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Alpair 10 Gen. MAOP Prototype TW-1

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Hello Chaps,
Here's some pics of the new MAOP prototype Alpair 10, essentially a Gen. 2 driver with 2 major tweaks:

1 - You'll note the cone. This is a standard Alp10 Multiform cone that has been treated with a new variant of the MAOP coating process. Comprising of a bonding layer onto the cone alloy substrate, and 2 other semi porous layers of material to make the finish you see on the pics. I'll release more details on this process once I've completed the results analysis from last weekend's tests.

2 - Matsubara san has been busy with yet another modified version of the Alpair 10 low mass spider. I think there's some pics on other threads of this component. I'll post another just in case.

More info coming soon.

Cheers
Mark.
 

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Hi Mark,
Can you explain the MAOP process and expected benefits in a little more detail. I've searched but can't find anything illuminating. Or is that for next week? :-D
Cheers, Simon

Hi Simon,
MAOP, short for Micro Arc Oxidation Process.

Its a coating process thats been around for a while although new compared to other more traditional methods such as Anodising, powder etc.

While MAOP has some similarities to traditional applied oxide based processes, a higher potential is passed via the alloy substrate (the cone bass material) to effectively grow a crystaline oxide over the substrate. This process is ideal for adding weather protection, reduced wear on contact surfaces and also provides for electrical isolation.

There is a reference to this process in Wiki. While its not comprehensive, it may help to illustrate the basics of the process:

Plasma electrolytic oxidation - Wikipedia, the free encyclopedia

We've got access to a company that has moved this process on. They can provide a particular type of Multi-layered MAOP that allows close control of process, to a degree similar to that we current apply be conventional anodising.

The advantage we get with MAOP is closer control of the coatings on the substrate. The other advantage is the ultra low addition of mass, only around 0.3% increase on a standard Alpair 10 unfinished cone, that compares well to anodising.

See the attached pic. This is an illustration of the process at this prototype stage as per Alpair 10 Gen.2 TW. We may yet further develop the layers but at this point, the process is pretty ready to launch a variant of the Alp 10 as a "special".

Cheers

Mark.
 

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Thanks Mark. Interesting process. That just leaves why are you playing with it, what effect does it have on the sonic properties of the driver?

Hi Simon,
Thats the interesting question. Theoretically, the porous layers should help disperse the micro-resonance more evenly as they pass over the cone's surface. I have my own measuring equipment that detects these micro characteristics but I'll need more time to calibrate for the different refractive capacity of MAOP. While I can measure the micro-resonant difference in the coatings, this won't really tell us of the potential audible change in the sound. For that, I'm going to pass the drivers to listening groups and ask them to feed back.

I'm about to post the LMS results.

Cheers

Mark.
 
Hi Guys,
Here's the MAOP - TW data:

Technically, I like the look of the frequency. It looks well controlled across the range. There are a couple of moderate peaks at the 8 to 10-kHz region but nothing wild. The new Mastubara san spider is looking good. The parameters are close enough to the standard model to make retrofitting into most existing box plans easy.

Revc= 7.200 Ohm
Fo= 36.905 Hz
Sd= 8.992K mm²
Vas= 26.949 Ltr
Cms= 2.347K uM/N
Mmd= 7.434 g
Mms= 7.924 g
BL= 5.345 T·M
Qms= 2.740
Qes= 0.463
Qts= 0.396
Levc= 88.933u H
No= 0.283 %
SPL= 86.534 dB
X max= 8.5-mm (1 way)
Power = 35 watts nom. 70
Max Coil = 25-mm alu body with rectangle copper winding.

Thanks
Mark.
 

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Interesting results. It appears that one of the drawbacks might be that the measurements seem to indicate a bit less high frequency extension (though the response is a bit smoother). Not being critical, it looks highly listenable, veru smooth, nothing stands out as possibly annoying or detractive. Very nice.

Was the driver sufficiently / completely broken in for the measurements?
 
Hi Guys,
Here's the MAOP - TW data:

Technically, I like the look of the frequency. It looks well controlled across the range. There are a couple of moderate peaks at the 8 to 10-kHz region but nothing wild. The new Mastubara san spider is looking good. The parameters are close enough to the standard model to make retrofitting into most existing box plans easy.

Mark.

The response is pretty darn flat considering the bandwidth it covers and is a metal cone. Given the size of the driver, I'm guessing that the breakup should have started around 5kHz or so. Nicely, mitigated. (Perhaps, it is the new coating?) And I'm not a fan of metal cones in general. No need to extend the top end at the expense of listening to peaky cone breakup. Actually, the extension goes to about 17kHz so more than adequate for most, although most will be lost if listening off axis. Of course, I've never heard it yet, but it looks promising.

Mark, how does the "Matsubara san spider" affect the sound of the driver?
 
Hi Ult, Doorman, guys,

Yup, MAOP is an applied process so there will be a "damping" effect. So far its very subtle. To my ears its mostly evident in the lower to upper mids (1 to 8 kHz) regions. But rather that trusting my ears, I'll get other guys to try them and feedback.

THe Matsubara san spider looks like a winner. I've ran a 1000 hour test, its the most linear so far remaining well inside its 1.9/50 spec @ +0.7. Normal commercial rated spiders will vary by +1.3 to +1.8 after being worked for 1000 hours. Its really good to work with Matsubara san and the other X Foster group guys and Evan Yu who's excellent sample maker. Between us all, there's some 200 working years of technical knowhow being put to good use.

The first test will be this afternoon and Tony and Kenneth's place in Fotan on some super-duper 300B monblocks in Pensils. Graham (Alpair 12, Ella KT88 guy: Graham's hifi page) will also be there. All these guys are very picky so I'm feeling a bit nervous.

Cheers

Mark.
 

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is it possible to apply this process in a masked or CNC controlled pattern?

Hi Chris,
Sadly, at this stage we don't have a masking method available. I talked to Dave last week about how this process could also be added into the Enabling mix.

I was thinking of making a new set of Multiform moulds with CNC's pattens pressing into the cone. This might be a very nice job but the cost won't be low.

Cheers

Mark.
 
Hi boris,
No, its the same sub assembly as Gen. 2
M

Mark, does that mean the difference is caused by measuring variations? Or is it due to a new coil winding or interaction between spider and coil?

Built in patterns will be quite interesting, and I wonder if that can be done by drawing via oil based ink prior to the MAOP, and then remove the ink with organic solvents... I am not sure if that's the right way to get the patterns though...
 
Mark, does that mean the difference is caused by measuring variations? Or is it due to a new coil winding or interaction between spider and coil?

Built in patterns will be quite interesting, and I wonder if that can be done by drawing via oil based ink prior to the MAOP, and then remove the ink with organic solvents... I am not sure if that's the right way to get the patterns though...

Hi Boris,
Designing the dynamics of the power-train for non-linear loads takes allot of work. For example, the spider: The resistivity, mechanical compliance and positional excursive stability are just 3 factors of 9 that apply to the operational capacity of just this component. Changing the operational specification on just 1 component within the power-train has the potential to radically change its total performance envelope.

Re MAOP and your ink idea. Such a method would risk too much surface contamination.

Thx
Mark.
 
Hi Boris,
Designing the dynamics of the power-train for non-linear loads takes allot of work. For example, the spider: The resistivity, mechanical compliance and positional excursive stability are just 3 factors of 9 that apply to the operational capacity of just this component. Changing the operational specification on just 1 component within the power-train has the potential to radically change its total performance envelope.

Re MAOP and your ink idea. Such a method would risk too much surface contamination.

Thx
Mark.
Hi Mark,

Thanks for explaining that. It seems the new design trades off a bit high end and efficiency for smoother response curve. I suspect that's due to the new spider, right? I was somehow worried about the flexibility of the new spider when I saw those reinforcements but now I am not.

And yes I forgot about the contamination issue. The ink may make its way down to the MAOP so it's impossible to remove all of the ink. Maybe I should come up with another way...
 
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