Some Thor models to mull over

[MJK]

Jack,

You can find those plots attached at the back of my ML TQWT article. They were generated by modeling the air volume with acoustic elements using the ANSYS finite element program. Basically, they show the pressure profile of the different standing waves that exist in the two types of boxes at the applicable resonant frequencies. They are normalized mode shapes so the absolute value of the pressure is not presented, the relative values of the pressure at different positions in the box is what is being shown.

Also from the plots you can assess where the velocity maximums and nulls are located in the boxes. At a pressure maximum the velocity will be zero. Where the pressure is zero the velocity will be a maximum. Look at the output of the port (borrom front edge modeled as a slot) to see where the velocity is a maximum in each of the fundamental frequency plots. In the higher frequency plots there will be velocity maximum and minimums inside the box.

Hope that helps,

[Niall Hayward]

Hi guys back again I have finally started working on my Thor project, as I do not have a workshop I have been dependent on weather conditions (never seen so much rain ) the drawings for the small Thor tell me the port should be four inches long can someone tell me if this length is measured from the inside wall of the cabinet or does it include wall thickness, which in the case of my cabinets is 1" thick.
Many thanks
Niall

[imjatse]

Total port length is 4". At least that is how I made mine. Since the internal volume is the same regardless of wall thickness, the port length is constant too. I had this same question when I was building mine. Can't wait to see the work and your reviews of the speakers!

[planet10]

Port length will always be specified as the length of the port,,, it is from the outside of the cabinet to the inside end of the port.

dave

[Niall Hayward]

Thanks Dave and Patric, for your rapid and invaluable advice.
Niall

[cnankervis]

Originally posted by Scottmoose
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

Hi Scott,

I am a newby on diyaudio.

I have been researching TL designs for a while now as I am looking to build my second set of floor standing speakers. This time I would like to up the ante on things and build some higher end speakers.

I have been looking at the designs and there seems to be only brief dimensions marked. I particular I would like to know the dimensions for the swiss cheese hole cutouts for the braces and the length and diameter of the port used?

I will intend to use the Seas kit from Madisound, however I'm located in Brisbane Australia. Is there anywhere in Australia that you may know that can supply the items in the kit from Madisound to save me on posteage costs?

You assistance with this would be greatly appreciated.

Kind regards,

Christian

[JC]

Linolll

I don't know if you are still following this thread from several years ago, but I am curious as to the details of your crosover mod. I had the same reaction to the sound as you did with the original crossovers.