enclosure for Altec 904 8A

[GM]

Greets!

You're welcome!

8 ohms series R results in half space max flat, so F3 = ~35 Hz. MLTLs are inherently better damped than a much more rectangular cab and any of the 604s will work in this one, just the amount of series resistance changes, though of course for max LF BW, any model will need bigger cabs tuned to Fs at the expense of efficiency.

LOL, yeah, LF can be fun to play with when it's not being destructive. I've got an invite to go visit Tom Danley's 'skunkworks' to see his latest secret project that could be REAL entertaining/destructive: http://www.diyaudio.com/forums/showt...65#post1115465

GM

[GM]

Oops!

Just noticed a typo, the driver position should be 36.93", not 35.75".

[GM]

Greets, part deux!

'Best' 604-8G T/S max flat based on published specs is Vb = Vas, Fb = Fs, or 21.98 ft^3/25.8 Hz:

L = 65.06"
WxD = 584.25"^2 - recommend 30.75" W x 19" D
driver up from bottom = 36.93"
vent = 8" dia. or other equal area shape x 1.5" long near the bottom for flattest response.

Damp to suit, recommend lining top, back and one wall with 1" acoustic fiberglass insulation or similar.

GM

[RonSSS]

GM,

I'm intrigued by your design suggestion for a 904 Cabinet.

Could you point me at some literature explaining this type of design?

Thanks,

Ron

[GM]

Greets!

Hope you have plenty of time!

The basics: http://www.geocities.com/rbrines1/

The physics if you want to delve into it at the wave propagation theory level and/or get the 'goods' to do sims: http://www.quarter-wave.com/

GM

[RonSSS]

Thanks GM

I'll start reading.

Ron

[Sibi]

Hello,

thank you guys for the huge feedback regarding my question!

@RonSS
You recommend to mount the 904 8A in an 2 cubic feet enclosure ? in an older post you mentioned 2,5 cubic feet ?

@bowtie427ss
I did not hear the 604 yet and therefore I do not want to recone the speakers.
Nevertheless it seems to me, that changing the diaphragms is mandatory.

@GM
Exact! Basically, I do not want to use a subwoofer in combination with the 904 8A?s.
Assuming your recommendation is not a ?standard? bassreflex construction ? what means ?MLTL?? A modified transmissionline? I?ll start reading too!

Maybe some construction details or plan would be helpful to envision the whole dimensions.

Thanks again,

Thomas

[GM]

Greets!

Plans?! It's as simple as it seems, a tall rectangular pipe with a driver at ~ear height when seated and a vent down next to the floor. Its length is long enough for 1/4 WL TL action to occur, mass loading the vent and why it's called a mass loaded transmission line (MLTL, or in earlier times a tower or column). If you sim this Vb/Fb alignment in a typical box program the vent will be longer for a given area, so if you used its calc'd vent in a MLTL the Fb would be lower/more rolled off.

GM

[Sibi]

Ron,

LOL!

BTW, how do you feel about GM's suggestion? After reading a couple of the articles (links) mentioned in GM's post, it seems to me that it is a good possibility to get more bass out of the 904 8A's.

Greetings

Thomas

[Sibi]

GM,

thanks for explanation!

Thomas