NXT.......rubbish??....THINK AGAIN!

Odal3 · « **Reply #2620 on:** 4 Dec 2015, 10:34 pm »

But I agree, it would be fun to meet up and compare notes.

Btw: when you do measure your panels can you include the KEF as a reference point for room impact.

OB_Newbie · « **Reply #2621 on:** 4 Dec 2015, 11:56 pm »

Quote from: Odal3 on 4 Dec 2015, 10:34 pm

But I agree, it would be fun to meet up and compare notes.

Btw: when you do measure your panels can you include the KEF as a reference point for room impact.

Dang, that would have been smart. I'll have to get more measurements on Sunday when I can measure again. Have to validate my calibration file too as the the high freq. do not seem to match what I have measured with Omnimic.

Posting measurements soon before company arrives...

OB_Newbie · « **Reply #2622 on:** 5 Dec 2015, 12:18 am »

Measurements at 1 Meter with panels pulled out into the room. REW + UMIK-1 from MiniDSP.

This taken with the same power level.
I'm surprised by the sensitivity differences; thought it would be closer:

Changed the power levels so the freq. response levels matches fairly close for comparison purposes. Green = 1/8" Ply | Purple = 1" XPS:
The ply is not as smooth as I thought it would be but is more extended and nearly on par if not smoother in relation to the mid-range.

Distortion plots:
XPS 1M - Smoother distortion plot but slightly higher than the ply.

Ply 1M matching level. A tad lower in dist but larger spikes.

Under construction... will add more measurements and comments.

osssyvan · « **Reply #2623 on:** 5 Dec 2015, 03:36 pm »

OB newbie,

How do you like the umik + minidsp combo. I am one click away off from buying.

Good that you get us some data.

I had dinner with friend who is old colleague of mine. We have both studied material science so and he got excited as well. I am planning of now getting umik and minidsp and go play around with some fun materials. They have different composites etc. so we will test and measure what we get. Through science to ultimate speaker

. I am still planning on checking print store out but that might take a while.

Meanwhile I'll just keep reading on what niceties you are doing next. And making those frames ready. Got some cloth for the grills but I am still long way from ready.

Sorry that I havent had the time for the shaker tests yet.

-ossi

OB_Newbie · « **Reply #2624 on:** 5 Dec 2015, 04:38 pm »

Hello Ossi,
I have not used the MiniDSP 2x4 but do like the UMIK; nice fit and finish and is reasonably priced. While its more of an investment, the Behringer DCX2496 is very flexible and powerful. Think I will like the EQ function of the MiniDSP however. The Parametric EQ of the DCX2496 works well but the MiniDSP EQ will be very nice to make a perfectly smooth target response.

Exciting to hear more about materials. There are many materials to try but cost has played a factor for me thus far and the potential that the panel may not sound any better than the cheaper and more highly available materials. I still hope to order some more exotic materials after I play with a few designs I have in mind. More for fun but I have a Aura Sound shakers that I want to make a large panel sub with and possibly combine with a smaller, higher quality panel. I like the sound of smaller panels and can easily cover 150-200Hz and above.

Science is needed but we need to try more materials and listen with our ear first. The measurements above begin to show some insight to the materials usage but provides absolutely NO indication as to how the material sounds. For me, ears first... science to follow to tweak and get the best of the material chosen.

Will report back on the MiniDSP after this weekend...

Odal3 · « **Reply #2625 on:** 5 Dec 2015, 06:13 pm »

I got the Umik as well. Works really well and I'm happy with it. I bought it from cross-spectrum acoustics to get it fully calibrated. http://cross-spectrum.com/measurement/calibrated_umik.html

I'm not sure if it makes a difference for the type of measurements we do, but it didn't cost too much more.

Every so often I loose the sound-card in REW, but not sure if that's computer, mic or REW related. Easy fix is to just restart.

Odal3 · « **Reply #2626 on:** 5 Dec 2015, 06:25 pm »

OB - looking fwd to your comments and further measurements. 10db drop is what I see for the ply as well. The trusthers seems to start dropping off around 6k in my measurements too, the 30HESF-4 takes it up 3-4000 more.

+/- 5db in the room measurements (which is what really counts) over that large freq band is pretty good imo!

How do I read the distortion measurements? - What should I look for?

OB_Newbie · « **Reply #2627 on:** 8 Dec 2015, 03:13 am »

Here is why the DAEX32Q-4 doesn't sound so good...

This is on 2'x2' XPS vs. Thruster on 24"x30" Ply:

OB_Newbie · « **Reply #2628 on:** 8 Dec 2015, 03:28 am »

Thrust on 24"x30" XPS vs KEFQ500, 1 Meter, same mic position.

Odal3 · « **Reply #2629 on:** 8 Dec 2015, 04:50 am »

Very Interesting! But not sure what conclusions to draw from the KEF comparison- HF drop much sooner and faster as expected and perhaps mitigates the room better in the <200Hz.
What's your take?
Anything else that you could see with less smoothing applied?

OB_Newbie · « **Reply #2630 on:** 8 Dec 2015, 04:56 pm »

If you ignor the floor bounce observed with the KEF, its much smoother and has a pleasant FR curve I would say. Slightly recessed in the mid-range is more enjoyable to listen to for me. It really is a very nice speaker for the money... they do nothing wrong and many, many things really well. KEF has been a leader in driver technology and the Uni-Q drivers are no exception. I personally like full-range speakers and the Uni-Q's have much of the coherency that I like from a high-quality full-range driver with better performance in the upper registers.

But on to the panels, the dropping high frequencies are compensated by the tilted up in room power response. From the graphs I've seen, the power response peeks at 7.8db just shy of 16KHz. I've EQed panels perfectly flat and can verify that the power response is indeed tilted up as the graphs indicate... very thin, bright and strident. I began researching the best way to measure the power response of a speaker but it doesn't appear that there is a common, standard approach. At the same time my measurement system developed a large peak around 60Hz with all measurements so got off track on this. I also didn't know how best to measure DML's with their near Omni-directional radiation pattern. Considering all of this, my interest in measuring the power response died with the measurement system.

Maybe come back to it later but for now I am trusting my ears for tonal balance and have been EQing the panels with that tilted down frequency response so that the FR and Power Response sum to a balanced speaker. Whether this results in a perfectly balanced I can't say for sure at this point. But have to admit, some of the motivation to purchase the KEFs was to serve as a reference so I can compare a pretty well regarded speaker to the panels we are building.

Have not switch back to the KEFs for weeks and weeks now. The panels are more fun to listen to...I just enjoy them more and since purchasing the KEFs I am even more interested in improving these panels. I want to built more elaborate panels in hopes to elevate the performance panels and their appeal to a more mainstream crowd; less panel coloration, better balance with improved response at both extremes.

I really like what I hear today with my simple panels sitting on test stands but even small, steady improvements should help to take them to higher and higher levels.

OB_Newbie · « **Reply #2631 on:** 9 Dec 2015, 11:00 pm »

Quote from: Odal3 on 8 Dec 2015, 04:50 am

Very Interesting! But not sure what conclusions to draw from the KEF comparison- HF drop much sooner and faster as expected and perhaps mitigates the room better in the <200Hz.
What's your take?
Anything else that you could see with less smoothing applied?

Hey Odal! I looked at the responses with less smoothing and nothing else really stood out. To be honest, the panels are measuring better than I imagined overall.

Want to get them outdoors or proper gate these measurement to remove the room but the decay on the panels are so much longer than a normal speaker I'm afraid that it won't give as accurate picture. Reading more tonight on how to measure with REW for a gated response... always something to do and its taking me away from building... itching to finally make a framed panel and covered with grill cloth, etc., etc.... arg!

osssyvan · « **Reply #2632 on:** 10 Dec 2015, 04:33 pm »

Always too much to do! I hope I have the time to finish my frames on Sunday. They are huge and I will definitely not get a chance to keep them

. They were cheap though and fun to build. I listened a bit with my strange new fastening method. I pinned the panel between cardboard lightly and got some nasty hiss. Multimaterial accidental experiment gone awfully wrong! Now the panel is just resting against the bracing behind and on two rubber stoppers meant for doors. Sounds a great deal better now. I kind of miss my ply panels though. They are still at work and have to be fixed for next week's movie night.

I am aching to see what kind of frames you will build.

My next panel might be actually home theater screen. Any suggestions on what materials would double nicely as speaker and screen? I am going to go and buy a projector next weekend hopefully don't have to use the wall for too long. I am not going let the opportunity pass to make a huge speaker out of screen

but it will have to look good.

-Ossi

P.S. I pulled the trigger on minidsp and umik. I want to test OB woofers with panel.

Quote from: OB_Newbie on 9 Dec 2015, 11:00 pm

Hey Odal! I looked at the responses with less smoothing and nothing else really stood out. To be honest, the panels are measuring better than I imagined overall.

Want to get them outdoors or proper gate these measurement to remove the room but the decay on the panels are so much longer than a normal speaker I'm afraid that it won't give as accurate picture. Reading more tonight on how to measure with REQ for a gated response... always something to do and its taking me away from building... itching to finally make a framed panel and covered with grill cloth, etc., etc.... arg!

OB_Newbie · « **Reply #2633 on:** 10 Dec 2015, 06:39 pm »

Quote from: Odal3 on 2 Dec 2015, 02:24 am

So what do you do when you loose them? Only asking so I can try to avoid it, and perhaps we as a group can come up with ways to mod the exciters to be more durable.

I took apart the last failed Ultra last night and this one was different. The leads are not solid copper... it is flexible and completely intact. This one died because the voice coil became unglued to the flange that mounts to the panel. I had another one like this earlier; sounded like something was rattling inside the exciter. That one too must have failed like this and I just assumed it was the broken leads.

This is sad as all the parts and pieces of the exciter are fine... just the adhesive bond failed. Probably a cent worth of adhesive is what is causing this latest failure...

Odal3 · « **Reply #2634 on:** 10 Dec 2015, 06:55 pm »

The ones that failed on me have been due to the leads coming loose. Do you play the full range. I often do and let the panel decide the roll off, but probably shouldnt do that.

guest42212 · « **Reply #2635 on:** 10 Dec 2015, 07:31 pm »

> just the adhesive bond failed

Do you mean simply that the exciter fell off the panel ?

OB_Newbie · « **Reply #2636 on:** 10 Dec 2015, 08:17 pm »

Quote from: hitsware on 10 Dec 2015, 07:31 pm

> just the adhesive bond failed

Do you mean simply that the exciter fell off the panel ?

Well I've had that happen too but that is my fault.

The voice coil became unglued to the flange that mounts to the panel. Impossible to fix on the Ultra as the motor and VC are encased in the plastic case.

OB_Newbie · « **Reply #2637 on:** 10 Dec 2015, 08:24 pm »

Quote from: Odal3 on 10 Dec 2015, 06:55 pm

The ones that failed on me have been due to the leads coming loose. Do you play the full range. I often do and let the panel decide the roll off, but probably shouldnt do that.

I play both full-range and crossed to a sub from 100-150Hz.

But this failure makes sense as I was playing them at a very low level. I'm sure the glue had been giving way at some spot on the exciter and once it starts, its probably only a matter of time until the entire flange becomes unattached to the voice coil. It just happened to be at a strange time.

I was happy with the leads on this failed exciter though... it was flexible and long enough so that the excursions of the plastic exciter didn't pull it to a point of breaking. Once they get this currently problem fixed hopefully we will have durable exciters as we would expect.

OB_Newbie · « **Reply #2638 on:** 10 Dec 2015, 08:50 pm »

For anyone who has had an exciter die... can you verify the cause?

Broken tinsel lead?

Rattling of the voice coil in the gap? (adhesive between the voice coil and mounting flange failed)

or ???

I emailed Parts Express and let them know about this latest failure and want to provide more input. If we can get this problem fixed, we will have some durable exciters as should be expected.

Thanks guys!

Odal3 · « **Reply #2639 on:** 15 Dec 2015, 06:23 am »

Broken lead is what I have seen if I don't count the Ultras that bottomed out. The other thing to point out is that the mounting flange of the heavier 40w exciters are really slippery and glue or VHB tape doesn't stick as well. This is dispite rough sanding the flange. I have had several fall off. On the other hand, my 5W exciter has a much better flange surface that things stick to much better.

NXT.......rubbish??....THINK AGAIN!

guest42212