Some Modula Series driver testing...

[JonMarsh]

Nothing goes as quick as I'd like even on long weekends like this.

Some progress has been made in some driver testing/evaluations with regards to planned Modula series builds.

I did get the Millenium Excel tweeter mated with an H-65 waveguide- results weren't bad, but they weren't everything I'd hoped for, compared with the results using the Scanspeak D2608/9130.

First, here's a series of curves taken at 5 degree intervals from 0 degrees to 45 degrees




A little confusing, but one which is clear is that there's something going on with the behavior at about 12 kHz causing a dip and deviation from pattern control.

Trying to make a little more sense out of this, I plotted some different regions- first, the curves in the 0 to 30 degree range:




I also plotted three curves in the 25 to 40 range:




Note quite my predetermined idea of perfection, but look at what the Accuton C13N looked like in a H-65 waveguide:




Makes the Millenium Excel results look rather splendid in comparison, huh?

Well, I think I'm going to go ahead for now and try working with the Excel, beef up a couple of waveguides, and get a new test panel ready.

[JonMarsh]

Re distortion in the waveguide

I did do a basic distortion analysis on a sweep, with some interesting but not surprising results- the distortion is lowered in the 2-5 kHz area compared with direct operation, by nearly 10 dB.



As this would be right at the lower crossover point in the Modula Xtreme application, can't hurt, can it?

These were measured at 2.83 VRMS drive, about 90 dB output

[JonMarsh]

C173-T6-90 in test cabinet

Just to see what we have to work with if the 0.5 cu ft enclosure is used- same enclosure used for the Excel WG testing, and the WG is mounted. A series of curves from 0 to 45 degrees

Not much filtering on this measurement and floor bounce and other room effects are visible, as well as the limitations in dispersion from a 4-1/2" diameter cone!



Updated to include pic of test cabinet

[JonMarsh]

More testing in progress...

It's all very well to model interesting ideas, but the proof is in the measurements.

More testing underway, and it's looking pretty interesting. Will also have that sample Z curve for the 26W/12867 poster soon.



This is a 1 cu ft PE sub enclosure, in case anyone is curious. Nice cute little size. One might almost say "petite". Not the thing folks that like rubenesque bass might be looking for, but with good potential for a relatively compact high output system. NOT a sub, but with two for the woofer part on each side.

[Paul W]

That 10-11k dip near axis, disappearing off-axis, looks suspiciously like the on-axis dip in both my large WGs and Earl's Summa WGs...except yours is higher in frequency and extends further off-axis. Notch depth is about the same. Higher frequency makes sense since yours is much smaller, broad off-axis, dunno. Earl says it is a resonance across the mouth caused, ironically, by an accurate implementation of an axi-symmetric WG.

He suggested two solutions, one is an asymmetric HxV profile, the other is modifying the mouth profile to break up the on-axis symmetry. I haven't gotten to it yet, but was going to try some felt pads on two opposite quarters of the WG mouth...got felt?

[JonMarsh]

Yes- have felt and a few ideas, as well- figure I'll just proceed with upgrading the waveguide construction, make new baffles for the final set, and then experiment after I get that configuration together. A lot else seems to be falling into place, so I'm going to keep heading down this path for now.

[Bear]

That Accuton + Waveguide looks tight in that cabinet. Wow. That being said, isn't ~14L a little big for the '90?

[JonMarsh]

Think Midrange IB... :W It has to provide useful output down to about 100 Hz. Then, there's also crossover parts.

[JonMarsh]

Relevant measurements - nearfield 26W with FCA

Measurements with varied FCA



Blue line with ~400 uF meets target expectations. Black is raw box curve.

Same configuration will be tested with RS270.

[JonMarsh]

NE180W Private Investigations...

The new Vifa's have a number of people intrigued... especially when they're called full range drivers. Not that I see it likely this crowd would use them that way....





First, a 6" nearfield plot which is the quickest thing to do that will resemble an infinite baffle measurement in an open area or dead chamber; gate is 200 msec. -10 dB corresponds to 90 dB at 1 meter.




This is a sealed box test, no port.

Next, distortion under the same measurement conditions- actually, the same data. Due to being a 4 ohm driver, the output level is about 3 dB higher than the typical 7" 8 Ohm midwoofer, so keep that in mind if comparing to other measurements, which may be at lower output levels with the same 2.83 VRMS drive.





Isn't that nice performance from 300 Hz to 10 kHz? You don't see that every day in any kind of cone midrange, much less a 7" midwoofer. Far too often we see rising distortion above 800-1,000 Hz.

Last up, some curves on and off axis, 0 deg, 10 deg, 20 deg, 30 degrees, 45 degrees. This is on a 9" wide baffle cabinet, and of course, room effects are not avoidable.

Nice behavior up to 2500 Hz, about as high as you can expect for a 7" frame driver, I'd say. Certainly looks like it's workable with a 2-2.2 kHz crossover point.

[Mark K]

NE180W Private Investigations...

The new Vifa's have a number of people intrigued... especially when they're called full range drivers. Not that I see it likely this crowd would use them that way....





First, a 6" nearfield plot which is the quickest thing to do that will resemble an infinite baffle measurement in an open area or dead chamber; gate is 200 msec. -10 dB corresponds to 90 dB at 1 meter.




This is a sealed box test, no port.

Next, distortion under the same measurement conditions- actually, the same data. Due to being a 4 ohm driver, the output level is about 3 dB higher than the typical 7" 8 Ohm midwoofer, so keep that in mind if comparing to other measurements, which may be at lower output levels with the same 2.83 VRMS drive.





Isn't that nice performance from 300 Hz to 10 kHz? You don't see that every day in any kind of cone midrange, much less a 7" midwoofer. Far too often we see rising distortion above 800-1,000 Hz.

Last up, some curves on and off axis, 0 deg, 10 deg, 20 deg, 30 degrees, 45 degrees. This is on a 9" wide baffle cabinet, and of course, room effects are not avoidable.

Nice behavior up to 2500 Hz, about as high as you can expect for a 7" frame driver, I'd say. Certainly looks like it's workable with a 2-2.2 kHz crossover point.

Wow! that does look very nice. I'll have to put it on the "I want one to test" list...

[jkrutke]

Wow, exactly the same results I got with a preliminary set I tested 8 months ago. I never wanted to post the results because I couldn't say if they would be at all similar to the production versions, but since they are obviously the same, here's some consistency data for all. I'd call it a good (but not great) cone and soft part design, with a class leading motor. Reminds me of an XG18 but improved.






I noticed they lost the heat sink fins. To bad, they were sexy. But if that's all they were, no real loss I suppose.

[Mark K]

Oh wow, that's nice. I wonder about the 8".

Anyone have/test the FR on the 8?

[JonMarsh]

Reminds me of an XG18 but improved.

Exactly my thoughts after the first test- still have a pair of the XG18 around.

[Hdale85]

I have to agree, that C90 with the waveguide looks like an interesting compact speaker!

[JonMarsh]

More follow up on the NE180W

Took the impedance curves later yesterday- no surprises there, considering the published data.




From evaluations of this driver, the RS270, and of course the existing work I've done with the D2608-9130, I'd say the Modula Xtreme SO is also a go for a build/test. It should be able to give the "prime" version a good run for the money, regardless of Scanspeak and Accuton street cred and performance.

[JonMarsh]

That 10-11k dip near axis, disappearing off-axis, looks suspiciously like the on-axis dip in both my large WGs and Earl's Summa WGs...except yours is higher in frequency and extends further off-axis. Notch depth is about the same. Higher frequency makes sense since yours is much smaller, broad off-axis, dunno. Earl says it is a resonance across the mouth caused, ironically, by an accurate implementation of an axi-symmetric WG.

He suggested two solutions, one is an asymmetric HxV profile, the other is modifying the mouth profile to break up the on-axis symmetry. I haven't gotten to it yet, but was going to try some felt pads on two opposite quarters of the WG mouth...got felt?

Thanks again for the comments, Paul- second time reading it made mores sense! :T Fiddling with this is going to be an evening project this week...

[Beau]

Has anyone thought about "Golfballing " the surface of the wave guide like B&W did with their ports a few years back?