Effects on sound from fiberglassing an enclosure?

[j-roadtatts 1,129]

The goal of this topic is to discuss the possible effects fiberglassing the inside of a subwoofer enclosure has on the sound?

I am currently building my enclosure and am using fiberglass to make the box more ridged, prevent air leaks, prevent flexing, raise the boxes failure point of the box, and I just like building things heavy duty.

I honestly never thought about the fiberglass effecting the sound until Pork Chop brought it up last night. I used the search function but did not find anything about effects on sound from fiberglassing an enclosure.

I would like to hear some opinions about this from people that have experience with a fiberglassed sub box. I would also like to hear the science about how this effects sound waves even if its not audible.

Thanks in advance.

J-Road

Edited February 5, 2010 by j-roadtatts

[antonmiller 8]

I heard from some one that it makes the bass a little more muddy and unclear if you use alot, but that doesnt make any sense to me... also i believe it helps remove some more resonence of the already "resonance dead" MDF. but IDK, this should be a good discussion. i know that adding wooden dowels and fiberglassing the inside of my box added me .3 DB going from 144.3 to 144.6, but thats all i know.

Edited February 5, 2010 by Anton Miller

[Kanaworm$ 292]

In talking with the local audio shop here, they said it can give kind of a "echo, hollow" sound.... .... Just what they told me.

[Thumpper 266]

fiberglass acts as a mirror for sound waves

[///M5 2,833]

The goal of this topic is to discuss the possible effects fiberglassing the inside of a subwoofer enclosure has on the sound?

10ths on a meter, nothing really audible.

I am currently building my enclosure and am using fiberglass to make the box more ridged, prevent air leaks, prevent flexing, raise the boxes failure point of the box, and I just like building things heavy duty.

It won't help with much of the above and if by fiberglass you mean resin alone it will actually make the mdf weaker. If you mean glass, well then you should reinforce it as glass isn't particularly great in flat areas. Doing that though will knock the 10ths off from above.

If you aren't competing or aren't worth building a few different boxes to play around I wouldn't bother.

[j-roadtatts 1,129]

It won't help with much of the above and if by fiberglass you mean resin alone it will actually make the mdf weaker. If you mean glass, well then you should reinforce it as glass isn't particularly great in flat areas. Doing that though will knock the 10ths off from above.

Yes I am using cloth with the resin. The box is built out of lots of short spans of MDF, not to many large flat area's. Also four walls of the box will be encased in expandable foam from the outside. the other two walls are the double baffle and the back wall is braced so probly won't much flex much anyway.

.If you aren't competing or aren't worth building a few different boxes to play around I wouldn't bother.

M5 I respect your opinion and the box is already built so will you check my build log and tell me what you think about the glass in this particular situation?

[///M5 2,833]

beat you to it

[j-roadtatts 1,129]

M5 do you think a little flex will make a softer or "warmer" sound?

[///M5 2,833]

The opposite, peakier sound. Either way, it won't be audible to your ears. Measurable perhaps, but no audible. Completely the wrong idea unless you are chasing tenths on a meter and then only perhaps helpful, could be the opposite.

[j-roadtatts 1,129]

Glad to hear you say it won't be audible!!!

I was really more worried about the box leaking as I won't be able remove once installed. I was under the impression that the glass would make the MDF act a thicker was my only other reason. Ridged is maybe not always better?

Now that the box is glassed a knock test sounds a little higher tone, not as dead sounding as MDF without glass?

[antonmiller 8]

fiberglass acts as a mirror for sound waves

anyway you could elaborate on this?

[Duran 387]

If you want to fiberglass something do the corners.

[j-roadtatts 1,129]

If you want to fiberglass something do the corners.

I am doing the corners and kerf bend twice. The false ceiling on my port is bracing the back wall. All the other walls are pretty small because of the box design. Like I said I was worried about air leaks more than flexing because the other 4 sides will be encased in expanding foam and the front is double baffle.

Do any of you guys thing my box needs Bracing?

[Duran 387]

If your worried use allthread with bolts and washers.

As for sealing your enclosure just use silicone. You really like over kill don't you?

[j-roadtatts 1,129]

If your worried use allthread with bolts and washers.

As for sealing your enclosure just use silicone. You really like over kill don't you?

I can't put false back on the box this time and DON'T want to see bolt ends. Not my style.

If you think The back needs more bracing I will do dowel or a few flat metal brackets inside? The little extra volume won't hurt me.

As far as overkill I definetly like to over think things and get carryed away.

I respect your opinion alot Duran so please don't hold back.

Edited February 5, 2010 by j-roadtatts

[j-roadtatts 1,129]

The goal of this topic is to discuss the possible effects fiberglassing the inside of a subwoofer enclosure has on the sound?

10ths on a meter, nothing really audible.

I do NOT compete. I only listen at full tilt driving on the highway by myself.

More interested in knowing if the fiberglass will change the sound?

.

[j-roadtatts 1,129]

fiberglass acts as a mirror for sound waves

When you say "acts like a mirrior for waves" does this mean the sound waves are more true (being mirriored) to what the speaker is producing? That is how I read this statement.

Does this Possibly Refect more mechanical noise?

Edited February 5, 2010 by j-roadtatts

[Impious 1,476]

Any hard surface acts as a "mirror" for sound waves.

Luckily for us, the wavelengths of the of subbass soundwaves are significantly longer than the dimension of the enclosure....so these reflections aren't a problem.

[Don Ganso 13]

This is some good stuff...

[j-roadtatts 1,129]

I want to start out by saying THANKS to you guys that took the time to school me yesterday.

Next I want add that I am NOT here to show off. I am here to learn and get the most from my set up. I LOVE to build things but must sometimes learn from my mistakes.

Like I said I am here to get my box right and I WILL listen to what you guys tell me. I tried to PM that guy on here that claims to help people design boxes to go over a box design, but he never PMed me back after two weeks So I Just went for it.

At this point I would like someone to help me finish my box design. I DON'T think I will waste anymore time fiberglassing. I think I should add two oak dowels from the front to back wall. I will do 45's in the corners IF you think its necessary? ANYTHING else you guys think I should or shouldn't do?

I would love to have someone double check my math ALSO. This is my first box design and being built in to the trunk I want to make sure it's right. Let me know if you would like to help and I will post all the numbers. I will use areo ports if needed.

I am a VERY humble guy and just want to get the most out of my money and sytem.

Thanks again in advance for ALL the help and you WILL get my vote.

J-Road

[///M5 2,833]

What do you have for specs on the box so far?

[j-roadtatts 1,129]

What do you have for specs on the box so far?

[/qoute)

The box specs are:

gross vol. 6.4cf

sub,port,kerf vol. 1.55cf

net vol. 4.85cf

port opening 4.25 x 14.5

port lenght 26"

I start measuring port lenght from where the kerf ends so I am NOT using any kerf opening as lenght. The port has three bends and I measure down the center and removed 2 1/8" for the end correction. Actual port wall NOT counting the kerf is 19.75". I have a false ceiling on the port that extends past the port 14.5" so the sub thinks ports ceiling is correct.

Other than my tuning math, I need to know if i account for the kerf opening and if the false ceiling is acceptable? I will go to areo ports as a last resort.

[j-roadtatts 1,129]

What do you have for specs on the box so far?

[/qoute)

The box specs are:

gross vol. 6.4cf

sub,port,kerf vol. 1.55cf

net vol. 4.85cf

port opening 4.25 x 14.5

port lenght 26"

I start measuring port lenght from where the kerf ends so I am NOT using any kerf opening as lenght. The port has three bends and I measure down the center and removed 2 1/8" for the end correction. Actual port wall NOT counting the kerf is 19.75". I have a false ceiling on the port that extends past the port 14.5" so the sub thinks ports ceiling is correct.

Other than my tuning math, I need to know if i account for the kerf opening and if the false ceiling is acceptable? I will go to areo ports as a last resort.

[///M5 2,833]

Full measurements would be helpful...

[j-roadtatts 1,129]

Full measurements would be helpful...

just outside dimensions or full drawing with all numbers?

I am leaving work right now so I will have em' in about an hour.