You can model that pretty easily in Hornresp. I'm of a mind that an offset driver is pretty necessary to smooth out the 2nd and 3rd harmonics, But HR will show you everything.
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
@Eggguy said:
In an analogous circuit of a vented speaker the air mass adds a reactive component compared to a sealed box, increasing the roll off rate and group delay. I think a TL without a large coupling chamber, the air mass couples directly to the cone mass, therefore not adding another reactance. What if someone could build a TL with a taper ratio fairly high, approaching 10, containing 3 lines of equal length but radically different taper ratios? Also no driver offset and no fiber stuffing. The attenuation of overtones would be achieved by multiplying their occurrences and thereby lessening their severity.
I think you may be describing what B&W does with the Nautilus. I am not knowledgeable about transmission lines, though.
That's a pleasant brew all things considered. Fun story - many years ago in my robot guy days our entire "D Crew" team was given $500 to throw a party. Part of that coin was spent on a keg of Amberbock. We polished it off.
@Eggguy said:
Yes I agree. We all have a potential for bias. However since we are on a subject that interests me, and of which I strive for a fuller understanding, I do not understand how a TL can be considered 4th ord. An MLTL yes. A MLTL has no line, instead it has a port, two separate volumes of air acoustically coupled. So I can see how it is 4th ord. I agree with Ben that it is just a BR in a tall form with stuffing. Please correct me if I am wrong, because I often am, but isn't the order of the enclosure determined by the number of chambers. And more chambers can often times mean more group delay?
A TL is a 4th order response below its tuning frequency as it rolls off at 24db/octave. A MLTL does the same. When referring to a BP, then yes the order is determined by the number and placement of the chambers. A 4th order has 2 chambers with one vented, 6th order will have 2 chambers with both vented, an 8th will have 3 chambers with at least 2 vented.
Scott gave the moderators on the project pad a "first look" and asked for critiques of his work before releasing those 2 papers. We had some questions and Scott made a few clarifications based on that input. As part of this, I took a couple of older builds and tested the terminus output of a BR and MLTL. The loss of SPL in the MLTL was very similar to what Scott found. My testing wasn't as conclusive or empirical as his (I'm just using my Omnimic so cant take super high SPL) but the loss was still there.
I very much appreciate the work done by Scott and others. It is not only time consuming but risky, in that it exposes ones-self to critique. I would probably never take such a risk. So kudos to such men.
I need to learn more about ported systems. If I desire in myself the ability to explain the differences between Sealed, BR, TL and MLTL, I will need a thorough understanding of each.
Agreed. Always a good idea to keep our aging brains extremely active. For myself, I'm envisioning a "supercharged" TL that accelerates the rear wave past an H-PAS subchamber and then exits the speaker through a high velocity "swoopy" port! Lots of time consuming trial and error would be involved, but, I'm retired and this would certainly be a good project to keep me busy and out of trouble.
He seemed to miss that the whole point of a tapered line is to push the resonances higher up in frequency, making them more easily absorbed with less damping material. Smaller exit area increases velocity of air closer to that of a ported speaker, but reduces the amplitude of higher frequency resonances at the exit. Unfortunate, these sort of things should be easily observed in Hornresp, which Scott is quite experienced with.
I’m finishing up my Sugrivans, but the line after the stuffing is “clean”, bare wood. Hopefully the resonances in the line will be greatly diminished by the folds in the TL plenum. Measurements will tell!
Agree that Scott is very smart, but seems to have some bias which could be solved with more measurements. We shall see, Brianne Steele does not agree either. The burst energy simulations may point to way to measuring real advantages with TLs.
But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
Comments
Stretching my brain hurts almost as much as stretching my new knee.
You can model that pretty easily in Hornresp. I'm of a mind that an offset driver is pretty necessary to smooth out the 2nd and 3rd harmonics, But HR will show you everything.
Any thoughts on Amber Bock?
I think you may be describing what B&W does with the Nautilus. I am not knowledgeable about transmission lines, though.
That's a pleasant brew all things considered. Fun story - many years ago in my robot guy days our entire "D Crew" team was given $500 to throw a party. Part of that coin was spent on a keg of Amberbock. We polished it off.
Good story
Took us about ten hours to do so - we had a lot of fun that night.
A TL is a 4th order response below its tuning frequency as it rolls off at 24db/octave. A MLTL does the same. When referring to a BP, then yes the order is determined by the number and placement of the chambers. A 4th order has 2 chambers with one vented, 6th order will have 2 chambers with both vented, an 8th will have 3 chambers with at least 2 vented.
Scott gave the moderators on the project pad a "first look" and asked for critiques of his work before releasing those 2 papers. We had some questions and Scott made a few clarifications based on that input. As part of this, I took a couple of older builds and tested the terminus output of a BR and MLTL. The loss of SPL in the MLTL was very similar to what Scott found. My testing wasn't as conclusive or empirical as his (I'm just using my Omnimic so cant take super high SPL) but the loss was still there.
I very much appreciate the work done by Scott and others. It is not only time consuming but risky, in that it exposes ones-self to critique. I would probably never take such a risk. So kudos to such men.
I need to learn more about ported systems. If I desire in myself the ability to explain the differences between Sealed, BR, TL and MLTL, I will need a thorough understanding of each.
Agreed. Always a good idea to keep our aging brains extremely active. For myself, I'm envisioning a "supercharged" TL that accelerates the rear wave past an H-PAS subchamber and then exits the speaker through a high velocity "swoopy" port! Lots of time consuming trial and error would be involved, but, I'm retired and this would certainly be a good project to keep me busy and out of trouble.
https://techtalk.parts-express.com/forum/tech-talk-forum/45403-for-those-who-were-at-mwaf-phil-clements-h-pas
Scott Hinson just posted another paper on transmission lines. Well written and easy to understand.
https://drive.google.com/file/d/1JtZLHIwyb9iHJaD8LLQStdeA1gS32APi/view
He seemed to miss that the whole point of a tapered line is to push the resonances higher up in frequency, making them more easily absorbed with less damping material. Smaller exit area increases velocity of air closer to that of a ported speaker, but reduces the amplitude of higher frequency resonances at the exit. Unfortunate, these sort of things should be easily observed in Hornresp, which Scott is quite experienced with.
I’m finishing up my Sugrivans, but the line after the stuffing is “clean”, bare wood. Hopefully the resonances in the line will be greatly diminished by the folds in the TL plenum. Measurements will tell!
Agree that Scott is very smart, but seems to have some bias which could be solved with more measurements. We shall see, Brianne Steele does not agree either. The burst energy simulations may point to way to measuring real advantages with TLs.