I only tried nomex once before and didn't know this technique at that time. I used way too much glue (and wrong kind). I've since seen the technique you described but have not tried it yet. Lately I've been trying CF construction with fabric (not prepreg) which makes using nomex more challenging though not impossible. Something like balsa or foam works better than honeycomb when working with carbon fabric. I'm not sure where I'll end up yet.
Eric
I wondered about using the lightest CF weave which is about .1 mm thick or possible random CF cloth and doing a manual setup with epoxy and maybe thicker 4-5 mm Nomex.
It could be laid up on a piece of plate glass with release agent and a vacuum bag. Probably many ways to skin the cat. The trick is keeping costs down so hobby types can play.
Have you tried plexiglass as a panel ? AER seems to have pulled it off. Not sure how thick their panel is.
It could be laid up on a piece of plate glass with release agent and a vacuum bag. Probably many ways to skin the cat. The trick is keeping costs down so hobby types can play.
Have you tried plexiglass as a panel ? AER seems to have pulled it off. Not sure how thick their panel is.
I spoke with this company Carbon Fiber Sheet | Carbon Fiber | Carbon Fiber Tube | Carbon Fiber Sheet | Carbon Fiber CNC Machining Parts | Dongguan Xiechuang Composite Material Co., Ltd. mid last year about carbon fibre skinned foamboard, not sure if they do honeycomb cores. They quoted a sample price of US$65 per piece for 2x 600mm x 500mm 2mm thick (0.5mm CF skins on 1mm foam core) plus US$45 for shipping. I don't know if they go larger, I know they go thicker. They also take Paypal from their proforma invoice. They also cut, and machine parts.
I didn't/haven't ordered yet due to the crappy Australian $. Wasn't exactly sure what I needed either. Might wait for you guys to experiment a little more
I hear about a lot of great performers from these forums or other 'audiophile' sites.
I don’t know for sure but 2 mm seems really thin. That is thinner that what I am setting up. Might be worth 65 as an experiment. Do it and report back. I used the Nomex I had on hand and am trying a process to build the panels cheaply. Thin CF is cheap (15-20 bucks/ yard) Nomex can be had cheaply. Carbon fiber plate of any thickness is crazy expensive. Premade panels with Nomex or foam and CF are also very expensive.
The old NXT panels that I have( prior post ) have 2-3 mm thick panels for a 8x12 ish panel
The old NXT panels that I have( prior post ) have 2-3 mm thick panels for a 8x12 ish panel
davelang, your guitar(s) look great, well done. Have you ever tried toneboard(?) as a panel material? Expensive, and not available in large sizes I imagine.
I see you appreciate Markaudio drivers as well.
Yes, I think 2mm was their idea, I was thinking of 5mm total thickness. Not sure if they offered thinner skins.
I'm sure you seen this youtube video, but if not the guy does some panel mode experiments around 17:20, in a similar fashion to your guitar mode tests, plus some panel damping as well.
YouTube
A Russian company(?) making some DML's for the audiophile market, I think.
YouTube
I see you appreciate Markaudio drivers as well.
Yes, I think 2mm was their idea, I was thinking of 5mm total thickness. Not sure if they offered thinner skins.
I'm sure you seen this youtube video, but if not the guy does some panel mode experiments around 17:20, in a similar fashion to your guitar mode tests, plus some panel damping as well.
YouTube
A Russian company(?) making some DML's for the audiophile market, I think.
YouTube
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Yes I have tried Tonewood as a panel. I tried a 5mm thick 20x20inch spruce board with a Dayton Thruster. It sounded weak. Formular 150 is better than my spruce tone wood and a lot less dense. Using wood has a romantic appeal but I think composites hold the most promise for all the reasons discussed in this thread. I didn’t want to risk good guitar wood by thinning it to try as a DML. That You tube video “Worlds Best Speakers” is the one that got me going on this. I didn’t believe it. I had no idea that a DML forum has been on diyaudio for so long.
I must try some XPS soon. Do you treat the faces of the Formular 150 when you use it? Sanding with the 'classic' wood glue water treatment?
The only other stuff I've tried for panels is Bamboo Ply. Made some small framed ones with 3mm ply. From memory they weren't too bad. Still have them in the garage, so might get them out and have a listen and do some measuring again. Tried some 1.8mm(?) bamboo ply in the larger frames I have now, and it was just too flexible. Think I could hear it buzzing internally as well.
The only other stuff I've tried for panels is Bamboo Ply. Made some small framed ones with 3mm ply. From memory they weren't too bad. Still have them in the garage, so might get them out and have a listen and do some measuring again. Tried some 1.8mm(?) bamboo ply in the larger frames I have now, and it was just too flexible. Think I could hear it buzzing internally as well.
I followed the classic Parts Express article and made panels 24 x 36 inches. Foamular 150 1 “. I did sand and treat the front and back with brushed on solution of regular titebond glue diluted 50% with an equal volume of water. I tinted the glue solution with a woodworking dye called Transtint. It works better than ink. I hang my panels as described in the ubiquitous video with epoxied in cotter pins and fish line.
I think one or two Dayton thrusters sound best as drivers.
I made a second set the same way with my son. A friend made a third set the same way. All three sets sound really really good. Actually, drop jaw amazing and consistent results. Esp for the price.
I equalize mine slightly with Roon’s built in software parametric equalizer. Also, my system uses large open baffle subs actively crossed over at about 150hz. DSP or a 1/3 octave eq might be better to fine tune the panel. I am driving the panels with a clone Aleph J ( diyaudio of course) 40 W Class A. You will be disappointed without using subs.
I could be completely satisfied with this setup as it is but I love to tinker and push the envelope. Build a set from the Foamular and I think you will be happy. It is also a really nice and cheap baseline from which to compare other panels you build and provides a standard from which others can compare new concepts and projects in the diy community.
Now to go see how the Nomex Mylar panel side one worked out... ...And have a cup of coffee!
Sorry for blathering on and on. Have a good day
I think one or two Dayton thrusters sound best as drivers.
I made a second set the same way with my son. A friend made a third set the same way. All three sets sound really really good. Actually, drop jaw amazing and consistent results. Esp for the price.
I equalize mine slightly with Roon’s built in software parametric equalizer. Also, my system uses large open baffle subs actively crossed over at about 150hz. DSP or a 1/3 octave eq might be better to fine tune the panel. I am driving the panels with a clone Aleph J ( diyaudio of course) 40 W Class A. You will be disappointed without using subs.
I could be completely satisfied with this setup as it is but I love to tinker and push the envelope. Build a set from the Foamular and I think you will be happy. It is also a really nice and cheap baseline from which to compare other panels you build and provides a standard from which others can compare new concepts and projects in the diy community.
Now to go see how the Nomex Mylar panel side one worked out... ...And have a cup of coffee!
Sorry for blathering on and on. Have a good day
Thanks davelang, no one around here should ever have to apologise for "blathering on" while helping others.
I hope the Nomex Mylar panels turn out for you as planned. This is what Podium used in their panels, is it not? Wished I could hear a pair of Podiums one day, if just for a reference.
Good to add another common interest between us. DML's, Markaudio and coffee. I saw the portafilter handle on your bench in one of your photos. If you like red wine, we're a match made in heaven. Enjoy that cup of coffee. Have a good, safe day too.
I hope the Nomex Mylar panels turn out for you as planned. This is what Podium used in their panels, is it not? Wished I could hear a pair of Podiums one day, if just for a reference.
Good to add another common interest between us. DML's, Markaudio and coffee. I saw the portafilter handle on your bench in one of your photos. If you like red wine, we're a match made in heaven. Enjoy that cup of coffee. Have a good, safe day too.
Does anyone here think 0.2mm fibreglass sheet would be worth a try for panel skins? There is a fair amount of information about density and strength in this link, but sadly underatanding that is not my forte.
Isoval 11 - G11 Epoxy Fibreglass Sheet from Swift Supplies
Isoval 11 - G11 Epoxy Fibreglass Sheet from Swift Supplies
Sorry, I was just referring to this same ratio as here:
... wherein the panel is such as to have ratio of bending stiffness (B) to the cube power of panel mass per unit surface area (µ) in all orientations of at least 10;
But my keyboard doesn't have a µ, so I just typed it out as "mu", the name of that greek letter.
So, that quote and equation tells us the panel must be light and stiff. It also tells us the panel must be isotropic( same mechanical properties in length and width.
Veleric. I looked this one up and need to know what units are being used for the calculations of bending strength and mass per cubic area to be sure calls are correct.
Also, as the NXT patent or license might be up, does anyone out there have the NXT software for panel calculations?
Veleric. I looked this one up and need to know what units are being used for the calculations of bending strength and mass per cubic area to be sure calls are correct.
Also, as the NXT patent or license might be up, does anyone out there have the NXT software for panel calculations?
In fact, you could use resin alone on a polyester skinned polypropylene honeycomb core - no fiberglass or carbon fiber. An 8x4 sheet is around $40-$80 locally depending on thickness and the resin is $75(?).
Personally, I won't spend much more than that because in my magical thinking I think I've run into diminishing returns on materials. I might already be past the point of diminishing returns with what I've used. I did use carbon fiber but only because I already had it. It's possible that I degraded the panel by using CF, I have no idea.
Personally, I won't spend much more than that because in my magical thinking I think I've run into diminishing returns on materials. I might already be past the point of diminishing returns with what I've used. I did use carbon fiber but only because I already had it. It's possible that I degraded the panel by using CF, I have no idea.
Attachments
Yep, I think they could. The properties that matter most, I believe, are the Flexural Modulus (higher is better) and density (lower is better).
I don't fully agree with bradleypnw that it's as good as carbon fiber composite (CF), since CF has even higher modulus and lower density. But the properties of the full skin/core/skin composite will depend heavily on the exact construction. So depending on the core material you have available, and the panel size you have in mind, fiberglass might actually be a better than CF in some cases, I can imagine.
Eric
Dave, I am on board with you and quite a few others here, on the DML's needing bass help from conventional drivers. With HolmImpulse measurements I saw harmonic distortion higher with the panels than open baffle cones, even around 250 hz, so currently crossing over at 350.
I too have the Parts Express design, using 1" Foamular 250. I thinned the school glue with 100% ink jet printer ink, assuming it has alcohol in it and would dry quicker.
Wow, this thread has been great to follow lately! Amazing skills and knowledge shared by you guys! If anything good can come from Covid-19, it may be DIY DML innovation, from having more time to play!