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Post subject: Hy-Tech paint
Posted: Tue Aug 18, 2015 5:47 am
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Aspiring Musician
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A friend just told me about Hy-Tech paint and paint additive. It's intended to act as a thermal insulator, but apparently it also acts as a sound insulator. The additive has "ceramic microspheres" which apparently have vacuum interiors, and the paint dries in a way that sucks the spheres into a matrix so you get a very thin coating that insulates really well. Paint it on a tin roof and you can't hear the rain.

So, what happens if you paint it on the backside of the tower of an Expo?

Will it do the good thing and kill the sound from coming off the sides and rear of the speaker array case? Or will it do the bad thing and stop heat dissipation and burn out the speakers? Or both?

Any experience? Any well-informed conjecture? Inquiring minds want to know.


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Post subject: Re: Hy-Tech paint
Posted: Tue Aug 18, 2015 10:54 am
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I think the additive you mention is substance called Microballoons. (If that is the same product)I have some experience with it. It is most commonly used in polyester resin as a filling agent. The more you add to the resin the thicker and lighter it becomes. It can also be added to catalyzed primers or other epoxies to better fill imperfections and create a smoother finish. The stuff is inert and as harmless as the media its mixed with. As for the paint you mentioned its probably Noxudol 3101, its water based and relatively inert. I don't think it will physically hurt anything. I don't know how or if this paint will affect the sound in a positive way. There are many true experts in amps and cabinets here, they would know those sound issues much better than I do. you could give it a shot, you can always sand it off if it doesn't work...


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Post subject: Re: Hy-Tech paint
Posted: Wed Aug 19, 2015 5:35 am
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Everything you say makes sense, though the one idea that has not been addressed yet is that while this paint is supposed to be a good sound insulator, it is also a good thermal insulator. If Fender is using these aluminum cases as heat sinks for the speakers, insulation might fry the speakers. I'm not sure how much heat builds up in the speakers.

The paint would either replace or boost the effect of the two layers of moving blankets that I've used a couple times now with a pair of Expos to deaden the remarkable amount of sound that comes off the back of these aluminum tower cases.

I'm considering painting the tower cases along the back and sides of the speakers, but not for the cap at the top, or for the blank section at the bottom of the towers. Likely, there's not much sound coming out in either place, and it would still provide a place to dissipate heat. Aluminum is remarkably good at dissipating heat.


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Post subject: Re: Hy-Tech paint
Posted: Wed Aug 19, 2015 11:04 am
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I agree, if you feel the towers after a long session are they hot? I don't think the speakers themselves produce much heat, are the amplifiers in these cases. I only knew a bit about the products, I've never seen the towers you're talking about.


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Post subject: Re: Hy-Tech paint
Posted: Wed Aug 19, 2015 12:06 pm
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It's not that a speaker puts out a lot of heat. It's that the tower has nine speakers in it in a very small air space. Together, they do put out noticeable heat. It hasn't been like, "Ow, I burned myself," hot, but it has been like, "This is more than slightly warm" hot. Like, "I need to test this before I assume I won't burn myself" hot, especially after they've had the moving blankets over them for a couple hours at about half volume.

I know that the speaker cases are acting like heat sinks. The question is, were they designed to be heat sinks? Do the speakers require the dissipation of heat through the aluminum into the air, or is this just an accidental byproduct of the choice of making the cases out of aluminum?

The power amps are in the wooden sub-woofer box. The towers contain passive speakers driven by the amps in the subwoofer box. There's an electrical junction between the two for six connectors. That's hot and ground for each of three signals -- low-mid, high-mid, and tweeter. The signal for low-mid and high-mid each go to four (3.5") speaker arrays (totaling 8 speakers), while the tweeter signal goes to a single 1" tweeter.

Sound from the tweeter goes forward, determined by the horn shape. Sound from the eight mid-range speakers goes EVERYWHERE, including straight out the back of the towers. The aluminum tower case acts like a ribbon speaker for the mid-range. Only the tweeter is directional. That's what I'm trying to fix.


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Post subject: Re: Hy-Tech paint
Posted: Tue Sep 29, 2015 8:41 am
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First test of the paint is impressive. HiTech has paints and finishes with their additive already in it. I talked with a salesperson and she recommended a paint they have specifically designed to deaden sound. It's more than $70 for a gallon, but considering what I spent on the Expos, if it fixes the sound issue, it's worth it.

The paint is white, and it's somewhat like painting with whipped cream or pudding. There's no worry about the brush dripping. The paint itself doesn't go on as thick as I initially expected. I masked and painted, and on the first attempt to remove the masking tape, I tore off some of the paint. It's like a sheet of rubber. I used a box cutter to cut the paint at the margin of the tape before pulling the rest of the masking tape. The paint is more cohesive than adhesive, though it's adhesive enough.

I'll paint black over it later, but I only had time for three coats before this test. I used one Expo for a small dance. I placed it front and center, so I was standing almost behind it while calling from next to the band. The tower is now much more directional; much closer to the advertised 130 degrees. The caller's voice doesn't annoy the band so much. They hear the monitors much louder than the main speaker, which is what I wanted.

I painted only the top half of the tower sides and back. I left the top unpainted, as well as the lower part of the tower, so that if heat is an issue, the aluminum can still carry it off the top and down and out the sides and back of the bottom. This was enough to get the sound issue fixed, yet didn't add anywhere near enough thickness or weight to interfere with the use of the gig bags (which I had fixed earlier by moving the pads to the other end).


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Post subject: Re: Hy-Tech paint
Posted: Tue Sep 29, 2015 8:58 am
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Oh, and for other details, the hall was small and acoustically dead (a good thing). There were maybe 30 or so dancers in a line of foursomes from the speaker, back to the back wall. I put the one Expo on a camping tray about a foot tall to bring the tweeter up above head (and ear) level to not hurt anybody standing next to it, and the sound at the back of the hall was clear and sweet.

Good bass from the piano. Good tone on the fiddle. My voice was clear. People could understand me well, and since this is a "called" dance, it's not like singing. The dancers need to understand my words, or the dance falls apart.

The Expo worked flawlessly at about 1/3 volume for both bass and mid/treble controls. The array effect is perfect. Not too loud up close. Not too quiet at the back of the hall, and in this case, the front dancers were within arm's length of the speaker. It's amazing how well this system distributes sound over distance.

I've used them for much larger venues and they have plenty of volume. The only time I've had them turned all the way up was when I was using them on a friend's system as mid-hall speakers. He had his 1,000 watt mains cranked high, and was sending all of the active speakers a signal that never got above 20% on the VU meters.

He generally runs things with the power amps cranked, and the signal going to them remarkably weak, so I had to crank the volume on the Expos to hear them at all. I normally send them hotter signals, touching the amber at peak in the VU meters, and with that signal, the Expo is plenty loud, with a full range of volume controlled at the speaker. It also has plenty of bass that way.

The friend, with his 1,000 watt mains decided that he needed a pair of subwoofers, though I personally suspect that need was created by the low signal he was sending to the speakers. If he had the power amps lower, or had smaller wattage speakers and sent them hotter signals, he'd have plenty of bass without the subs.

But in the end, his sound was fine. He successfully compensated for the weak signal by adding subwoofers. And besides, he likes adding more speakers. It's sound-geek bling.


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Post subject: Re: Hy-Tech paint
Posted: Fri Oct 02, 2015 7:29 am
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Contracaller, I read your posts with great interest but will admit I must be a simpleton when I realize I'm not always sure what you were trying to accomplish. Don't take that as a slam, it's not meant to be, I just must not be as "in-depth" when it comes to sound.

We have continually been happier with our Expo's as our familiarity and experience grows. As I said before we use three of them for our 4 pc rock band and they have proven to be sufficient for good sound and volume.

My initial "complaint" with the Expo's was a noticeable lack of "presence" or thump from the kick drum. Of course the subs in the Expo's couldn't match the old pair of 18" speakers we had in our old configuration. We have since added a 500 watt active sub, daisy chained after the last Expo. It has a built in crossover to eliminate high/mid freq's and when combined with the Expo's our sound has noticeably improved.

Just an FYI, for the whole setup, our mics/instruments are all plugged into a Peavy PVI8500, mixer. I like this mixer due to ease of operation, built in effects, USB port to use for break music, etc. We take the "main to ext amp" output direct to the first Expo, and daisy chain the rest as indicated. We have been very happy with this setup, no feedback issues, good mix overall with the addition of the sub. I have had my share of folks share their opinions in hating a Peavy mixer and why on earth we would use it over some other more expensive board, but in our situation I play bass/sing/do sound from stage so I need to be able to operate on the fly quickly.

So I guess I'm still uncertain on the "reflection" issue that you are addressing with the paint you described. Again, not dissing you or meaning disrespect, just trying to understand because I like to learn things. Thanks for any more information you want to share.

Here is a photo from our setup at a casino a couple weeks ago. It's taken from the guitarist's side of the stage so the mixer is on the far side and not too visible.

Image


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Post subject: Re: Hy-Tech paint
Posted: Mon Oct 05, 2015 8:26 am
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I see nothing disrespectful in anything you've said. Your setup looks perfect for what you do with it. The Expos give you lots of volume that projects far out from the stage without feedback.

My experience is that unless you place a microphone low enough to feedback in the subs or high enough to feedback in the tweeter, the high-mid and low-mid speakers don't feed back, even at high volumes because of the array effect. The sound is clear and balanced, though for rock and roll, adding a big-diaphragm subwoofer is justified, just as you say.

My usage is somewhat specialized. I do sound for folk dances that have a live, acoustic band and a caller. The musicians want to hear the music and they don't want to hear the caller, so the sound coming out of the Expos needs to be different from the sound the musicians are listening to. The dancers need to hear the caller clearly, and the band needs to, as much as possible, not hear the caller except as a faint, distant echo off the back wall. They want to ignore the caller.

So, I have to put the Expo with its back to the band, facing the dancers, and give the band monitor speakers with a different mix that does not include the caller.

My problem is that if you stand behind an Expo, you can hear the caller almost as well as you can standing in front of the Expo. The aluminum housing on the towers will vibrate in sympathy with the high-mid and low-mid speakers almost like a speaker diaphragm. The subwoofers are in a wooden box, so the lows don't transmit out the back so much, and the single tweeter doesn't project out the back, either, but all 8 of those mid-range speakers make the tower housing vibrate, transmitting sound out the back and sides at maybe 80% of the volume coming out the front. That's my subjective guess.

So, I painted the surfaces that have been transmitting sound with a very effective sound-deadening paint. It doesn't affect the sound coming out the front of the speakers, but it brings the sound coming out the back down to maybe 20% of the volume coming out the front. You can hear the caller, but not much, and with any volume in the monitors, they can easily drown out the caller bleeding out the back of the Expo towers.

You don't need this paint for your setup. The sound coming out the back of your Expo towers plays to the wall behind the stage. Nobody cares. And you don't need to isolate the sound. You want all the sound everywhere, and that's exactly what the Expo delivers, out of the box.

It's great that the Expo gives you the rock and roll volume that you crave, and also gives me the acoustic fidelity and verbal clarity I need for acoustic instrumental music and speaking-voice instruction mix. Add that a lot of my audience members are old and cranky enough to complain if it's too loud in front, next to the speakers, or not loud enough back at the back wall of the room. It's a picky crowd, and they love the sound my system makes.

Only two people have ever dissed the Expos at my dances. One is another sound guy who bought speakers that cost more than twice as much as mine, and who thinks that if your speakers aren't from Italy, your gear is not as cool as his gear. The other is a purist who thinks that he can hear the "edges" of the sound from a digital mixer and prefers the "warmth" of analog gear, and considers himself to be the exclusive authority of What A Speaker Should Sound Like, and unsurprisingly, he believes that his speakers sound that way. He doesn't talk like a sound guy. He talks like an audiophile. He also complains about how hard it is to put his massive speakers at the top of a speaker stand; something I don't have to do with the Expos.

I like these guys, but they are biased against anything from Fender because it's not exotic enough. I don't think they are capable of putting their preconceived notions aside long enough to objectively listen to these things.

They sound great. Not just okay. Not just pretty good. They sound great.

Other kinds of speakers can sound great, too. I'm not just praising Fender like rooting for a football team. I actually like the sound from these speakers a LOT, and find them easier to store, transport and work with than anything else that sounds as good, plus the array effect is real and makes sound distribution down a long hall actually work. Anybody who disses these speakers isn't really listening.


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Post subject: Re: Hy-Tech paint
Posted: Mon Oct 05, 2015 9:45 am
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Contra, thanks for the explanation. Sometimes in text, emails, or online the tone of what you are saying is misunderstood, and I was just being certain that my post was seen as general curiosity was all I meant. I now have an understanding of what you're trying to accomplish.

As for the purists that "diss" whatever they don't like. There's some in every crowd, we've got them too. But once I hit 50 I care a whole lot less about negative opinions, if it sounds good to me and the majority of the audience then I'm good.

And I agree, not shouting about Fender Expo's just because they're Fender gear. I may have bought them because I've liked my Fender gear, but I praise them because they've worked great for us.


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Post subject: Re: Hy-Tech paint
Posted: Fri Oct 30, 2015 7:24 am
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Back to say that while the paint significantly improves the isolation of sound from the Expo to forward and from behind, once the volume ticks above 50%, it still cuts through with three coats of the paint and the double-layer, hand-sewn moving blanket-socks I made for the speakers.

So, back to the lab for more experiments in sound shielding...


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Post subject: Re: Hy-Tech paint
Posted: Thu Nov 12, 2015 7:39 am
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Okay, so I cut ½" thick plywood into four 5" wide strips 56" long, glued and screwed them together in an "L" cross-section and painted two coats of white Hytech sound-absorbing paint, followed by one coat of flat black Rustoleum (I'll but a second coat on after this weekend, but I wanted to make sure these things weren't sticky for the gig Saturday).

So, I have a pair of Expo speakers that I'll put between the band and the dancers, to either side of the stage area, and I'll stand each of these acoustic shields on the top of an Expo base to cover the back and the inside surface of the tower, so the band should not be able to hear anything directly through the back or side of the Expo. They have monitor speakers, so they'll hear themselves and not the caller in their mix. The dancers will hear the caller.

The band will only hear the caller's voice echoing off the back wall, much MUCH quieter than they'll hear themselves in their 200 watt RMS floor monitors. This should be their normal experience with more conventional speakers that have plywood housing.

Callers are used to not hearing themselves, unless they step out in front of the house speakers, so this should not be a problem for the caller.

I'm figuring that with the air space between the back of the towers and the shields, plus the mass of the plywood of the shields and the sound-deadening paint on all surfaces of the shields, this ought to lay to rest all complaints from the band about hearing the caller. We'll find out Saturday.


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Post subject: Re: Hy-Tech paint
Posted: Sat Nov 14, 2015 12:31 pm
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Its good to see someone committed to getting the best sound out of there gear, i hope it works out.


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Post subject: Re: Hy-Tech paint
Posted: Mon Nov 16, 2015 6:15 am
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Well, the sound out in the hall was great, as always. I love the performance of these speakers. Chrystal clear, with a strong, natural bass.

My unusual need for silence on the back side is significantly improved, but even with two coats of sound-deadening paint on the tower itself, two layers of moving blanket (like a tall, thin balaclava), and an air gap, then a plywood shield with two coats of sound deadening paint on all surfaces, I can still hear the caller's voice coming out of the back of the speakers. I can touch the acoustic shield and feel the vibration. And this is with the Expo at one click below half volume.

So, this is good enough, if I can get some distance between the speakers and the band. It worked this weekend. If I do this again for the Fall Festival sometime, it would work if I don't put the speakers up on the rather small stage, near the band. That, or make a second, larger shield that sits on the floor...


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