Hello guys!
I have been reading some TL-articles from MJK and also in Vance Dickason's Loudspeaker cookbook (7th ed.).
Many interesting things in there that I didn't know, I was quite delighted to learn so much stuff. On my quest to keep learning I want to ask you guys:
Does anyone of you maybe have some articles written by MJK or, preferably, Augspurger on the TLs?
Especially Dickason's Loudspeaker-cookbook made me very interested in Augspurgers side on this. To be more precise: The articles he wrote for the "Speaker Builder" Magazine in 2000 where he contributed one article per magazine during the year, from an introduction to a more detailed text, I think.
I have already scoured the interweb, but came up with nothing usable. Maybe someone can help me out?
I have been reading some TL-articles from MJK and also in Vance Dickason's Loudspeaker cookbook (7th ed.).
Many interesting things in there that I didn't know, I was quite delighted to learn so much stuff. On my quest to keep learning I want to ask you guys:
Does anyone of you maybe have some articles written by MJK or, preferably, Augspurger on the TLs?
Especially Dickason's Loudspeaker-cookbook made me very interested in Augspurgers side on this. To be more precise: The articles he wrote for the "Speaker Builder" Magazine in 2000 where he contributed one article per magazine during the year, from an introduction to a more detailed text, I think.
I have already scoured the interweb, but came up with nothing usable. Maybe someone can help me out?
The three Speaker Builder articles were basically lightly revised versions of his AES paper:
http://diyaudioprojects.com/Technical/Papers/Loudspeakers-on-Damped-Pipes.pdf
George & Martin's work was (since George hasn't done anything on it for the last 2 decades) basically complimentary -George used Bart Locanthi's analogue electrical model to analyse his test pipe, and covers some geometries Martin didn't explicitly study (although the latter's MathCAD worksheets are / were perfectly capable of all that & more), different types of damping, & to derive his alignment tables & software modeller. His standard alignments aren't max-flat impedance types, but related; in essence he was targeting a similar sort of response to a sealed box but with more output, no more than 1dB null at F3 and 0.5dB higher harmonics (more or less a given, with the former). Martin however looked at various geometries George didn't, uses a slightly different alignment for his tables & expanded his work to cover more detailed areas e.g. more refined offset capacity, and also took it into related fields of QW design, more complex geometries like horns etc. You can take elements from both; Martin's is ultimately much more flexible however. George probably could have been, but once he did his initial work, he moved on to other fields and didn't do any further research or expansion.
http://diyaudioprojects.com/Technical/Papers/Loudspeakers-on-Damped-Pipes.pdf
George & Martin's work was (since George hasn't done anything on it for the last 2 decades) basically complimentary -George used Bart Locanthi's analogue electrical model to analyse his test pipe, and covers some geometries Martin didn't explicitly study (although the latter's MathCAD worksheets are / were perfectly capable of all that & more), different types of damping, & to derive his alignment tables & software modeller. His standard alignments aren't max-flat impedance types, but related; in essence he was targeting a similar sort of response to a sealed box but with more output, no more than 1dB null at F3 and 0.5dB higher harmonics (more or less a given, with the former). Martin however looked at various geometries George didn't, uses a slightly different alignment for his tables & expanded his work to cover more detailed areas e.g. more refined offset capacity, and also took it into related fields of QW design, more complex geometries like horns etc. You can take elements from both; Martin's is ultimately much more flexible however. George probably could have been, but once he did his initial work, he moved on to other fields and didn't do any further research or expansion.
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Thanks for the information! So I don't really need the magazine-articles, then.
Also: I can't believe I didn't know about this website. Lots of interesting stuff to read through!
As Scott says, the 3 poart article is an updated version of his AES paper (which i was presen tfor when he released the research at AES 1999 NYNY.
Note that at the time i was working to format Martin’s original work for the web.
The last revison of Dickason i read was no-where on properly describing TLs.
dave
Note that at the time i was working to format Martin’s original work for the web.
The last revison of Dickason i read was no-where on properly describing TLs.
dave
Ha, interesting. How so? Is it scientifically wrong, or does he set an emphasis on things that don't really matter in the real world?
He is still stuck in classical mdesign (ie a bit better than a guess).
Modern quarter-wave modelers are really needed for their proper design given the very large number of degrees of freedom.\
dave
Modern quarter-wave modelers are really needed for their proper design given the very large number of degrees of freedom.\
dave
I need to re-read the v.6 and v.7 copies of LSDC that I have, but as I recall, Vance uses Augspurger extensively in both; IIRC v.6 came out around 2000 so he revised that section to include George's work / tables. I don't have any earlier editions, but I assume he was using what data was available from other methodologies, which are also referenced in the most recent editions albeit with a major nod to George for being one of the first well-known figures in the industry itself to start breaking down the Bradbury [dramatic] velocity-reduction notions (in fairness, Bullock & Backman sort of did this in the '80s by noting poor corrolation of their software in the LF to comparative measurements, & even Bradbury himself confessed his theoretical model lost accuracy as frequency decreased -which objectively speaking makes you wonder why so much credence was given to an attractive idea that the author himself admitted didn't fit reality all that well. Probably a case of faute de mieux on the research front & inertia / habit / more limited data accessability & transmission in the pre-internet era & the niche interest aspect. YMMV as always).
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That is new to me… Augspurger is much more limited than where MJK, and those who have taken advantage of his modeler (includes Scott) have taken things further and explored much more of the design space that his modeler opened up.
dave
“A bit better than a guess” that’s what makes speaker building fun, there is no one perfect solution. There are so many variables.
There indeed are a huge number of compromises in a loudspeaker, Building a bad TL is not what i would consider one of those.
dave
dave
I have the 7th edition from 2006, as far as I know. The TL-section has a lot of Augspurger's papers mentioned in the sources-section, that's why I wanted to ask 😀
Just as a brief 'warning' re the above: although they're all interesting in their way, neither the Bates nor the Bailey articles provide any particular design guidance beyond a few general suggestions. The latter had value as it demonstrated some impulse characteristics, but even that falls down a bit since Arthur didn't really provide any comparative data nor, apparently, were the vented boxes optimised using contemporary methods. If they were -he didn't really give much of a hint.
Rick's Alpha TL article was basically an extension of Augspurger's alignment tables for a straight pipe. If you want a simple, relatively flat impedance TL alignment then it will give you that, just as George's tables did for some types of tapered, offset driver and coupling-chamber line geometries. I'd suggest that the primary value of George's work (and Martin King's, which came out more or less at the same time) was in tightly relating driver characteristics to line proportions, specifically Vb and Fb, in the same way Novak, Thiele & later Small did for sealed & vented enclosures (although in fairness, Thuras did to a point). Secondary factors (still very important) were demonstrating the effect of pipe geometry on Fp, and accurate damping models -in that last aspect, George did more work than Martin, as he measured different types of material, so there's something to be taken from both, even though Martin's approach is more flexible and has been expanded / refined over the last 20yrs where George called it a day once he'd done his initial research.
Rick's Alpha TL article was basically an extension of Augspurger's alignment tables for a straight pipe. If you want a simple, relatively flat impedance TL alignment then it will give you that, just as George's tables did for some types of tapered, offset driver and coupling-chamber line geometries. I'd suggest that the primary value of George's work (and Martin King's, which came out more or less at the same time) was in tightly relating driver characteristics to line proportions, specifically Vb and Fb, in the same way Novak, Thiele & later Small did for sealed & vented enclosures (although in fairness, Thuras did to a point). Secondary factors (still very important) were demonstrating the effect of pipe geometry on Fp, and accurate damping models -in that last aspect, George did more work than Martin, as he measured different types of material, so there's something to be taken from both, even though Martin's approach is more flexible and has been expanded / refined over the last 20yrs where George called it a day once he'd done his initial research.
Rick regurgitated much of his stuff (i heped him prepare it) that we already knew, but simplied it (to our loss) and was thin on really theory.
Like Augspurger intersting and good to have, but one of those dead-end evolutionary tracks.
dave
Like Augspurger intersting and good to have, but one of those dead-end evolutionary tracks.
dave
Just to flesh out the archive...
I don't remember finding any letters after the second (1972) article.
@Scottmoose what "contemporary methods" were you thinking of?
I don't remember finding any letters after the second (1972) article.
@Scottmoose what "contemporary methods" were you thinking of?
Standard high quality vented box design practice for the era, which would either follow Novak's filter-based method for ducted types (essentially the work Thiele expanded on / broke down slightly further), or if high efficiency were desired, then one of the large volume W.E. / Altec / RCA et al varieties, which would then have the vent critically damped via measurement and / or click-testing until there was no audible ringing.
But Bailey was taking a completely different approach -- intentionally different from those run-of-the-mill vented boxes. So why would he employ those techniques?
Bailey said he was taking a different approach to enclosures from those that he felt were not as good as the new drivers that were available.
I know y'all have taken over the name but Bailey had a different goal. That's the story the articles tell.
Whether he was successful is a different story...
Bailey said he was taking a different approach to enclosures from those that he felt were not as good as the new drivers that were available.
I know y'all have taken over the name but Bailey had a different goal. That's the story the articles tell.
Whether he was successful is a different story...
Bailey’s title suggests the target was an anechoic line with no gain from the back wave. What he built and showed did have some, using the (mostly) fundemental resonance to reinforce the bottom.
You can see the unwanted harmonics appearance in the ripple from 40-200 Hz.
He did a good enuff job to spawn a wave of (classical) TL development (Radford/IMF/TDL + many diy articles). Augspurger, and especially King’s models showed us and allowed virtual experimentation in a much larger design space, taking more degrees of freedom into account.
dave
You can see the unwanted harmonics appearance in the ripple from 40-200 Hz.
He did a good enuff job to spawn a wave of (classical) TL development (Radford/IMF/TDL + many diy articles). Augspurger, and especially King’s models showed us and allowed virtual experimentation in a much larger design space, taking more degrees of freedom into account.
dave
Agreed. I think Bailey did a good job stating his approach and achieving his goals.
He aimed to build an enclosure that minimized harmful resonance effects rather than fiddling around with them. That he used one productive resonance effect shouldn't detract from his effort (nor should the piling on of the expansion.
I'm an "original six" guy.
He aimed to build an enclosure that minimized harmful resonance effects rather than fiddling around with them. That he used one productive resonance effect shouldn't detract from his effort (nor should the piling on of the expansion.
I'm an "original six" guy.
No problems with that, but have you ever run into those that are amandant that it isn’t the title it isn’t a TL and ignore the content of the article.
The loudspeaker that really inspired me to start diying loudspeakers was the Radford S90.
We (Ted & i) built a lot of TLs.
dave