Need advice on a TL build

[planet10]

No, contracting, or what I choose to define as a TQWT. Expanding means a horn to me, so must be longer than either a TQWT or TL (straight taper) for a given tuning.

Scott & i went thru a long private discussion on your nomencalture. I dug into historical reference, and TQWT is synonymous with a Voigt. All the terms are in place as early as his original Voigt patent to grandfather the name, and MJK's use of the term in his ground-breaking ML-TQWT article set it in stone.

Your use to mean something else just confuses a lot of people. You'll just have to think of a Voigt pipe as a very specific kind of tapped horn.

dave

 

[planet10]

Other than actual bracing, those 45-degree corner braces don't perform any function, certainly not any acoustical ones.

It turns out that acoustically they can actually degrade performance. The expansion of the line around a fold acts as a low pass filter, incrementally improving the low pass function of the TL terminus.

dave

 

[pkitt]

Okay, I guess I wasn't thorough enough in my comments. You're correct in that the lack of angled deflectors actually has a benefit, but my point was addressing their original, incorrect use to "steer the sound waves around the turns". But, while I agree with you in concept, I would think the stuffing effects as a low-pass filter would be much larger than that of non-deflectorized corners?
Paul

It turns out that acoustically they can actually degrade performance. The expansion of the line around a fold acts as a low pass filter, incrementally improving the low pass function of the TL terminus.

dave

 

[planet10]

I would think the stuffing effects as a low-pass filter would be much larger than that of non-deflectorized corners?

It is. But every little bit of low pass you can gain in the geometry means a bit less stuffing which can translate to more TL gain (ie more bass augmentation)

In cases where there is no stuffing -- Scott's Olson-style manifold horns for instance -- this is very important. On a typical single fold TL, not so much.

dave

 

[GM]

Scott & i went thru a long private discussion on your nomencalture. I dug into historical reference, and TQWT is synonymous with a Voigt. All the terms are in place as early as his original Voigt patent to grandfather the name, and MJK's use of the term in his ground-breaking ML-TQWT article set it in stone.

Your use to mean something else just confuses a lot of people. You'll just have to think of a Voigt pipe as a very specific kind of tapped horn.

dave

Bully for you, but as I previously noted, I choose to use only one definition for TQWT in the interest of clarity and the various Voigt pipes don't conform to it.

What's apparently 'set in stone' is continuing to perpetrate an outdated, confusing way of describing distinctly different pipe configurations and then there's the folks that view them all simply as TLs, their closest electrical equivalent.

But since my repeated attempts at enlightening folks on these types of designs are counter to the powers that be at DIYaudio combined with me wanting to make the most of my limited forum time I think speakerdoctor's admonition that TL design Qs are best left to the experts at QW is a great idea.

GM

 

[TerryO]

Bully for you, but as I previously noted, I choose to use only one definition for TQWT in the interest of clarity and the various Voigt pipes don't conform to it.

What's apparently 'set in stone' is continuing to perpetrate an outdated, confusing way of describing distinctly different pipe configurations and then there's the folks that view them all simply as TLs, their closest electrical equivalent.

But since my repeated attempts at enlightening folks on these types of designs are counter to the powers that be at DIYaudio combined with me wanting to make the most of my limited forum time I think speakerdoctor's admonition that TL design Qs are best left to the experts at QW is a great idea.

GM

Greg,

I certainly appreciate what you're trying to do towards getting more precise definitions of different topographies that are too often lumped together and create a rather vague, nebulous idea of what exactly is being discussed.

Consider your definitions adopted (by me anyway).

As I've certainly benefited numerous times from your expertise beginning back many years ago on the old Bass List, I'd like to thank you for all your help and efforts on behalf of DIY speaker builders.

Best Regards,
TerryO

 

[planet10]

I choose to use only one definition for TQWT in the interest of clarity

I applaud your intentions, but unfortunately it only caused more confusion. Same with the term reverse taper. Expanding or decreasing taper i understand, but reverse implies the opposite of taper, but a taper can go either way. Whenever you use the term it just confuses me (ie what the H does he mean)

dave

 

[pkitt]

What would really be interesting would be to build 4 versions of the same line, starting with no folds, a single fold and two segments, two folds with 3 segments, then 3 folds with four line segments, obviously making all of the line areas, volumes and lengths the same as well as locating the driver at the same point in the lines. You could then measure the output of the terminus (and driver, too?) without any stuffing, then with stuffing to see just how much effect those rectangular corners have. Too much work for me and I don't have the necessary equipment anyway.
Paul

It is. But every little bit of low pass you can gain in the geometry means a bit less stuffing which can translate to more TL gain (ie more bass augmentation)

In cases where there is no stuffing -- Scott's Olson-style manifold horns for instance -- this is very important. On a typical single fold TL, not so much.

dave