It took a very long time to get to this enclosure but I'm glad it's getting back on track now, it floated around in my head for years!
Today I have put in the the two drivers, FRS8 - 8 Ohm and hooked them up in parallel, to a channel of my amplifier. They sound surprisingly good.
If anyone is curious enough to put it in a simulation program, I would be very happy and interested. Let me know what numbers you need.
The thought of a pentagon was preceded by a triangle but the problem here is, that the volume of the TL is reduced by half compared to a rectangular box while a pentagon is larger than a rectangle. I didn't want to use a rectangle because of the parallel sides that support standing waves and it looks nice!
The length is the standard width of a sheet of plywood; 1m22cm.
Pure theoretical this would give a frequency resonance of 70Hz, way lower than the drivers can produce properly.
So, being a prototype and awaiting the build of four definitive boxes for home theatre, all input is greatly appreciated.
At the moment I do not have much time on my hands, working overtime and living alone, only lets me play around half a day at weekends.
My original thread about this:
http://www.diyaudio.com/forums/full-range/179628-simple-tl-cheap-speaker-use-home-cinema.html
I had some questions in another thread, if anyone would like to have a look, they are related to this project too:
http://www.diyaudio.com/forums/full-range/111724-extreme-basket-tricks-3.html#post2474736
Thanks for watching!
Today I have put in the the two drivers, FRS8 - 8 Ohm and hooked them up in parallel, to a channel of my amplifier. They sound surprisingly good.
If anyone is curious enough to put it in a simulation program, I would be very happy and interested. Let me know what numbers you need.
The thought of a pentagon was preceded by a triangle but the problem here is, that the volume of the TL is reduced by half compared to a rectangular box while a pentagon is larger than a rectangle. I didn't want to use a rectangle because of the parallel sides that support standing waves and it looks nice!
The length is the standard width of a sheet of plywood; 1m22cm.
Pure theoretical this would give a frequency resonance of 70Hz, way lower than the drivers can produce properly.
So, being a prototype and awaiting the build of four definitive boxes for home theatre, all input is greatly appreciated.
At the moment I do not have much time on my hands, working overtime and living alone, only lets me play around half a day at weekends.
My original thread about this:
http://www.diyaudio.com/forums/full-range/179628-simple-tl-cheap-speaker-use-home-cinema.html
I had some questions in another thread, if anyone would like to have a look, they are related to this project too:
http://www.diyaudio.com/forums/full-range/111724-extreme-basket-tricks-3.html#post2474736
Thanks for watching!
An externally hosted image should be here but it was not working when we last tested it.
there were the pentachord speakers (2 way crossing to sub and a tall colum also crossing to a sub). Both used dual 50mm bandors per speaker I think.
Ideally, you'd want the line to resonate lower than the drivers to add bass down there.
I have a love/hate relationship with my dual 4" tang bands (see my avatar).
But it's doing better with 8" sealed run with it now.
Good luck with playing with them !!!!!!!!!!!!
Norman
Ideally, you'd want the line to resonate lower than the drivers to add bass down there.
I have a love/hate relationship with my dual 4" tang bands (see my avatar).
But it's doing better with 8" sealed run with it now.
Good luck with playing with them !!!!!!!!!!!!
Norman
An externally hosted image should be here but it was not working when we last tested it.
you may need a bit more cone area.
Norman
Dave, thanks for the complement.
Norman, This TL needs to have three brothers and a center speaker, total of ten little drivers. But it's my goal to give them a break beneath 80Hz and cross to a decent sub. So this is mostly a HT setup but I know they will sound good for some occasional or background music too, as one box already sounded surprisingly good and nice without any filtering.
Squeak, I can't find a tube nice enough and/or rigid enough to use for this project. The finish would not be so nice because it can only be painted. A wooden box can just be varnished and show the grain. Also a pentagon is a total different thing to look at then a regular tube.
But you're right of course, it would be the same result with the only difficulty, being the baffle plates.
Am I correct to conclude that these five boxes can deliver 102dB if they're fed 100W in total? (efficiency is 82dB/W/m)
That would be 108dB at 300W, right?
These drivers can handle 30W nominal and 50W peak(music).
How much RMS would this be? I guess 15W.
Just trying to put a number on those maximum dB. For HT I think I can go with the music power handling of 50W, so this means they will be more then sufficient for HT I reckon.
A lot of people tell me 82dB/W/m is not enough for HT... I think it ís!
Norman, This TL needs to have three brothers and a center speaker, total of ten little drivers. But it's my goal to give them a break beneath 80Hz and cross to a decent sub. So this is mostly a HT setup but I know they will sound good for some occasional or background music too, as one box already sounded surprisingly good and nice without any filtering.
Squeak, I can't find a tube nice enough and/or rigid enough to use for this project. The finish would not be so nice because it can only be painted. A wooden box can just be varnished and show the grain. Also a pentagon is a total different thing to look at then a regular tube.
But you're right of course, it would be the same result with the only difficulty, being the baffle plates.
Am I correct to conclude that these five boxes can deliver 102dB if they're fed 100W in total? (efficiency is 82dB/W/m)
That would be 108dB at 300W, right?
These drivers can handle 30W nominal and 50W peak(music).
How much RMS would this be? I guess 15W.
Just trying to put a number on those maximum dB. For HT I think I can go with the music power handling of 50W, so this means they will be more then sufficient for HT I reckon.
A lot of people tell me 82dB/W/m is not enough for HT... I think it ís!
Lots of excellent woodworkers here.
And you don't get good without practise. Nice to see something other than another monkey coffin.
dave
MDF is easy to shape, fill and sand smooth, easier than plywood.
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It kind of looked like plywood to me.
MDF cuts real clean, it's easy to CNC and mistakes are easy to fill/fix.
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Squeak,
Putting the five sides together at the same time is a bit difficult but once I tighten everything up, the corners line up automatically.
This prototype was less than perfect because the angle was off a bit.
I would have to get the panels cut by a pro but the rest would be up to me.
LOL; "monkey coffin"
AEIOU,
I agree on the MDF advantages but veneer is out of my league at the moment, I'm not an experienced woodworker.
My prototype is plywood and I'm curious about what Dave said about MDF.
Thanks for all the responses!
Putting the five sides together at the same time is a bit difficult but once I tighten everything up, the corners line up automatically.
This prototype was less than perfect because the angle was off a bit.
I would have to get the panels cut by a pro but the rest would be up to me.
LOL; "monkey coffin"
AEIOU,
I agree on the MDF advantages but veneer is out of my league at the moment, I'm not an experienced woodworker.
My prototype is plywood and I'm curious about what Dave said about MDF.
Thanks for all the responses!
Squeak,
Putting the five sides together at the same time is a bit difficult but once I tighten everything up, the corners line up automatically.
This prototype was less than perfect because the angle was off a bit.
I would have to get the panels cut by a pro but the rest would be up to me.
LOL; "monkey coffin"
AEIOU,
I agree on the MDF advantages but veneer is out of my league at the moment, I'm not an experienced woodworker.
My prototype is plywood and I'm curious about what Dave said about MDF.
Thanks for all the responses!
I am an experienced woodworker, but I still make a lot of mistakes. That is how you learn. Ha! Sometimes I cut up an entire sheet of MDF and still haven't accomplished anything. Anyway it seems that everyone has their own material preferences when it comes to building loudspeaker enclosures.
Pretty much any wood product will work, you just have to know how. I sometimes use plywood and pre-veneered MDF too.
I always do the "knuckle" test on my completed enclosures. My enclosures are incredibly tough and have a quick, tight, low periodicity of resonance. My completed enclosures are quite strong and deliberately trying to demolish one takes a lot of energy.
Veneer isn't too hard, but good veneer can be expensive. There are plenty of YouTube videos showing how to apply veneer. I personally like painted finishes more than wood grain/stain.
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Thanks for the tips. The knuckle test is also what I like to do.
[jealous mode]Nice shop![/jealous mode]
Yeah, it's not my shop but I get to use it all I want!
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The hex is ply.
We have no problems with any cut, CNC or mistakes fixed. And we end up with a better sunding box.
dave
Feedback from a knuckle wrap should be high frequency (800 Hz + is a good target), and almost ringy lke a bell. A quickly dying thunk is not a good sound.
Better to use a mechanics stethescope.
dave
Of course you are entitled to your own opinion, but personally I'd prefer that all my enclosures make no sound of their own what so ever. A loudspeaker is supposed to reproduce music, not produce sound.
A musical instrument produces sound!
Of course plywood cuts just fine, all one needs to accomplish that is the appropriate sharp blade(s). Heck, you can even cut aluminum on a table saw if you use the correct blade! But MDF routes, machines so much better than plywood.
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You will never have no resonances. The only thing you can do is try to make it so they are never excited. A LF thud that quickly dissapates is a LF, LowQ resonance and much more likely to be xcited and because of the low Q more audiable.
It has been 30+ years of of questing for the holey grail of no cabinet rsonance, and i'm pretty comfortable with how far i'v gotten.
Exactly. Low diffraction on the outside & a box that has resonances that never get excited is my practical target.
No issues here with plywood.
dave
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