I would really appreciate some help with some uncertainties I am having with QW designs (TQWT, MLTL).
Reading through the forum and Mr. King's site I see solutions that I do not know/understand the reason behind.
Please forgive me if some of the questions are "stupid" the the enlightened, and naturally for posting so many questions (I still have many left).
I suppose many answers would be inconclusive like; "It depends", please also leave those as they are helpful regarding further studies.
NOTE: Im posting this in "Multi-way" as I intend to use it in a 2-way setup, but maybe "Full-range" is better suited ???
1.1 Are flat ends used to bounce back waves directly where they came from ?
1.2 If so are flat hard surfaces best in the ends (glas, cement) ?
1.3 Is a rough surface desirable on the long sides to disrupt "nice patterns" ? (like sandpaper under the padding).
1.4 Do we tapper the line just to avoid standing waves (it appear also to influence the length needed for a specific tuning) ?
1.5 If so would a cylindrical line be just as good as an tapered (maybe center padding is needed for those few standing waves) ?
1.6 Would a tapered cylinder (cone) be optimal ?
2.1 If we bend the line, is it best to reflect the wave with a flat surface (like a ball bouncing off a wall) or to lead the air-pressure around with rounded corners (like water in a canal) ?
3.1 Aparently I get better (less spikes) results when placing the port in the wider end, is this correct, why ?
4.1 when building TL's are there any best practice for connecting the driver to the line without disrupting it, (Relevance of the question can vary depending of the relative size between driver and line).
4.2 If there is to be a "chamber" holding the driver before the line, are there any guidlines ?
5.1 I have seen multiple drivers in TL's, but imagine the will interct in bad ways (back-waves will interact untimely)
5.2 If one bigger driver always desirable ?
5.3 can it be made to work if the share a common chamber before loading the line ?
6.1 If the narrow line have a problem with baffle-size, I have seen back-mounted drivers used, is this recommendable ?
6.2 If so would it be better to offset the two drivers in time to make up for the difference between them (offset=time for sound from back to front driver set in DSP) ?
Thank you for reading all this🙂
Reading through the forum and Mr. King's site I see solutions that I do not know/understand the reason behind.
Please forgive me if some of the questions are "stupid" the the enlightened, and naturally for posting so many questions (I still have many left).
I suppose many answers would be inconclusive like; "It depends", please also leave those as they are helpful regarding further studies.
NOTE: Im posting this in "Multi-way" as I intend to use it in a 2-way setup, but maybe "Full-range" is better suited ???
1.1 Are flat ends used to bounce back waves directly where they came from ?
1.2 If so are flat hard surfaces best in the ends (glas, cement) ?
1.3 Is a rough surface desirable on the long sides to disrupt "nice patterns" ? (like sandpaper under the padding).
1.4 Do we tapper the line just to avoid standing waves (it appear also to influence the length needed for a specific tuning) ?
1.5 If so would a cylindrical line be just as good as an tapered (maybe center padding is needed for those few standing waves) ?
1.6 Would a tapered cylinder (cone) be optimal ?
An externally hosted image should be here but it was not working when we last tested it.
2.1 If we bend the line, is it best to reflect the wave with a flat surface (like a ball bouncing off a wall) or to lead the air-pressure around with rounded corners (like water in a canal) ?
An externally hosted image should be here but it was not working when we last tested it.
3.1 Aparently I get better (less spikes) results when placing the port in the wider end, is this correct, why ?
An externally hosted image should be here but it was not working when we last tested it.
4.1 when building TL's are there any best practice for connecting the driver to the line without disrupting it, (Relevance of the question can vary depending of the relative size between driver and line).
4.2 If there is to be a "chamber" holding the driver before the line, are there any guidlines ?
An externally hosted image should be here but it was not working when we last tested it.
5.1 I have seen multiple drivers in TL's, but imagine the will interct in bad ways (back-waves will interact untimely)
5.2 If one bigger driver always desirable ?
5.3 can it be made to work if the share a common chamber before loading the line ?
An externally hosted image should be here but it was not working when we last tested it.
6.1 If the narrow line have a problem with baffle-size, I have seen back-mounted drivers used, is this recommendable ?
6.2 If so would it be better to offset the two drivers in time to make up for the difference between them (offset=time for sound from back to front driver set in DSP) ?
Thank you for reading all this🙂
Last edited:
No, wavelengths of interest are so long as to ignore almost any pertebation you could put at the end or on the sides.
Line taper is used along with the parameters of interest (Fs, Qt, Vas) to end up with a line that fits the target requirements.
For instance, we have an ML-TL that worked very well, but for one specific experiment we needed more height, so an ML-Voigt was developed.
Cross section shape makes little difference.
Maybe aesthetically. Some of the metronome precursors were designed (and 1 built) with a tapered cylinder.
The Metronome
Again wavelength size. In fact the expansion of the line at a bend which does not have deflectors creates a beneficial high-pass filter which can be used to get a bit more bass reinforcement.
How much ripple you get depends on many factors. While a line that gets narrower towards the terminus can just be a line, if a line tapers like a Voigt it is almost always beneficial to mass-load it. This relates to how tha taper affects the redistribution of the unwanted quarter-wave modes.
A driver is usually not big enuff to perturb the line function. Even significant bloackages such as the midTweeter TL in our big MTM ML-TL doesn’t seem to significantly affect the line function.
As long as average driver position is at the designed Zd, one usually just gets a broadening and decrease in amplitude of the ripple… again long wavelengths.
Depends.
That just complicates things.
What do you mean by this?
dave
Dear Planet10, Dave
Thank you very much for taking the time to explain this to me, much appreciated.
Regarding 2.1; Bend
I do not fully understand your reply.
Are you saying that the natural expansion that will happen with a bend is beneficial or are you saying that it would be beneficial to expand the line further at the bend ?
Regarding the behaviour of the long wavelength in the bend I still do not understand if the rounded corners are better than straight (90 deg or 45 deg), my intuition tells me the "standard" (90 deg) corners (as in first image) will partly behave as 1/4 and partly as two 1/8 tubes.
Regarding 6; Baffle Sorry for the bad formulated question and missing sketch.
I have seen TL's with 2 opposite mounted speakers, I'm not sure about the reason behind or if these where bi or di-pole.
I have read about problems induced by baffle-geometry/size and the effect of the airspace in isobaric designs.
And thought some of this could be helped by offsetting the drivers (di-pole) in time.
So I would have the front driver fire after the rear driver (by distance/speed of sound), this is where the DSP come into play.
My childish theory is that this would remove part of the air-spring inside the speaker box and make the front driver handle faster, and outside initiate an airflow on the baffle corners to smooth out turbulence here.
While this might "clean" the front waves (initially) on the outside I have no idea what happens to the back-waves as they must be equally "dirty" (maybe a damping on the backwall to handle this ?), on the inside the later movement of the front speaker will eventually reach the back driver and ??? create more dirt..ups!.
Please let me know if you think this is a stupid experiment.
Best regards
Thank you very much for taking the time to explain this to me, much appreciated.
Regarding 2.1; Bend
I do not fully understand your reply.
Are you saying that the natural expansion that will happen with a bend is beneficial or are you saying that it would be beneficial to expand the line further at the bend ?
Regarding the behaviour of the long wavelength in the bend I still do not understand if the rounded corners are better than straight (90 deg or 45 deg), my intuition tells me the "standard" (90 deg) corners (as in first image) will partly behave as 1/4 and partly as two 1/8 tubes.
An externally hosted image should be here but it was not working when we last tested it.
Regarding 6; Baffle Sorry for the bad formulated question and missing sketch.
I have seen TL's with 2 opposite mounted speakers, I'm not sure about the reason behind or if these where bi or di-pole.
I have read about problems induced by baffle-geometry/size and the effect of the airspace in isobaric designs.
And thought some of this could be helped by offsetting the drivers (di-pole) in time.
So I would have the front driver fire after the rear driver (by distance/speed of sound), this is where the DSP come into play.
My childish theory is that this would remove part of the air-spring inside the speaker box and make the front driver handle faster, and outside initiate an airflow on the baffle corners to smooth out turbulence here.
An externally hosted image should be here but it was not working when we last tested it.
While this might "clean" the front waves (initially) on the outside I have no idea what happens to the back-waves as they must be equally "dirty" (maybe a damping on the backwall to handle this ?), on the inside the later movement of the front speaker will eventually reach the back driver and ??? create more dirt..ups!.
Please let me know if you think this is a stupid experiment.
Best regards
Last edited:
Dear Dave
Thank you again.
The conclusion regarding the geometry of the bend surprised me, as I thought this would create standing waves at 1/8 tuning.
My experiments had more variables and I proberly rushed to conclusions, I made two similar small lines as first and second drawing, BUT the 1st was wood and the 2end cement.... next experiments will have only one variable.
Ha ha. Cat in the hat !
Yet another missing part in my education, never heard about that book/movie before, but I see what you mean.
Should I ever go down that road for final design I have an inspiration for naming.
I was concerned about how much power would be induced in the line with the dipole, but thought even just a little helps if the rest of the system behaves as a nice open baffle.
I do not understand the reason behind the systems I have seen if they where bipole, as it should be better to fit both drivers on 1 side.... or even better it should be possible to exchange them with 1 driver of the combined properties.
Thank you again for taking the time to give leasons.
Br
Thank you again.
The conclusion regarding the geometry of the bend surprised me, as I thought this would create standing waves at 1/8 tuning.
My experiments had more variables and I proberly rushed to conclusions, I made two similar small lines as first and second drawing, BUT the 1st was wood and the 2end cement.... next experiments will have only one variable.
Ha ha. Cat in the hat !
Yet another missing part in my education, never heard about that book/movie before, but I see what you mean.
Should I ever go down that road for final design I have an inspiration for naming.
I was concerned about how much power would be induced in the line with the dipole, but thought even just a little helps if the rest of the system behaves as a nice open baffle.
I do not understand the reason behind the systems I have seen if they where bipole, as it should be better to fit both drivers on 1 side.... or even better it should be possible to exchange them with 1 driver of the combined properties.
Thank you again for taking the time to give leasons.
Br
Last edited:
There is no 1/8th anything. A line open at one end only has quarter wavelength behaviour.
A dipole would put no energy into the line.
Push-push can provide tremendous benefits, particularily with woofers.
dave
- Status
- Not open for further replies.