Hello
I wish to build a cabinet for my pair of Hartley 24" speaker (the one with pipe sticking out from the middle)
It would be cross over at 150 Hz.
Any suggestion on the parameters of the cabinet?
I am new to speaker building, from searching, the Fs = 28-29 Hz, Q = 1.1 - 1.2
Could anyone suggest the size of the cabinet to be build?
Thanks alot!
I wish to build a cabinet for my pair of Hartley 24" speaker (the one with pipe sticking out from the middle)
It would be cross over at 150 Hz.
Any suggestion on the parameters of the cabinet?
I am new to speaker building, from searching, the Fs = 28-29 Hz, Q = 1.1 - 1.2
Could anyone suggest the size of the cabinet to be build?
Thanks alot!
Hi Sushii,
U need at least three parameters to calculate box size.
Fs, Vas and Qts
Now it's the Qts missing. But I bet if it's not in the TS-database, u won't find it anywhere else.
http://www.thielesmall.com/database.asp
If Q=1.1~1.2 is the Qts, it'll only be useful either in open baffle or in huge sealed box. We're talking 200+ liters of volume.
U need at least three parameters to calculate box size.
Fs, Vas and Qts
Now it's the Qts missing. But I bet if it's not in the TS-database, u won't find it anywhere else.
http://www.thielesmall.com/database.asp
If Q=1.1~1.2 is the Qts, it'll only be useful either in open baffle or in huge sealed box. We're talking 200+ liters of volume.
Those are definitely some odd looking drivers, and perhaps fairly rare too.
Without being able to obtain any parameters, and for a project this large, I'd say testing for Thiele-Small's yourself might be in order. A Woofer Tester 2, or anything similar, would probably provide you with the information you need. However, if Qts is as high as you say it is, banana's statement regarding OB or IB are probably correct. On the other hand, I think I came across some older guy using a pair of these in separate TL's. I think they went up through his attic, if I remember correctly, with the drivers coming out of the walls in his living room.
Without being able to obtain any parameters, and for a project this large, I'd say testing for Thiele-Small's yourself might be in order. A Woofer Tester 2, or anything similar, would probably provide you with the information you need. However, if Qts is as high as you say it is, banana's statement regarding OB or IB are probably correct. On the other hand, I think I came across some older guy using a pair of these in separate TL's. I think they went up through his attic, if I remember correctly, with the drivers coming out of the walls in his living room.
An externally hosted image should be here but it was not working when we last tested it.
Hi,
I'd say definitely open baffle. A box with no back is folded open baffle.
The sort of drivers you put into walls between rooms for uber bass.
edit : I'm estimating Vas is an utterly monstrous figure.
/sreten.Any closed volume larger than this folded application uses would be sufficient!
http://www.diyaudio.com/forums/showthread.php?postid=993847#post993847
b
I wanted to say Vas but written Qts...... that's a typo
I have a speakerworkshop jig that could measure Vas. But I use added mass method that might damage the cone. Knowing the exact Vas is not necessary, since it's going to be enormously large.
There's one more opinion, build the largest box u can have (say 300~500Ltr), and then add flow vent.
Are u crossing it actively? If so, Linkwitz transform will also do.
I have a speakerworkshop jig that could measure Vas. But I use added mass method that might damage the cone. Knowing the exact Vas is not necessary, since it's going to be enormously large.
There's one more opinion, build the largest box u can have (say 300~500Ltr), and then add flow vent.
Are u crossing it actively? If so, Linkwitz transform will also do.
Contact for Hartley
http://www.audiolab1.com/
Richard has been known to post on this forum; suggest a Search
El Gippo
howard99 said:
http://www.audiolab1.com/
Richard has been known to post on this forum; suggest a Search
El Gippo
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.
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.
Hello,
Did you build the seal box?
I am planning to do the same project and I am looking for information.
Thank you,
Victor
Hartly 24 inch
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.
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.
When they build a 3400 l cabinet at a university lab this can't be that wrong.
Caltech Music Lab Home Page
Caltech Music Lab Home Page
Nice sized closet!
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.
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.
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
Last edited:
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.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.