Vifa P17WJ + D27TG-35-06 TL (non MTM)? - Page 3 - diyAudio
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Old 28th November 2008, 03:02 PM   #21
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So - no folds in the cabinet?

But will it sound the same as the other TLs?

When I listened to the QWTL w/the folds and the slot opening (without seperate smaller vent tube) it seemed like there was a distinctively more punchy and tight sound/feel to the bass.

EDIT: I'm familiar with the ~1/4 positioning to produce mutually disruptive resonances - but I'm not sure how to design the layout of tapered folds in the cabinet...

A similar benefit can be achieved by dividing the internal space in the enclosure with an acoustically resistive barrier.
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Old 28th November 2008, 03:15 PM   #22
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critofur,

It will be a good exercise to simulate a tapered line in order to compare the results.

Quote:
will it sound the same as the other TLs?
I guess both would have to be built and compared...maybe we have a sub-agenda for the next diyDayton?

I'll work up a tapered line. In the meantime, do you have any thoughts about:

--the parameters to use in the design?

&

--the "target slope" desired in the output?

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Old 20th December 2008, 12:10 PM   #23
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Default another (better) view

Up against the wall, metaphorically...I just can't make the response of a tapered line approach that of a MLTL. Today I found this:

MLTL vs. ML TQWT

which contains a link to a post by Brines which brings the situation into focus:

Single Driver Speakers Forum

which means, at least to me, that a properly executed MLTL is better and smaller than an ML TQWT.
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Old 20th December 2008, 12:54 PM   #24
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Oops - I guess I got it wrong again in my reply to that other thread.

I keep thinking that M*** Loaded in B]ML[/B]TL refers to the STUFFING lining the TL, not to a BR type port...

So then, how exactly does a MLTL differ significantly from a BR???

edit : DOH - I guess the censorbot is not so smart, the M*** above is Mass, and why is *** censored anyway? That's more silly than putting diapers on dogs!
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Old 20th December 2008, 12:59 PM   #25
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Anyway, what I'm most interested in is the exact physicaly layout of the angled boards inside the cabinet forming the taper...
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Old 20th December 2008, 01:19 PM   #26
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Default Re: Re: Vifa P17WJ + D27TG-35-06 TL (non MTM)?

Quote:
Originally posted by 00940
...combined with the low power rating of the p17wj means you cannot get very loud listening levels (which is perfect for my parents )
Specs:
88db sensitivity
40 W Nominal Power
150 W Long Term Max Power
350 W Short Term Max Power
and
120 W Music Power

Low?!? Those actually seem moderately high, to me. I would think what's more likely is that you'll run out of x-max before you run out of power handling, unless they were tuned at about 80 hz or higher?

I should go ahead and build a simple sealed cabinet and see how loud they will play in my garage... My Onkyo TS-DX787 reciever is good for about 120 watts.
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Old 20th December 2008, 01:24 PM   #27
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Hi critofur,

The resistance to flow (movement) created by the port is the mass loaded portion of the design.

On the surface, a BR and a MLTL appear the same...they have the same components. The difference is in how those components are positioned wrt each other.
Martin's software brings the ability to evaluate changes in the position of the elements. This is used to optimize the response and eliminate standing wave reinforcements and/or nulls.

Quote:
diapers on dogs!
LOL ...never a good idea until they poop in the wrong place
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Old 20th December 2008, 01:30 PM   #28
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Quote:
you'll run out of x-max before you run out of power handling
Exactly. The voice coil will handle more power and drive the cone beyond x-max. You may not enjoy the results.
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Old 7th September 2009, 04:39 AM   #29
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I am very interested in your results and curious as to if you went the mass-loaded method or tried a folded design.
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Old 7th September 2009, 11:20 PM   #30
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Click the image to open in full size.

For 1 watt input;
5 mm excursion for ~18 watt input yields ~99dB output

This sim is for a MLQW

Internal height: 36.0", by 9.0" deep x 7.5" wide
Distance of driver from top: 10.6"
Port from top: 29.95"

2.0" port dia. x 5.0" long
Stuffing: ~ 0.17 pounds, evenly distributed in the top ~14"

I have been working on other projects. My preference is for a drooping response which will be compensated for by room gain. YMMV The above describes the one I will build.
The TL sim's I did were not as smooth. Also, a TL doesn't provide as favorable (to me) low frequency profile. This is explained in links earlier in the thread.
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