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03-28-2016

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Sean19
Posts 5
Joined on 02-24-2016

Post #:	1
Post ID:	22582
Reply to:	22582

Altec radial phase plug vs concentric phase plugs

I have always thought my old Altec 802's with the concentric ring phase plug sounded better than my newer 802 G with the Radial phase plug. If i had to describe the difference i am hearing i would say the concentric ring style just simply sounds better & smoother. I have read before the radial phase plug Altec developed was just a way to cut production cost and actually was not a improvement in the sound. This should not be surprising at a time when audio gear was advertised in every magazine and so many companies were fighting for their share of the market.

Altec engineer Clifford A. Henricksen reported on the differences between radial and "circumferential" types of phase plugs at Audio Engineering Society conventions in 1976 and 1978.[12][13] The radial design is easier to produce, but it does not differentiate between sound waves from the perimeter of the diaphragm and sound waves from the center. At high frequencies, the diaphragm does not act as a perfect piston; instead, it displays rippling, modal properties related to its stiffness and density. Because of the speed of wave propagation through the diaphragm material, the center of the diaphragm moves slightly later than the perimeter. Radial slots in the phase plug do not correct for this small time difference, which affects the highest frequencies. Concentric circular slots are able to correct for the diaphragm's rippling behavior but the positioning of the slots is critical.

Clifford Henricksen has 9 patents including the patent for the radial phase plug. So it looks like all those old timers that did not like the radial plugs had actual reasons not to and people that thought they disliked them because they were made from plastic were wrong. Some of the best sounding drivers made Western electric , JBL , TAD , Yamaha etc all use the concentric phase plugs. Looks like the adds Altec used from 1976 to 1980 for the radial phase plugs in model 19's & 604's worked well and are still working considering most Altec fans want the radial phase plugs drivers.

03-30-2016

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	2
Post ID:	22583
Reply to:	22582

I always was a bit suspicious with those concussions.

Sean, this subject is tricky. You might like your original Altec 802 better than your new 802G. (I did not even know that they do new version). I have no doubts about your preferences but how sure are you prefer the sound of the old driver juts because it has concentric ring phase plug? There is many other reasons why even the same driver made 40 years back and last year would sound very much different.

In a wider scene the subject of concentric ring phase vs radial is not as convincing as you think. There are advantages and disadvantages for both plugs and the key is to make a driver that sound right with whatever plug they use. I do not trust researches with their long expose into advantage one over another. Tomorrow thier agenda change and they will be with the same confidence to advocate very opposite opinion side. What I am saying is that I have seen “scientific” explanation why any of the plug types is better. I have also see explanation why neither of them is good and only combination of concentric AND radial was good, or only tangerine style of plug was good, or only half-length whole are good, or only spiral are good, or only 18-sound type are good. The realty is not there. If you have a bad radial plug but use it with slightly different suspended deafragm and slightly less compression, or slightly higher cone mass, or with a small drop of glue on the very top of dome then will the radial loos the disadvantages?

What I am saying is that design of plug is important but it is more important how a given, selected by maker phase plug is implemented in context of the entire loaded driver. I might agree with you that the best sounding drivers were made mostly with concentric phase plugs but I am very seriously doubt that the type of the plug made them to be best. There are plenty of bad sounding drivers concentric phase plugs…

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-30-2016

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Sean19
Posts 5
Joined on 02-24-2016

Post #:	3
Post ID:	22584
Reply to:	22583

I always was a bit suspicious with those concussions.

Romy the Cat wrote:
Sean, this subject is tricky. You might like your original Altec 802 better than your new 802G. (I did not even know that they do new version). I have no doubts about your preferences but how sure are you prefer the sound of the old driver juts because it has concentric ring phase plug? There is many other reasons why even the same driver made 40 years back and last year would sound very much different.

In a wider scene the subject of concentric ring phase vs radial is not as convincing as you think. There are advantages and disadvantages for both plugs and the key is to make a driver that sound right with whatever plug they use. I do not trust researches with their long expose into advantage one over another. Tomorrow thier agenda change and they will be with the same confidence to advocate very opposite opinion side. What I am saying is that I have seen “scientific” explanation why any of the plug types is better. I have also see explanation why neither of them is good and only combination of concentric AND radial was good, or only tangerine style of plug was good, or only half-length whole are good, or only spiral are good, or only 18-sound type are good. The realty is not there. If you have a bad radial plug but use it with slightly different suspended deafragm and slightly less compression, or slightly higher cone mass, or with a small drop of glue on the very top of dome then will the radial loos the disadvantages?

What I am saying is that design of plug is important but it is more important how a given, selected by maker phase plug is implemented in context of the entire loaded driver. I might agree with you that the best sounding drivers were made mostly with concentric phase plugs but I am very seriously doubt that the type of the plug made them to be best. There are plenty of bad sounding drivers concentric phase plugs…

Both versions of 802's have GPA diaphragms both are used on the same horn in a model 19 clone. Over longer periods of time the older versions are easier on my ears. The model 19 clones i have sound good but i am selling all my 1" Altec stuff and i am going to a 3 way system using my 416-8b's and Radian 1.4" 745neopb crossed from 800hz to 10000khz i have not decided what to use from 10000khz up any suggestions. I also want to use a passive crossover if i build A7 cabinets i can vertically align all the drivers easily so i was going to try a 4th order L&R crossover but the crossover is not set in stone just yet.

03-31-2016

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Romy the Cat

Boston, MA
Posts 10,166
Joined on 05-28-2004

Post #:	4
Post ID:	22586
Reply to:	22584

You are missing my point.

Sean19 wrote:
Both versions of 802's have GPA diaphragms both are used on the same horn in a model 19 clone. Over longer periods of time the older versions are easier on my ears.

You deal with random result. Pretend that you have your both versions drivers but the driver with “inferior” radial plug has a diaphragm with slightly different Mylar suspension that happens to be work better then GPA cone with concentric plug. You just do not have this experience. So, do not look for individual symptoms but look for a health of entire body. In my view the design of phase plug is a VERY mercy subject and I do not like anybody feel that their conclusions are definitive.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

04-01-2016

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Sean19
Posts 5
Joined on 02-24-2016

Post #:	5
Post ID:	22589
Reply to:	22586

Altec radial phase plug vs concentric phase plugs

Romy the Cat wrote:
Sean19 wrote:
Both versions of 802's have GPA diaphragms both are used on the same horn in a model 19 clone. Over longer periods of time the older versions are easier on my ears.
You deal with random result. Pretend that you have your both versions drivers but the driver with “inferior” radial plug has a diaphragm with slightly different Mylar suspension that happens to be work better then GPA cone with concentric plug. You just do not have this experience. So, do not look for individual symptoms but look for a health of entire body. In my view the design of phase plug is a VERY mercy subject and I do not like anybody feel that their conclusions are definitive.

I think not having experience with compression drivers is the fun part it's once you know a great deal and still have problems getting the right sound is when it gets aggravating. And for me it's not just the end result it's having fun learning and enjoying getting there. And i can only imagine the satisfaction one gets when he reaches his very own audio bliss. Hopefully i can experience that one day with my own build.

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