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Old 16th January 2013, 12:22 AM   #1
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Default NEWS: Markaudio driver up-grades

Hi Guys,
I've designed a device that fits inside the magnet (motor set) sub-assembly to provide over-load protection. The device is known as an "Arrestor".

The Arrestor operates by limiting the power-train's stroke length at the extreme length of travel. The base of the coil contacts the arrestor. The first stage is a cushioned contact designed to reduce the motive speed of the power-train. Since the stroke is performance extreme, the driven load will have to be LF generation for the system to operate. All other frequency generation remains unaffected. For the first stage operation, users will hear an audible warning from the Arrestor in the form of a "thudding" sound. That means you've reached the safe operating excursion limit, I recommend reducing output volumes if you regularly hear the Arrestor cutting in. The Arrestor's full compression compression stage is purely for accidental overload protection. It should save the driver in these system fault situations. Here's a pic of the device.

Arrestor draw stroke cut-in operation:

Alpair 6M/P: Arrestor contact stage (audible overload warning) = 5mm
Alpair 6M/P: Arrestor at full compression stage = 5.6mm

Alpair 7: Arrestor contact stage (audible overload warning) = 5.5mm
Alpair 7: Arrestor at full compression stage = 6.1mm

Alpair 10: Arrestor contact stage (audible overload warning) = 7.5mm
Alpair 10: Arrestor at full compression stage = 8.1mm

CHR/P/BW: Arrestor contact stage (audible overload warning) = 5.5mm
CHR/P/BW: Arrestor full compression stage = 6.3mm

All production drivers are now being fitted with Arrestors (with the exception of the Alpair 12P). Look out for an "A" on the driver's label (e.g. "CHR-70A"). All dealers are now taking up the new "A" drivers as they re-stock for 2013.

Some of you might recall allot of chat about X-max last summer. I came in for some flack from 1 or 2 members who thought drivers should be capable of operating continuously at their rated X.max. I'm certain no sane diyer/end-user would continuously operate their systems in such an extreme manner. All the same, I understood the point about the fragility of Full-Range drivers when subjected to higher loads.

My big thanks for Matsumoto San (Tokyo) for his valuable help testing of the Arrestor. My thanks also to Evan Yu for his efforts to assist in the development of the Arrestor. For those who wish to learn more about Matsumoto's san testing, please see: http://lean-audio.blogspot.hk/

So chaps, for those who like to blow out their ear drums, an Alpair 10 will 7.5mm on tap might get you going. But like all things, I'd still much prefer it if you treated my babies with some care. While they are now much better protected, please remember the drivers a still lower-load designs.

Any questions?

Cheers
Mark.
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File Type: jpg arrestor-fig-1-sml.jpg (41.0 KB, 853 views)

Last edited by markaudio; 16th January 2013 at 01:46 AM.
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Old 16th January 2013, 12:41 AM   #2
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That's great news Mark. A valuable and worthwhile upgrade to keep the drivers save with overenthusiastic volume knob twiddlers.

jeff
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Old 16th January 2013, 12:48 AM   #3
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Nice engineering solution.
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Old 16th January 2013, 02:02 AM   #4
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Is a retro-fit available for drivers not so equipped?
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Old 16th January 2013, 03:54 PM   #5
zman01 is offline zman01  Bangladesh
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Smart move Mark, a good feature to have.
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Old 16th January 2013, 04:05 PM   #6
11opas is offline 11opas  Canada
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Great upgrade!!

Mark: have you considered a grill for your drivers, something similar to Accuton drivers.. It would help protect the delicate cones from curious little fingers, and other mishaps... I personally perfer the look without grills, but if done correctly they can look really classy. Might be something for the Alpair 8????
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Old 16th January 2013, 07:45 PM   #7
toobhed is offline toobhed  United States
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Very cool Mark!

Now those of us who visually inspect excursion while listening don't have to wonder if we are "mistreating the baby" and inviting a knock on the door from DPS (Driver Protective Services)
Well done indeed.

Mario
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Old 16th January 2013, 08:08 PM   #8
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Interesting! A good step forward!
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Old 16th January 2013, 11:05 PM   #9
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Hi Fellas,
I'm glad this idea looks promising. We've tested the arrestors on 10 hour, 50 and 100 hours at full excursion with perfect results. All the same, I'll need your help to feedback as the real test is how well the Arrestor works in your homes.

The arrestor design is adjustable so we can vary the operational stroke length. In particular, the Alpair 10 is set at just inside the extreme operational limit. We could set down a little further (e.g. 7-mm) if the long term need arises.

At this stage, I'm confident the Arrestors will save drivers from accidental over-loads and give more peace of mind.

Re grilles, yes I'm happy to look into that idea. I'll need to find some time as Alpair 8, possibly an Alpair 10P, woofs, some increasing OEM and re-branded production are demanding allot of effort.

Cheers
Mark.


Cheers
Mark.
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Old 16th January 2013, 11:22 PM   #10
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Given the brouhaha surrounding the xmax issue of these drivers, I find it very encouraging to find that you've managed to come up with a simple, yet elegant way, to make sure that these issues are hopefully rendered inert.


What are the arrestors made of, if you don't mind me asking?
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