Rolls SX21 [24db] crossover question

[rpb]

See page 29 of the mini dsp manual.

[HIFY GUY]

will do
moved the speaker slightly off axis to show this but these are results are what I have been getting
woofers only at 24db

[HIFY GUY]

Ok been skipping past the the first eq. think I'm back on track now.
-6 db sounds better Looks like the simulation is right-on.
It is fun when it works!!

[rpb]

What I'm suggesting is to add an EQ notch, just on the woofers to eliminate the response peak that you show in the factory measurement. You can go beyond eliminating the bump, and pull it down even further. This could be a sharp notch, or a more shallow notch. The thinking is that the woofer does not sound good at the frequency of the peak, so reducing it should make the woofer sound better. There's often a trade-off on how much you might want to reduce it though.

The other thing I'm suggesting is to use the shelf filter. Again, just on the woofers, to level out the baffle step rise. The woofers should then measure more, or less just like my posted passive measurement. A first order low-pass might accomplish the same thing as the shelf filter. As I stated previously, there's a couple hundred ways to do this. Which ever works the easiest for you.

When you measure, try to get setup so that you can gate at 300hz, or lower. I use 300hz all the time, but can get to 250hz, or even 200hz on occasion.

Like this.


I'd still like to see the raw woofer response from the woofers center line.

Here's the raw woofer response before a filter was added. The filter took this response, and turned it into the one above. The added line was drawn to help identify the baffle effect above 300hz.

[HIFY GUY]

Tough to straighten it out in the that range.

[please disregard post 32, that might have been the wrong mic]

[rpb]

Here's a HOLM tip. Zoom in on the impulse similar to mine. Then adjust the gating so that the first reflection doesn't make ripples in the response. Use the mouse, and select the portion from about -10 to +10. Sometimes auto zoom will get pretty close.

[rpb]

I can't tell what you are doing with the dsp. If you start with a completely raw woofer measurement, it probably will look a lot like the one I posted above that has a line drawn on it. You will need the woofers away from the wall, or other things that reflect sound. The measurement needs to be taken on the line directly between the woofers. For the moment, totally ignore the tweeter. The tweeter part should be very simple. The woofer is where the important stuff goes on.

[HIFY GUY]

distance 36", 18" and 2" from the mic

[rpb]

Are you on the tweeter axis, or on line with a point half way between the woofers?

Have you turned off all filtering?

Post #25 (factory response) shows the woofer response drops like a brick above 5k. Post #35 above shows response out to 9k.

[rpb]

Not sure what your schedule is for speakers, and I need to get some chores done. Here's what I would dial into the mini dsp on the woofer. I'd rather see a good measurement first, but odds are good that this is close. First, a shelf filter to correct for baffle step. Next, a low pass filter. Maybe 1.6k. I wouldn't go lower if you don't have to. Third, a notch at 4.5k about 12dB deep. After all that on the woofer, try the filters you've been using on the tweeter or alter until you get a good response. I'll check back this evening. Have fun!

[HIFY GUY]

Filtering is off, removed/bypassed the minidsp completely with a RCA female/female connector.
On axis and right in the center line (height) of the woofers.

I was also a little surprised that the W20's went up that high, but my ears confirmed what I was seeing.
Maybe there is some reinforcement with double woofers.

I've leaned a lot, thank you much for all you've done so far.
Oh my speaker schedule,,, started as a teenager and will never stop.

Are you on the tweeter axis, or on line with a point half way between the woofers?

Have you turned off all filtering?

Post #25 (factory response) shows the woofer response drops like a brick above 5k. Post #35 above shows response out to 9k.

[rpb]

I wouldn't normally suggest 48dB filters, but temporarily, I'd try some on the woofer if for no other reason, to see the measurements.

Maybe cross a little higher, as this high order makes the tweeter work harder. Try 2k maybe.

[rpb]

Just a couple thoughts on your measurements.

With HOLM, you can sweep one, or both speakers. Did you turn off the other speaker? It's hard to tell sometimes.

The picture of your measurement setup shows a column behind the speaker. Even though it's behind the speaker, it will affect how low you must set the gate. There should be nothing within about 4 feet of the speaker, or mic. If you stand directly behind the mic, you will cause a reflection.

Make sure that no other speakers, including the laptop, are playing the sweep. To check, you can unplug the speaker wire, and run a sweep. You shouldn't hear anything.

Zoom in on the impulse to magnify it. You can see how long before the first reflection comes to the mic. In my posted measurement, (post # 34), the first reflection is that dip between 5 and 6. Keep the gate away from that first reflection. When you get close to it, the measurement will start to distort. This is not more accurate, the smoother response is.

Zoom in on the measurement. Crop anything outside of the 80hz to 20k range, and outside the -15dB to -70dB range. You can also stretch the graph vertically by dragging the line between the measured response, and impulse downward. The better you can see what's going on, the more useful you'll find the measurement. It will make your posts easier for other members to interpret as well.

Look at the stand just under the speaker. That flat surface will cause a reflection. Slide the speaker forward till it's mostly flush. Don't let it fall over, it can hurt! Ask me how I know.

[HIFY GUY]

I'm here and been up to no-good (0;

Decided if going to start making eq. adjustments, I might as well remove the wavecor and go back to SB 29's, which I have extras on hand an only one(1) spare wavecor. I made the swap this morning and made sure it is tight with an flush-adapter-insert.

With HOLM, you can sweep one, or both speakers. Did you turn off the other speaker? It's hard to tell sometimes.
Just the one, well one of each now, one Wavecor one SB29, everything else is the same. Using a 22uf cap for tweeter protection.

The picture of your measurement setup shows a column behind the speaker. Even though it's behind the speaker, it will affect how low you must set the gate. There should be nothing within about 4 feet of the speaker, or mic. If you stand directly behind the mic, you will cause a reflection.

I did move to the Den and hung blankets everywhere, plenty of room around the speaker(s)

Make sure that no other speakers, including the laptop, are playing the sweep. To check, you can unplug the speaker wire, and run a sweep. You shouldn't hear anything.

Ok, we're good there.

Zoom in on the impulse to magnify it. You can see how long before the first reflection comes to the mic. In my posted measurement, (post # 34), the first reflection is that dip between 5 and 6. Keep the gate away from that first reflection. When you get close to it, the measurement will start to distort. This is not more accurate, the smoother response is.

I need to catch up on "Impulse", it hasn't worked right in a long time, and all I had to do was click "Reinitialize"

Zoom in on the measurement. Crop anything outside of the 80hz to 20k range, and outside the -15dB to -70dB range. You can also stretch the graph vertically by dragging the line between the measured response, and impulse downward. The better you can see what's going on, the more useful you'll find the measurement. It will make your posts easier for other members to interpret as well.
Will work with that next.
Ok but how to go back? I usually end up closing out and re-opening the program.

Look at the stand just under the speaker. That flat surface will cause a reflection. Slide the speaker forward till it's mostly flush. Don't let it fall over, it can hurt! Ask me how I know.
I did work on the stand after that pic was taken, it has a bigger base (at the floor) and thick towel on top.

Below is this morning results with SB 29 (22uf protection cap) no delay is needed, if fact a very impressive V reverse polarity
The woofer is crossed higher the the tweeter cut:
Woofer 2,900 @24db
Tweeter 2,500 @24db
Sounds ok but need to add the eq in the middle.

[HIFY GUY]

First attempt: