Oh blimey, not that Marshall rubbish. Don't go there. Go here instead:
http://www.quarter-wave.com/TLs/Alignment_Tables.pdf
Excel spreadsheet derived from above:
http://www.quarter-wave.com/TLs/Alignment_Tables_Calculator_3_3_09.xls
A summary of the physics:
http://www.quarter-wave.com/TLs/TL_Anatomy.pdf
Note that Martin's alignment tables assume you are tuning to the driver Fs, which isn't all that obvious / clear on first glance. Personally I prefer to tune a classic style TL with only a small amount of taper a bit higher than that.
And for variety, here is an alternative approach with slightly different goals & methodology but equally accurate in terms of the physics:
http://diyaudioprojects.com/Technical/Papers/Loudspeakers-on-Damped-Pipes.pdf
It's ultimately just a matter of degree. It's a resonant QW pipe with a driver & a terminus offset from the respective ends; it doesn't matter in that sense whether it's mass-loaded or not.
I've used an offset driver and port a number of times in ML-TLs and find it to be very advantages in some cases depending on several factors. What doing this does is to smooth out the response to a better degree as compared to having only the driver offset, but with an increase of f3 by 1-2 Hz.
Paul
Paul
Hi all,
Thanks for the answers and the support
Now I have to read a lot, very interesting stuff
But, from first understanding, a linear tube at 1/4 wave is the easy way to start with, then the tapered one with narrow opening end will be second study
Learning the MATH CAD correction tables is very helpful.
What is ML and offset driver?
Best regards
Williams
Thanks for the answers and the support
Now I have to read a lot, very interesting stuff
But, from first understanding, a linear tube at 1/4 wave is the easy way to start with, then the tapered one with narrow opening end will be second study
Learning the MATH CAD correction tables is very helpful.
What is ML and offset driver?
Best regards
Williams
ML means the end (the open end) of the line is Mass Loaded by a port. In an ML-TL the line usually has a constant area and the line's length is not long enough to allow its 1/4-wavelength resonant frequency to be the sole tuning mechanism. The port is added near (usually) the end of the line to complete the tuning process. An offset driver means the driver being loaded by the TL is not located at the very beginning of the line (the closed end), rather it's located away from the closed end of the line, typically around either 20% of the line's length or 33% of the line's length.
Paul
Paul
Hi all,
Learning slowly the material,
If the line is not 1/4 wave and the load is as BL, there is a freq. shift from driver fs?
If the driver given Vas is134 liters, is it equivalent to Vd?
Then in this volume have to build the folded tube?
Suppose I have this volume in cabinet, the linear tube is a square structure; it will be same structure all the way to the open end port?
As a square structure tube say, long 2.5m and SO/SL=1, driver Sd=220cm² then the port should be same size, 220cm²?
By basic theory this will give 34 Hz resonate tube, is should be higher or lower then driver fs?
Can design a rectangular linear tube with same surface area? It is easier.
Thanks for your time
Williams
Learning slowly the material,
If the line is not 1/4 wave and the load is as BL, there is a freq. shift from driver fs?
If the driver given Vas is134 liters, is it equivalent to Vd?
Then in this volume have to build the folded tube?
Suppose I have this volume in cabinet, the linear tube is a square structure; it will be same structure all the way to the open end port?
As a square structure tube say, long 2.5m and SO/SL=1, driver Sd=220cm² then the port should be same size, 220cm²?
By basic theory this will give 34 Hz resonate tube, is should be higher or lower then driver fs?
Can design a rectangular linear tube with same surface area? It is easier.
Thanks for your time
Williams
I'm going to respond to some of your questions. If you have a line with a constant area and a length that provides the 1/4-wavelength resonant frequency you want, the open end of the line (the terminus) will need to have the same area as the line, essentially independent of the driver's Sd. This would likely be called a classic TL, but you won't like the response shape you'll get as it will be full of significant dips. The line will have to be stuffed rather heavily in order to smooth out the response, but that will likely completely eliminate all of the terminus' contribution to the bass response. The optimum 1/4-wave resonant frequency depends on both the fS and Qts of the driver. If Qts is close or equal to 0.4, then the 1/4-wave resonance should be close to fS. As Qts becomes lower and lower than 0.4, the 1/4-wave resonance needs to be higher and higher than fS, and as Qts becomes higher and higher than 0.4, the 1/4-wave resonances needs to be lower and lower than fS. A 2.5-meter line with a constant area will have a 1/4-wave resonant frequency of ~34 Hz, but a tapered line will likely perform much better because the tapering will smooth out the response and require less stuffing and the line can be shorter. For instance if the line is tapered at 10:1 (area decreases from closed end to open end, the terminus), a line with a 34-Hz resonance would need to be only about 1.5 meters long.
Paul
Paul
No simple answer to that I'm afraid. Depends on what you're defining as a TL, and how the enclosures are tuned / their respective alignments. Generally they aren't like-for-like equivalents.
Assuming a TL in terms of a max-flat impedance line, then probably yes; it's likely to have tighter control over the driver and an LF rolloff that is largely 2nd order, the price being a higher F3. Whether you'd actually tune an MLTL or a mildly resonant line to the same frequency though is extremely unlikely though.
Assuming a TL in terms of a max-flat impedance line, then probably yes; it's likely to have tighter control over the driver and an LF rolloff that is largely 2nd order, the price being a higher F3. Whether you'd actually tune an MLTL or a mildly resonant line to the same frequency though is extremely unlikely though.
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You don't appear to have used any driver offset, and the line cross section appears very small indeed, so I would expect the pipe to be very over-damped. Answers to your questions are to be found in Martin's alignment tables (and George Augspurger's, although the latter doesn't use tapers as large as 10:1) that I provided links to some posts ago. If you don't want to read those, then you can use the Excel file (also linked to) which calculates dimensions based on those alignment tables, your chosen driver's T/S parameters and preferred taper. Note that a highly tapered pipe (narrowing toward the terminus) is physically shorter than an untapered pipe for the same tuning frequency. The ratios are in Martin's alignment tables & Excel file for a given tuning frequency (as noted, they assume you are tuning to driver Fs). In practice as noted I would tune higher to get a bit more output, as you appear to be doing already.
'So' as Martin abbreviates it is the throat (sealed end) of the pipe, i.e. the opposite end to the open. In your drawing it would be directly above the woofer -the slightly angled panel that separates the line from the small sealed chamber.
End loading a pipe with the driver provides maximum excitation of the pipe fundamental resonance, but it also provides maximum excitation of all the harmonic modes (unwanted), hence the reason that a driver offset is usually preferred.
'So' as Martin abbreviates it is the throat (sealed end) of the pipe, i.e. the opposite end to the open. In your drawing it would be directly above the woofer -the slightly angled panel that separates the line from the small sealed chamber.
End loading a pipe with the driver provides maximum excitation of the pipe fundamental resonance, but it also provides maximum excitation of all the harmonic modes (unwanted), hence the reason that a driver offset is usually preferred.
If it's the one on the defunct Leonard Audio site that was described as 'TL Basics' to be honest, it wasn't as good as it could have been. Especially because it continued to imply that driver Sd has any direct relationship to line CSA. It doesn't, and the focus on Sd is responsible for many poor performing QW / TL designs.
Pipe CSA should be determined, like any other vented enclosure, from the driver Qt, Vas, Fs and the target Fb / alignment.
Pipe CSA should be determined, like any other vented enclosure, from the driver Qt, Vas, Fs and the target Fb / alignment.
TL front port
Hello everyone,
Thanks for the criticism in the past; It guided me on the right path.
I decided to use King Martin's XCEL calculator, hoping it's close to his calculations. I have a built enclosure so I had to squeeze the TL inside as close as possible to the results from XCEL. Any advise is well come. Attached the basic drawings and the TL line from XCEL calculator.
Best regards,
Williams
Hello everyone,
Thanks for the criticism in the past; It guided me on the right path.
I decided to use King Martin's XCEL calculator, hoping it's close to his calculations. I have a built enclosure so I had to squeeze the TL inside as close as possible to the results from XCEL. Any advise is well come. Attached the basic drawings and the TL line from XCEL calculator.
Best regards,
Williams
TL CALCULATOR
HI all,
I am back with a question.
I built the TL box using the Excel spreadsheet :
http://www.quarter-wave.com/TLs/Alig...tor_3_3_09.xls.
There is some one using this calculator? Is a good one, there are some updates to it?
Is kinde of a wild world design in this matheria, I use it for my pleasure and not commercial.
Best regards,
williams
HI all,
I am back with a question.
I built the TL box using the Excel spreadsheet :
http://www.quarter-wave.com/TLs/Alig...tor_3_3_09.xls.
There is some one using this calculator? Is a good one, there are some updates to it?
Is kinde of a wild world design in this matheria, I use it for my pleasure and not commercial.
Best regards,
williams
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