What's so special about the Augsburger mastering monitor?

[Lee in Montreal]

They seem to use TAD components and have that angled front baffle (against standing waves?) I love the simple two-way design (only one frequency crossing to f.ck-up)

http://www.gearslutz.com/board/attachments/high-end/122825d1243506249-gear-face-just-laughs-augspurger_monitors.jpg

http://augspurgermonitors.com/wp-content/uploads/2012/05/TheVillageStudios1-680x417.jpg

[Carl_Huff]

You mean besides looking absolutely cool? I've always been enamored by the bright eyed Big Bird look that they have about them. And they sound good too. It would be fun to clone a pair. George's latest monitors are MTM towers but I prefer the looks of his older model that you show.
_____________
Best Regards,
Carl Huff

[pos]

These have already been talked about a lot here.
The horn is way too small to maintain a low enough crossover frequency with the dual 15" (horizontal or MTM), and its construction is not that great either (fins are just thin curved wood strips...)

[Carl_Huff]

TAD 160x drivers can be crossed reliably at 900Hz plus. They have a longer reach upwards than most 15 inch drivers. George Augspurger (their designer) is a competent engineer. However having said that I have never seen empirical plots of these systems. I don't even know what their crossover is set at. Does anyone have something they could post?
____________
Best Regards,
Carl Huff

[pos]

The issue will be directivity on the 15" pair axis (even with folding).
90° beamwidth will probably be reach as low as 500Hz (or lower in MTM configuration), and then it will start to seriously beam.

[Carl_Huff]

The issue will be directivity on the 15" pair axis (even with folding)
90° beamwidth will probably be reach as low as 500Hz (or lower in MTM configuration), and then it will start to seriously beam.

Interesting ...

Anybody have empirical measurements to share? I confess, I've never satisfied myself that I understood the point of the 'wedge baffle' for the 15" pair. I had assumed that it was an effort to match the beamwidth characteristics of the horn at the crossover point.
____________
Best Regards,
Carl Huff

[pos]

That is fairly easy to simulate: the dimension of the source (or combination of sources, like a twin 15") will dictate its directivity behavior (with some additional suitabilities like cone shape, but this can mostly be ignored). Here is for example the polar plot of a 12" 2206H (I think this was simulated by RobH) : http://techtalk.parts-express.com/attachment.php?attachmentid=9155&stc=1&d=1276107496

You can scale that to a 15", or to a pair of 15" (lets say a 29" if they are folded, or maybe 31" otherwise ?...)
Of course what count is the effective cone diameter, but scaling from the total diameter is close enough here...

Of course with a MTM configuration you would have to add the height of the horn.

[Lee in Montreal]

Is it possible that the angling of the front baffle was intended to "spread" the beaming. BTW I see many TAD 160X used in a two-way configuration with a horn. So, indeed as Carl mentionned, they might be better than other 15" drivers at reaching higher. The horn seems small, so I doubt it goes down to 500Hz. 800Hz remains possible.

[allen mueller]

Is it possible that the angling of the front baffle was intended to "spread" the beaming. BTW I see many TAD 160X used in a two-way configuration with a horn. So, indeed as Carl mentionned, they might be better than other 15" drivers at reaching higher. The horn seems small, so I doubt it goes down to 500Hz. 800Hz remains possible.


I am fairly certain that is the case. I think it was in an interview with him I had read that the design intent of the angled baffle was the increase the coverage of the 2 woofers to better match the horn and to give more constant sound as the engineer moved around the console.

Al

[Aaron]

Another example of the same idea:

http://www.billfitzmaurice.com/XFCabs.html

[Ian Mackenzie]

Guy have a look at the monitors on the Reyaudio.com web site. There is a diagram of the geometry for the angled woofers.

[Fort Knox]

Guy have a look at the monitors on the Reyaudio.com web site. There is a diagram of the geometry for the angled woofers.
Looks like an oriental Rube Goldberg ....

[Ian Mackenzie]

If you look at the monitor front on and imagine an arc that passes horizontally through the voice coil of the left woofer and through the apex of the centre point which = the compression driver diaphragm presumably and across to the right hand woofer that distance is maintained regardless of the angle.

That is what makes it image through the crossover point. Its rather clever actually.

[Lee in Montreal]

If you look at the monitor front on and imagine an arc that passes horizontally through the voice coil of the left woofer and through the apex of the centre point which = the compression driver diaphragm presumably and across to the right hand woofer that distance is maintained regardless of the angle.

That is what makes it image through the crossover point. Its rather clever actually. Clever indeed. Reminds me of old geometry classes: Thru three points, you can only align one cercle. That circle will have a center, which in this case is the focal point. But, by instinct, I would use as reference points the compressor's diaphragm in the center and the domes on the woofers. I don't think that spiders generate any sound.

[Ian Mackenzie]

Theses all have DSP crossovers now

http://www.proaudiodesign.com/augspurgerga215h.html

[pos]

Wow, twice the price for the exact same driver, except for the foilcal :

http://www.proaudiodesign.com/Pro-Audio-Devices-GAH4K-B.html
http://www.usspeaker.com/radian%20950Bepb-1.htm

Same goes for their woofers apparently...

[allen mueller]

I found the interview again here's the link:

http://www.prosoundweb.com/article/print/re_p_files_control_room_acoustics_with_george_augs purger

From the above link:

R-e/p: Why use two fifteen inchers per cabinet?
GA: You use two fifteen inch woofers in high-power monitors simply because you have to, to be able to get the power levels that are required without blowing out woofers.
It would be nice in some respects if you could do it with a single fifteen, but if you really want to give them assurance that they’re not going to blow woofers out, the dual fifteen seems to be absolutely necessary.
The woofers are mounted on an inverse “V” which is really not deep enough to be called a horn.
It is an attempt to do two things. Number one, to push the woofers back a little bit to get a more desirable relationship between the woofers and the high frequency driver. I know that about six to eight inches is what we want there to make the crossover network come out right.
Number two, the woofer angle gives more horizontal dispersion up in the mid range where they start becoming directional.
In this case, it happened to work out just right, because one woofer is turned toward the mixer and the other is pointed toward the producer and we get a pretty good balance across the console.


Al

[natehansen66]

I've been lurking Audio Heritage for a couple years now, but I've never posted. Some of you are wondering about the directivity of the dual 15's....and I have data :D

These are dual AE TD15M in 3 cu ft sealed cabs, angled in to create about a 120° angle between the baffles. Ground plane measurement at about 12':

https://lh6.googleusercontent.com/-o9Ev8bNCmBo/U-b-BRyHODI/AAAAAAAAAPU/g0R6FLf50pU/w797-h384-no/dual%2Btd15m%2Bsealed.png

I also have data for parallel baffles, and with the baffles at 90° with a board over the top to create a "horn". I can tell you that angling the baffles in has a negligible effect on the directivity (which is obviously beaming by 500-600hz) at least measured in the far field. If you are within about +-5° of the center axis of the speaker I guess you're ok.

I don't have any JBL stuff here so I'll go back in my hole :o:

[pos]

Thanks for that measurement!
So it appears the angling does not affect directivity other than by reducing the horizontal span of the source.
This was to be expected ;)

I hope you post more often here, and even if none of your drivers have a JBL foilcal on their back I am sure most of them bear a strong Lansing lineage :D
I think your approach to speaker design and directivity control would interest a lot of people here, and bring new ideas for those JBL drivers we all have laying around.

http://www.diyaudio.com/forums/multi-way/219344-4-way-dipolar-disorder.html
http://www.diyaudio.com/forums/multi-way/258674-diy-18-elliptical-waveguide.html
http://www.diyaudio.com/forums/multi-way/259724-dsp-midrange-directivity-control-aka-kinda-cardioid.html

[natehansen66]

Will do :thmbsup: