Thread: 2x12 speaker enclosure plan

G'day.

I'm not sure that a pair of Greenbacks should go in a sealed enclosure...
I'm not an expert by any means, it is just that I have something in the back of my head that says "that doesn't sound right."

sealed enclosures are not that good for guitar
the open back gives a much more 3d sound
sealed enclosure gives directional punch and focus - ok if your being miked up through a PA but is pretty limiting in most other situations

size is not that important so just make a box that fits both in and aint too heavy - use any 2x12 fender combo cab as a template for dimensions

get that from the fender amp field guide

Thanks Ray, I just needed that to be confirmed.

I'd have to "question" that, considering most extn cabs are closed back. What needs to be determined is whether the speakers efficiency is enhanced or compromised by either design.

One of the nicest, most balanced sounding "quads" I've heard is a friend's old Mesa......the lower half is closed, the upper open and at the time it was built, Mesa were fitting it out with 150Watt speakers giving it a 600W rating.

reguarding greenbacks in a sealed enclosure, thats exactly what a marshall cab is, but with 4 greenbacks not 2.

im not sure what type of music you play, but a sealed enclosure will give you a tighter sound, where the open backed will give a looser sound. the closed back will be veery directional, and not quite as loud. the open backed design will fill the room up, as it is bi directional(front and back).

i'd probably do an open backed design, to keep it simple. on close backed cabs the volume (space, not sound level) will effect the sound you get, meaning you could make it not sound great (adding a hump in the mids would be something easy to do).

if i were going to make a cab for it, i would determine the size of the baffle (piece the speakers are mounted on) and then design the cab around that.

the forum below has some photos of some work people are doing, which should get you started, and has plenty of threads dealing with questions reguarding cabs and combo's

http://music-electronics-forum.com/f...splay.php?f=24

Why not cut your losses and make an enclosed cabinet with a removable rear panel. It would have to be well made and seal well thou. I have found low volume practice amp style things work best with open back, you get a bit more bang for your buck at lower volumes. If your worried about projection what about directional ports?
Anyway, you could fairly easily try both options and see which one floats your boat. I dont know that there is a RIGHT or WRONG way to do it, just like everything else luthiery there are heaps of options and proponents and oponents to everything you do.

As for the design. There are a few software tools that you can download where you input the specs of the driver and can play around with frequency response, volume, sealed vs ported etc and work out the design. I haven't used any of these yet, but I think that one day I might revisit my 15" bass cab and see if the driver could be in a better cab.

Peter

i was going to mention the software, but i dont think the greenback's thele/small peramiters are available, making it useless. for a bass cab it is nessisary, but for guitar not so much so imo.

if anyone does want to use some, try win isd, works perfectly and is free, just search on google.

Originally Posted by praga37

I've got this set of Celestion Greenbacks (25w) with which I plan to build a sealed enclosure to be used with my new Orange Tiny Terror amp. I need directions for a plan to build such a project.

If you post the T/S specs for the drivers I can calc a design for you. Do you want an isobaric configuration (in 4th-order bandpass box) or simple sealed or vented box (depending of driver specs).

Regards,

Mark

i just checked the celestion website, and they dont release their thiele/small parameters for guitar speakers as they say that their guitar speakers are not linear enough to produce a meaninful and repeatable result. otherwise i'd plug them in. i did also read on another forum that greenbacks seem to sound best in a closed back design, otherwise they become very muddy.

i'd probably make the cab around 420 by 900 at the front, and maybe 350mm deep, depending on what you make it from, and do a closed back design. it really is unfortunate that the proper numbers aren't there to make a cab design using them.