ALPAIR 7P - launch - specs - diyAudio
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Old 17th August 2014, 07:53 AM   #1
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Default ALPAIR 7P - launch - specs

Hello Guys,
I've finally found some time and energy to complete the specs for the Alpair 7P extended Full-Ranger (hope you like it).

So what's been going on with this driver?......Well quite allot. Most of the development work is illustrated in this thread (for those that want to earlier background):

Alpair 7P developments

Here's the attached PDF specification sheet thats being released to all dealers and end-users.

A video recording of the No.2 7P was done using a Canon 5D Mk2. While its audio recording is limited mostly to mid-high frequencies due to the position of the camera body, it gives you some idea of the character of the Alpair 7P. You may also be able to see some detail within the cone body fibre material:

https://www.youtube.com/watch?v=QT_7...ature=youtu.be

I've been playing the first production pair for + 300 hundred ours, mostly on tube amps with pleasing results. Last Friday I swopped to the Amp Camp Mono's with pleasing results. These amps are featured in this thread:

Amp Camp Kit with Markaudio drivers

Its difficult for me to express detailed characterisation of a new driver. I'm much more comfortable discussing its technical and operational features. But since allot of this detail appears in the development thread, I'll do some short explanation here.

It falls firmly into the Markaudio "paper" family (as expected). Those members and end-users who are familiar with Alpair 6P, 10P and 12P's will appreciate this driver. It exhibits a slight dry vintage sound, classic of paper drivers but with less of the "flatness" associated with older paper coned units. This is to be expected given its extended range well passed 20kHz. The 7P's rising response serves it well when cabinets are angled from 10 to 15 degrees off axis. For those listeners using soft-warm tube amplification, you might want to reduce the off-axis placement from Zero (on axis) to 10 degrees. But like so many things in audio, experiment to please yourself.

The 7P's cone's re-enforcment is working well adding a modest level of damping while increased rigidity illicit's an extended working frequency response. Box sizes should easily range from 5.5litres to 11litres (BR or slot) for those who want to remain "purist" with single point source application; While others who wish to take advantage of partnering the 7P with its new bigger brother, the Alpair 12PW should have allot of fun.

For me personally, I'm pleased with the results. I have to stretch my limited energy over a longer working period so please accept my apologies for the longer duration to get this driver (and others) ready.

Cheers
Mark

Last edited by markaudio; 6th September 2014 at 07:17 AM.
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Old 17th August 2014, 09:18 AM   #2
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On paper it looks to have a really nice response! I'm sure it sounds great too. Congratulations Mark.

My hearing only goes up to 15khz so I don't think I would need much of a toe in.
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Old 17th August 2014, 10:06 AM   #3
ttan98 is offline ttan98  Australia
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Hi,

Looks good, looking forward to using this driver, any other details like availability, pricing, etc is most welcomed.
BTW, I own 2 pairs of Chr-70, 2 units in parallel on each side to give me the required spl, very happy with them.
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Old 17th August 2014, 10:32 AM   #4
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Very nice (the scale drawings on the pdf are bordering on the illegible however).

Pensil for the 7P would be (internal HxWxD):

35.5in x 6in x 10in.
Zd = 7.125in
Slot vent 1.25in tall at bottom of front panel.
Default damping: stuff 0.6lbs ft^3 uniform density throughout enclosure -ensure kept away from driver. Adjust to suit; usual removable back suggested for easy adjustment.
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Old 17th August 2014, 09:03 PM   #5
Bigun is offline Bigun  Canada
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It looks super nice.

Very interesting driver specs - the response looks very good. And like 'Bill poster' my ears would low pass this quite nicely, quite nicely indeed

Question: the rising response between 15kHz and 20kHz is not accompanied by any wiggles in the impedance curve - usually a cone resonance enhanced response has some tell-tale bumps in the impedance curve, what is the physics going on with the 7p ?
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Old 17th August 2014, 10:47 PM   #6
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Quote:
Originally Posted by Bigun View Post
It looks super nice.

Very interesting driver specs - the response looks very good. And like 'Bill poster' my ears would low pass this quite nicely, quite nicely indeed

Question: the rising response between 15kHz and 20kHz is not accompanied by any wiggles in the impedance curve - usually a cone resonance enhanced response has some tell-tale bumps in the impedance curve, what is the physics going on with the 7p ?
Hello Bigun, Bill P, Guys,
Thanks for you comments and support. My 56 year old ears also need just a lick of toe-out.

Interestingly, if you take a historical look at the design of many Full-Rangers, their designers (those with experience) will take advantage of the rising response phenomenon. A combination of a low mass cone with a suitable profile couple with a trick coil + other design properties will illicit the effect. The natural desire to place boxes inside rooms in-line with walls suited the use of the rising response.

Hence why I always suggest keeping designs simple when doing in-room tuning and tweaking. I realise for some hobbyists, building complex designs and complicated cross-overs is fun, but the actual acoustic outcome/result may be questionable and/or acoustically disappointing.

Big's question on impedance variation in the upper frequencies is interesting but very complex to describe in terms of the properties of low-mass full-range driver design.

Take a look at many of the low-mass Full-Rangers and you'll notice relative/progressing linearity in the rising impedance curve above the oscillatory lower ranges. A good Full-Range driver designer will use parts of the emitting surfaces and power-train where mass is ultra low, to transfer/emit while minimising the driven losses in the upper bands. The result is extended rising upper output registration while corresponding electrical and mechanical resistive loads remain progressive.
Where you will likely observe more variation in impedance is in the oscillatory lower bands. Typically around the transfer from mechanical oscillatory to semi and static resonance. This area of driver function has greater/increase mass to power variance. Typically, getting the coil, cone and suspensions to convert electrical energy into mechanical energy in the transfer region where oscillation and static resonance collide, is where a Full-Range driver designer gains most of his/her grey hair.

Thanks
Mark.

Last edited by markaudio; 17th August 2014 at 10:57 PM.
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Old 17th August 2014, 11:26 PM   #7
doorman is online now doorman  Canada
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Looks good !
There's a pair in my future.
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Old 18th August 2014, 03:51 AM   #8
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Quote:
Originally Posted by Scottmoose View Post
(the scale drawings on the pdf are bordering on the illegible however).
My drawing, original here: http://frugal-phile.com/boxlib/marka...ion-230611.pdf

dave
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Old 18th August 2014, 05:59 AM   #9
AlanL is offline AlanL  United States
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Questions:

What's up with the (optional?) second magnet?

In rereading the break in instructions, keeping high passed use in mind, would it be better to do the break in fullrange or with crossover? If only used above, say, 2k would the Alpair 7p ever fully break in? Would it matter?

Thanks.
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Old 19th August 2014, 09:03 PM   #10
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This looks like a great little alternative to the A7.3 (of which I am very fond).
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