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Old 25th February 2009, 07:54 AM   #21
Vigo is offline Vigo  Sweden
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I made a sketch after design information i get from pkitt ito see if i understod it correct.

I hope i get it right this time and that it is not supose to be any divider in the center.
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Old 25th February 2009, 03:31 PM   #22
pkitt is offline pkitt  United States
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Vogo, your sketch of the ML-TL I described and modeled is correct except for the mass-loading port's length. That total length is 44 mm, so twice the thickness of the wall you're using. And, don't forget the stuffing in the top half or so of the cabinet as I stated.

As to what would sound better? Any properly designed and implemented TL, regardless of the specific type, should sound just as good as any other type with similar response and performance. I'll take a look again at a tapered TL to see just how big the cabinet would have to be to get an F3 about the same as this ML-TL and an acceptably smooth overall response.

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Originally posted by Vigo
I made a sketch after design information i get from pkitt ito see if i understod it correct.

I hope i get it right this time and that it is not supose to be any divider in the center.
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Old 25th February 2009, 07:42 PM   #23
pkitt is offline pkitt  United States
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Default Thumbs down on a tapered TL

Vigo: I don't know if others could be more successful but I sure can't come up with a good-performing tapered TL for these drivers in any reasonable-sized box. I went back an re-read your first couple of posts and realized the cabinet being taller than what I modeled in the ML-TL would be okay with you. So, taking the ML-TL cabinet from my modeling for which you did the sketch, increase the internal height to 1145 mm, and keep the internal width and depth the same. The tweeter's center would again be located 250 mm from the inside of the top; this will likely bring the tweeters' center more aligned with your ears when you sit down to listen. With the increase in height, there's an obvious increase in internal volume, and this allows the port's length to be cut in half for the same F3, which means the port's length is just the 22 mm thickness of the baffle (and still 25 mm high and 200 mm wide). The port is again located at the very bottom. If you have to place your speaker cabinets much less than 12" from the wall behind them, a baffle location for the port is probably best, but if the cabinets can be 12" or more in front of that wall, a rear panel port location is good. With the increased height and cabinet volume, you'll need more stuffing, 500 grams, and it should be uniformly distributed in the top 600 mm of the cabinet's height to achieve a stuffing density of 0.75 lb/cu.ft. I assume you realize you'll need bracing in the cabinet and I'd suggest a "window frame" type brace, and at least 3 or 4 of them strategically located from top to bottom. I'd located on between the tweeter and the lower woofer, another about 1/2-way down the cabinet to act as stop for the stuffing, and one or two more between there and the bottom.
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Old 25th February 2009, 08:12 PM   #24
Vigo is offline Vigo  Sweden
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Yes i remember the port and the stuffing i just did not put it in this very early sketch. Thank you for reminding me

Ok sow it looks like the ML-TL might be the way to go then.
Sow I will start to design a proper drawing form your new specification.
yes i amused that it would need some kind of support.

With "window frame" brace I guess that you mean a big square that covers all 4 side then you have four rectangular holes in them.

How much of the brace need to be open to not have any negative effect on the sound?

When you change the length of the cabinet did you get a lower f3 or any other change in the plot?.

Thanks for all help, it have brought me a very good start to design from.
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Old 25th February 2009, 10:09 PM   #25
pkitt is offline pkitt  United States
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Yes, the window frame brace is as you described it. I usually use that type of frame and depending on the specific design, I make the width of the four sides and the two cross pieces either 3/4" or 1". For this design, that would mean the four rectangular holes will each be about 2-7/8" wide by about 5-5/8" deep. With this increase in height and volume, F3 didn't go more than about 1 Hz lower, ending in the 36-38 Hz range.

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Originally posted by Vigo
Yes i remember the port and the stuffing i just did not put it in this very early sketch. Thank you for reminding me

Ok sow it looks like the ML-TL might be the way to go then.
Sow I will start to design a proper drawing form your new specification.
yes i amused that it would need some kind of support.

With "window frame" brace I guess that you mean a big square that covers all 4 side then you have four rectangular holes in them.

How much of the brace need to be open to not have any negative effect on the sound?

When you change the length of the cabinet did you get a lower f3 or any other change in the plot?.

Thanks for all help, it have brought me a very good start to design from.
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Old 26th February 2009, 12:40 PM   #26
Vigo is offline Vigo  Sweden
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I have uppdated the sketch now after your latest simulaitons.

I will now start to make a cad model to make a more detaild design.

Will post the model as soon as i finish it.
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Old 26th February 2009, 04:30 PM   #27
pkitt is offline pkitt  United States
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Vigo, your sketch is correct but make sure the top of the second brace, the one used as a "stop" for the stuffing, is the correct distance from the top. Also, I feel it's necessary for a cautionary comment. I modeled with the T/S values as published by Tymphany, which you provided, and if the actual T/S values for your four drivers are appreciably different than those published, the model may not be as optimum as it could be.
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Old 26th February 2009, 07:41 PM   #28
Vigo is offline Vigo  Sweden
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Yes the second brace is but sow that the stuffing stops at 600mm from the top.

Yes i understand that it depends on that the values for the driver is correct. But i dont have the possibility to test them. Sow lets hope that the people at Peerless know what they are doing .

But what i read, it seam like Peerless driver normally is quite correct with the data official data.

Sow i will continue with the work and hope for the best.

Thanks for all your support
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Old 27th February 2009, 07:38 PM   #29
Vigo is offline Vigo  Sweden
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Here are some different design, they all share the basic design the only different is the shape of the face plate and colours.

Will the the faceplate have big effect on the sound??
I think that the biggest difference diffraction from the edges.



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Old 27th February 2009, 11:48 PM   #30
pkitt is offline pkitt  United States
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Neither of your proposed baffle shapes will affect the performance of the TL proper which is essentially limited to what goes on below 1000 Hz. However, the crossover design will be affected and you'll need to optimize that for whatever baffle shape you choose.
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