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Old 10th November 2011, 11:48 PM   #931
zacster is offline zacster  United States
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Thanks. When I did a search the other day, half the results pointed back to my own searches from years past!

And maybe YOU could measure them. I wouldn't have a clue where to start.
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Old 11th November 2011, 12:33 AM   #932
GM is offline GM  United States
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I could, but I don't have them. Do a Google search, there's loads of posts and even whole threads and websites devoted to the subject.

GM
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Old 11th November 2011, 02:34 AM   #933
zacster is offline zacster  United States
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At this point I'm just going to build them. They're going to end up as speakers for my teenage kids. They're not picky. I can't even convince them to get decent headphones/earbuds. They like the cheap ones even when I'm paying.
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Old 11th November 2011, 07:38 PM   #934
tmblack is offline tmblack  United Kingdom
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I'm a total newbie when it comes to the metronome.
What's a ML-QQWT or a Mass Loaded Quadratic Quarter-Wave Tube mean?
And TQWT?
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Old 11th November 2011, 08:53 PM   #935
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TQWT = TQWP = Tapered Quarter Wave Tube/Pipe

These are a pipe/transmission line open at one end, where the closed end is smaller then the open end.

Also called a Voigt Pipe.

These suffer from a lot of ripple and can be dramatically improved by mass-loading them (restricting the terminus/opening). This is often implemented with a small pipe as in a bass reflex (which confuses a lot of people)

Hence ML-TQWT = ML-TQWP = ML-V

When the 1st ideas of this kind of load in the form of a cone (which Steve took to a pyramid) it was completely missed that with a taper in 2 axis, the actual "shape" of the volume is quadratic and not linear. They are closely related and as tolerent as they are a Met can usually be simmed as an ML-V.

http://www.frugal-horn.com/metronome.html

Click the image to open in full size.

dave
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Old 14th November 2011, 04:43 PM   #936
tmblack is offline tmblack  United Kingdom
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There's a Mathcad simulation of horns and ML-QQWT out there but I can't find it.
Anyone know what I'm talking about?
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Old 15th November 2011, 04:44 AM   #937
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Quote:
Originally Posted by tmblack View Post
There's a Mathcad simulation of horns and ML-QQWT out there but I can't find it.Anyone know what I'm talking about?
Hi there: Google-up: quarter-wave.com the Martin J King site. ...regards, Michael
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Old 16th November 2011, 04:25 PM   #938
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Have any of these been built with Mark Audio drivers? Specifically the Alpair12?

Scott
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Old 16th November 2011, 05:36 PM   #939
sherpa is offline sherpa  United States
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So they are finally finished. I broke the drivers in mounted in an open baffle for 200+ hours. They are built using 3/4 birch plywood. The top 4 feet of the insides are lined with 4mm laminate flooring felt. First impressions, The image is incredible and detailed. Right away i was hearing parts of the music that i could not hear with my Zigmahornets. These things revealed the limitations in my SE EL-84 amp and the 6EM7 amps i have. When i run my DIYTube ST-35 the sound is clear and clean. I have had several people listen to them so far and have come up with some limitations. The midrange is almost too forward and the bass is lacking. I know they will never be a rock and roll kick you in the chest style speaker but the bottom end is just not balanced with the rest of the frequency. I believe i have three options to tune these things in, Stuffing, Play with the port size and length, or a BSC filter. Where should i start? What changes can i expect from each method? I have considered that my amp is lacking the bottom end reproduction. running with a friends old heathkit solid state 120w amp there was an improvement in the bottom end. If i can sell some of the equipment i have it will fund the building of the tubelab SE with some CSXE 25W Edcor outputs. I hope these pictures came through.
Thanks,
Paul
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Old 17th November 2011, 02:13 PM   #940
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Hi Sherpa,

The first thing that concerns me is that you appear to have lined three sides. When I did my first build (FE108eSigma) I lined all sides of the interior. What a disaster! I had to cut into the port baffles on the bottom to get in so I could remove the lining from the front and sides. On all three of my Met builds I have lined only the back, from top to bottom.

The FE108eSigma Mets have a BSC of 1 mH and 4.5 ohms. The F120A didn't need any BSC. The Fe167e have a BSC of 0.7 mH and 2.2 ohms. Not sure what the FF125wk might need, but it sounds like they need some.

Cheers, Jim
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