# Cabinet constructing material



## bhnidan (Jan 13, 2010)

Hello all I am trying to build my own cabinet and have my rough dimensions down but have one serious question. I was going to consider making the cabinet out of fiber glass. I have looked this up around the web and have not found any information about it. Talked to some local guys and they said that I could get away with it, they were un sure of how the material would handle and change sound quality. I have a friend who builds high end car audio systems and I was wondering how the use of fiber glass would affect a guitar cabinet. Any comments are much appreciated

Ben


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## greco (Jul 15, 2007)

Hi Ben...Welcome to forum !! Hope you enjoy all that it has to offer and that you post often.

I can't help with your question, but I'll be following this thread with interest.

Cabinet design and construction comes up quite regularly.

IIRC, recently, someone was wondering why they weren't seeing more cabs made out of plastic building materials that are now much more available.

Cheers

Dave


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## GuitarsCanada (Dec 30, 2005)

Certainy an interesting concept. Maybe some of our experts here can weigh in with an opinion


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## Xanadu (Feb 3, 2006)

I think that custom car audio drivers are still housed in a MDF box, it's just fiberglass on the outside to give it a clean look.


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## Mooh (Mar 7, 2007)

I don't know about fibrelass, but there are lots of molded plastic-like (sorry, what are they made of) cabs.

Peace, Mooh.


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## Bevo (Nov 24, 2006)

Not an expert but know a bit of the difference between car audio and guitar stuff.

In car audio the number on thing is to control the back preasure of the speaker, this allows it to react based on speaker design paramaters.
Vibration in these cabs is not good, just rattles the cars.

In Guitar the idea is different, woods vibrate the cab in different ways, MDF being bad, Baltic Birch being good. This vibration livens the sound and give the cab its own feel.
Back preasure is not that big of a deal other than in Bass cabs and then not to the same degree as car audio.

So fibreglass will absorb the vibrations and contain the preasure, not the best for our stuff.

Even home audio does not like vibration, I have seen 300 pound speakers with one 6 inch driver in it..crazy but amazing sounding.

Next time you have your amp cranked put your foot on the speaker...pretty cool eh!


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## greco (Jul 15, 2007)

Bevo said:


> Next time you have your amp cranked put your foot on the speaker...pretty cool eh!


Not cool...I put my foot on the speaker and it went right through the paper part and the speaker doesn't work at all now....


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## shoretyus (Jan 6, 2007)

I would rather cut a board than get out the fiberglass. But that's me.


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## Bevo (Nov 24, 2006)

Greco....I meant the wood part...

I would love to know what you said at that time..

Doh!
Sh*t!
Ouch!
WTF!
Damn!
Who put that there!

I don't really swear to much so don't know all the words...no jokes!


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## Xanadu (Feb 3, 2006)

Bevo said:


> I don't really swear to much so don't know all the words...no jokes!


That's alright I curse more than enough for the both of us.


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## greco (Jul 15, 2007)

Bevo said:


> Greco....I meant the wood part...


I was just having some fun..I'm sure you know that !!...9kkhhd

Cheers

Dave


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## Bevo (Nov 24, 2006)

:food-smiley-004:


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## bhnidan (Jan 13, 2010)

*Thanks for the support*

Ben here. I would like to thank all who commented the support is much appreciated. My friend and I might try to go ahead making the Cab for fun despite the potential for failure. I think our intentions are to make the top, bottom, and both sides (not the front and the back obviously) out of a one piece mold 31" wide and 29" tall. Our width is yet to be determined. I think we are going to try a modified open back and go from there. When we go ahead with this I will keep you updated on our success or failure and the final product sound quality if that may interest anyone. We plan on trying a 3/4" thick fiber glass with either 4 Eminence, Dayton, JBL or if need be 4 Celestion vintage 30 speakers. Any comments or predictions positive or negative are more thank welcomed! 

Thanks Ben

P.S If it does fail we will just pull the expensive part, the speakers, out and build a cab the traditional way haha


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## bhnidan (Jan 13, 2010)

hey Dave I was just wondering, I am new to using forums and am not a computer wizz, I am just wondering how to "Thank someone" as I notice some people are "thanked 13 out of 13 times" they post a reply. Thanks!


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## Bevo (Nov 24, 2006)

I say go for it, why not.. you will get a cool cab and it may sound good.

The comparison between the vibration of the glass and wood cabs really don't come into play if the volume is low.

My only concern coming from a past car audio guy is the joint between the wood and glass. It may not stick to well, the wood is to porus and soft.
Just thinking out loud..I would use a 1X2 inch piece of light angle iron, caulk the bottom and screw it to the wood with the longer section taking the glass..Much better bonding this way.


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## Wild Bill (May 3, 2006)

Bevo said:


> Not an expert but know a bit of the difference between car audio and guitar stuff.
> 
> In car audio the number on thing is to control the back preasure of the speaker, this allows it to react based on speaker design paramaters.
> Vibration in these cabs is not good, just rattles the cars.
> ...


Just some minor corrections, Bevo. MDF is a fine material acoustically. It has some worksmanship problems that I had described in another post but if you can get around them there will be no problems with the tone.

Also, even guitar woods are NOT supposed to vibrate! If they do they will suck energy, which translates as loudness or volume. It will be worse with the bass frequencies.

Where some of the confusion comes is that the baffle board can sometimes be designed to vibrate in sympathy with the speakers. This CAN boost efficiencies as the baffle board becomes an addition to the speaker cones! The trick is to have a baffle board thin enough to vibrate but not too thin so that it splits from high power.

Solid fibreglas could be a good material if it was thick enough to be solid. I have absolutely no experience with how thick that would have to be or how much it would weigh. Since it has such a shiny surface you might find it reflects highs a bit too strongly as they bounce around in the back. Wood cabs can have the same problem and the cure is the same. You just staple some fibreglas insulation batting to the walls, but just on two sides. This will absorb the waves before they can reflect to the opposite wall.

ANY material that is strong enough and very rigid will do fine in a cab! We used to see construction articles in the magazines for cabs built with concrete! Others used clay sewer pipe. On old trick that was quite popular in Britain back in the late 40's and 50's was to space pieces of 1/2" or even 3/4" wood with lots of wooden dowels, to give a hollow centre of at least another 1/2". Then they filled up this hollow with fine sand that had the moisture baked out of it to be very dry. 

It weighed a ton of course but for non-portable applications like home hifi they worked fabulously!

:food-smiley-004:


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## greco (Jul 15, 2007)

bhnidan said:


> hey Dave I was just wondering, I am new to using forums and am not a computer wizz, I am just wondering how to "Thank someone" as I notice some people are "thanked 13 out of 13 times" they post a reply. Thanks!


Just click on the little button that says "Thanks"...in the bottom right hand corner of the posting box.
The button is not always present.

Cheers

Dave


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## RIFF WRATH (Jan 22, 2007)

keep Google ing..........there was an "article" a few years ago where some guy's were building fiberglass enclosures but I am quite sure this was for a hi-fi application and not for instruments......


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## Bevo (Nov 24, 2006)

Bill you make good points as always, great to have your expert opinion.

Having worked with a friend changing speakers in a 4-12 cab it was surprising to note the difference in sound. Cabs were a Randall 4-12 that he modded to Vintage 30's. We changed speakers and put them in a..can't remember the name Baltic birch cab. Might of been Avatar, was made in Canada and ordered in.

The new cab was very different to the point of the amp settings needed to be changed, much brighter. The bottom end also had very strong clear bass.

Both cabs were ply and almost the exact same size, using the same speakers we got two different tones.
Bracing and construction probably had lots to do with it but it does prove that cabs can sound different even though they look the same.


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## Wild Bill (May 3, 2006)

Bevo said:


> Bill you make good points as always, great to have your expert opinion.
> 
> Having worked with a friend changing speakers in a 4-12 cab it was surprising to note the difference in sound. Cabs were a Randall 4-12 that he modded to Vintage 30's. We changed speakers and put them in a..can't remember the name Baltic birch cab. Might of been Avatar, was made in Canada and ordered in.
> 
> ...


Yeah, you've demonstrated one of the sad things about buying wood these days - moisture content! In the glory years lumber yards seemed to let their woods dry out for a much longer time. Now they can't wait to flog it off the shelf!

The moisture content affects the overall weight of the wood and also the density. That's what likely caused the tone differences you heard, although you may be right about the bracing and how the joints were glued or screwed.

There's a story going around about how some builder made a replica of the classic Fender 4-10 cab from the early 60's and gave it to Clapton to play. They were shocked when he told them it didn't sound the same as an original that he had. They thought they had replicated it exactly. Finally they thought about the moisture content of the wood being higher. They sourced some old farm pine barn board, planed it down and used that for their cab. Clapton then claimed he couldn't hear the difference!

Don't know if the story is actually an urban myth but it's been around for a while and it makes sense!:smile:

:food-smiley-004:


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## Bevo (Nov 24, 2006)

Huh, well that is interesting. We have discovered the same thing with some of our construction projects using high end woods. Some of the woodwork was shrinking...this explains that!


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## dylanreimer (Nov 16, 2009)

*Would This Work?*

Hey there Friends!

I'm building a custom cab. but the cab itself will be wood (not sure what kind yet). and i was wondering if it would work to have an acrylic baffle board? (sorry if i use the wrong lingo) i play in a... happy techno hardcore band haha. i wanna put lights behind it! 

Peace,
Dylan


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## greco (Jul 15, 2007)

Hey Dylan....sounds like a VERY cool idea!!

I'm not an expert in plastics but I'm thinking that you might need to look at using Lexan as it is tough and doesn't shatter/crack with drilling. However, it will be heavy and expensive. I'm not sure how well the various plastics will conduct all of the frequency ranges of the speaker into the cab. What thickness of plastic/acrylic were you thinking of using?

I'll be interested in what others respond with.........good luck........be sure to post a pic if you decide to try the plastic baffle concept.

Cheers

Dave


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