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Guitar cab MDF or no? Studio Monitors
Old 10th December 2010
  #1
Here for the gear
 

Guitar cab MDF or no?

whats up slutz?

After hours of research for building my first cab there is one thing I still cant seem to get a straight answer on. Will I be waisting my time using MDF over a hardwood?

I happen to have 2 4x6 sheets of 1'' thick MDF. Yes, I know, Its heavy as a mofo. But this cab wont be moving so weight is of no issue. The dimensions are going to be based on the Orange PPC212-OB and will be loaded with 2 G12H's.

I actually used to be into car audio. Build many Sub cabs made for super High SPL ranges, like 140s+ DBs. Thus the reason I have the 1'' MDF laying around. I AM willing to go buy some good hardwood if it will make the cab sound better though.

That being said, since I am loading them with 500+ dollars in speakers, I want this to send the best that It can. Would you guys recommend using the MDF for this application or should I invest in some pine?
Old 10th December 2010
  #2
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mattjew24's Avatar
 

I can't answer your question, but I think it may depend on what style you want to play most. What kind of amp head?
Old 10th December 2010
  #3
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Blues, rockabilly, punk, ska. Pretty much everything.

Head for now is a silvertone 1485. Will be getting an orange ad30 within the next 6 months. Thanks!
Old 10th December 2010
  #4
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mattjew24's Avatar
 

Quote:
Originally Posted by MikeSantor View Post
Blues, rockabilly, punk, ska. Pretty much everything.

Head for now is a silvertone 1485. Will be getting an orange ad30 within the next 6 months. Thanks!
Ooo Orange amps are niiice. I think you might as well use what you currently have! With those speakers it had better.
Old 10th December 2010
  #5
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Silent Sound's Avatar
Yes. Thick MDF is my first choice for guitar cabinets. Usually what you want from a speaker cab is something that is heavy and won't resonate, that way the speaker produces most of the sound and you don't have to worry about the cabinet picking up sympathetic vibrations thus creating it's own sounds that may make the overall sound worse.

So with that in mind, I definitely wouldn't use pine. Some cabinet makers use hardwoods, but I believe that is more for aesthetic reasons or for making them seem more "boutique". I guess if you matched the right hardwood to the right speaker using the right dimensions, you could make something rather pleasing as the sympathetic vibrations may be engineered to enhance the speakers characteristics. But that would take some considerable engineering and probably a few prototypes.

So MDF, in my opinion anyway, will be your best bet. Also, I'd make a sealed cabinet (or infinite baffle) because they are more predictable because you don't have to worry about whether the phasing of the speakers and ports are complimentary. But then again, most open back cabinets I've seen weren't designed with this in mind and they tend to work pretty well.
Old 10th December 2010
  #6
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Plywood is the normal choice for speaker cabinets, usually 10-14mm.

Quote:
Originally Posted by Celestion
GUIDELINES FOR CABINET DESIGN
A UNIQUE AREA OF LOUDSPEAKER DESIGN
A loudspeaker is usually a transducer, designed to faithfully reproduce the acoustics of the signal presented to it. An electric guitar speaker however is a creative part of the music, contributing its own character and tonality. The ‘instrument’ an electric guitar player uses is really a combination of guitar, amplifier and speaker. All three parts are vitally important to a good sound.
As guitar speakers are different, so their cabinets are different to hi-fi or PA cabinets. Deep, thunderous bass is not required (the low E of a standard-tuned lead guitar is 82Hz). High frequency reproduction is a positive disadvantage, allowing unpleasant harmonics and electronic noise to be heard. Distortion-free sound would be a disaster.
TWO ELEMENTS, A DRIVE AND A BOX
The box design is acoustically less critical than that for hi-fi or PA systems, but proper construction is essential. The cabinets should be solidly built to ensure no joint vibration (unpleasant buzzing), and be of adequate strength to withstand hard use. Remember that guitar speakers are quite heavy and amplifiers that sit on top of guitar cabs are even heavier. Internal bracing is generally not required, but battens inside the joints are good if your woodwork skills do not extend to complex corner joints, and a central bracing post can be advantageous in a 4x12.
Most quality cabs use 15-18mm plywood for the main cabinet, with MDF for the baffle (the part where the speaker(s) are mounted), but they can be constructed of any material. Many budget cabs are made of chipboard (cheap, but poor in terms of strength, ruggedness and sound) or MDF (easy to machine, but heavy and dead). Maple, mahogany and walnut are often used for high quality cabinets.
The important characteristics of the cabinet material are strength, sound and ease of use. Lively resonant materials, such as plywood or real woods, vibrate in sympathy with the speaker and enhance the sound, but should be at least 13mm / 0.5" thick, or they will unduly colour the sound. Most woods or wood composites will be strong enough at this thickness. When considering price, you should also consider cabinet finish. Cabinets can be painted or stained, or covered with a vinyl or carpet finish. Real woods finished with a stain can be very exclusive and expensive looking!
Generally, open back or sealed boxes should be used.Open back gives a looser low end with less depth, and 'figure 8' directivity (sound field looks like an 8 when looked down on from above the cab). Sealed boxes give tight, deeper low end but are more directional, giving less spread of sound. Vented / tuned / ported / reflex boxes do not generally offer an advantage to lead guitar speaker operation. If such a loading is required. it is recommended that the alignment should be chosen with care as inappropriate reflex designs can cause speaker damage. The box size is not critical. The baffle size is more important in open back boxes (larger = more low/mid presence), and for closed back boxes larger volume means deeper but looser bass. Do not use internal acoustic wadding, it is inappropriate for guitar cabs, reducing sparkle and life.
Mount the speaker securely using bolts into T-nuts, not self tapping screws. Do not overtighten so the housing rim bends. Ensure the speaker is protected from the front, as the cone is easily damaged. The speaker can be front or rear mounted.
IN SUMMARY
Plywood or real wood construction is preferable
Strong, rigid construction means no buzzes or rattles
Size is not critical
Ensure the speaker is adequately mounted and protected
Avoid air leaks if using sealed box construction
CAUTION
We do not advise mixing different impedances of driver within the same cabinet. This can lead to uneven power sharing between speakers, causing one speaker to be overdriven and damaged, while the other is underdriven.
THIELE-SMALL PARAMETERS
Thiele Small parameters are useful for controlling the low frequency response of sealed or ported cabinet systems by changing the cabinet internal volume, and port dimensions. However they are of limited use when designing a guitar speaker cabinet.
Electric guitar speakers do not reproduce 'low' frequencies (the low E string of a lead guitar has a fundamental of 82Hz) and so the frequencies at which Thiele Small parameters have significance are mostly below the operating range.
Also, the parameters are measured at very small signal levels. Guitar speakers become non linear at very low levels compared to other types of speaker, greatly reducing the significance of Thiele Small parameters in actual speaker use. Using the Thiele Small parameters of a typical guitar speaker, you will find that halving or doubling the cabinet size makes minimal difference to the response.
They have no relevance to open back cabinets.
Care should be exercised designing ported (or reflex) cabinets for guitar speakers as the increased cone excursion below the tuning frequency can cause speaker damage.
The cabinet size, shape and construction are of far higher significance than the internal volume. Cabinet design using Thiele Small parameters ignores these most fundamental aspects. Important factors include the material you make the cabinet from, the panel sizes and shapes, how they are joined, how the cabinet is finished, the mounting of the speaker, etc. These, not Thiele Small parameters are the critical factors in the design and ultimately the sound of a guitar speaker cabinet.
Old 10th December 2010
  #7
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This is the exact problem Im having. Half the things I read say MDF is a great choice, The other half say ply is better. Damn counter dictions...
Old 10th December 2010
  #8
Gear Nut
 

If you use MDF, don't EVER drop it. That's why plywood is the material of choice, it'll handle the road.
Old 10th December 2010
  #9
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Quote:
Originally Posted by Flogger59 View Post
If you use MDF, don't EVER drop it. That's why plywood is the material of choice, it'll handle the road.
Indeed. All commercial speaker cabs use ply, all roadcases use ply. Hint hint.

It is agreed by most that in the case of guitar cabs, the acoustics of the cabinet are less important than it's ability to be thrown in and out of a tour bus a hundred times a year or more.

Considering the mic always ends up an inch in front of the speaker, I would say that this is a fair opinion.
Old 11th December 2010
  #10
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Ron Vogel's Avatar
 

If you can tune the cab, then use solid pine (I love to hear the wood).

But really...I'm a lunatic...don't listen to me, use MDF.
Old 11th December 2010
  #11
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Great Info Guys.

Considering This will be put in the man cave and never move (Basicly it dosnt have to be that durrable) I dont think there is any reason for me to not use this 1inch MDF I have laying around. After I Build this bad boy I will throw up some pics. Thanks everyone!

Ps, Ron V, I live about 20 minutes south down 55 from you...
Old 11th December 2010
  #12
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Ron Vogel's Avatar
 

mine...and I am a lunatic
Please help me name my new custom amp!!!
Old 11th December 2010
  #13
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kafka's Avatar
Quote:
Originally Posted by Flogger59 View Post
If you use MDF, don't EVER drop it. That's why plywood is the material of choice, it'll handle the road.
+1. MDF has absolutely no fiber strength, and will break when subject to any kind of bending. Think compressed cardboard. There are some appealing sonic qualities because it's totally dead and very heavy, but those qualities don't extend to durability. MDF is more suited for speakers that won't be moving around, like stereo speakers. For a guitar cabinet, my first choice would be for plywood, and the second would be for southern yellow pine (a softwood, not a hardwood). However, if it's going to stay in your man-cave, then there's no reason not to use the MDF. It's cheap, and if you don't like it, it'll give you a little experience so you can go back and make the next one better.

As far as hardwoods go, they're really heavy, and I don't think I've heard anyone say they're particularly suited as far as sonic qualities. Mahogany is about as dense as southern yellow pine, so I can see it might make an ok material. Maple and cherry are very heavy and very hard. They're pretty, but I don't think they're necessarily any better sounding. And in all cases, plywood is the most flexible, most resiliant material you can use.
Old 11th December 2010
  #14
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Count me in the "No MDF" camp.

Plywood is much more more resistant to wear and tear, and wieghs a heck of a lot less.

MDF is used in Hi-Fi, home theatre, audiophile and studio monitor construction. In these applications it's density and consistency are of real value, and the structural integrity of the material isn't challenged because the speakers will normally stay indoors, rarely be moved, and drivers will not produce anywhere near the kinds of vibrations that an instrument amp will generate.

A high-powered guitar cab will get moved around, rained on, liquids spilled on, dumped or even dropped, and will vibrate like hell. Ply excells for these situations.

The Celestion quote above mentions bracing. That would be where I'd look of you were trying to get closer to MDF's tonal properties using plywood. Strategic bracing to add rigidity and minimize resonances.
Old 11th December 2010
  #15
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From what it sounds like MDF IS the product for me. It wont be moved, EVER. It will be covered in tolex so I dont have to worry about spills. And Above all, I have it so Thats one less thing I have to buy.

If I ever build a cap that will be traveling with me, Then Ply it is. For my application, from the decision I have made from everyone opinions on the 2, MDF will be fine...
Old 12th December 2010
  #16
Gear Nut
 

Not to be alarmist, but from Wikipedia:

Safety aspects of MDF

When MDF is cut, a large quantity of dust particles are released into the air. It is important that a respirator be worn and the material be cut in a controlled and ventilated environment. It is a good practice to seal the exposed edges to limit the emissions from the binders contained in this material.
Formaldehyde resins are commonly used to bind MDF together, and testing has consistently revealed that MDF products emit urea formaldehyde and other volatile organic compounds that pose health risks at sufficient concentrations, for at least several months after manufacture. [4][5][6] Urea formaldehyde is always being slowly released from the surface of MDF. When painting it is good idea to coat the whole of the product in order to seal in the urea formaldehyde. Wax and oil finishes may be used as finishes but they are less effective at sealing in the urea formaldehyde.[2]
Whether these chronic emissions of formaldehyde reach harmful levels in real-world environments is not yet fully determined. The primary concern is for the industries using formaldehyde. As far back as 1987 the U.S. EPA classified it as a "probable human carcinogen" and after more studies the WHO International Agency for Research on Cancer (IARC), in 1995, also classified it as a "probable human carcinogen". Further information and evaluation of all known data led the IARC to reclassify formaldehyde as a "known human carcinogen"[7] associated with nasal sinus cancer and nasopharyngeal cancer, and possibly with leukemia in June 2004.[8







Old 12th December 2010
  #17
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Pay someone else to cut it or make sure you have a very good mask when you do.

Since weight is not an issue and you already have the MDF gop with it.

Reality check:

Most commercial speaker cabinets are built of MDF these days because it is CHEAPER.

Higher quality stuff should be built of baltic 1/2" or 3/4" marine grade low void plywood, but very often isn`t.
The marine style ply is very light in relation to its strength and durability, but you do need to brace all the panels, especially if it is for a bass cabinet.

OP: Remember if this is actually for guitar and in a studio/rehearsal romm, you might find you will be better off going for high efficiency low acoustic resistance speakers.
I built a clone of a `53 wide panel Deluxe and put a 20 watt 12" Celestion G12S in it.
Very efficient, so it is LOUD even with 11 watts, but also has a great cone breakup at just the right level for in a smallish room.
Old 12th December 2010
  #18
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kafka's Avatar
Quote:
Originally Posted by Fast Frets View Post
Not to be alarmist, but from Wikipedia:

Safety aspects of MDF
Not alarmist at all. While man-made products present their own chemical hazards, a dust mask is necessary for all woodwork. Some woods are toxic. This is a natural defense against disease that trees have evolved. Trees are also repositories for any poisons or pollutants in the environment. Wood dust can cause severe allergic reactions in the respiratory system, and prolonged exposure can lead to cancer due to micro-scarring, even when no toxins are present.
Old 12th December 2010
  #19
Gear Head
 

Woodworking is a hobby of mine, but before I use MDF I make sure that I can hook the table saw up to a dust collector. If you're using a handheld circular saw you can connect it to a shop vac. I like to use a double filter: a paper bag that's sold for fine drywall dust, in addition to a pleated cartridge filter (HEPA filters made of Gore Tex are great). Otherwise the pleated filter will clog almost immediately.

As far as material choice, my understanding is that MDF is used in home theater and audio speaker cabinets because it is so dense and won't resonate or color the sound as much. On the other hand, a guitar cabinet is not a hi fi speaker. Clapton is said to have experimented with various materials for the cabinet of his reissue tweed twin combo, finally settling on recycled wide pine boards from church pews in the south. Now that's some serious mojo, but the truth is that the Fender Custom Shop amp you can buy is the same one they ship to EC (according to Mike Eldred at Fender).

Anyway the point is that pine can color the sound since it will resonate, kind of like tonewoods on a guitar draining and reflecting some frequencies from the strings. Plywood will move less than pine, and MDF will move even less. So it all depends on what you like in the sound. And of course the choice of open back versus closed back is a bigger issue than the material it's made of.

BTW even 1" MDF is flexible so depending on the size of the box it might be necessary to brace it to keep it flat. For instance, you really can't build case work or bookshelves out of 3/4" MDF.
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