DIY Flat Panel Speaker Love

[Kornbread]

Re: DIY Flat Panel Speaker Love

This is interesting as you have broken all the "rules" :-) ie, hard mounted the panel into a frame, used non NXT panel dimensions etc. Your reports sound like it is working well. One question... how did you decide the location you attached the exciter to the panel?

Kind of what I was thinking, but you know, don't think I ever braced the exciter and took measurements with a solid panel, it was the other way around, first loosened the panel from the frame then braced the exciter.

Waaaay off topic ... anyone have advice on a building a Tesla coil?

[Fshow]

Re: DIY Flat Panel Speaker Love

This is interesting as you have broken all the "rules" :-) ie, hard mounted the panel into a frame, used non NXT panel dimensions etc. Your reports sound like it is working well. One question... how did you decide the location you attached the exciter to the panel?

Hi Gary

I didn't break quit all the rules, bent yes..

-Spline..... The Podium, Tectonics and others I have seen on the web use a spine.

-Outer frame and suspension...... The Podium, Gobel and others I have seen use a frame and some kind of suspension. I also believe in using a suspension, its just that on my earlier prototypes I started out with a compliant suspension, which didn't work, so I tried many other things until the suspension was very stiff. On these panels I just started with fixed panels thinking I could weaken it up if necessary. So far it's working as is but I may try something else.

-exciter placement..... I think I used the golden ratio, which is nearly identical recommended 3/5 rule.

-panel size....... My first panels followed the rule, but on these panels I copied Rich's panels, also I could get 2 panels from one 4x8 sheet of XPS. Besides they look like Magnapans. If I were to do it over, I would made them closer to the rule.

The panels are working well, but they are in no way perfect, they are just another step on the road

Fred

Http://ep.yimg.com/ay/yhst-95622685483394/vantage-hearth-premium-series-smooth-face-b-vent-gas-fireplace-with-refractory-fiber-logs-and-electronic-ignition-36-inch-36.jpg

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hi Gary

I didn't break quit all the rules, bent yes..

-Spline..... The Podium, Tectonics and others I have seen on the web use a spine.

-Outer frame and suspension...... The Podium, Gobel and others I have seen use a frame and some kind of suspension. I also believe in using a suspension, its just that on my earlier prototypes I started out with a compliant suspension, which didn't work, so I tried many other things until the suspension was very stiff. On these panels I just started with fixed panels thinking I could weaken it up if necessary. So far it's working as is but I may try something else.

-exciter placement..... I think I used the golden ratio, which is nearly identical recommended 3/5 rule.

-panel size....... My first panels followed the rule, but on these panels I copied Rich's panels, also I could get 2 panels from one 4x8 sheet of XPS. Besides they look like Magnapans. If I were to do it over, I would made them closer to the rule.

The panels are working well, but they are in no way perfect, they are just another step on the road

Fred


Http://ep.yimg.com/ay/yhst-956226854...36-inch-36.jpg

I don't know if there are really any "rules" here... maybe more so best practices or guidelines.

The Podiums have very light suspension and a rigid spline with exciters in a single vertical row(not optimal in my opinion). Then uses passive crossovers to high-pass specific exciters to reduce the effects of high frequency cancellation on the panel. The light and rigid honeycomb panel *should* require a fair amount of damping to prevent it from ringing. However the designer personally thought a DML panel should "ring like a bell". He also stated that he created a panel with a larger number of sound bridges which required no crossovers and measured flat. Great huh?!? Well, it didn't sound good so he chose to release the Podiums with light suspension and movable bridges. Design choices and listening preferences.

TAL and their Tectonic Plates are different beasts as well. They required high power handling and sensitivity so a larger number of exciters per panel. Instead of dealing with the HF cancellation of an all DML panel, they choose to cross their panels over at approx. 6Khz to a high sensitivity AMT. Their requirements are different than ours as the plates need to operate at high SPL's... likely many entirely different design choices were made to meet their product parameters.

I enjoy the fact that we all can build a panel that sounds good to our ears, in our room with the equipment that we have each assembled.

There is a lot of potential in these panels... and I've been having a blast getting the most from them!!

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hey UBS,
I will be taking a few hints from the Bertagni speakers myself. I've always wanted to build a DML panel array so I am building a panel from a single piece of XPS then routing adjoining grooves (front and back with Core Box bit) to divide the panels into 2 (not matching) parts.

Will likely use different exciters and positioning on the panels to smooth the summed freq. response. Smaller exciters have better high freq. extension due to their smaller voice coils. So I am also considering a smaller 3rd panel integrated into the single large/divided panel to house a small exciter covering the last octave or octave and a half. Probably crossed passively similar to what Katz did with his panels... but we shall see how the panel sounds.

All lightly suspended of course. I ran distortion tests Friday night into the wee hours of Friday night(very early morning actually ) and light to no suspension provided slightly lower fundamental and second order distortion measurements and significantly lower 3rd/4th order (almost 10dB improvement) compared to my normal panel damping. Don't quote me on these results... this was directional validation more so then a scientific study of precision. Well placed suspension might change this but will use listening and distortion tests to guide the placement and quantity of damping needed using my "less suspension is best" approach. Note, smaller panels need less suspension and damping. My 2'x4' had drum resonances and needed more damping than my normal 24"x30" panels.

This is where I'm heading on my next build... fun stuff and looking forward to the holidays for multiple reasons!!



Play on fellas!

[rmeinke]

Re: DIY Flat Panel Speaker Love

Can you clarify the two legs supporting the panel in the middle? Do I understand you have nothing touching anywhere on the panel edges?

Fred, if your wood frames are not functioning as standards, have you considered using balsa to provide more stiffness to the panels? I am strongly considering this myself as it firmed up my early ply panels. I also found that even rounding the corners and edges reduced high frequency output by about 2dB from 8-9KHz on up. The 2x2 panels without rounding is notably stiffer... a few lightweight balsa strips will add very little to the weight but should stiffen the XPS significantly.

Hope that this also reduces the underlying "vibrational" tone I get with XPS. Planning to add balsa strips an inch or so off of each panel edge.

[Fshow]

Re: DIY Flat Panel Speaker Love

Fred, if your wood frames are not functioning as standards, have you considered using balsa to provide more stiffness to the panels? I am strongly considering this myself as it firmed up my early ply panels. I also found that even rounding the corners and edges reduced high frequency output by about 2dB from 8-9KHz on up. The 2x2 panels without rounding is notably stiffer... a few lightweight balsa strips will add very little to the weight but should stiffen the XPS significantly.

Hope that this also reduces the underlying "vibrational" tone I get with XPS. Planning to add balsa strips an inch or so off of each panel edge.

Hi Rich

I am not sure I understand "standard", but the problem I had, was around 50 and 100 hz there was a dip in response. As you know those exciters are extremely powerful and they can excite the frame at certain frequencies.I noticed if I picked up the panel holding the frame in the middle this dip in response was reduced, the panel itself seems to be stiff enough.. So I just added support legs on the side to keep the panels of off the floor.
I did build some large poster board panels and they were too floppy so I added 1/8 inch struts on the panel like the inside of a classical guitar. I found that they seemed to work fine helping both the bass and treble., with no ill effects.

When I applied the PVA I did stop one inch short from the outer edge, supposedly to add some damping from reflected waves. I have no idea if this did any thing.

I don't hear any panel noise,

Fred

[rmeinke]

Re: DIY Flat Panel Speaker Love

Sorry Fred... auto correct in action here. It should be... "if your wood frames are not functioning as stands..."

I understand how you have the panel and feet arranged now... strike my comments above... makes sense to me know. Was following Gary's line of thought and didn't consider your previously posted pics and how the feet might be arranged.

Odal over at AC reported the same improvement with his ply panel by getting them off the ground.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Finally got time last night to get back to the panels. Did some REW measurements of the 24x30 XPS panels using the Dayton Thruster. The measurements posted a few pages back were NOT accurate due to lost settings (went back to defaults for soundcard and mic) which, it seems, seems to happen way to often. In any event, below are the XPS|Thruster measurements. Raw and un EQed as well as EQed and high-passed at approx. 100Hz to be integrated with the inexpensive Dayton 8" sub that I've been using with the panels.

[Gary.M]

Re: DIY Flat Panel Speaker Love

That looks really good. I have several panels cut in double layer corrugated cardboard, and also 3mm bamboo ply. Size is 380 x 530mm approx (15" x 21"). Will be mounting in a frame once surface treatment is completed. I'm looking for a panel good from 200-300Hz to 20kHz to pair with an H-Frame woofer.

[rmeinke]

Re: DIY Flat Panel Speaker Love

A quick re-post from AC...

I should be building today but after 5 hours of shoveling and snowblowing mine and other's driveways in the neighborhood I've decided to take it easy and listen to the panels this afternoon and evening. Now another admittance :o After hooking up the CD player and listening to them with music I noticed that they sounded bass heavy... ummmm... the loudness button on my Luxman integrated was on. Soooooooo... once again the measurements are not accurate.

Can't tell listening to sweeps or after being EQed and crossed but when I went to listen full range I was impressed by the bass output. Silly boy. Anyway, had to share... what a day!!

I also got out the KEF's after a long hiatus and am listening to them now. It is easy to forget certain performance aspects, tonal balances or coloration of a speaker until you inset a new speaker into the system. I was disappointed by the panels performance when switching from the KEFs and was anticipating that again and be reminded of their neutrality and overall excellent balance and performance. Strangely, this was not the case. I was taken back by the boxy resonances and lack of detail and general clarity and detail of the panels. I asked my wife what she thought and she said the same thing... not as clean as the panels; "vocals are not as clear". These were the aspects that I enjoyed most when I first put the paneling in place. The lack of a box has great value to speaker performance. Beyond that, initially coming from an resonance free Open Baffle system, even compared to them (which uses the highly regarded Tang Band W4-1879 4" full range driver) the DML panels have greater clarity and detail. Despite the XPS panel coloration's and other tonal considerations these panels absolutely hold a position in the listening room.

After a few hours of listening, I am really enjoying the Q500s. A really nice sounding speaker with the coherence of a high quality full range speaker (which I favor)... impressed by what KEF has been doing recently. But I am beginning to fight switching back to the panels for a quick hit of panel magic. :D Still feeling love for these flat panels!!!

[rmeinke]

Re: DIY Flat Panel Speaker Love

That looks really good. I have several panels cut in double layer corrugated cardboard, and also 3mm bamboo ply. Size is 380 x 530mm approx (15" x 21"). Will be mounting in a frame once surface treatment is completed. I'm looking for a panel good from 200-300Hz to 20kHz to pair with an H-Frame woofer.

Hey Gary! I think you will like the ply if it performs like birch. My cheap cardboard panels measures very smooth but not liking the sound quality and, weird, they are not as transparent (no disappearing act here) as either ply or XPS. Over damped I would say... strange considering they measure well.

You have a great plan Gary. These panels sound great with OB bass bins. I'm going to be putting a set of dual (12's or 15's) OB bass panels together after my next project. After listening to the KEF's, I'm thinking I *need* dedicated OB bass bins for my panels.

I like 1/6 smoothing for measuring DML's... little easier to see the overall balance:

[Kornbread]

Re: DIY Flat Panel Speaker Love

rmeinke, don't recall ever seeing what you drive your panels with, and what model kef's? I've used the 15w PE lepai168ha, that sounded awful, and a carver 705x, which sounded much better driving the panels; lost exciters on both amps.


My $.02 on the panels so far, there kind of a give and take thing, they do something right but there is also something that bothers me ...

Awaiting response from PE which will determine if my experiment with these panels continues ... or not.

[rmeinke]

Re: DIY Flat Panel Speaker Love

rmeinke, don't recall ever seeing what you drive your panels with, and what model kef's? I've used the 15w PE lepai168ha, that sounded awful, and a carver 705x, which sounded much better driving the panels; lost exciters on both amps.


My $.02 on the panels so far, there kind of a give and take thing, they do something right but there is also something that bothers me ...

Awaiting response from PE which will determine if my experiment with these panels continues ... or not.

Hey KB! Right now I'm driving them with a vintage Luxman LU-105U which is *much* better than I anticipated. Before that a modded class D amp (Sure based TPA3122D2 board) was my previous fav and only just recently knocked aside by the Luxman. Have a number of amps that can come into the rotation... vintage Sansui, Sony, Sumo, NAD to name a few... I like buying and trying vintage gear. Have a pair of SMSL SA-36A Pro's on their way as well after the glowing reports from Rory on PETT. The modded TPA3122D2 bested everything I have had around the house the last year+ so have been interested in class D amp boards.

The KEF's I have are the Q500. After reading favorable reviews and researching KEF's Dual Concentric drivers I was curious. Always favored mini monitors for clarity, detail and imaging but, more recently, totally diggin' full-range speakers in OB. So this particular model naturally appealed to me... so I took the plunge.

You are not to far off on the panels. I was a bit horrified switching from the KEF's back to the panels, but after adjusting to the short comings of XPS (coloration's and some tonal issues), I still really enjoy listening to them... they don't sound like speakers... more like music. The near omni directional radiation pattern + clarity and detail are pretty unique. If you can forgive them for their shortcomings they are fun to listen too.

After reading your posts, I felt that you reacted to the panels the way I did initially. It wasn't all good. Personally, I think your panels are too big. Everyone at AC was building large panels but I found them to have more resonances than I could enjoy. Smaller panels are more rigid and sound cleaner with less of the annoying resonances. I'm afraid your large but very lightly suspended panels will have more resonances than what a good DML panel should have. Second, while DML bass shares some qualities with a traditional open baffle speaker, the quality is NOT the same IMHO. Given your Calipers and Amazings... you will probably find DML's and OB bass panel combo the most to your liking. Finally, I think EQ is best for these panels... DML's are not the smoothest drivers right? Based on random, vibrating nodes to generate sound pressure, they are not going to be perfectly smooth. EQ is a very good addition for the best performing panels.

One last point... think you might like birch ply better than XPS. I've been enjoying birch panels and have been going back and forth as to what I prefer but think, by and large, that more will probably prefer ply over XPS.

Anyway, hope PE gets things right for you either way!

[Kornbread]

Re: DIY Flat Panel Speaker Love

My intentions were to have a crossover-less full range speaker and get some measurements out there, so the experiment started with larger panels. They could eventually become whittled down to something nearer your panels proportions or they could go the way of typical cones and domes; crossovers with different type exciters/size panels for specific purposes.

Why is it every visit to a home improvement store involves searching for likely panel candidates???

Awaiting on PE, depending on what they decide the experiment may be going a totally different direction with the exciters and material ... or not at all.

Had this, 'Sure Electronics AA-AB32971 2x100W Class D Audio Amplifier Board (T-Amp Technology)' and 'Sure Electronics PS-SP11184 24 VDC 8.8A 200W Regulated Switching Power Supply' in the cart but dropped them in favour of a low $ project with some of their buyout 6½ drivers, Dayton 12" classic and some old Audax tweeters that weren't getting used.

First time hearing KEF's was in 1995 with Jolida tube amps. IMO, they were the kind of speaker that when you became burnt out of trying to listen to other speakers/systems/whatever you could grab a refreshing beverage, put on a stack of cd's, sit back and relax. Different end of the spectrum than what I've heard from these panels ... so far. ;)

[rmeinke]

Re: DIY Flat Panel Speaker Love

LOL... yeah, I can't go into a home improvement store either without looking for material to stick exciters to... i get that... :(

KEF has always built very well engineered and balanced speakers... consistent and solid engineering. I hadn't heard a KEF since the late 80's and think your assessment is spot on from that general era. Nice, well done, but I never would have purchased a set myself. I always favored small, more detailed speakers. These aluminium coned coaxial's are both detailed yet very balanced. Detailed but not etched in anyway... just very well done in my opinion... KEF has engineered some excellent drivers. Have considered dropping these coaxial in an open baffle. Used to be able to get them for under $120 just a few years ago but now $175 each (if you are a KEF owner) so won't be doing that any time soon.


Have been playing all kinds of music on CD and Spotify all afternoon and evening and can say that the panels really expose poor recordings. Bad recordings sound bad, good recordings sound very good. They are revealing of source and equipment I would say. They also seem to benefit from a good warm up... at least the Thruster with it's steel spider!?!? Not as much with the Ultra. I'm surprised that others haven't report that. That said... once warmed up...I can and do listen to these for hours and hours without fatigue.

What levels are you listening at and what music do you tend to listen too??

We need to get your panels performing correctly KB. I'm afraid you have some resonances that need to be dealt with. Even without EQ I was able to get my panels sounding pretty decent though they do benefit from EQ and support below 100Hz... you can EQ the low freq. to get a full-range panel but adding a sub and removing the lowest bass does help clean them up. OB bass bins are excellent with these panels but even the inexpensive 8" Dayton sub performs surprisingly well if listening at moderate volumes. I may have said this before... but it performs as well as the KEF's with very similar extension, output and quality. This still surprises me.

Happy New Year to all!!!