Enclosures for Hartley 24"

[JohnL]

I second Howard99's suggestion, 30"x30"x20" box with no back. Line the sides of the box with something absorbative and then sit back and enjoy the sound. I have a set of Hartley 24s, and I've never heard anything like them.

If you want a sealed box of some sort, they are going to be huge (~20 cubic feet each). If that's an option for you, you could give that a try.

[Sushii]

Thanks alot for the advice, I will try the seal box method...

From my calculation, I think I will build a box of 40' h x 30' w x 29' d

That should give me 24 cuft. is this correct?

Thanks alot!

[vmcfer]

Originally Posted by Sushii

Thanks alot for the advice, I will try the seal box method...

From my calculation, I think I will build a box of 40' h x 30' w x 29' d

That should give me 24 cuft. is this correct?

Thanks alot!

Hello,
Did you build the seal box?
I am planning to do the same project and I am looking for information.
Thank you,
Victor

[Wavebourn]

Originally Posted by JohnL

If you want a sealed box of some sort, they are going to be huge (~20 cubic feet each). If that's an option for you, you could give that a try.

Is bathroom sufficient?

[John Busch]

OK

This is an open baffle woofer, like it or not. No reasonable box size will provide equal bass extention. Just the way it is. So why fight it?

You only have to deal with the minimum distance requirements from the back wall, and if you build a huge box as has been suggested, you already are placing the baffle front far enough away from the back wall anyway.

A 26" width baffle with a 6" wing depth and a 40" baffle height will give you more or less flat bass into the lower 30's at a 6 db per octave roll off below that. No box problems or reflections any greater than what a big box will create. Try 3rd order butterworth around 125 Hz to create a standard low pass and go on to what ever midrange you like. This woofer could work well with a quality 8 inch or larger full range.

Your only worries are controlling the full range typical upper frequency rise and establishing the proper pad (if any) to match the woofers efficiency with the full range. A simple pad. And you can take care of the full range rising repsonse (and they ALL have a rising response) with a simple inductor-resistor parallel trap.

You have the makings of a great, yet simple full range speaker. Just don't over think the situation.

[el`Ol]

When they build a 3400 l cabinet at a university lab this can't be that wrong.
Caltech Music Lab Home Page

[John Busch]

120 cu ft.! Wonder what the F3 ended up being?

IIRC, the X-max of the Hartley 24" isn't all that much, 2 or 3 MM, or close to that. But with a surface area equal to a couple of 18" woofers, you don't need much, even in an open baffle set up.

And if you have a stereo pair you will have enough area to play into the mid twenties with out much if any roll off. Should be pretty efficient too.

[GM]

Originally Posted by howard99

Hart;ey recommends a fairly small box with no back with stuffing, I think the box is 30"by30"by20". Richard at Hartley, Audio Lab in NOrth Carolina can help you with that. It is his design, otherwise that box is going to be huge.

Indeed, in a '54 issue of Radio Electronics, H.A. Hartley recommended the classic reflex formula to determine cab net Vb which only uses Fs and vent area = Sd or ~61 ft^3 [1727+ L] assuming 28 Hz/10" [25.4 cm] effective radius/0.75" [1.9 cm] vent length; though a dimensionless cutaway drawing of his own open back cab design shows it with a series of stretched screen filters to decay away the back wave. Assuming his later cabs are the same basic design, then it would be ~8 ft^3 [~226.5 L] net, so well stuffed, the current recommended open back cab should be an acceptable substitute.

GM

[cyclecamper]

Originally Posted by Sushii

From my calculation, I think I will build a box of 40' h x 30' w x 29' d
That should give me 24 cuft. is this correct?

No, that would be 34800 cubic feet. Which would also work for a very low Qts, and puts the "infinite" back into "infinite baffle"

Unless you meant that to be in inches,
1 cu ft = 1728 cubic inches
24 cu ft = 41472 cubic inches
40" X 30" X 29" = 34800 minus the space occupied by the driver and enclosure wall thickness and internal brace.
So no, that's still wrong, it need to be bigger.

[cyclecamper]

All the Hartleys I ever saw were in open-back baffles of some kind.

Probably the wrong choice for a tapped horn, but it would be nice to capture that back wave in some additive fashion.