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Old 15th June 2011, 10:46 PM   #241
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Hi Chaz
A little less so. The correction is now wider. I've spent more time flattening out much of the frequency range.
Mark.
Hi Mark,

Overall, very impressive "flat" response. Pushing the breakup(?) past 10kHz, makes me imagine a very smooth sounding driver. Did not know it was possible with a reasonably priced 4" metal cone. I might have to try a pair out, despite my bias against full range metal cones.

I've noticed the drop at around 400Hz and the corresponding impedence blip (seems to be present in the CHP too), what part of the driver is causing this? Does this even out as one moves further away from the speaker?
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Old 15th June 2011, 10:52 PM   #242
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Asked on the CHP70.3 thread... best to post here.

CHR70.2 vrs CHR70.3 FR compare

dave
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File Type: gif CHR70_gen2-v-gen3_fr.gif (51.0 KB, 275 views)
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Old 15th June 2011, 11:26 PM   #243
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Hi Mark, I want to use these in a TL but because of the high qts and good bass response I am not sure what length line- close to Fs as normal or much lower?
Hi Bill,
Its OK to go close to the drivers resonance frequency. I'd recommend following Dave's advice by not tuning below. Having said that, it would be interesting to experiment. Have you got access to a local wood merchant who can do some simple cuts for you?

If only I had the time to do more box work. I'm already on to the next production and more experimentation (more Alp6, Alp7, Alp10, new shallow profile cone for Alp12, new extended coil for Alp12, frame mods for Alp12........)

Hoping you like to try TL and post this project

Cheers
Mark.
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Old 15th June 2011, 11:37 PM   #244
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Rarely a good idea to tune any TL to below Fs.

dave
yes I know, but on the chr 70 thread I saw a design tuned to 50 hz -

In a BR cab the gen 3 driver has a theoretical F3 somewhere in the 40s so if I'm tuning the TL length to around 68 hz.. its way, way above (because of the high qts).

Last edited by Bill poster; 15th June 2011 at 11:41 PM.
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Old 15th June 2011, 11:45 PM   #245
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Hi Mark,
Overall, very impressive "flat" response. Pushing the breakup(?) past 10kHz, makes me imagine a very smooth sounding driver. Did not know it was possible with a reasonably priced 4" metal cone. I might have to try a pair out, despite my bias against full range metal cones.
I've noticed the drop at around 400Hz and the corresponding impedence blip (seems to be present in the CHP too), what part of the driver is causing this? Does this even out as one moves further away from the speaker?
Hi Ult,
Good observation, the reason is the change to Japanese coils. Its my first time with this type of "ultra" tight wind coil. Very interesting time being with these guys. That and the new spiders from Matsubara san have also helped to overall flatten the responses. This new CHR-70 is a nice step forward from the previous drivers. Norio, Nakjima san, Evan, me, Phil and Morris (mix of east and west) have spent time collectively "fine tuning" to get the Gen.3's sounding more "wide" without getting too harsh. We think we've got it about right.

Re the 400 dip, once in box, there will be a natural further flattening of the lower responses so won't be an issue. I very much wanted to take advantage of the coils and spiders, they gave me the design opportunity to keep the 400Hz to 4-kHz range more clean. As you can see from the old unit (thx Dave for posting comparison), the earlier drivers lifted around 600 to 800Hz. I was never 100% satisfied with having this much BSC correction inside the lower vocal range. It worked OK but was a "engineers niggle".

Generally, I'm pleased because I've taken on board all the feedback for DIYers on this forum and pretty much made what guys wanted (wider response, more Spl, 8 ohm coil etc etc) . Hope you all like the results.

Cheers

Mark.
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Old 15th June 2011, 11:58 PM   #246
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Originally Posted by markaudio View Post
Hi Bill,
Its OK to go close to the drivers resonance frequency. I'd recommend following Dave's advice by not tuning below. Having said that, it would be interesting to experiment. Have you got access to a local wood merchant who can do some simple cuts for you?

Hoping you like to try TL and post this project

Cheers
Mark.
Cheers Mark, I didnt see the reply til just now - I'm not sure what to do, if i tune just above fs, would i get useful extension compared to a BR- .. hope that makes sense.
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Old 16th June 2011, 12:02 AM   #247
mp9 is offline mp9  United States
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...on to the next production and more experimentation (...new shallow profile cone for Alp12, new extended coil for Alp12, frame mods for Alp12........)
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Old 16th June 2011, 12:33 AM   #248
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Cheers Mark, I didnt see the reply til just now - I'm not sure what to do, if i tune just above fs, would i get useful extension compared to a BR- .. hope that makes sense.
Surely,
I'm curious to see guys push the box design envelop. Remember these drivers are pushing the emitter design envelope.

I well remember some years back being told by a certain driver designer that it was impossible to get a single cone full-ranger to breach the 25-kHz barrier; And extending excursion in full-rangers would (and I'm quoting) "be a bloody disaster" (unquote). Well, take a look at the new Alp7 (pretty much BBC broadcast standard) 70Hz going to 30-kHz, all from a cone only 71-mm in diameter, or the Alpair 10.2 with its large X-max, or the Alp-12 with its single load bearing suspension on a 126-mm Dia cone! Theoretically, the Alp12 shouldn't work, yet it does.

Alpair 7 Gen.3 Coming soon

So if you fancy do a bit of extra wood work, see what happens if you extend the TL a little. Might work, might not work but in tradition of "Brit" design engineering (and others) be prepared to experiment. Have fun!

Cheers
Mark.

Last edited by markaudio; 16th June 2011 at 12:56 AM. Reason: additional
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Old 16th June 2011, 12:37 AM   #249
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new shallow profile cone for Alp12, new extended coil for Alp12, frame mods for Alp12........)
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So Alp12 next gen is in motion, though no explicit mention of the paper cones, Mark has thrown us some new leads it seems
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Old 16th June 2011, 12:55 AM   #250
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So Alp12 next gen is in motion, though no explicit mention of the paper cones, Mark has thrown us some new leads it seems
Also a new treatment for cones "MAOP". Ummmmmmmph.....would you like to know more?..

But not on this thread.......I promise to start a new Alp 12 thread soon.

Cheers

Mark.
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