Need good drivers for 'copper' speaker cabinet

[kstlfido]

Hello fellow diyaudio peeps-

Some of you might recall my copper speaker at Burning Amp. It is one of a pair that I put together for my camp at Burning Man. The speaker cabinets were not assembled by me; I just 'dressed them up' with copper and brass; and added the tripod stands. Cabinets are made on 3/4" MDF.

While on the playa, the drivers blew out. They were fairly cheap University 8" full range units from the 60's (model 308's).

I would like to find a suitable replacement driver; possibly a full range unit that can handle al least 60 watts. I intend to add some form of tweeter assembly above or mid/tweet in the center. It needs to be fairly durable as it will be exposed to the hot desert elements for a week.

I calculated the internal cabinet volume, appx 1.25 cubic feet. There is a port (3in dia. X 3in long) but this can be closed or changed if need be. Driver size can be anything up to ~9".

I realize this is not going to go down too low; I would be lucky to get to 100hz!

I am not much of a speaker designer and there seems to be a wide choice of 8" units.

This is how they appeared on the playa, below. If anyone can help, I would be grateful!

Cheers- Kent

[454Casull]

Put some thin subs on the sides in the form of wings and you have yourself a TIE Fighter.

[musgofasa]

Sounds like a job for the pioneer BOFU to me.

http://www.parts-express.com/pe/show...number=290-045

Lots of other options too. I believe you could seal off the port, maybe do a little tweaking or possibly just add tweeter and have something that sounds pretty good. These drivers have a pretty awesome reputation considering their price.

Good luck
Robert

[sreten]

Hmmm .......

8" units that are genuine bass / midranges are increasingly rare.

http://www.parts-express.com/pe/show...number=296-175

Looks relatively easy to work with according to PE sample
measurements, i.e. no large or narrowband peaks / dips.

http://www.parts-express.com/pdf/296-175g.pdf

It will get you down to at least 40Hz but genuine freefield as
in your picture is an entirely different matter to use in a normal
sized room.

My experience of Audax drivers is they are very robust and take
abuse. An 8" fullrange by default must have a delicate voice coil.

Its ideal for your box size and IMO a 2" diameter 5" long port.
Thats ~ 33Hz tuning though you can go up to ~ 40Hz.
Lining your port with 1/2" foam is workable, ~ 37Hz.

The tweeter one has to suggest :
http://www.parts-express.com/pe/show...number=297-409
Just because of the packaging.

It needs a proper crossover at > 3kHz, simple will not work
well nor will trying to cross lower, 5th harmonic distortion
has a peak at 1.5Khz you neeed to avoid.

I suggest you read up on Baffle step compensation and
diffraction effects of cabinets if you want a good crossover.

You may be able to get away with a single large inductor
on the bass driver, this will be a lot larger than than a
"textbook" cross over value, due to response tailoring.

http://www.parts-express.com/project...m?project=Sc51

Is worth perusing as an example of how not to go about
crossing over two drivers, off the shelf does not work.

http://www.rjbaudio.com/Audiofiles/FRDtools.html
http://www.geocities.com/woove99/Spk...esigningXO.htm

As a minimum experiment with various series inductors to get
the driver ~ flat and bring in the tweeter at 3KHz, using an
L-pad to set its level. Tweeter c/o 2nd or 3rd order electrical.

/sreten.

[infinia]

Hi
My guess is that sheer SPL and "survival" is more important than bass to this application? If so, then a BSC design is out.
Assuming that then, a 8" pro driver that rolls off quickly to match the tweeters sensitivity would be ideal. But after mulling that over, you might probably want a 1" compression tweeter with a new DIY biggish copper horn?

[sreten]

Originally posted by infinia

.... If so, then a BSC design is out .....

Hi,

Quality versus quantity (SPL) is always an issue, I go for the first.
Active (line level) BSC is another option if the ampifier chain is fixed.

/sreten.

[infinia]

I go to the application/requirements first. If you can't hear it or if it busts down, then quality doesn't matter in the end really. The same shoe rarely fits all feet.

[sreten]

Originally posted by infinia
The same shoe rarely fits all feet.

Indeed, that is the point , /sreten.

[Pano]

Those are some great looking "Steampunk" speakers!

I did a pair of copper faced speakers, once. Tall and narrow, the theme was Tiki. My wife did the copper bas-relief with the tweeter in the tiki's mouth, woofer in it's belly. (see my avatar for an idea of her work)

Wish I had taken photos.......

Good look with your project - I hope you find drivers as sturdy as those cool boxes.

[kstlfido]

Hi Chaps-

Thanks for great ideas & driver selections. Very helpful!

Yes, I can pad the interior. There is some carpet glued to some of the inside panels already. I would like to keep away from paper cones and foam surrounds due to the sun and elements. I like that teardrop tweeter- seen it before. Yes, 'survival' is more important than bass for this project.

Cosmetics- one idea was to use a translucent cone-
http://www.parts-express.com/pe/show...number=290-055
I had an idea to 'light' the interior, this would look cool. Hey, it's Burning Man, fun night-time lighting is big part of the event! But coupling it with the teardrop shape tweeter will leave a big suckout in the 2-3k range...

Hmm....a diy horn? Now you got me thinking! It might get kind of long- I need to do some modeling to figure out sizes.

Yes, the term steampunk has been used before describing these. I prefer the term 'Jules Verne-esque'.