Why not Higher Freq extension out of RSS315 HO ??,Help

Who cares how they sound; they look sweet.

Box tuning probably has something to do with it.

What is the sub amp? You definitely have a lot of room reinforcement below 60hz.

This should be an approximation of what your room is doing to the simulated anechoic (winISD) response of your sub, without accounting for additional room modes (50 hz peak)



Your measured response is still extended, but the sub gets a lot of gain below 100hz just because its in a room near the floor/wall.

Impedance difference and its effects on the LP filter.

Turn the subs around, aiming them at the wall. As you have them you're getting Allison Effect cancellation in the midbass. You'll probably get a lot better response at the LP with one in the front of the room and one in the back. As you have them they look nice and symmetrical, but low frequencies and symmetrical placement don't get along very well.

I see a rising level as you drop in frequency with a peak at 25 and 50hz

the subwoofer plate amp probably has a low pass filter which is messing up the top end.

sometimes they have one that is adjustable and another one that is hard wired. not sure why and not sure about that specific plate amp.

that is a very interesting optical illusion that you have created there.

jay, winisd is 2 pi space. anechoic is 4pi.

Half-space anechoic is 2 pi. Full space anechoic is 4pi. He should have stated half-space anechoic.

Probably the amp is rolling off the highs.
With a nu3000DSP (for example), you could probably set the XO at 200hz/48db.
With the DA1000, it probably doesn't have that ability.

But me personally, I've never liked the resulting sound when my subs were playing notes much higher than 120hz/24db or 140hz/48db (at the highest); too many lower vocals bleed through.

That said, I do have 4 18's @ 354hz/48db, but they are directly radiating into bass trapping material (8 cubic feet of it) and are 180 degree's rotated away from my face.
That's how I get perfectly flat sound above 40hz, without vocal bleed sound.

nice catch mayhem. so the 200hz crossover probably isn't really 200hz because the impedance of 8 ohms is higher than the 4 that the amp is likely expecting, as a result the crossover point is much lower than what is thought?

How is impedance involved in this at all? It's an active cross over.

Randy, I honestly don't know what would cause that. The kef driver might have a rising response. Or the box is to small so it has a falling response (as frequency decreases the output descreses). That would be my guess. The kef should be in a bigger box and tuned lower. The best way to find out what is going on is to get some nearfield measurements.

I thought so too......until Randy stated that the Dayton uses the SA1000 and the Kef was using its plate amp......now the solution is more obvious that the filter slope of the Dayton amp is steeper than the Kef which is probobly second order. I originally thought Randy said both were using the SA, where the driver impedance would effect the overall filter slope.

You need to send the subs a left or right signal to test the upper range effectively. Set both amps to the same low pass filter setting and re measure.

Isn't that what he did. He did a 200hz even. I think it's the low end output of the Dayton is SO much more it looks like it has less HF output.

This

If that was to take effect at lets say 65hz ish you would need to have them 1.3m out from the wall.
http://www.mh-audio.nl/CancellationFreq.asp

I said midbass. By the look of it the baffle may be far enough from the wall to cause a midbass dip. There will also be a dips from the sidewall reflections, though not being able to see the sidewalls it's difficult to say at what frequency. And of course there will be dips caused by the ceiling and rear wall reflections, where depending on the listening/measuring position relative to those boundaries.

Yes, and i looked at the graph and picture posted. I dont know how deep thoose subs are but lets just say 50cm, and standing 10cm from the wall. 60cm.
The dip at 65hz cant be cancellation from the closest wall since it would have to be 1.3m out. There seemes to also be a dip at 90 and 180hz which would mean 95cm and 48cm out from the wall.
60cm out would cause a dip around 140-145hz.
The ceeling and wall behind the listening position is to far away to cause any direct cancellation in the midbass region. And the sidewall as you say cant be seen so who knows.

How are you able to tell where the dips are at based on the boundries?

3 posts up...

But how are you level matching things? The input sensitivity of the SA1000 may be lower compared to the Kef amp. In reality, if both subs were to be getting 2.83V at the woofer terminals, the dayton might have 3db on the Kef even at 100hz (where the difference is largest). That would move the whole line way up showing that the Dayton kills the Kef, except at high frequencies then the battle is a little closer, which is what I'd expect.

I'd suggest doing the same measurements with the same amp. And not because of the low pass, that's all taken care of in your receiver. Keep that at 200hz if you really want to know the high frequency performance of the Daytons.