[willys36@aol.com]

OK, I thought for sure this had been covered on the board before but a search came up empty. I plan on upholstering my pickup myself and as the photos show, I hid my speakers behind interior panels- doors in front and seat ends in the rear. My question is, how can I cover them with upholstery and a) not hurt the sound, and b) protect them from an elbow or foot going through them? I am using rubber backed tweed cloth.

[Justin Mc]

Hiding speakers behind any Chloride, rubber threads or composites is a real bad idea. I am an audio engineer so I you hang with me I will tell you why. Sound waves operate just like water waves as Im sure you know (In fact identical). So If you took a piece of your material and formed a circle with it> Then put it in shallow water> throw a rock in the center of it and watch how many waves escape. They will get through but not very well. So you want a solution and one that will keep your ride clean. First of all you will want to counter sink your speakers about 1 and 1/2 inches into you panel (This will allow time for the higher octave waves to travel half an octave therefor making it easier to pass through the material without resistance . You are not worried about lower octaves because the waves are to big for any thin woven material to stop. Form a en-closer to hold the speaker (This will create more wave stability). Stability will give the waves a boost in turn you will gain sound quality. I would highly recommend using BOSE speakers and a 50 to 100 watt amp., simply because these speakers are designed for this sort of application. Although you could save yourself a lot of trouble and money by just using a stylish mesh cover for your speakers. You can always paint the mesh cover to give your ride some excitement.

[Dubz]

I was wanting to make a sub box similar to the back seat i have in the car at the moment, using fiberglass to make the shape of my seat frame and counter sinking the subs. I'll be running 1000W though 2 12" subs, and was planning on upolstering over the subs so it looked like a stock back seat.

Justin Mc, i would appreciate your input as to if this would be an allright plan or if i should go about it some other way

[Justin Mc]

This is for Dubz
Your plan sounds great as long as you taper the fiber glass at least 45 degrees of of your box face. If you have a adjustable router then you can use this to get your angle after you cut your holes out for your speakers. You want to do this so waves wont mask themselves (cancel out). When sound leaves your speaker it starts its cycle of waves, and if there is anything stopping the wave in the first part of its cycle it will bounce the wave in a opposite 45 degree motion or whatever octave the wave is and the degree of the impeder. Crossing waves will cancel out a whole section of octave sound. Are you using thin sheet glass or tool glass. Make sure you use a flex resin (Helicopter resin is ideal> should be a pearl green color when mixed). This will allow for a slight shift in yours glass reducing vibration. Also make sure you have formed you en-closer with at 1/2in to 3/5in thickness. Anything else is to much, and anything less is to little. Be sure you have 0 voids or else you glass will surely demolish itself under flexing pressure. Are your subs Dual Voice Coil?

[willys36@aol.com]

That's is the kind of tip I was looking for. The 1 1/2" standoff sounds reasonable as does the rear enclosure. I will incorporate both. I am not a 'sound horse' - I have heard the $$$$ systems and they don't really impress me except they can do auditory damage w/o sound distortion! I have always been very happy with the cheapie speakers that they sell with radios @ Best Buy. My speakers came with grilles and I have no problem with their appearance but I had surface mounted speakers in these locations previously and the grilles really take a pounding. The rear speakers came out of an '86 Caprice that my wife totaled (she got run over in the Tule fog by an 18-wheeler. Not a scratch but it sliced the top off the car!). I see hidden speakers all over the place in hot rods and OEM cars so I know it can be done. I guess the best thing to do for 'grilles' may be to find plastic door panels with hidden speaker @ the junk yard and cut and splice the integral grilles into my upholstery. I realize the sound won't go thru the rubber backed upholstery but thought they might make an 'acoustic grade' tweed that I could use. I am positive I can't just put upholstry in front of the speakers 'cause I would put a foot thru one eventually. If I could find an acoustic tweed, I could back it up with some hardware cloth for protection.

[Dubz]

not sure which fiberglass i'd be using, and the subs are phenoix gold single voice coil subs. Had them hooked up in an improper sized box running them off each channel of the amp instead of in parallel cause i didn't read the directions or remember my impedance laws or anything of the sort, and they sounded great. Can't wait to get them in a good box hooked up right

Where would i get the helicopter resin from? and what is the difference between tool glass and sheet? How many layers of each would be 1/2"

what material would be best to cover the mock seat with for sound purposes?

[Justin Mc]

I could not tell you where to get the resin you need in you area, however I could tell you to shop around on the NET. It doesn't have to be helicopter resin but be sure it is not a polymer base or Polly base. I get all of my resins and materials from GRACO. Im not sure if they have site (they are local to me). Tool glass is a thick waffle or none linear glass, and sheet glass is precision linear glass (recommend). When you buy your glass it should have a labeled measurement of thickness. For instance it may be .050 in > so to acquire your your proper dept you use simple math, and lay .050 up until it is the dept you want. Tool glass is usually thick .50 in and Omni directional, and this in turn makes it harder to mold for perfection. If you have a digital caliper you can use it to check the thickness of your product (molding) after it has been lay-ed up, and if not its a good investment (You can use a cheap one).
Phoenix Golds are great speakers as long as you run them at 2 OHM or less. They have great sound quality because it has a inter-active magnet.

The material question is kind of hard to answer unless you give me a few choice ideas. Otherwise I will have to write a million different options.

[Dubz]

Originally posted by Justin Mc
I could not tell you where to get the resin you need in you area, however I could tell you to shop around on the NET. It doesn't have to be helicopter resin but be sure it is not a polymer base or Polly base. I get all of my resins and materials from GRACO. Im not sure if they have site (they are local to me). Tool glass is a thick waffle or none linear glass, and sheet glass is precision linear glass (recommend). When you buy your glass it should have a labeled measurement of thickness. For instance it may be .050 in > so to acquire your your proper dept you use simple math, and lay .050 up until it is the dept you want. Tool glass is usually thick .50 in and Omni directional, and this in turn makes it harder to mold for perfection. If you have a digital caliper you can use it to check the thickness of your product (molding) after it has been lay-ed up, and if not its a good investment (You can use a cheap one).
Phoenix Golds are great speakers as long as you run them at 2 OHM or less. They have great sound quality because it has a inter-active magnet.

The material question is kind of hard to answer unless you give me a few choice ideas. Otherwise I will have to write a million different options.

good good, thanks for all the info. I'm running the subs of a sony xm-2100G amp, and at 2ohms, shooting for sound quality more than spl, or slp or whatever that lingo is.

for material selection i would like something that looks like it might have been in the car when it was new. This limits it to pretty much anything at all I'll shop around and see what i come up with then shoot you a message to see which would be best

[paperairplane]

Hey Willys - are you just against using grills on your doors for aesthetic reasons?

I think any material you are covering the speakers with - especially on smaller speakers (because they produce more of the high notes) will cause decreased performance.

I had surface mounted speakers in these locations previously and the grilles really take a pounding.

This indicates to me that grills are important for your application.

What if you mounted the grills behind the door panel - this would keep the grill as tight to the door as possible and would not make it look like a surface mounted grill screwed into the door panel. And as stated above, you could always color match paint the grills to help them blend in....

Did that make any sense?

If I was really looking to hide speakers, I would mount the midrange under the dash or in the kick panel area, highs would be a pillar mounted tweeters, subs can go in the trunk.

[willys36@aol.com]

It is mainly a problem with kicking the grilles off the speakers with surface mounted ones. Actually I like the look of the grilles that came with my speakers. Since I committed to sink the speakers as much as 1 1/2" anyway, I can sink the grilles to level with the surface of the door panel. The pillars on a '53 Chevy pickup are anemic to say the least and my kick panels are pretty busty already so no real room there. I think I will just embed the speakers with flush grilles.

[kristkustoms]

Why not do this? Purchase some perforated metal (like this stuff ) which can be found for relatively cheap, and make the grill part of the design of the door panel. It can be mounted flush in the panel, painted to match the material, and you dont have to use the standard round grille that comes with the speaker. Its alot better looking, in my opinion.




Examples of what i am talking about:



The lower right portion of the door is the speaker grille, i even mounted the power window switch in it for the hell of it. The color is a bit off in the picture, but i had paint mixed to match the UltraLeather and painted the grilles.

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The tiny oval in the "hoop" of the kick panel is a little tweeter behind some grille metal.

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I used stainless mesh here with custom aluminum rings.

[willys36@aol.com]

Thanx Krist, that is EXACTLY what I was looking for. In fact I have been looking for a good source of perforated metal for over 40 years. Needed some for the grille I designed for my first Fisher Body Craftsman's Guild entry. Ended up using one of my sister's perforated aluminum hair curlers! Don't let her know that is where it went, OK?

An acoustic question; does it make any difference what mesh size to get for best sound transmittal?

Look what else they sell!!

AND look at the classes they offer!!!! Fun site!

[kristkustoms]

Willys, request a catalog from them, them have some pretty cool stuff.

[horvath]

Here's how I'm doing mine:

When I finish making all the interior panels, you won't see that speaker box, just the grill.

I experimented with a number of speakers before finally determining that with the small cab of a pickup truck, too many speakers just gets sound bouncing all over the place, and that two speakers do the best job -- notice I have the passenger-side speaker pointed at the driver's head and the driver-side speaker pointed at the passenger's head.

Here's how I built the speaker boxes:
Click Here

Alan
54 Chevy Pickup