it possible that there is a resonant in the box that messes with it's excursion or something?

[WaVeInFoRm]

all i can think is that when you play an explosion sound it has content way below your tuning frequency.

with a reflex port all frequancys, from a few hz down from your tuning of 33hz, cause the woofer to act as if it was in free space.

try shoving something in the port and see if it is the same

you may need a subsonic filter, i have no experiance of reflex boxes, i dont know weather in real life situations the boxes are easly unloaded r not.

[Einric]

If I plug the port completely the excursion is limited and the bass is definitely tighter.
The HT Receiver has a 100, 150 or 200hz filter on it to cross the mains to the sub.

[Einric]

Is it possible that this is the first speaker I have had that has a woofer that "wants" to try and reproduce subsonic and has the means to do so.
All my other speakers have been commercial woofers 5.25"-6.5" with inflated low extension (I'm sure).

[5th element]

Generally the more capable a woofer is of reproducing low frequencies, the less it has to move to reproduce them.

I am very surprised that a high pass of even 100Hz (which is normally 2nd order) isn't enough to stomp out excessive excursions at low frequencies. It makes me wonder if the filter is faulty or if something else somewhere is amiss.

[Einric]

OK, I think I have solved the mystery.
At 12 WRMS @ 32hz tuning in 1 cuft this woofer exceeds rated Xmax @ 50hz & down.
It all makes sense now.

[sreten]

Originally Posted by 5th element

Generally the more capable a woofer is of reproducing low
frequencies, the less it has to move to reproduce them.

Hi,

Don't know what your trying to say. In fact the less capable a speaker
is of reproducing low bass, e.g. due to high driver Fs, the less it will
move, and consequently it will handle more low bass power.

the DA175 in 1 cuft vented to 32Hz will have pretty impressive bass
extension albeit at a modest level due to excursion limitations. Bass
power handling is 10W or so, good full range for a 30-50W amplifier.

For high pased HT use I'd say 0.5cuft sealed would probably be better.

rgds, sreten.

[Einric]

Yes I was thinking about sealed .5 cuft.
I wanted a little more low end for stereo listening though so I went with 1 cuft BR.
I finally hooked up my EQ and experimented with the subsonic filter.
The woofers are well behaved now, I have tuned the EQ to enhance the low bass and with the subsonic on I don't have wild cone movement anymore.

My amp is a 120W Class H+ Panasonic, it has plenty of power to drive the speakers to destruction.
Unfortunately the EQ can only be in the loop with analog sources.

[5th element]

Originally Posted by sreten

Hi,

Don't know what your trying to say.

It was a generalisation that when you go up in driver size, for a given average hifi type sensitivity, in a standard ported box, that the overall excursion for a given frequency would go down. This was aimed at the point that the OP thought, because his cones were flapping a lot, that he had a system that was now more capable of reproducing low low bass, where all that's likely to be happening is the driver is unloading with HT booms. Maybe it was too much of generalisation.

[Einric]

5th.....Nailed It

Now with the Subsonic Filter the over excursion problems are gone.