George Augspurger...didnt make Tl's?!

camplo

Member
2019-02-25 2:27 am
Today in a debate over enclosure qualifications, some one made the comment that George Augspurger used a BR for his studio monitor designs....

First of all...I don't know this to be true...MLTL gets confused for BR all the time...when I look at pictures of his designs it looks like BR at first glance...I see the inside being stuffed with dampening material...typical of TL not BR, so I thought.

Is anyone here, knowing whether or not George Augspurger studio monitors were actually BR or TL....if a BR whats the deal with the dampening material...and last, if George Augspurger did all this work on TL....only to eventually design a product using BR...did he come to the conclusion that TL is a waste of time...or is he just another designer cutting corners?
 

camplo

Member
2019-02-25 2:27 am
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Sorry but I can't find any type of written information to support claims either way....
 

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Regular Small type vented box AFAIK, but the short version: it doesn't really matter.

The point of transition from a Small type vented box (which technically isn't a bass reflex) to a mass-loaded QW occurs when one dimension is stretched sufficiently relative to the others for the longitudinal standing wave to alter the alignment you would obtain from a straightforward Helmholtz loading with the same Vb and vent dimensions.

That apart -well, QW loading can (as in 'can') provide the designer with more tuning options, or acoustical damping for a given set of vent dimensions if appropriately sized (i.e. long enough), but it's also still a vented box variation. It just doesn't happen to be using Helmholtz [cavity] resonance alone or as the primary mode.
 

camplo

Member
2019-02-25 2:27 am
What about all that stuff about a BR being a one note wonder? So if I create the same FR using a HelmHoltz resonance and another using quarter-wave....and then dampen each....its going to essentially be the same thing?

And what Design is G. Augspurger using in his studio monitors?
 
From what i hear, is that he build his monitors tailored to the controlrooms he did design. He did use many techniques, depending on the situation in the room. Most of his studio monitors were custom builds for a specific studio, wich had their controlrooms done by him and were tuned inside the room and won't work outside that room. You did not buy a speakerset from Ausburger, but a total studio acoustic treatment including main monitoring tailored to that studio.
 
What about all that stuff about a BR being a one note wonder?

It's twaddle if it's a competently designed one. A bad Small type vented box (as noted, these are not bass reflex enclosures) can behave like that. So can a bad example of any other vented load.

So if I create the same FR using a HelmHoltz resonance and another using quarter-wave....and then dampen each....its going to essentially be the same thing?

Well, if they're tracking exactly the same alignment then in that sense yes: it's the same alignment, just achieved via different methods. In a wider sense there may be other differences, but this varies with the design specifics. The greatest differences would occur with a 'real' MLTL when one dimension is stretched sufficiently that the longitudinal mode provides some vent damping at Fb (i.e. it uses less forcing). Very few fall into this category though for practical reasons of size / proportions.

And what Design is G. Augspurger using in his studio monitors?

Already said. Regular Small type vented / Helmholtz, but it doesn't really matter.
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
^ Having built a couple of Augspurger alignment TLs I'd have to say they seem very similar to well proportioned closed boxes, and that's a good thing. Just a little harder to set up.
I guess what I am truly wondering is how dampened did G. Augspurger find to be adequate... I should try and find some impedance charts for his designs.
Perhaps. I wouldn't be inclined to assume he made careless choices.
 

WBS

Member
2007-01-03 12:13 am
Napa Valley
I was lucky to have bought a pair of TAD 1601a woofers right before they were discontinued that I mounted into some cheap Parts Express knock down boxes while I looked for a better option. I recently researched Augspurger's designs because he used 1601a's, but I was unsuccessful in finding any details. Visually, it looks like his designs were lifted from, some might say inspired by, the TAD Exclusive 2401 and 2402.

I'd like to hear from someone who's listened to both designs to get an idea how they compared. Info on the 2402 is pretty scarce as well, but at least you can find the dimensions online, except for the port size and length.
 
I guess what I am truly wondering is how dampened did G. Augspurger find to be adequate... I should try and find some impedance charts for his designs.

...I wouldn't be inclined to assume he made careless choices.

Careless they are not. George's goals are referenced in his AES paper: +/- 1dB passband ripple for what he described as his optimised alignments ('optimised' in the sense that they were optimised for that specific objective) with a response ~ equal to a sealed box of equivalent internal volume, & reduced cone excursion.* They have a relatively well-damped impedance, but are not max-flat impedance pipes as that wasn't his primary consideration.

*At some point, being an open pipe, it will eventually unload @ 24dB/octave, but for these pipes it will be at a low frequency and sufficiently low level for this to be academic and not of practical concern.
 
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Wouldn't a well designed TL have less high frequencies reflected back onto the driver? I was thinking of the second Bailey design with the three triangular pipes.

Not really / necessarily. It certainly can make life easier, but the frequencies in question are almost always relatively short wavelength & should be addressed by damping in any competent cabinet design. Having the damping present in a TL merely makes life easier on that front. The triangular pipes in the box referred to don't necessarily reduce HF reflections, just shift them around a bit. Potentially a small advantage, but in practice, there's not much in it since reflections are generally already handled by the internal damping / lagging.
 
I have two Tad tm1201 which I am thinking of mounting side by side under a Tad th4001 horn (90 deg dispersion) with an Xo around 800ish hz. The side by side mouting is to try to achieve 90 deg dispersion at xo through lobing/cancellation. Are there any one who have suggestion to what angle the two 12-inch drivers should have between them?
 
Not really / necessarily. It certainly can make life easier, but the frequencies in question are almost always relatively short wavelength & should be addressed by damping in any competent cabinet design. Having the damping present in a TL merely makes life easier on that front. The triangular pipes in the box referred to don't necessarily reduce HF reflections, just shift them around a bit. Potentially a small advantage, but in practice, there's not much in it since reflections are generally already handled by the internal damping / lagging.


Thanks.
I guess if I'm that concerned about it, I should just use the TL for bass and crossover to a midrange at a low frequency like 200Hz.
But at that point I might as well go to an aperiodic or acoustic suspension enclosure to get a very well damped bass. Certainly a lot smaller and simpler.
 

camplo

Member
2019-02-25 2:27 am
Interesting stuff, I hope I still have everyones attention.

So should I just put my 18H+ in a heavily stuffed large sealed box and call it a day?
Or build TL thats long and heavily stuffed, basically matching the output of the sealed.

I can't seem to model a Aperiodic vent in HR
I also just realized that I have to use winISD to see transfer function magnitude....
 

camplo

Member
2019-02-25 2:27 am
It has been said that a large sealed box with an aperiodic port and a basic tl fully stuffed have the same sound....I am trying to achieve a more neutral tone by elimination of back-wave and box resonance. So if thats my goal, what do you recommend?
 
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Depends how you define 'sound' and the alignments involved; if they're targeting the same alignment, or as close as possible, then perhaps, although it's not guaranteed. If they aren't, they won't.

For the sake of interest, there is no such thing as a sealed box with an aperiodic port -the box is either sealed design or it isn't. ;) And 'aperiodic' itself is technically a misnomer in this context (although we're never likely to get shot of it) -'resistive vent' is technically more accurate.

Either approach is effective (as are sealed boxes) if designed well, so name your poison really. If you don't know anything about TL design and don't want to spend a long time wading through the mires of misinformation, I'd suggest you go with a resistive vent design.