[kryptonitewhite]

I would guess a "full wave" TL/horn/what have you would be out of phase and cancel out? So is there a such thing?

 

[Bill Fitzmaurice]

I would guess a "full wave" TL/horn/what have you would be out of phase and cancel out? So is there a such thing?

Every TL and horn is a 1/2 wave device, one octave up from the 1/4 wavelength frequency. Just like with a reflex cab port output from the TL terminus is way down an octave above Fp, and if the pipe is properly stuffed is inconsequential. With a rear loaded horn a 1/2 octave dip is intrinsic, and is the major flaw of the design in a fullranger. A well designed rear loader sub places the dip above the passband where it can't pose a problem.

 

[kryptonitewhite]

Every TL and horn is a 1/2 wave device, one octave up from the 1/4 wavelength frequency. Just like with a reflex cab port output from the TL terminus is way down an octave above Fp, and if the pipe is properly stuffed is inconsequential. With a rear loaded horn a 1/2 octave dip is intrinsic, and is the major flaw of the design in a fullranger. A well designed rear loader sub places the dip above the passband where it can't pose a problem.

Thank you Bill, i've been impatiently waiting for an answer to that...it's going to take me a bit to obsorb a lot of that info.


Every horn is a 1/2 wave device...makes sense to me thus far... one octave up from the 1/4 wavelenght feequency...I'm lost.

So let's start with a 10Hz device, as my other thread implies that as a good fantasy. 1 octave up being 20Hz. So 1/2 wave is 10Hz, and 1/4 is 20, and 8th would be 40??

What is a reflex cab port? Some day when i have more time I'll Google all this, but if you could give me a summation, that would be great.

Fp, frequency or port? lol... just a guess... I'm assuming something like Fb

Thanks!

 

[Bill Fitzmaurice]

So let's start with a 10Hz device, as my other thread implies that as a good fantasy. 1 octave up being 20Hz. So 1/2 wave is 10Hz, and 1/4 is 20, and 8th would be 40??


Thanks!

The other way around.

 

[kryptonitewhite]

So at 1/2, 1/4, 18th, 16th... I assume there are peaks and dips, ripples, and such

 

[Bill Fitzmaurice]

So at 1/2, 1/4, 18th, 16th... I assume there are peaks and dips, ripples, and such

Not necessarily. Well designed TLs and horns are ripple free, though ripple free horns tend to be very large. But with the EQs now available ripple is no more a concern than a room mode, so reasonably sized horns are quite practical.

 

[kryptonitewhite]

I know everything is a matter of opinion, but it seems to me if $$$ were unlimited, as well as space and such, these would be the way to go.

 

[Bill Fitzmaurice]

I know everything is a matter of opinion, but it seems to me if $$$ were unlimited, as well as space and such, these would be the way to go.

Horns are considerably less expensive than direct radiators, as they get far better results per driver. My 8 cubic foot HT sub is loaded with a $35 eight incher, and goes as low and loud as SHMBO will tolerate. Commercial horns are expensive due to their high labor costs to build. That's not a factor in the DIY realm.

 

[Mike P.]

Shmbo?

 

[Bill Fitzmaurice]

Shmbo?

Oops, SWMBO.

 

[Mike P.]

Now that we got the spelling correct, what does it mean? :bigsmile:

 

[Bill Fitzmaurice]

Now that we got the spelling correct, what does it mean? :bigsmile:

That you're apparently a bachelor.:yay:

 

[kryptonitewhite]

Horns are considerably less expensive than direct radiators, as they get far better results per driver. My 8 cubic foot HT sub is loaded with a $35 eight incher, and goes as low and loud as SHMBO will tolerate. Commercial horns are expensive due to their high labor costs to build. That's not a factor in the DIY realm.

pics/vids/links??

 

[kryptonitewhite]

Oops, SWMBO.

she wears my b____ no, not it...

 

[Mike P.]

That you're apparently a bachelor.:yay:

I've been married 28 years. A Google search turned up "She Who Must Be Obeyed". Apparently I don't have that problem. :whistling:

 

[Bill Fitzmaurice]

pics/vids/links??

On my website.

I've been married 28 years. A Google search turned up "She Who Must Be Obeyed". Apparently I don't have that problem.

Have submitted your name to Ripley's 'Believe It or Not' !

 

[kryptonitewhite]

So I am using this lazy day to finally do some much needed research....and I've already found some info that surprised me. Toward the top, I am being told a transmission line loudspeaker is merely an infinite baffle, where the sound is absorbed... basically to make it run "free air" yet isolating the rear wave. I assume this refers to midrange speakers, not subwoofers, as toward the end it speaks of the rear wave emerging "in-phase" to enhance low frequency output. While speaking of the loudspeaker, though, it did say it will extend low frequency below 1/2 wavelength....

http://en.wikipedia.org/wiki/Acoustic_transmission_lines

The difference between a transmission line loudspeaker and a vented loudspeaker system is clear: the rear wave is audibly absorbed and the cavity does not form a tuned system.

Transmission Line Loudspeakers have:

1. minimal acoustic output from the enclosure except from the driver;
2. accurate bass, without 'boom';
3. excellent transient response;
4. typically, extended bass below a half wave frequency of the reflected line length e.g. 30Hz=8 foot length;
5. typically, smoooth impedance curves, possibly from a lack of frequency-specific resonances;
6. low efficiency.








"Transmission line" is also the name of a specialized audio speaker enclosure topology, in which sound from the back of the bass speaker chassis passes along a long (generally convoluted) path within speaker enclosure and emerges from the open end of the path "in-phase" with the sound radiated from the front of the driver, enhancing the output level at low frequencies.



It all makes sense, the only new news to me is that it is saying for upper range it acts as an IB of sorts, until the 1/2 wave is reached, then it reinforces... which is really the whole idea, right?

 

[Bill Fitzmaurice]

It all makes sense, the only new news to me is that it is saying for upper range it acts as an IB of sorts, until the 1/2 wave is reached, then it reinforces... which is really the whole idea, right?

It all makes sense, but much of it is incorrect. The problem with wikipedia is that anyone can post anything, and accuracy is not guaranteed. The definitive work on TLs was done in the late 1990s by George Augsperger, his results were published in the JAES and AudioXpress Magazine. As to who he is, should you ever submit a treatise on loudspeakers to the JAES chances are it will be George who passes judgment on it.

 

[kryptonitewhite]

I went to walmart, glanced at pillows on the way, probably should have looked in the fabric/hobby section for pillow stuffing? Didn't see any by the actual pillows. How much should I use? Does it need to run throughout, or just a section?
I'm guessing my massive 4" with 6mm p-p won't warrant chicken wire and stapling...