Beyond the Ariel

[phivates]

Leaky perhaps. Or Lossy. Or just make it big enough. Small is for other stuff.

[jeff mai]

Thanks.

Now I see Lynn recently discussing resistive vents in post 7846. I saw mention of this earlier in the discussion, but at that time there was an additional LF section in the mix.

[GM]

Not IME with any of the original 416 series, though in retrospect wouldn't necessarily include GPA or others re-cones. Ditto GPA's 416-8C, which I've no experience with, though based on published specs it might need to be gapped a little from the baffle [mostly sealed] if driven with a matching impedance, but does anybody do this in a high SQ app these days?

For a truly aperiodic alignment, all would require huge cabs to hold enough stuffing.

GM

[badman]

Originally Posted by phivates

Or just make it big enough. Small is for other stuff.

Good advice for speakers in general.

[ScottG]

Originally Posted by GM

Not IME with any of the original 416 series, though in retrospect wouldn't necessarily include GPA or others re-cones. Ditto GPA's 416-8C, which I've no experience with, though based on published specs it might need to be gapped a little from the baffle [mostly sealed] if driven with a matching impedance, but does anybody do this in a high SQ app these days?

For a truly aperiodic alignment, all would require huge cabs to hold enough stuffing.

GM

I've never heard of a truly aperiodic alignment before.


I tend to think of aperiodic as some measure of flow resistance or targeted compliance damping. It doesn't really matter what the size of the box is (or the resulting response), rather it "focuses" on flattening impedance around Fb - whatever Fb happens to be. (i.e. some measure of a mechanical version of a series LCR at Fb.)

[GM]

According to the dictionary, it means ‘without period’. I take this to mean it must completely flatten the driver’s impedance at Fs as practical, not just squash part of it at Fb and the only way I know how to do it other than electrically is to do it acoustically with a compression horn or mechanically via a stuffed TL, so size and tuning does matter in this case.

GM

[BudP]

Should include our own Dave Dlugos of Planet 10, who has also managed it with an unstuffed rectangular cross section slant load transmission line, with drivers mounted mag to mag. Impedance begins to rise below 20 Hz, using two SDX7 6.5" woofers with Dan Wiggens XBL long throw technology. Astoundingly clear, tons of texture for higher frequencies to attach to and significant output at 30 Hz and below. Easily matches my EnABL'd Lowther PM6A drivers.

Bud

[ScottG]

Originally Posted by GM

According to the dictionary, it means ‘without period’. I take this to mean it must completely flatten the driver’s impedance at Fs as practical, not just squash part of it at Fb and the only way I know how to do it other than electrically is to do it acoustically with a compression horn or mechanically via a stuffed TL, so size and tuning does matter in this case.

GM

I've not seen this accomplished. Sometimes close, but often not much better than a well done sealed design with some lossy venting. (..though poor examples of the later abound as well.)

The most flat impedance mechanically derived example I've seen was Gary Pimm's designs that truly were tuned resistive partitions. Technically though it was a cardioid and dipole (at much lower freq.s). Interestingly however, they weren't that big.

I think a big problem here will be changing driver conditions that will never really allow for a truly resistive impedance. The suspension changes over time. It also changes under different pressure conditions caused by increased excursion and compression. Finally, depending on the input and the motor's ability to remove heat - driver parameters can also change. (..practically speaking a compression driver can overcome these hurdles though.)


It will be interesting to see what Lynn comes up with, but in this case I'd expect just some modest flattening of impedance (..if resistive venting is used at all).

[ScottG]

Originally Posted by BudP

Should include our own Dave Dlugos of Planet 10, who has also managed it with an unstuffed rectangular cross section slant load transmission line, with drivers mounted mag to mag. Impedance begins to rise below 20 Hz, using two SDX7 6.5" woofers with Dan Wiggens XBL long throw technology. Astoundingly clear, tons of texture for higher frequencies to attach to and significant output at 30 Hz and below. Easily matches my EnABL'd Lowther PM6A drivers.

Bud

..Oooh, link please!

I think this is sort of "claimed" for the Tango RSI speakers as well, but I'd strongly bet that it's a series LCR:

6moons audio reviews: Acoustic System Int. Tango

[BudP]

I am a little lost with the Planet 10 organization schemes, but, here is one link
Transmission Line Speakers
and here is a link to Planet 10
planet_10 hifi
If you PM me with an email Dave may allow me to send you a copy of the construction diagram that the prototypes I have were built to. I do know he has gone well beyond what I have.

Bud