Alpair 10 - Generation 2 - sneak peek - Page 5 - diyAudio
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Old 5th May 2010, 12:29 AM   #41
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Hi Guys,
Here's one example of the development work that's progressing. Together with Mat and Lui Yp Ping (suspension maker), I'm further refining the front suspensions (rubber cone surrounds) for Alp's 6 and 10. This means thinner, lower mass front suspensions. These new suspensions are so low mass, they can't support the cone's alignment in the power-train during the assembly process. I've developed a series of tools to do this work, this pic is my latest design. The Mat factory and CHi Shing (tool and mould maker) will follow my work by building rapid-prototypes while I'm away in Australia. This new tooling will become part of the build process. You can obverse the new tool on the right hand side of the 3D pic, its the white clamp shaped device that fits over the edge of the driver frame.

Typically, front suspensions have enough rigidity to level and support the cone when being installed into the power-train. But there's a catch. Thicker front suspensions add mass and often introduce increased non-linear motion. This is due to process and heating differential limitations when making suspensions that require larger volumes of material. Often, the outcome will be variations in the flex-stiffness ratio in various locations within the piston wall of the suspension (rounded section of the component). Such variation aren't normally an issue for commercial grade drivers, or Full Rangers with limited Xmax. However, for drivers with low mass power-trains, wide frequency generation and larger excursions, the tolerance and mass of this component becomes service critical.

More significantly, thicker front suspensions limit a can a cone's ability to resonance at higher frequencies. For those of you who own Alpair 12's, you can observe just how thin the front suspension is by very gently touching it from the back of the outer frame. Please Note the word "gentle"! The thin suspension forms part of the Alp12's ability to go +20-kHz on a single cone design, without the use of whizzers, plugs or co-axial assistance.

As you may deduce, the more I push the Full Range design envelope, there's a corresponding increase in the complexity of build process............I need this Aussie vacation!

Cheers

Mark.
PS - Paul and Greg, I've edited, hope the new text makes for clearer explanation)
Attached Images
File Type: jpg CHR100_Al_piece_clamp-1-1b.jpg (68.6 KB, 766 views)

Last edited by markaudio; 5th May 2010 at 05:13 AM. Reason: additional info.
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Old 5th May 2010, 04:50 AM   #42
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Keep pushing the envelope Mark!
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Old 8th May 2010, 03:57 PM   #43
vactor is offline vactor  United States
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eagerly awaiting more news. 3 of these in my car would be a perfect front stage!!
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Old 19th May 2010, 11:24 PM   #44
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I'm back to full range drivers !!!!!!!!!!!!!

Watching "the fourth kind" (alaskan alien abductions) I had a hard time understanding the voices. I told my wife "hang on, I can fix this this, give me 7 minutes." So out went the klipsch rb75 and back in with the dual 4" tang band bamboo.

Ah, better. I lose some crisp, but now I understand dialog better.
And it was so improved that I could make out every line from Bill Murry in "Caddyshack" last night. Run wide open it folds in nicely at low to medium volumes with the dual 15" that has an 80hz f-mod (seems to roll at 6db/octave).

All I'd need now is a transparant active 24db crossover at 200hz that doesn't cost an arm or a leg.

I look forward to the Gen2 alpair 10s.

Norman
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Old 21st May 2010, 02:54 PM   #45
lazyfly is offline lazyfly  Australia
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I'm loving the Alp7's so far. Actually that's not true. I was hating them for a few days because they sounded rather 'wishy-washy', around a couple of KHz at a guess. It was rather unpleasant but persistence is certainly paying off as it's beginning to smooth out and find it's equilibrium.

The FE127's they've replaced took quite some time to settle in but the changes weren't drastic, just some peakiness vanished -- in my experience, that is. The Alp 7's however, are going through a rather dramatic settling in period, going from 'Bloody hell, what's all the fuss about?' to 'Now I'm starting to get it *big grin*' They haven't been worked too hard yet, but they're beginning to ask for a bit of a workout I wont get in to all the usual 'They do this awesome, that sucky, this and that brilliantly...' etc. What is more useful is to let others know to give them a go, then giving them some time as is recommended.

Thank you Mark. Now I have to explain to the missus where the money has gone that will pay for some 12's I may be okay, the missus loved them immediately, which is high praise indeed (if your me). That's over the fe127's (vented, brynn), fr125's (sealed, vented, mtm) and Coral Flat 10 ii's! (sealed, vented, OB).

Hospital visiting hours are between 4 and 6PM.

Last edited by lazyfly; 21st May 2010 at 03:04 PM.
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Old 21st May 2010, 05:08 PM   #46
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I have found that the MA drivers take more break-in than the Fostex. Sometimes quite a bit more.

Chris has our A7 in the dMar-Ken7. With the raves we've had for the similar CHR box, i am looking forward to hearing them

dave
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Old 30th May 2010, 11:07 PM   #47
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Hi Chaps,
I'm back from my holiday in Australia so must get back to work! more work has been done on coils by Matsubara san in Japan while I was away. The plan for June is to test another set of coils and suspensions. The coils have been further developed:

Coil set No.1
Copper square winding on 800 micron Alu+paper former
Copper rectangle hybrid winding on 800 micron Alu+ composite former

Coil set No.2
CCAW square winding on 800 micron Alu+ paper former
CCAW rectangle hybrid winding on 800 Alu+ composite micron former

Coil set No.3
CCAW square winding on 800 micron Alu+ paper former
CCAW rectangle hybrid winding on 800 Alu+ composite micron former

Coil set No.4
Copper round winding on 1000 micron Alu+ paper former

Coil sets 1 to 3 are lighter. I'm expecting to see changes in effective frequency range, driver resonance (Fo) and efficiency (SPL). This leads me to an interesting situation. Diy member Tresch has been running low frequency output experiments using CHR-70 (see this thread):

My CHR-70+DSP Linkwitz Transform experiment (4" driver playing flat to 20hz!)

Given that I'm at the stage where it's reasonably easy to "tweak" components, there's a balance to be struck on the new Alp10 between, excursion, power handling and efficiency. Please feel free to feedback your opinions, I'd value more input from members.

Cheers

Mark.
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Old 31st May 2010, 03:58 AM   #48
tresch is offline tresch  United States
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Quote:
Originally Posted by markaudio View Post
Given that I'm at the stage where it's reasonably easy to "tweak" components, there's a balance to be struck on the new Alp10 between, excursion, power handling and efficiency. Please feel free to feedback your opinions, I'd value more input from members.
This is all interesting and exciting stuff! I wish I could have my A10 experiment put together and testing much sooner, so I could provide some feedback with those drivers before you finalize your design, but I think it's going to be at minimum a couple weeks out before I have something playing.

Based solely on the direction that I'm going with my current experiments, which is to say, sealed boxes EQed flat (linkwitz transform), my biggest concerns are how much the new changes are going to affect the durability of the drivers, since I'm generally going to be pushing them to their limits of excursion. I can certainly speak for the robustness of the original CHR-70, as well as the Alapair-10. Considering their high-frequency abilities, these are fairly tough puppies, all things considered.

Obviously, better sounding is always the goal, and since I don't know that much about the physical construction of the speakers, this might not be an issue at all. Just a thought!

I'll touch on the things you mentioned:

Excursion: In my case, more is better! More excursion not only means more capability for the low stuff, but more linearity overall (hopefully) which is especially important when you're playing low AND high stuff. True doppler distortion will become an issue eventually when low frequency cone velocities get extreme, but I haven't personally heard these effects yet, so bring it on.

Power handling: Not quite as important, since I'm primarily designing for low output levels. However, since I'm using loads of boost for the low frequencies, a lot of "peak" power handling is good, but the real low stuff doesn't tend to be sustained. That said, I suppose there are instances where one might be listening to a movie that has some sustained low frequency rumble, which could theoretically be running 60-100watts to each speaker even at relatively low output levels and melt the coils... so I guess I'm up in the air.

Efficiency: Honestly not all that important to me at this moment. Since I'm designing these systems to run between 80-90db @ 1meter, not much RMS power is required at all. I'm already looking at powering a pair of A10s with a 2x60W RMS amp, which, frankly, is ridiculous save for the very lowest of frequencies.
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Old 31st May 2010, 04:01 AM   #49
tresch is offline tresch  United States
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Oh yeah, and I do love me some budget speakers. With the Alpair line getting fancier and trickier all the time, I can't imagine them getting any cheaper.

I love the CHRs, but they just don't have QUITE the displacement capability that would be optimal for me... any thoughts on a CHR-100?
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Old 31st May 2010, 05:31 AM   #50
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Hmmm.... with my Alpair 7s I've been thinking how I probably need to move to an open baffle with LF assistance a la Martin King's work in order to reduce excursion and allow the Alpair to really deliver its very best through mid range and up.

More excursion means doppler distortion etc...

Efficiency is probably more important to what I would be looking for, and matching power handling with that for normal domestic usage.

Any work being done on cones / breakup modes etc?

Quote:
Originally Posted by markaudio View Post
Given that I'm at the stage where it's reasonably easy to "tweak" components, there's a balance to be struck on the new Alp10 between, excursion, power handling and efficiency. Please feel free to feedback your opinions, I'd value more input from members.
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