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Quarter Wave / T-Line tutorial-UPDATED


Forevrbumpn

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What happens when you run a t-line with a subwoofer that doesnt have a qts of .40 or lower? Lets say the qts is .5 to .7 but the qms is still below 7.

It sounds the best it can sound.

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What happens when you run a t-line with a subwoofer that doesnt have a qts of .40 or lower? Lets say the qts is .5 to .7 but the qms is still below 7.

It sounds the best it can sound.

Can you tell me a little more about what the op was saying about eq'ing the frequencies? Also he said that if you tune the box the speakers fs that it will sound the best that the sub possibly can. What happens if i go over or under the fs?

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What happens when you run a t-line with a subwoofer that doesnt have a qts of .40 or lower? Lets say the qts is .5 to .7 but the qms is still below 7.

It sounds the best it can sound.

Can you tell me a little more about what the op was saying about eq'ing the frequencies? Also he said that if you tune the box the speakers fs that it will sound the best that the sub possibly can. What happens if i go over or under the fs?

I disagree with that portion of the OP and only because my experience is different. For a full range loudspeaker I keep with the Fs of the driver but for subs, I normally tune below Fs. Especially high power handling car audio subs, which usually have an Fs above 34. My go to frequency for car audio lines is 30Hz and it works every time.

The reason, I think, that people persist with the myth that a driver has to have this or that TS properties, that the line must be stuffed, that low power is necessary, et al, is that the majority of scholarly work on lines has been done using home audio drivers with the goal of an ideally flat response curve.

Such is simply not the case for us car audio bassheads, lol.

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What happens when you run a t-line with a subwoofer that doesnt have a qts of .40 or lower? Lets say the qts is .5 to .7 but the qms is still below 7.

It sounds the best it can sound.

Can you tell me a little more about what the op was saying about eq'ing the frequencies? Also he said that if you tune the box the speakers fs that it will sound the best that the sub possibly can. What happens if i go over or under the fs?

I disagree with that portion of the OP and only because my experience is different. For a full range loudspeaker I keep with the Fs of the driver but for subs, I normally tune below Fs. Especially high power handling car audio subs, which usually have an Fs above 34. My go to frequency for car audio lines is 30Hz and it works every time.

The reason, I think, that people persist with the myth that a driver has to have this or that TS properties, that the line must be stuffed, that low power is necessary, et al, is that the majority of scholarly work on lines has been done using home audio drivers with the goal of an ideally flat response curve.

Such is simply not the case for us car audio bassheads, lol.

I agree. I can make nearly any driver work in a transmission line.

I think the main reason that there's a lot of folklore about what does and does not work in transmission lines is due to three things:

1) Although Akabak has been around for over a decade, nobody really noticed until Danley started talking about it. I believe the program originated in Germany, so it was very obscure. Even today, it's exceptionally difficult to use.

2) Fifteen years ago, there was basically no easy way to model transmission lines and horns. If you were willing to do the math, you could knock out a design in something like 4-8 hours of number crunching.

3) David McBean's hornresp changed *everything.* The interface is easier than Akabak, it's relatively user friendly, the documentation is more concise. There are still some things that Akabak can do that Hornresp can't, but you'd have to be a real masochist to ignore Hornresp. The fact that it's free, and David routinely does enhancements for free, is just icing on the cake.

TLDR: there's a lot of folklore about speaker enclosures that's false. You can do some crazy alignments using software now; nearly anything is possible.

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I agree. I can make nearly any driver work in a transmission line.

I think the main reason that there's a lot of folklore about what does and does not work in transmission lines is due to three things:

1) Although Akabak has been around for over a decade, nobody really noticed until Danley started talking about it. I believe the program originated in Germany, so it was very obscure. Even today, it's exceptionally difficult to use.

2) Fifteen years ago, there was basically no easy way to model transmission lines and horns. If you were willing to do the math, you could knock out a design in something like 4-8 hours of number crunching.

3) David McBean's hornresp changed *everything.* The interface is easier than Akabak, it's relatively user friendly, the documentation is more concise. There are still some things that Akabak can do that Hornresp can't, but you'd have to be a real masochist to ignore Hornresp. The fact that it's free, and David routinely does enhancements for free, is just icing on the cake.

TLDR: there's a lot of folklore about speaker enclosures that's false. You can do some crazy alignments using software now; nearly anything is possible.

I concur. And while I have Hornresp, I don't use it. Probably because I'm too mathematically stupid to learn it, lol. But mostly because I have only built a couple of lines that didn't perform as I expected so, there isn't a lot of priority in my mind for learning the mathematics associated with them.

That said, I'm doing some self education on physics and it's pretty fucking interesting so I would imagine the math will get easier for me. I've never been one who can be forced to learn something. I have to have an interest in the subject matter before I can internalize it.

Another thing that's kinda mind boggling to me is the mythology that designing lines is somehow difficult. Granted, you can make it as difficult as you like but at the same time, they are to me the easiest enclosures to calculate and built... and I came from a background of building a lot of 6th orders before I learned about t-lines.

You'd have to have either a gun or a lot of money to get me to design and built a 6th order now, lol.

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Tuning to Fs requires a few other motor parameters to be met if you are tuning to a higher Fs than 35 and wish to still perform down to 30hz, in my opinion. I would rather just tune to 30hz and not worry about it not working in the specific environment its going in.

MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..."

Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through.

Hammerdown... 1%

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