Short Thor is also on that thread -post 122. I've attached Dave's drawing of it. Small THor has not yet been drawn -it's in the waiting list for Dave's Thor Revisited article I understand, but it's dimensions are described in post 231. It's 48" tall, 7.5" wide x 10.5" deep (internal). The tweeter centre is 12" down from the top of the line. The port is on the front panel, 3" diameter, 4" long, positioned 4" up from the internal base. Stuff 0.35lbs ft^3 from the top to 20" above the internal base.
However: you design and engineer an enclosure for a specific driver combination, so you can't just stuff any drivers into an enclosure and hope it will work -if only life were that simple! Send me a private email and we'll see if we can come up with something specifically for the drivers you're looking at.
Of course, when you get to gigantic sized rooms things start to vanish. A Linn Kan mini-monitor in Wembly Arena doth not a sensible combination make. But as a room becomes smaller, low frequencies are progressively attenuated, meaning you need more power needs to be fed into the speaker if you want to maintain bass levels. So, up to a point, a small room with sound 'louder', but only until you reach that point where attenuation begins. From then on, it's dependant upon how much air your drivers can shift (preferably without distorting) and how much current your amplifier can pump. A big driver will almost invariably have an easier time of it than a small one, in any size room (though common-sense dictates a monster speaker is not always appropriate in a small room, usually more for practical than for sonic reasons). There's no accurate way of simulating a room's resonant qualities, as you note, because although we can get a good idea from the dimensions, it's construction materials and furnishings all play a big part. There's still art there in this respect.
Best
Scott
However: you design and engineer an enclosure for a specific driver combination, so you can't just stuff any drivers into an enclosure and hope it will work -if only life were that simple! Send me a private email and we'll see if we can come up with something specifically for the drivers you're looking at.
Of course, when you get to gigantic sized rooms things start to vanish. A Linn Kan mini-monitor in Wembly Arena doth not a sensible combination make. But as a room becomes smaller, low frequencies are progressively attenuated, meaning you need more power needs to be fed into the speaker if you want to maintain bass levels. So, up to a point, a small room with sound 'louder', but only until you reach that point where attenuation begins. From then on, it's dependant upon how much air your drivers can shift (preferably without distorting) and how much current your amplifier can pump. A big driver will almost invariably have an easier time of it than a small one, in any size room (though common-sense dictates a monster speaker is not always appropriate in a small room, usually more for practical than for sonic reasons). There's no accurate way of simulating a room's resonant qualities, as you note, because although we can get a good idea from the dimensions, it's construction materials and furnishings all play a big part. There's still art there in this respect.
Best
Scott
Attachments
SilverJS said:
I modeled a pair of RS180s in a Fat Thor (using the old spreadsheets) If stuffed to .75#/foot, it rolls off rather early. I suggest either stuffing only to .25#/ft or shortening the height of the cabinet by 6" keeping the position of the bottom of the divider the same sutffed to .75#/ft (the angle will change, but the taper ratio will not). Either way you'll get in room extension to 30 Hz or below. the tradeoff will be passband smoothness (short line) vs deeper extension (light stuffing Fat Thor)
modeled response:
All of which confirms the ludicrous quantity of stuffing used in the original enclosure. If a cabinet needs more than 0.5lbs ft^3 of stuffing as an absolute maximum, it's not properly designed and should be scrapped in favour of something that is.
A tweak I can suggest to the above: use the 0.25lbs ft^3 suggested by Bob, but stuff only the first half of the line, across the top, and down the first 5" of the second half of the line. The stuffing will then attack the harmonic modes whilst preserving the Fundamental, the point of maximum velocity of which occurs at the terminus. So the response shouldn't rise as much as indicated in the frequency responses shown.
Best
Scott
A tweak I can suggest to the above: use the 0.25lbs ft^3 suggested by Bob, but stuff only the first half of the line, across the top, and down the first 5" of the second half of the line. The stuffing will then attack the harmonic modes whilst preserving the Fundamental, the point of maximum velocity of which occurs at the terminus. So the response shouldn't rise as much as indicated in the frequency responses shown.
Best
Scott
SilverJS
I have also done some modeling for the Modula in a MLQW case. I'd be glad to share with you. I have trouble posting the views here: lack of software on my end and loss of resolution. Send me an e-mail and I'll send it along.
Scott,
One of the things I've focused on in my sim's is a "flat" response. I think I need to relax that somewhat in order to make the most of room lift...thereby arriving at a "flat" in room response. I'm looking forward to Martin's revisions.
I have also done some modeling for the Modula in a MLQW case. I'd be glad to share with you. I have trouble posting the views here: lack of software on my end and loss of resolution. Send me an e-mail and I'll send it along.
Scott,
One of the things I've focused on in my sim's is a "flat" response. I think I need to relax that somewhat in order to make the most of room lift...thereby arriving at a "flat" in room response. I'm looking forward to Martin's revisions.
I know what you mean Ed. Martin's new sheets help enormously here, because you can now get the ideal roll-off for your own room's gain, rather than attempting a generic solution a la the commercials. About 4db below 100Hz is a typical generic response. Not particularly ideal, but gets into the approximate ball-park.
When I post a design on forums (increasingly infrequent), I usually go max-flat. A) That's what many people expect to see, and it's time-consuming explaining why the bass looks like it's drooping every time, and B) all rooms are different, and provide different levels of LF gain. Therefore better in my view to provide a known flat anechoic situation when making a generic, rather than a specifically tailored speaker that multiple builders can then adjust to suit their own wildly differing rooms, usually by modifying vent dimensions.
Cheers
Scott
When I post a design on forums (increasingly infrequent), I usually go max-flat. A) That's what many people expect to see, and it's time-consuming explaining why the bass looks like it's drooping every time, and B) all rooms are different, and provide different levels of LF gain. Therefore better in my view to provide a known flat anechoic situation when making a generic, rather than a specifically tailored speaker that multiple builders can then adjust to suit their own wildly differing rooms, usually by modifying vent dimensions.
Cheers
Scott
Small Thor Drawings
Hi guys, I am new to this forum so please bear with me, I have read much information about Thor projects. I recently built a pair of Odins my first pair of speakers
I would like to give the Thor a try and I am looking for drawings for the small Thor, if any body can help, it would be greatly appreciated
Hi guys, I am new to this forum so please bear with me, I have read much information about Thor projects. I recently built a pair of Odins my first pair of speakers
I would like to give the Thor a try and I am looking for drawings for the small Thor, if any body can help, it would be greatly appreciatedPost 296 on this page, in the middle
Here you go. I built the short thor and am a big fan - though I haven't heard the "small". Let us know how it goes!
Here you go. I built the short thor and am a big fan - though I haven't heard the "small". Let us know how it goes!
hi guys, i need a little help. i'm pretty new to the hobby and my original plans were to try my hand at designing a set of dipoles somewhat mirroring SL's orions. however i ran across an unbelievable deal on a set of thors with the upgraded xover and wanted some tips to maximize their performance in the standard cabinets. the consensus seems to be the cabinets are excessively stuffed. how much should i take out (please be as specific as possible)? anything else you guys recommend? would it be worthwhile making a new set of cabinets, and if so does the original xover work well in this design? i'll stop there, i dont want to get ahead of myself on other cabinets because i really do want to maximize their performance as they are.
thanks,
Andres
thanks,
Andres
Scott has described remedial steps to improve the stock box (empty the last half of the line IIRC -- Scott??).... from the feedback from people that have built the new variations it is well worth building them. All 3 designs were restricted to a baffle width the same as the original to maintain compatibility with the origina;l XO.
dave
dave
Hi guys, first of all thanks to Patric again for help with Small Thor drawings.
Again I hope somebody will be able to help with my question. As I originally intended to build the SEAS Thor I purchased 25mm A-grade plywood, which I would now like to use for the small Thor, which is designed, around 19mm material, herein lies my query: Scott and Dave have designed the Small Thor to be nine inches, across (external dimensions) using 19mm side walls, this is in keeping with the original Thor dimensions, however D'Appolito uses 25mm side walls. Resulting in an internal dimension discrepancy of half and inch or 12mm aprox. Yes I can simply apply the extra 12mm to external dimensions in so doing keeping internal the same as Scott and Dave's Small Thor. However I am trying to keep the speaker as slim as possible. So can somebody tell me what sort of results I could expect from reducing the internal width down from Scott and Dave's model and or can this loss in volume be added to the rear of the cabinet?
Many Thanks
Niall
Again I hope somebody will be able to help with my question. As I originally intended to build the SEAS Thor I purchased 25mm A-grade plywood, which I would now like to use for the small Thor, which is designed, around 19mm material, herein lies my query: Scott and Dave have designed the Small Thor to be nine inches, across (external dimensions) using 19mm side walls, this is in keeping with the original Thor dimensions, however D'Appolito uses 25mm side walls. Resulting in an internal dimension discrepancy of half and inch or 12mm aprox. Yes I can simply apply the extra 12mm to external dimensions in so doing keeping internal the same as Scott and Dave's Small Thor. However I am trying to keep the speaker as slim as possible. So can somebody tell me what sort of results I could expect from reducing the internal width down from Scott and Dave's model and or can this loss in volume be added to the rear of the cabinet?
Many Thanks
Niall
Hi guys back once more, with yet another question on cabinet volume. to be as brief as possible I want to mount the drivers, not directly in the 25mm front baffle, but stepped out a further 25 mm using a Bakelite panel. This stuff is extremely dense and resin rich. and I believe will offer substantial rigidity to the front baffle as well as improving refraction. My question is do i have to compensate for the difference in driver volume displacement? Also how critical is this difference can I get away with it?
Many thanks
Niall
Many thanks
Niall
I just looked at the smaller Thor and other box models, and am a little confused about the internal brace that appears to separate the front of the speaker forming the driver enclosure from the back of the speaker which includes the port. If the port is isolated from the drivers, how does the speaker work? I'm sure I'm missing something obvious - thanks for any help,
John
John
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