An Improved Transmission Line Alignment

[GM]

Those aren't the same acoustic pathlength due to considerably differing pipe end corrections.

 

[BP1Fanatic]

I honestly DONT understand all the hype(?) about ‘standard’ transmission lines unless they’re honestly compared to the exact same box volume in other configurations (apples/apples) ??

Why add the extra pipe resonance and offset driver position to help fix it(white graph verses green)

I questioned a TL a few years ago and it gained performance when the same enclosure was changed to a standard BR enclosure by removing an internal panel or 2.

 

[Booger weldz]

i think(??) the generic ‘best’ design for dumbies like me is the long bass reflex hybrid ? (Assuming you want a vented sub box with a nice flat response and had to ‘choose’ ? )

 

[unaHm]

Ah, I see - your application is for a sub. The speaker I'm thinking of is a woofer that I'll use the front wave up to it's roll-off value, but the back wave will go through the pipe.

 

[Scottmoose]

I honestly DONT understand all the hype(?) about ‘standard’ transmission lines unless they’re honestly compared to the exact same box volume in other configurations (apples/apples) ??

Why add the extra pipe resonance and offset driver position to help fix it(white graph verses green)

Unless I've misunderstood the drawing, couple of points there. Firstly, that looks like the cross-section of a [simple] DSL style double-tapped horn / Jensen Transflex rather than a 'standard' TL (whatever that is -we're not likely to get much agreement 😉 ) as it's exciting the line at two acoustically different locations. Secondly -you're not necessarily going to get a meaningful, or at least a particularly revealing apples / apples comparison just by keying off the same Vb, unless you're assuming they are all sharing the same Fb and alignment, which isn't necessarily going to be the case, or even likely since a well-designed TL will probably be starting out with a larger Vb in the first place & the designer will have been aiming for a different alignment, for different purposes also.

 

[Booger weldz]

this pic is probably what I should have used , Scott/Bp1

(i just cut a cheesy ‘bypass’ hole in a closed end of a ‘perfect’ OD TL faking the same )

 

[Scottmoose]

I'm not sure that's faking a DSL style double tapped horn, if I'm understanding you correctly and you've simply cut a hole in one of the internal panels. It will certainly alter the resonant behaviour, as is sometimes done with induction / exhaust design, likely raising the fundamental, but it's not quite the same thing as driving the line at two physically (& significantly) different locations, as is the case in a Transflex or Tom Danley's inadvertent variations of Novak's old Jensen cabinet.

 

[Booger weldz]

What if we use this picture, but we move the driver to 66.66 cm (~.second pipe resonance) from the closed end (and 33.33 (further away from the 4x the ‘Z’ 1/4 wavelength freq of cancelation) from the vent/exit).

(ignore that little rear chamber)

 

[Scottmoose]

If the driver is internally mounted (as in both faces are driving the line, not just one) it's still a double-tapped horn / Transflex variation -or to put it another way, a 6th order bandpass taken to its logical extreme. You can model it in Hornresp but you'll need to do so as a tapped horn, not a regular TL.

 

[Booger weldz]

I’m quite aware of what they are and have built several of each? The second pipe resonance shifts a bit further down it seems?

 

[Scottmoose]

Second pipe resonance? As in harmonic modes?

 

[Booger weldz]

Yes sir. (Like the offset driver @ ~0.35 instead of @ the closed end) that all shifts further down (just like if i shoved the speaker vent in the corner or a car )

tapped pipe is just a tighter boundary condition initially If it’s not a substantial legth/girth from driver output to exit ?

 

[Scottmoose]

Not necessarily; depends on the compression ratio & to a point the physical layout.

 

[Booger weldz]

i fimd these totally differnet shapes (and driver entry points) truly amazing/exciting witht the 'same' results essentially

 

[Guerilla]

Would "Improved Transmission Line" be effiscient as bottoms in a PA system? (300 - 1000 people) Down to ~45hz.
Cheers!

 

[planet10]

IME TLs 9in the stricter sense) of any sort are not good for a PA. Danley’s tapped horns were designed specifically for PA, and then spread widely… lots of stuff here. They trad e quite limited bandwidth for greater efficiency.

Does the PA have to move (needs to be smaller and lighter or fixed — i imagine a horn each side of a theatre with floor to ceiling adjacent to each side mouths and an insane number of large PA drivers loading each one ;^)

dave

 

[tubelectron]

@planet10 - the question may have already been asked : is the "Frugel-Horn" a variant of TL, I mean a TL driving some kind of back horn ?

T

 

[planet10]

In the sense that TLs in the broader sense have become equated to quarter-wave designs which includes horns, Voigts, tapered TLs, noit taperered TLs, ML-MLs…

In the more traditional sense of a tapered or straight TL no, Horn loaded into a choke, Klipsch trick, and then the big flare loading th ewall or corner.

dave

 

[GM]

Basically rocket nozzle design.

 

[Guerilla]

@planet10

Yes this PA will be moveable.

I have tops going ~100hz up. They are DA SYSTEMS Impuls 6. Pulling my hair since I cant find brochure or specs on these ~y2k speakers.

Max portability without sacrificing sweetness of sound is priority.

I bought 6 cabinets including 4 sub enclosures for 110 dollars. I have plenty 15 inch plus a pair of Zomax 18s to stuff them with. Just looking for the best (alignment?) to rebuild them into.
Cheers!