Before I started building, I spent some time at this forum, but at that time there was very little work on curved speakers. So I went ahead on my own, learning on the way.
The construction is based upon five layers of 4 mm plywood which I formed over a frame. The frame was removed after lamination, and the two sides were joined by the 1.5" MDF front and a strip of MDF at the back. The internal transmission line divider acts as a brace, but the curved side is very dead as it is.
Yes, I could not bend the plywood enough at the rear end, so the back is formed by pieces of MDF. Then the whole thing is veneered with american red oak, including the recessed binding post hole.
I mostly hang out at a norwegian speaker building forum, but I've just started to make a web site documenting my projects. A few more construction pictures are here.
The transmission line in my speaker is slightly longer than the original Thor, and I spent a lot of time tuning the speakers. Over time, the low end has become deeper, and I also modified the crossover slightly to reduce the upper midrange a little bit.
Overall I am very happy with this speaker - it is by far the best speaker I have.
--
Rune R
The construction is based upon five layers of 4 mm plywood which I formed over a frame. The frame was removed after lamination, and the two sides were joined by the 1.5" MDF front and a strip of MDF at the back. The internal transmission line divider acts as a brace, but the curved side is very dead as it is.
Yes, I could not bend the plywood enough at the rear end, so the back is formed by pieces of MDF. Then the whole thing is veneered with american red oak, including the recessed binding post hole.
I mostly hang out at a norwegian speaker building forum, but I've just started to make a web site documenting my projects. A few more construction pictures are here.
The transmission line in my speaker is slightly longer than the original Thor, and I spent a lot of time tuning the speakers. Over time, the low end has become deeper, and I also modified the crossover slightly to reduce the upper midrange a little bit.
Overall I am very happy with this speaker - it is by far the best speaker I have.
--
Rune R
If the question was for me......
As I understand it, the curvature helps eliminate reflective back waves from exiting through the drivers.
I paterned several shapes, filled them with water, and observed how water ripples reacted when the waves encountered the curved walls. Think of milk jug cut in half and filled with water.
The shape that nulled the waves best was used. Sorry, no photos of the test were taken. (I forgot)
A plywood base with modeling clay was used to support the design templates, flexible plastic was used to simulate the curved walls.
Hope this helps,
Ron
As I understand it, the curvature helps eliminate reflective back waves from exiting through the drivers.
I paterned several shapes, filled them with water, and observed how water ripples reacted when the waves encountered the curved walls. Think of milk jug cut in half and filled with water.
The shape that nulled the waves best was used. Sorry, no photos of the test were taken. (I forgot)
A plywood base with modeling clay was used to support the design templates, flexible plastic was used to simulate the curved walls.
Hope this helps,
Ron
Attachments
Peter,
My wife tells me I'm a man.
I have measured the speakers and have the dimensions below.
Doing it over again I would make them ~1" deeper. Making them closer to the Fat thor design. Baffle MUST stay the same!
Note: even though I used 2 layers of 3/8" plywood the acutal thickness of the walls is just over 1". all other measurments are taken directly from the small Thor plans by Scottmoose and Planet10.
My wife tells me I'm a man.
I have measured the speakers and have the dimensions below.
Doing it over again I would make them ~1" deeper. Making them closer to the Fat thor design. Baffle MUST stay the same!
Note: even though I used 2 layers of 3/8" plywood the acutal thickness of the walls is just over 1". all other measurments are taken directly from the small Thor plans by Scottmoose and Planet10.
Attachments
Renron said:Peter,
My wife tells me I'm a man.
I have measured the speakers and have the dimensions below.
Doing it over again I would make them ~1" deeper. Making them closer to the Fat thor design. Baffle MUST stay the same!
Note: even though I used 2 layers of 3/8" plywood the acutal thickness of the walls is just over 1". all other measurments are taken directly from the small Thor plans by Scottmoose and Planet10.
So the baffle width is 9 inches right?
In making them deeper, would you extend the part that is not curved? I mean by that the first 7.5" from the front, extended to 8.5" ?
Not to sound ungrateful or very demanding, could yo trace the footprint of the speaker? Not sure the drawing can be accurate of the curvature used....
Peter
peter_m said:
So the baffle width is 9 inches right?
In making them deeper, would you extend the part that is not curved? I mean by that the first 7.5" from the front, extended to 8.5" ?
Not to sound ungrateful or very demanding, could yo trace the footprint of the speaker? Not sure the drawing can be accurate of the curvature used....
Peter
Answers to above:
Yes,
Yes,
No,
I have a base that is larger than the exterior. I also plan on making a new base from granite. I have hardwood floors. It was not all that critical anyway. Just scetch a lay out on paper (folding the paper in 1/2 makes it symetrical and easy), trace to wood, cut template with jigsaw and see if you like the shape. It will be Very Very close. Try adjusting the rear (back) size to your liking.
This is DIY after all.
These speakers sound better each day!
Ron
That's quite ingenious - I never thought of that one.Renron said:
I figured any curved shape would be better than a box, so I just made a lot of sketches, and chose the form that best fullfilled three criteria:
- pleasing to the eye,
- supported the required volume and height,
- supported the proper tapering of the TL.
--
Rune R
I have posted this in a different thread but I should include it here as well,
After well over 200 hours of break-in I was able to take these to a local High-End home theater to audition and compare with Wilson Watt Puppies and Custom made "Cat" brand speakers. We connected them to a High End Pioneer Elite used as a Pre-Amp for an Anthem Amp and used a CD player as a source. (I think it was an Elite too)
We listened to several recordings in a well designed home theater style room with 3 step risers and over stuffed leather lounge chairs. Carpeted flooring, heavy curtains, room acoustic conditioning and 2 semi bare walls, very much like you would set up a dedicated HT at your house, if you could afford one (I can't).
The room dimensions were approximately: 18 x 25 x 15 ceiling.
The speakers were placed about 4 feet from the front wall and about 4 feet from the side walls on carpeted flooring.
OK, We sat about 14 feet in front of the speakers at slightly higher ear level than the top of the speaker cabinets. I know we should have been lower.....closer to tweeter height, I digress.
After positioning the speakers to our liking, slightly toe in, we sat and listened for hours to different artists finally settling on Alison Krauss and Union Station live CD. A very clear recording with wonderful voicing and excellent musical instrument clarity. The Dobro solo really showed off what these speakers are capable of in terms of reality. Alison's voice brings tears to my eyes, very easy to listen to. Not being well experienced with high end speakers, I was at the mercy of my host and his opinions after listening to and comparing speaker.
In a nutshell and not quoted he said;
These are marvelous speakers and well designed QWTL, they compare well to commercially sold speakers that range in price from $10,000 to $15,000 !!! The Seas drivers are the same ones used in some of the "Cat" brand that he sells, Shhhhhh.......don't tell anyone, it'll be our secret........check out this over the top pair of "Cat" speakers.
Over the top CAT pair , yes, there are speakers in the photo
Things I plan on doing to my pair of Small Thors; (as per his recommendations)
1) Add additional mass to the top of the cabinet interior to help deaden resonance in that part of the cabinet. (I drilled out the top inner support to add to interior cabinet volume.) I will take out the upper driver and turn the cabinet upside down and pour in an inch or so of some dense liquid that will harden like concrete or plaster of Paris, If anyone has any ideas on material here please help me out.
2) Add a granite base or set the speakers on a granite block to isolate the cabinets from the flooring. I have a laminate floor on a raised foundation. (I was told this would help tighten the bass response) I can't use spikes because I have big dogs that have no respect and crash / bump into the speakers on occasion.
3) Make time to enjoy these Awesome speakers!
Thank you, Planet 10 and ScottMoose,
Ron
After well over 200 hours of break-in I was able to take these to a local High-End home theater to audition and compare with Wilson Watt Puppies and Custom made "Cat" brand speakers. We connected them to a High End Pioneer Elite used as a Pre-Amp for an Anthem Amp and used a CD player as a source. (I think it was an Elite too)
We listened to several recordings in a well designed home theater style room with 3 step risers and over stuffed leather lounge chairs. Carpeted flooring, heavy curtains, room acoustic conditioning and 2 semi bare walls, very much like you would set up a dedicated HT at your house, if you could afford one (I can't).
The room dimensions were approximately: 18 x 25 x 15 ceiling.
The speakers were placed about 4 feet from the front wall and about 4 feet from the side walls on carpeted flooring.
OK, We sat about 14 feet in front of the speakers at slightly higher ear level than the top of the speaker cabinets. I know we should have been lower.....closer to tweeter height, I digress.
After positioning the speakers to our liking, slightly toe in, we sat and listened for hours to different artists finally settling on Alison Krauss and Union Station live CD. A very clear recording with wonderful voicing and excellent musical instrument clarity. The Dobro solo really showed off what these speakers are capable of in terms of reality. Alison's voice brings tears to my eyes, very easy to listen to. Not being well experienced with high end speakers, I was at the mercy of my host and his opinions after listening to and comparing speaker.
In a nutshell and not quoted he said;
These are marvelous speakers and well designed QWTL, they compare well to commercially sold speakers that range in price from $10,000 to $15,000 !!! The Seas drivers are the same ones used in some of the "Cat" brand that he sells, Shhhhhh.......don't tell anyone, it'll be our secret........check out this over the top pair of "Cat" speakers.
Over the top CAT pair , yes, there are speakers in the photo
Things I plan on doing to my pair of Small Thors; (as per his recommendations)
1) Add additional mass to the top of the cabinet interior to help deaden resonance in that part of the cabinet. (I drilled out the top inner support to add to interior cabinet volume.) I will take out the upper driver and turn the cabinet upside down and pour in an inch or so of some dense liquid that will harden like concrete or plaster of Paris, If anyone has any ideas on material here please help me out.
2) Add a granite base or set the speakers on a granite block to isolate the cabinets from the flooring. I have a laminate floor on a raised foundation. (I was told this would help tighten the bass response) I can't use spikes because I have big dogs that have no respect and crash / bump into the speakers on occasion.
3) Make time to enjoy these Awesome speakers!
Thank you, Planet 10 and ScottMoose,
Ron
Re: Re: Thanks for the good scare
While you are correct that whatever resonance exists should be as high frequency as possible, you are wrong that it should be high Q. A high Q would mean that it would ring like a bell. There may be a narrower spectrum of frequencies that could excite a high Q resonance, but if there was any energy at all in that spectrum, you would definitely hear the resonance.
planet10 said:
While you are correct that whatever resonance exists should be as high frequency as possible, you are wrong that it should be high Q. A high Q would mean that it would ring like a bell. There may be a narrower spectrum of frequencies that could excite a high Q resonance, but if there was any energy at all in that spectrum, you would definitely hear the resonance.
planet10 said:
So in your mind the ideal speaker enclosure would be made out of crystal or something like that? Very little of the energy put into the box would be turned into heat in a high Q box. You want the box to store energy for a long time?
It seems to me that you have misunderstood the role of the Q factor.
Probably in the Clarity thread. Here is the origination thread on another forum http://www.htguide.com/forum/showthread.php4?t=26754&page=1&pp=35
dave
dave
jerko said:
I gon't know about crystal, but there has been some discussion about cold rolled steel.
I want the box to store energy for a very short time. Part of it is to get as little energy into the box as possible, spread it out as much as possible so that it can be damped, and make sure that resonances are not excited (for the energy to get out of the box thru the box walls the cabinet needs to resonate).
When i think of high Q i am thinking about the distribution of the energy required to excite that resonance, and that certainly takes on the form of a high Q shape (ie very narrow bandwidth vrs the height where the area under the curve represents the energy required to excite the resonance) And the use of the term high Q has to be taken in the context of the entire construction.
What are you thinking when i say high Q?
dave
planet10 said:
Well what I think of when you say Q is the definition:
http://en.wikipedia.org/wiki/Q-factor
If you want a high Q enclosure, then that means that you want the enclosure to both store lots of energy and lose that energy at a low rate. Since this is a mechanically oscillating system (and especially because it is made of panels), then if you have a high Q enclosure and a similar density and stiffness low Q enclosure, then that means that a larger fraction of the energy that comes into the panels on the high Q enclosure will be radiated into the air because less is being turned to heat.
The only advantages that something like steel has over something like MDF (for speaker building, of course) is its stiffness and density, but you can get both of those properties by using some combination of other materials that will give the box a lower Q. For instance, you might be able to get the stiffness with a sandwich of MDF between layers of fiberglass (I know you could do even better than steel if you used carbon fiber, but that would be a bit expensive).
jerko said:
I don't want a high Q enclosure, i want any resonances high Q (since there is no such thing as a no resonance cabinet you are just left with tailoring them)
If we go a bit further in that article we find
An externally hosted image should be here but it was not working when we last tested it.
The goal is to get delta-f as narrow as possible and fo as high as possible. To do that Q has to be high. The area under the curve is the area required to excite the resonance. Since the energy available to excite the resonance is inversely proportional to the square of the frequency and delta-f is small, it becomes VERY hard to excite the resonance since you need to have an immense amount of energy in a very narrow band and that is very unlikely to happen with music. If, in the unlikely event that, the resonance is excited it will radiate that energy very quickly, but in a very narrow bandwidth. Sonically that is, IMHO, a much better compromise than having a cabinet constantly oozing out time smeared low level energy.
dave
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