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Pros and Cons of Transmission Line speakers
Pros and Cons of Transmission Line speakers
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Old 13th January 2002, 02:27 PM   #21
Pete Mazz is offline Pete Mazz
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From a failing memory:
It was about 78" high with the base (which is obviously not on yet in the pic). The line length was ~122" which tuned it to ~28 Hz.

Pete
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Old 17th February 2002, 11:05 AM   #22
mefinnis is offline mefinnis
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Default Re: Optimised design....

Brett wrote:

Quote:
Originally posted by Brett
Bedroc,

The W18E001 also has a poxy small magnet (0.88T), so it's 10mm x-max useless as I would expect the IMD to be huge at even a fraction of those excursions. To borrow a description of djk's, at any reasonable level, voices would sound like they are "gargling". The more I examine this design the less I like it.

Build the Ariel, if you want an MTM TL design.
This seems like a somewhat contradictory statement!

What is the x-max of the P13WH ?

I too was looking at the Thor but was put-off by the high price of the drivers in Oz. I can't quite cope with $2000 in drivers for a speaker I haven't heard

I have looked at the Ariel for a long while but was put-off by the statements by Lynn that it simply and positively doesn't work with a SS amp .... alas, this cuts me out!

(I'm always a little dubious when people make statements like this ..... makes you wonder if there are pre-conceived biases ??)

My latest idea is to try building a "Thor-like" TL, but using cheaper drivers, specifically those from the VSS Eros ( http://speakerbuilder.net/web_files/...ct/vsseros.htm ).

This way I can play with the TL idea and if it all turns to "sh1t" then I can revert to the boxes from the Eros, which seems to be reasonably thought-of. The only problems with building the Eros are the multiple inconsistencies between the web description and the diagrams ...... a problem not adequately resolved by e-mailing the author ..... makes me somewhat nervous

cheers, mark
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Old 17th February 2002, 12:07 PM   #23
Hoffmeyer is offline Hoffmeyer  Denmark
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Mefinnis:
Once upon a time I chose the Vifa PL18WO-09-08, used in the kit You're refering to, because of the good-looking specs, and I haven't regretted it. I use them in a small 2-way system, Vb=10,6 liters, Fb=42Hz, and a cross-over point at 2,2kHz.
They do have a deep'n clean bass, and a good midrange, but if You're to use them in a TL, I'd suggest You use 2 woofers/speaker, or You might find the low end a bit thin.
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Old 17th February 2002, 12:24 PM   #24
mefinnis is offline mefinnis
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YEP .... I agree!

This is why I said a "Thor-Like" design, ie. following an MTM arrangement.

Now, how much of a problem do we create by going MTM in a TL. I have sent a private e-mail to Jon Risch and Dave ex the TL speaker site: http://www.t-linespeakers.org/design/classic.html .. asking this exact question.

Dr Joe turns this into a "benefit" .... "2 drivers exciting the line at different points helping to smooth and extend the bass response" .... now is this real, or just Joe in love with MTM and showcasing the Excel drivers as hinted at previously? Hell I don't know ..... this is why I asked the question. Ain't seen a reply yet ... please

What I am doing is applying Jon's "rules" along the Thor design lines. If we look at Thor, it has:

A1:Sd = 1.5 / A2:Sd = 0.5 for 3:1 taper

Jon's rules suggest this is a little steep, but then Dave says recent trends are to use a higher taper ratio ..... (see earlier post)

The current drawing of my boxes are 1.3:0.8, which are closer to the "old-school". I'v downloaded Martin's MathCAD models and am trying to adapt these to model 2 drivers .... not an easy task for a "dumbass medico".

Most importantly, at this stage, I'm having fun

All help and comments gratfully received .... mark
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Old 17th February 2002, 12:52 PM   #25
Hoffmeyer is offline Hoffmeyer  Denmark
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Mark:
I'm not shure weather 2 drivers will extend the frequency response, I merely see it as a way to increase output-level at the low end by rolling one of the drivers off at say 100Hz, 6dB/oct low-pass.
When calculating line-dimensions You'll have 2xSd, but a Fs being approximately unchanged.
I think a 3:1 taper is much to steep, I'd try with A1=2xSd, and A2=1xSd, but that's just my feeling, and I'd love to hear about the result, since whenever I'll get more room, I'll rebuild my speakers into TL's.
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Old 17th February 2002, 02:58 PM   #26
Asen is offline Asen  Bulgaria
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Bedroc

I'm a Odin owner. ODINs are nice speakers, but are very sensitive to the other part of the system and the room acoustics (You'll need a really good amp). They have extremely deep and tuneful bass, and are very detailed. I had to make lots of mods, and I even changed the whole crossover to make them sound good to me. The Thor is provided with more expensive tweeter, so maybe you wan't suffer from such problems.

Before that I owned a TL speakers (my own project). They sounded fery good for the drivers price. Sometimes I regret I've sold them.

My own oppinion is that TLs give good results, but be prepared to play a lot with the damping stuff. I think that the Thor will give good results being a Odin-TL hybrid. The XO looks simple for these Excel drivers though. It looks like that at least to me.

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Old 17th February 2002, 06:32 PM   #27
planet10 is offline planet10  Canada
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Pros and Cons of Transmission Line speakers
Quote:
Originally posted by mefinnis
The current drawing of my boxes are 1.3:0.8, which are closer to the "old-school". I'v downloaded Martin's MathCAD models and am trying to adapt these to model 2 drivers .... not an easy task for a "dumbass medico".
Just use one driver with twice the Vas at the midpoint of the MTM. This gets you in the ballpark.

dave
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Old 17th February 2002, 09:03 PM   #28
mefinnis is offline mefinnis
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Thanks Dave

Couple more "really dumb" questions if I can. Remembering I do not come from an EE background.

Since the drivers are in parallel, I assume I should use:

1x Fo
2x Sd
2x Vas
0.5x R_dc
0.5x Z_vcoil

??? for Qes, Qms, BL

cheers, mark
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Old 18th February 2002, 09:33 AM   #29
Oz_Audio is offline Oz_Audio
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I have built the TLb from planet10's www.t-linespeakers.org web site.
I have not heard the Ariel, but maybe it will sound very similar. It could be a good idea to build the TLb as it uses the same woofers and if you like the sound, then build the Ariel?
As for amps, build an AKSA (www.printedelectronics.com) The Ariel and an AKSA should sound good together.
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Old 18th February 2002, 10:05 AM   #30
mefinnis is offline mefinnis
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Ummm ... thanks, but I think I'm OK for an amp, or 2

See: http://members.ozemail.com.au/~dkfin...labs/index.htm

I was actually having a sideways shot at the comments from Lynn, who has probably forgotten more than I will know about speakers, but certainly appears to come from the "tube-camp".

Please lets not get into that here! I would really love to see some further input from the TL gurus. Especially on what values I use for the TS specs using 2 drivers in Martin's model.

cheers, mark
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