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

OB_Newbie · « **Reply #2400 on:** 9 Jun 2015, 02:23 am »

Quote from: captainjack115 on 7 Jun 2015, 02:51 pm

I found this photo of the Goebel crossover. Apparently it's not just for crossing over their bending wave transducer to their woofers. They mention that it's also for linearization of the bending wave driver.
To me that seems to infer equalization.

I can't help but wonder what Oliver Goebel's panel would do connected directly to a flat amplifier. They claim they're bending wave device goes up to 29,500 hz. "Does it" or does it need some help?
Admittedly the fluted corrugated plastic I used is lossy, but high frequency EQ seems to work.

Jack

Would not surprise me in the least bit if some modification of the freq. response was done. We do it with traditional dynamic speakers so why not with a DML panel right?

captainjack115 · « **Reply #2401 on:** 11 Jun 2015, 02:47 pm »

Quote from: OB_Newbie on 9 Jun 2015, 02:23 am

Would not surprise me in the least bit if some modification of the freq. response was done. We do it with traditional dynamic speakers so why not with a DML panel right?

Exactly my thoughts.

I noticed Tectonic uses a tweeter with their DML's, so even the pro's have an issue with high frequencies.

I've really given some thought to make an updated version of my 4 panel DML using high power exciters. Last night I did a quick Photoshop on my previous prototype and took out the feet. My Wife still "hates" the look of it. I guess I'm beating a dead horse.

Jack

captainjack115 · « **Reply #2402 on:** 11 Jun 2015, 06:37 pm »

Apologies if this site has been discussed before.

Has anyone seen the Kraken FP1 before?

Jack

http://www.cie-group.com/shop/audio-visual_1/loudspeakers_5/monitor-speakers_34/pair-superslim-dml-loudspeakers-black-carbon-finish_3639.php

dbishopbliss · « **Reply #2403 on:** 12 Jun 2015, 06:57 pm »

I have been reading through this thread and there are a number of different materials, sizes, dimensions, etc. described. I ordered a pair of DAEX32U-4 to experiment with. The drivers include pre-attached 3M VHB adhesive. I suspect that this adhesive is intended for permanent mounting.

How are people mounting the drivers when experimenting?

captainjack115 · « **Reply #2404 on:** 14 Jun 2015, 04:06 pm »

Quote from: dbishopbliss on 12 Jun 2015, 06:57 pm

I have been reading through this thread and there are a number of different materials, sizes, dimensions, etc. described. I ordered a pair of DAEX32U-4 to experiment with. The drivers include pre-attached 3M VHB adhesive. I suspect that this adhesive is intended for permanent mounting.

How are people mounting the drivers when experimenting?

I think in the beginning of this long thread people were using the Dayton Audio DAEX25. A low power exciter with 4 adhesive pads, 1 for the voice coil and 3 stabilizing feet.
Many of us removed the exciter from the plastic case and free mounted the exciter to to a panel using only the voice coil mount.

As for mounting while experimenting, I'd go with the pre-attached 3M VHB adhesive. You can always get more of it should it use it's stickiness.

May I suggest the Parts Express white paper, if you haven't already read it for starters on panel shapes and exciter mounting positions. For really heavy theory on how DML's operate, you may want
to look at this thesis: http://publications.lib.chalmers.se/records/fulltext/154618.pdf

I don't know how much reading you've done in this thread, but there's a wealth of empirical and working knowledge to be learned from some really dedicated people.

Enjoy!

Jack

Odal3 · « **Reply #2405 on:** 14 Jun 2015, 08:26 pm »

The VHB tape already on them works, and you can take it off with a razorblade if you are careful (but on fragile foam board it can sometimes tear the panel as well...). On wood they come off relatively easy with no damage. I haven't been able to re-use the VHB tape.

For quick experimentation I use a thicker VHB tape I found at the store (home depot in the US), which is easier to take off but at the expense at the HF and it doesn't stick as well. I put it just on top of the already VHB tape on there, but it sometimes a bit tricky to get it to stick.

For permanent mounting I recommend to use some glue. Been experimenting with these for a while now, and never got to the "permanent" mounting stage

, but if I ever do, I will probably use some type of epoxy.

captainjack115 · « **Reply #2406 on:** 15 Jun 2015, 01:14 am »

I'm returning a roll of Gorilla double stick tape I found at the hardware store. Never go shopping without your reading glasses, this stuff is almost 1/16th inches thick.

Jack

dbishopbliss · « **Reply #2407 on:** 16 Jun 2015, 08:13 pm »

I've been making my way through the thread. Lots of info here. I'm still waiting for my exciters since they are on back order. I will go out and buy some different double sided tapes to play with while I'm waiting. See which ones are sticky enough but allow me to still remove the exiter. I'm hoping duct tape will work... just because its duct tape.

captainjack115 · « **Reply #2408 on:** 16 Jun 2015, 08:54 pm »

Quote from: dbishopbliss on 16 Jun 2015, 08:13 pm

I've been making my way through the thread. Lots of info here. I'm still waiting for my exciters since they are on back order. I will go out and buy some different double sided tapes to play with while I'm waiting. See which ones are sticky enough but allow me to still remove the exiter. I'm hoping duct tape will work... just because its duct tape.

Scotch makes a double sided permanent tape available in most stationary departments. It's only 1/2 inch wide, I put 2 strips along side each other for extra width. It seems to hold tight enough for experimenting. There's also a double sided tape called "Terrifically Tacky Tape, I bought some at Michaels hobby store a while back. It's an inch or so in width and really sticky stuff.

Jack

Frank40 · « **Reply #2409 on:** 22 Jun 2015, 10:36 am »

DML at +/- 3mm Xmax no problem, with my own exciter. The camera can no reproduce the low ends.

Link: https://youtu.be/tNpxmHLq8fI

captainjack115 · « **Reply #2410 on:** 22 Jun 2015, 02:07 pm »

Interesting!

What is the panel made of?

Frank40 · « **Reply #2411 on:** 24 Jun 2015, 10:02 am »

I am a sheet of 3mm Depron with fibre glass on both sides.

dbishopbliss · « **Reply #2412 on:** 29 Jun 2015, 02:14 pm »

I received my exciters (DAEX32U-4) on Friday. I placed one on a 24x24x1 piece of untreated XPS from Home Depot. I used the Monacor recommendation for placement of the exciter. Currently, I'm underwhelmed. Its cool that the thing makes noise, but it is far from sounding good. I downloaded Room EQ Wizard (REW) and plan on taking measurements so I can compare it to a full-range speaker I have.

I'm looking at this as the first step in a journey. Next step is to make another XPS panel that has a "better" geometry to see if I can hear the difference and see if there is a difference in REW.

Odal3 · « **Reply #2413 on:** 29 Jun 2015, 02:31 pm »

Nice that you finally got the exciters. Tell us more about your setup and how you ended up attaching the exciter. Keep us updated on your progress.

If you want a more full range sound without equalization you may want to consider a slightly larger board plus treating it as described in previous posts.

Have fun experimenting !

OB_Newbie · « **Reply #2414 on:** 29 Jun 2015, 06:56 pm »

Quote from: dbishopbliss on 29 Jun 2015, 02:14 pm

I received my exciters (DAEX32U-4) on Friday. I placed one on a 24x24x1 piece of untreated XPS from Home Depot. I used the Monacor recommendation for placement of the exciter. Currently, I'm underwhelmed. Its cool that the thing makes noise, but it is far from sounding good. I downloaded Room EQ Wizard (REW) and plan on taking measurements so I can compare it to a full-range speaker I have.

I'm looking at this as the first step in a journey. Next step is to make another XPS panel that has a "better" geometry to see if I can hear the difference and see if there is a difference in REW.

When I first started listening I was pretty underwhelmed too. Given everything that I read i was really excited and expected a lot. I moved mine to a larger room and pulled out and away from walls. Also need to get them off the ground if they are not already.

Also you have to treat the XPS...bare they don't sound very good. They really need the skin removed and replaced with a harder, better sounding skin.

Even with all of this, they sound as though there is a lack of presence when you first start listening. They are more dispersed than a typical cone/dome sound and you will absolutely need to adjust to the presentation of a DML panel. You wont regret it.

But as Odal asked, A little more about your setup (positioning in the room, suspension, etc., etc.) will help us troubleshoot. They are a different beast and the guys here talked me through it for several days until I finally got the enjoyment out of them that I expected!

sedge · « **Reply #2415 on:** 30 Jun 2015, 02:02 pm »

I have sanded the back front and sides of a 5ft 6x2 ft xps panel and have been comparing the sound with a 5mm thick 2ftx2ft6in panel ,I haven't coated the panel yet but thought I'd buy a new panel and compare the coated with the untreated,but when I looked in wicks diy store in the UK the quality of the panel wasn't as good as before (too many holes in the surface)May try b&q to see if theirs is better,if not I'll just coat the panel and hope the difference is pretty obvious.
The things that already stand out with the larger untreated panel is the shear power and dynamics and the highest efficiency of all the panels so fare tested,using my TLs to help drive the room bellow 300hz gives the panel a sound that I can only describe as frightening .
Steve

Odal3 · « **Reply #2416 on:** 30 Jun 2015, 03:23 pm »

Quote from: sedge on 30 Jun 2015, 02:02 pm

...gives the panel a sound that I can only describe as frightening.

Can you clarify the size and the thickneas of the new panel

sedge · « **Reply #2417 on:** 1 Jul 2015, 01:48 am »

ODAL3
Sorry for the confusion,the panel is just one of my old 1inch thick xps sheets ,lately I have got carried away making smaller thinner panels.
I suddenly realized I hadn't made the 1inch thick larger panel with all my mods yet(only partial coatings )so I though I'd better put that right and see what happens.
Years back when I first tried this panel material ,what impressed me most was the amount of output for such little input,finally it allowed me to play loud without melting the coils .
As I have said before, making a large panel sound good is a lot easier than trying to make a small panel sound good.
Steve

Odal3 · « **Reply #2418 on:** 1 Jul 2015, 01:58 am »

Got it!

OB_Newbie · « **Reply #2419 on:** 1 Jul 2015, 02:40 am »

Hmmmm, you have my attention Steve

... frightening... I like it. Never did give the large panels a real good go of it so with time off coming soon just might have to build another set. I didn't treat mine nor did I do any type of suspension; this I'm afraid really hurt their performance (given such a large panel it was much more floppy than my small panels).

Are your large panels just leaning against something or did you suspend them in some way? Curious as you seem to like minimal suspension which I also prefer but given such a large panel they will need something I'm afraid.