Metronome for Alpair 10.3m and 12p

[Tom V]

Alpair 10.3M

With a 4.5" vent

 

[Tom V]

Pluvia Eleven

With 4.5" vent.

 

[Tom V]

Alpair 10.1P

With 3.5" vent.

 

[Tom V]

Tang Band w5-2143

With 2.5" vent.

 

[hajj]

Alaoir 10p and Tang-Band look good.
10.3M and pluvia 11 seem to be tuned too low

 

[GM]

Yeah, need to add some series resistance for low tuning.

GM

 

[Tom V]

>need to add some series resistance for low tuning.

How would I model that? And then just add a resistor to the red wire in the finished cabinet?

That "saddle" in the low range is very resistant to being taken out in the model. Shortening the line length and taking out volume seems to help but it still persists.

I am confused about the relationship of the quarter wave tuning vs the bass reflex tuning in a mass loaded transmission line.

 

[GM]

Increase Re if there's no field for [Rs or Rg or similar] to put it.

That's one way; I typically use a cheap 25 ohm pot to dial in each speaker since the room dominates, then swap it for a good quality non inductive resistor of whatever value I read off of it.

??? The metronome is a tapered MLTL..........

GM

 

[planet10]

??? The metronome is a tapered MLTL..........

ML-Voigt, or at least close enuff for modeling purposes.

dave

 

[GM]

.....or ML-TQWT depending on who you ask. Personally prefer ML-Voigt though. Mainly trying to get him to elaborate......

GM

 

[planet10]

Me too. Because of the way you use taper it became much more consistent to use ML-V. It also pays tribute to the giant that started us on that path.

dave

 

[GM]

Hear, hear! We stand on the shoulders of giants!

GM

 

[Scottmoose]

Too right. We all owe Voigt, Olson et al.

 

[Tom V]

Hey my name is Voigt!

And it was reading the Transmission Line Speakers site and about Voigt Pipes and Paul GAH Voigt that started me down this path. It was 8 years ago I discovered this forum which has been my happy online home ever since.

Now if I could just understand the technical details of ML-V's and Leonard Audio software to make my Metronome style speakers truly great!

-Tom Voigt-

 

[GM]

Cool!

Not much to know, the basics of the pipe is a closed cone: Resonances of open air columns

Shorten it well above the desired tuning, add a vent [open cylinder] to tune it lower and you're done.

Remember, in theory we want the damping of a vent with the same area [Av] as the driver's effective piston area [Sd], so now what's basically happening is you're trading a high aspect ratio's pipe action to shorten the otherwise too long/large vent it would ideally need to be well damped and in the case of the closed cone, it's inherently smoother, more evenly damped due to having both even and odd harmonics.

GM

 

[faithintruth]

Hi Tom V

I built Metronomes for Fostex 126's and loved the sound stage and imaging. I have gone on to build super pencils for the MA Alpair 10.1P and love the frequency response...the bass is great......but......I miss the imaging of the Metronomes.
I think I will throw the 10p's into Metronomes with your sims (3.5" vent). What is the inside diameter of the pipe?

 

[Scottmoose]

See post 100. Specified at 2in internal diameter. Note that 'imaging' with wideband drivers is heavily dependent upon the driver's inherent polar response. The baffle affects things, but generally speaking not as much as a multiway. The 10M's dispersion is good for a 5 1/4in unit, but the 126 is a little smaller & that will come into play. Assuming you size the metronome so the baffle area around the driver is smaller than the pensil, you may get a bit of a difference, but I doubt it will be gigantic. YMMV as always however as the driver height & angle will change relative to the pensil due to the different size & geometry of the baffle, which will probably make more difference than the nominal width alone.

 

[faithintruth]

I agree Scott. Looking forward to the test boxes. Thanks.