Hartley 24" - anyone have parameters?
I have had two in 20 cu ft sealed enclosures for many years. Now I want to build a proper enclosure as a summed sub woofer for just one of them. My guess is if I build transmission lines it does not matter much and all I have to do is make them as long as the 1/4 wavelength of the cut-off. But I still would like the parameters.
I have had two in 20 cu ft sealed enclosures for many years. Now I want to build a proper enclosure as a summed sub woofer for just one of them. My guess is if I build transmission lines it does not matter much and all I have to do is make them as long as the 1/4 wavelength of the cut-off. But I still would like the parameters.
The folks at Hartley were a little funny about T/S specs. Saying that because of the unique magnetic suspension T/S parameters didn't accurately represent the working of their drivers. I think someone subsequently tested the drivers and found the measured parameters were what would be expected. I've never seen a full set of T/s published anywhere for their drivers, but the LDSG published some abbreviated ones.
LDSG: Subwoofers 15" and Larger
Also note these specs are for the 218HS and 224HS, the newer 'heat pipe' style drivers.
John
LDSG: Subwoofers 15" and Larger
Also note these specs are for the 218HS and 224HS, the newer 'heat pipe' style drivers.
John
Member
Joined 2003
RDR,
I have a factory spec sheet on the 24 somewhere and I'm pretty sure xmax is spec'd as 3/4" p-p (unlike the LDSG spec). Like John, no T/S parameters were available from Hartley when I asked them. FS for both of mine is 13Hz which agrees with factory sheet and LDSG.
John,
At one time, I think you said you had a pair of Concertmasters. Can you describe -or better yet share a picture- of the damping material behind the driver? From years ago, I recall hearing about concentric rings of dissimilar materials, but my memory is a little too dim.
Paul
I have a factory spec sheet on the 24 somewhere and I'm pretty sure xmax is spec'd as 3/4" p-p (unlike the LDSG spec). Like John, no T/S parameters were available from Hartley when I asked them. FS for both of mine is 13Hz which agrees with factory sheet and LDSG.
John,
At one time, I think you said you had a pair of Concertmasters. Can you describe -or better yet share a picture- of the damping material behind the driver? From years ago, I recall hearing about concentric rings of dissimilar materials, but my memory is a little too dim.
Paul
I know I'm going to be sorry trying to do this from memory, but I just wanted to let you know I'll take a look and snap some photos for you in a day or two (I don't get home until late tonite).
I haven't disassmbled these, but I did poke around in the back. Mine are an older vintage, they still have alnico magnets and the woofers with dust caps. The 7" tweeter and 10" mid are in a sub cabinet with a back on it and a 1" dome tweeter on the back. The 24" is in basically a damped u-frame with fabric across the back. The damping would remind you of a low density rigid fiberglass, just not scratchy, and about 2" thick around the four sides. I don't recall there being a "boffle" on mine.
Disclaimer: That's from memory and subject to change upon photographic inspection.
John
I haven't disassmbled these, but I did poke around in the back. Mine are an older vintage, they still have alnico magnets and the woofers with dust caps. The 7" tweeter and 10" mid are in a sub cabinet with a back on it and a 1" dome tweeter on the back. The 24" is in basically a damped u-frame with fabric across the back. The damping would remind you of a low density rigid fiberglass, just not scratchy, and about 2" thick around the four sides. I don't recall there being a "boffle" on mine.
Disclaimer: That's from memory and subject to change upon photographic inspection.
John
Yes I have that article "The Big Bass Box"
In the 78 Audio Amateur. It is detailed on the construction of the labyrinth but does not explain the design.
I believe the Levinson systems used extremely large (45-50 cu. ft.) acoustic suspension enclosures, bordering of infinite baffles. Others have mounted them in walls or floors using the next room as a true infinite baffle. Hartley recommended a large open backed enclosure with some kind of acoustic absorbant. I think that is what John has? I am curious as to what the compliance of these are. I think the magnetic suspension is what allows these kinds of baffles.
Thanks for the information so far.
In the 78 Audio Amateur. It is detailed on the construction of the labyrinth but does not explain the design.
I believe the Levinson systems used extremely large (45-50 cu. ft.) acoustic suspension enclosures, bordering of infinite baffles. Others have mounted them in walls or floors using the next room as a true infinite baffle. Hartley recommended a large open backed enclosure with some kind of acoustic absorbant. I think that is what John has? I am curious as to what the compliance of these are. I think the magnetic suspension is what allows these kinds of baffles.
Thanks for the information so far.
How about Jensen Imperial horns for the Hartley
Try these for size. A pair of Jensen Imperial horns for the Hartley 24" (see pics below). To see the plans, go here (the links are at the bottom of the page):
Jensen Imperial horns for Hartley 24"
Enjoy,
Deon
Try these for size. A pair of Jensen Imperial horns for the Hartley 24" (see pics below). To see the plans, go here (the links are at the bottom of the page):
Jensen Imperial horns for Hartley 24"
Enjoy,
Deon
An externally hosted image should be here but it was not working when we last tested it.
Wow! I'm trying to downsize
from my two 20 cu. ft. enclosures. Those are enormous. Maybe OK when I used to live in a loft. I'm now thinking about putting some such huge box in the basement with a floor opening. Such craziness would probably not be tolerated by my wife. And not portable when we move.
from my two 20 cu. ft. enclosures. Those are enormous. Maybe OK when I used to live in a loft. I'm now thinking about putting some such huge box in the basement with a floor opening. Such craziness would probably not be tolerated by my wife. And not portable when we move.
Member
Joined 2003
If you can vent into the basement, do away with the box entirely and install a manifold IB in the basement. I've used mine in two different IB installations and SQ is really excellent.
My last installation was in a 14,000 cubic foot room so the Hartleys didn't have enough displacement for big movie bass but, in a smaller room or for music only, they are great.
Paul
My last installation was in a 14,000 cubic foot room so the Hartleys didn't have enough displacement for big movie bass but, in a smaller room or for music only, they are great.
Paul
Member
Joined 2003
Member
Joined 2003
IB=Infinite Baffle where a wall/floor/ceiling baffles the listening space from an "infinite" box like an adjacent room, attic, basement, etc. The manifold is just mounting for the drivers. The manifold has a few considerations (like keeping path length short and using an opening size close to piston area) but basically very simple.
So, rather than put a box in your basement, just use your basement as the box. A note of caution...if you overdrive the Hartleys, the voicecoil former will hit the backplate...so I don't recommend them for extremely large rooms like mine.
I lost a HDD and, I think, my Hartley pictures so here is 1/2 of my current attic IB (nine 15" left, nine 15" right). Google "cult of the infinitely baffled" for more info and ideas.
Gemini IB page
So, rather than put a box in your basement, just use your basement as the box. A note of caution...if you overdrive the Hartleys, the voicecoil former will hit the backplate...so I don't recommend them for extremely large rooms like mine.
I lost a HDD and, I think, my Hartley pictures so here is 1/2 of my current attic IB (nine 15" left, nine 15" right). Google "cult of the infinitely baffled" for more info and ideas.
Gemini IB page
An externally hosted image should be here but it was not working when we last tested it.
Paul, that looks impressive. I did not know what the manifold was.
My listening room is open to other parts of the house. The volume can be as high as 10,000 ft3 or as low as 4,000 ft3 if I close some sliding doors. SPLs are pretty good now down to below 30 Hz with 2 Hartleys in 20 ft3 enclosures with all doors open.
The available floor opening is in the next room just outside a large 6' x 7' opening and not too far from the main speakers. I think at an 80 Hz steep 24 or 48 db/octive crossover this should work.
My listening room is open to other parts of the house. The volume can be as high as 10,000 ft3 or as low as 4,000 ft3 if I close some sliding doors. SPLs are pretty good now down to below 30 Hz with 2 Hartleys in 20 ft3 enclosures with all doors open.
The available floor opening is in the next room just outside a large 6' x 7' opening and not too far from the main speakers. I think at an 80 Hz steep 24 or 48 db/octive crossover this should work.
Technically, I think they are still being made. The one person (!) who makes them is in North Carolina, is reputed to be very difficult to get ahold of and the 24"s go for about $1300 a pair. I think I found his contact info on the Asylum. There is a current manufacturer in Japan using his 10" fullrange, so I'm pretty sure the fellow is still in business. If you hurry, there is a set on ebay going off this morning. When I see a set on ebay, they usually go for over $1000 a pair. I think I've seen maybe three sets there in the past 6 months.
John
here is the ebay link
Hartley 24"
John
here is the ebay link
Hartley 24"
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