DIY Flat Panel Speaker Love

[rmeinke]

Re: DIY Flat Panel Speaker Love

In my head I see the suspension for my project being something with mild elasticity, something akin to a rubber surround on all sides.

Duct tape does tend to buckle at random points here and there and is far from an ideal material, this I freely admit. It is a step up from having the panels laying about, anything they touch in a casual way causes buzzing.
It's really quite remarkable the way the panels build up excursion as excitation travels to the edge, kind of like shaking a rope and seeing how much it;s moved at the other end. I can truly understand how a large panel surface can produce considerable low frequency output. I think Oliver Gobel had good reason to use just one panel for all of his speaker models. We're all curious about how his panels are made, but for me more so about how he suspends the panels.

Jack (AKA Capn' Duct Tape)

Each manufacture has different design requirements and the construction and materials have much impact on the end product. Podium goes for a full range product from a single large DML panel. Tectonic uses DML for bass to mid treble supplementing with a Heil AMT unit for 6KHz on up. Gobel flips it around and has conventional boxed speakers for bass and uses a smallish DML panel for mid/upper bass on up.

None are strictly better than the other and instead design choices to meet specific requirements and of course put one's own "finger prints" and philosophy in an effort to develop what they feel is the best product for the given set of requirements.

Without actual experience with the materials that Gobel use, it's not completely clear or easy to extract learning. I assume that the panel material in not well damped and will need much more termination and suspension to make the panel behave and perform as desired and not ring. On the other hand a XPS panel is well damped on its own (possibly over damped) and requires less suspension/termination.

Since I've been mainly working with XPS, I am still looking for ways to not over-damp the panel with suspension but still prevent the panel flexing that leads to the large excursions and the resulting peaks and dips at low frequencies. A "fully rolled" suspension gave the smoothest response and what I believe I want to accomplish for my panels... it is not clear what constitutes a "fully rolled" suspension but I have some ideas around this as to what my interpretation is (right or wrong) but need time to experiment. Seems to be the theme of my life since the snow has melted in Wisconsin. :-)

[captainjack115]

Re: DIY Flat Panel Speaker Love

Each manufacture has different design requirements and the construction and materials have much impact on the end product. Podium goes for a full range product from a single large DML panel. Tectonic uses DML for bass to mid treble supplementing with a Heil AMT unit for 6KHz on up. Gobel flips it around and has conventional boxed speakers for bass and uses a smallish DML panel for mid/upper bass on up.

None are strictly better than the other and instead design choices to meet specific requirements and of course put one's own "finger prints" and philosophy in an effort to develop what they feel is the best product for the given set of requirements.

Without actual experience with the materials that Gobel use, it's not completely clear or easy to extract learning. I assume that the panel material in not well damped and will need much more termination and suspension to make the panel behave and perform as desired and not ring. On the other hand a XPS panel is well damped on its own (possibly over damped) and requires less suspension/termination.

Since I've been mainly working with XPS, I am still looking for ways to not over-damp the panel with suspension but still prevent the panel flexing that leads to the large excursions and the resulting peaks and dips at low frequencies. A "fully rolled" suspension gave the smoothest response and what I believe I want to accomplish for my panels... it is not clear what constitutes a "fully rolled" suspension but I have some ideas around this as to what my interpretation is (right or wrong) but need time to experiment. Seems to be the theme of my life since the snow has melted in Wisconsin. :-)

I'm assuming you've been using Owens Corning XPS, is it 150 or 250? I have no experience with this product. It may be worth my time to experiment with this product, as I have resonance issues with the corrugated plastic. My panels do have a 530hz ring that I notch out with EQ.

I probably mentioned before that I seem to have better results with the "Thrusters" over the "Ultras", this could be that the Thrusters are a better match with corrugated plastic. The Ultras seem to have more self noise. Since you too have experimented with both exciters, I can only conclude that the Ultras are a better fit with XPS. It seems worth looking into on my part rather than limiting myself to one material, just because I have cut panels sitting in the garage.

BTW, The 4th generation ipod touch was retuned to Apple, I wound up with a new 5th generation because ios 8.4 had more apps. Very handy to use, but I want to look for a decent external microphone.

Jack

[rmeinke]

Re: DIY Flat Panel Speaker Love

Yo Capn'!

I am using the Owen 150 XPS. My HD didn't have the 250 when I purchased my panel material. I spotted a blue 250 Lowe's house brand that I intend to use next so will be making a Lowe's purchase soon.

On XPD the Ultra's were quieter and more detailed. The floating motor on the Ultra's result in less noise due to being more compliant. On ply that is not the case and might also be the case not so much with just the correlated plastic but also the tight suspension. I would imagine that the Thrusters would work better in that situation.

Yeah, working with XPS is really easy... specially if you have a HD close by... they cut it for you which is really helpful. I would absolutely give it a try; believe XPS will have better resolution, dynamics and high frequency response that the plastic. Assuming its the corrugated plastic sheeting I've had my hands on... to me it was a little over damped. I don't remember, did you post a FR plot? I imagine that the correlated plastic might be even more damped that the XPS and probably has a bit of roll-off on the last octave?

Cool on the new Touch. I use the Dayton Audio mic along with the Audio Tools app. I also have a 1/12 octave RTA ($4.99) which is pretty darn good resolution all things considered.

Rich

[buke9]

Re: DIY Flat Panel Speaker Love

Just got the VHB tape today the foam should be here before the weekend and bought another set of Ultra's to try on smaller panels next (my replacement Thruster is still on back order ). Still have enough XPS for two more sets of panels. We just picked up some foam at work for fixing a seat in one of our trucks and I'm thinking of trying that also. Should the foam run the length of the sides or can I put it in several spots along the edge? The blue XPS from Lowes is what I'm using now but the extrusion process they use leaves lots of pitting and slots that need lots of sanding. They didn't carry Owens is that any smoother? Frame prototype will be made this weekend .

[buke9]

Re: DIY Flat Panel Speaker Love

Forgot in the last post. As I am new to this what kind of equipment is needed for measuring the panels and speakers for that matter as I am thinking of building a center speaker for the HT ? I'm sure that the mic's I have won't work for this. I do have a mic that came with my HT receiver I don't know if that will work or do I need something better. I can't spend a lot right now so give me budget options please.

[captainjack115]

Re: DIY Flat Panel Speaker Love

Yo Capn'!

I am using the Owen 150 XPS. My HD didn't have the 250 when I purchased my panel material. I spotted a blue 250 Lowe's house brand that I intend to use next so will be making a Lowe's purchase soon.


Rich

I wish there was an H.D. near me, the closest one is in Indianapolis, 80 miles west. I do have Menards up the street, if they’ll cut some XPS for me I may be able to keep the pieces in our cramped garage.

I posted an FR plot back on page 16 of my results from a 12x12 piece of corrugated plastic. Even with notching out the 530hz peak my ears are telling me something is not as smooth as it could be.
I put in some listening time and try to evaluate, then try later in the day or next day as my ears get used to what I'm hearing.

BTW, Do you use balanced XLR interconnects throughout your system for your EQ? I noticed from photos there doesn't seem to be any RCA type inputs or outputs. Any hum problems?

Jack

[rmeinke]

Re: DIY Flat Panel Speaker Love

Hey buke, For the foam suspension, I personally would recommend as little suspension as possible. XPS is fairly is not overly damped by itself (hit it with a knuckle as a test) so me personally don't think it needs any special termination or additional suspension. Closer to the corners should help prevent panels from flexing if even a little. I listen to nearly freely suspended and can see visible excursions when there are heavy bass frequencies at the panels peak resonance... especially for larger panels. Small panels are generally fine given the rigidity of a smaller panel.

I'm going to use what I can find. The best foam would be the closed foam used for kids' swimming noodles... still looking for a product that is flat and wont require so much cutting to work. I have my eye on the magic eraser foam pads for cleaning. Should be closed, dense and strong.

Yeah, I also noticed the deep impressions in the Lowe's blue XPS. I would have taken one home that day had it not been for that. If i can't find the OC 250 I'm still intending to purchase the most dense panel material I can find. My next set will be behind grill cloth so as long as I removed the bad sounding XPS skin I wont mind any impressions that remain.

[rmeinke]

Re: DIY Flat Panel Speaker Love

As above, I started with Audio Tools, a 12 octave RTA ($4.99) and the Dayton Audio iMM-6 Calibrated Measurement Microphone for iPhone iPad Tablet and Android. It is pretty darn accurate in comparing it response vs. my OmniMic. Its handy for quick tests when you don't feel like breaking out the OmniMic and stand.

[buke9]

Re: DIY Flat Panel Speaker Love

As above, I started with Audio Tools, a 12 octave RTA ($4.99) and the Dayton Audio iMM-6 Calibrated Measurement Microphone for iPhone iPad Tablet and Android. It is pretty darn accurate in comparing it response vs. my OmniMic. Its handy for quick tests when you don't feel like breaking out the OmniMic and stand.

Thanks for the info. The mic is cheap enough ; ) Funny you mentioned noodles I just bought a generator to hook up to the house in case of power outage. In the packing it had a 1.5 x 26 x 22 inch sheet of foam that is almost like noodles. It is maybe a little denser but real close it is laminated from a 5 layers so it would be easy to size. All you need to do is buy a DuroMax 10kw hybrid generator and you have what you need ; ) but really if you can't find any local I would be more than happy to send you some of what I have. The Lowes stuff takes a little bit of sanding to get past the pitting but wasn't too bad. I just got my second set of Ultras today so I will build a smaller set of panels smaller than the 30 x 24 panels I have now. I have two pieces left 30 x 48 and 34 x 48 so I can make several. Now the Thrusters are back in stock I hope to get my replacement soon so then I will have 3 sets to play with. Thanks for all your help and putting up with a newb to all this.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Thanks for the info. The mic is cheap enough ; ) Funny you mentioned noodles I just bought a generator to hook up to the house in case of power outage. In the packing it had a 1.5 x 26 x 22 inch sheet of foam that is almost like noodles. It is maybe a little denser but real close it is laminated from a 5 layers so it would be easy to size. All you need to do is buy a DuroMax 10kw hybrid generator and you have what you need ; ) but really if you can't find any local I would be more than happy to send you some of what I have. The Lowes stuff takes a little bit of sanding to get past the pitting but wasn't too bad. I just got my second set of Ultras today so I will build a smaller set of panels smaller than the 30 x 24 panels I have now. I have two pieces left 30 x 48 and 34 x 48 so I can make several. Now the Thrusters are back in stock I hope to get my replacement soon so then I will have 3 sets to play with. Thanks for all your help and putting up with a newb to all this.

I actually laughed out loud... "All you need to do is buy a DuroMax 10kw hybrid generator and you have what you need". Lucky ba$stard... you now have an emergency power source AND possibly the optimal foam. Some guys have all the luck. Thanks for the offer but I still hope I'll find some locally... but if I don't I might ping ya later.

I'm still trying to figure out the best way to attach the foam and panel to the frame. I want a removable panel solution so still thinking through what that might be... resisting the temptation to glue directly to the frame...

Anytime man... this stuff is plain fun and look forward to hearing the results!

[buke9]

Re: DIY Flat Panel Speaker Love

I actually laughed out loud... "All you need to do is buy a DuroMax 10kw hybrid generator and you have what you need". Lucky ba$stard... you now have an emergency power source AND the possibly the optimal foam. Some guys have all the luck. Thanks for the offer but I still hope I'll find some locally... but if I don't I might ping ya later.

I'm still trying to figure out the best way to attach the foam and panel to the frame. I want a removable panel solution so still thinking through what that might be... resisting the temptation to glue directly to the frame...

Anytime man... this stuff is plain fun and look forward to hearing the results!

I thought you might like that : ) I have tried the 3M VHB tape to the fore mentioned foam and a piece of wood and it held firm and released with a little effort. I think it would hold the panel under use and release without too much problem if you want to try something else. The lighter foam would have to tear off but could be reusable. The tape was about $11 for 15 feet ( shipping was about the same as the tape). The stuff is great though. Just a note on my offer to send you some of the foam. I have a pair of Infinity Overture 2 speakers that the inductors on the crossover melted and couldn't find replacements . Most of the replacements were just too large that just wouldn't fit in the speaker housing. I came on this forum asking for help (after trying others) finding a replacement that could fit. One guy said if you want send me yours and I'll see if I can fix them. He did and didn't want anything in return. I sent him $5 for return shipping and he sent me $2 back. That says a lot about this community . I want to send him something in return but I don't want to offend him. He did this out of the love he has for this . So it will be paying it forward. I love this forum! You guys are awesome.

[captainjack115]

Re: DIY Flat Panel Speaker Love

I'll probably never get the chance to hear a set of Podium speakers, I was a little surprised by the comments posted at the following URL:

http://www.audio-forums.com/threads/podium-sound-speakers-revolutionary.99686/

Jack

[captainjack115]

Re: DIY Flat Panel Speaker Love

I did a little more reading to discover that Paul Burton from England is the original designer of the Podium speaker, not Dr. Shelley Katz. I don't know who owns the patent, but apparently Dr. Katz did his own tweaking on the Podiums after Paul Burton left the project.

A quote from Paul Burton from DIY Audio May 31st 2007:

]"Yes, it was me. I designed and built the prototypes shown at the Heathrow (London) Hi Fi show last summer. See http://blog.stereophile.com/hifinews2006/ for a photo of the originals (about 2/3 of the way down the report). I finished working on the Podium project last October, and have had little contact since, so I am a bit out of date.

What are they? The Podium 1s are large bending wave panels, using a honeycomb cored, skinned composite panel excited by 5 high-powered NXT-type exciters, in a vertical tapered line array. This can be clearly seen in the photos in the Hi Fi world review just published.

They originals were efficient, wide-band (good to below 40Hz), and as you would expect for a bending wave panel, non-directional, even at high frequencies. They were a diffuse dipole sound source, and so produced a very large room enveloping soundscape with no sense of a sweet spot. They also projected across large rooms unusually well. The originals sounded very fast and dynamic, with good bass weight. Oh, and they played loud too.... even on really tough stuff like the Telarc 1812.

I do not know how many of these original types were sold (if any).

Shelley Katz re-designed the Podiums after I left the project. The new ones have a wood frame and these are what are reviewed in Hi Fi World (July edition). They appear to be based on the original acoustic system I developed, but they have a higher impedance, lower sensitivity, and by the look of the frequency response and comments in the review, a different tonal balance as well."

I found this to be interesting reading. The Podiums could easily have been a pivotal inspiration for DML's in the DIY community.

[rmeinke]

Re: DIY Flat Panel Speaker Love

Very interesting reading indeed! Whether Katz modified Burton's original design for the worse we will never know I suppose. I took the forum posts in the link above at face value at first until they starting ripping on the Krell room as well... I stopped reading after that... seemed like typical pompous, elitist responses that some audiophiles take grief for.

Me personally, I do understand the forum posters on a certainly level. I myself was really disappointed the first few days and was ready to give up on them... where was the amazing sound quality of the panels?? Why would some of the guys give up their horns or electrostats for these panels?? If it wasn't for the fact that I had a week and a half of work to listen extensively to the panels I probably would have dismissed them. The presentation is very different from conventional speakers... a very diffused sound and a lack of presence, as if the sound emanated from behind the panels, through the panels and then to the listener. It is so different... if I only got to listen to them for a short period of time I would have agreed with the comments honestly. Only after listening for some time did that sensation go away and I began to hear some qualities that were very enjoyable and not heard in any other speaker technology I've had the pleasure of listening to. They certainly do not sound like a pair of speakers.

[captainjack115]

Re: DIY Flat Panel Speaker Love

After I posted the quote from Paul Burton, I had a thought that we might be able to track him down and ask specific questions such as the panel material he used in his prototypes.

I can totally relate to the sound qualities of DML's. I think the guy that walked in to the room where the Podiums were playing expected to hear speakers. The point of all this I think,is we forget that we're trying to recreate the sound of music, not the sound of someone else's speakers. Shouldn't that be what it's all about? There are a lot of different speakers out there that sound terrific, or at least our ears like it. But do they sound realistic, do they make us feel like we're in the original venue listening to the actual performers?
I like my MMG's, they sound good to me, but I must say, the little panels I've been playing with have a magical way of making me feel like I've been transported to the venue where the performance had taken place. Of course not all recordings will do that, many recordings are "manufactured" through a console. I'm speaking of live audiophile type recordings.

My only regret is my small listening space, the panels would have more bloom if I could get back from them. All in all, certainly worth the slight hardship.

Jack