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Old 10th October 2011, 01:48 AM   #91
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As long as pipe cross-section, height, Zd, and port area & depth remain the same it should be fine.

dave
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Old 10th October 2011, 12:25 PM   #92
Goto is offline Goto  United Kingdom
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Originally Posted by Studio Au View Post
This was the idea, keeping the pencils, internal dimensions, port size etc.

Simply a starting point, if anyone has any suggestions I'm all ears.

Click the image to open in full size.
Once you have the CNC files, turning a kit of parts out would be pretty straightforward - I'd probably buy a set.

Nice project.

Mark
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Old 10th October 2011, 08:55 PM   #93
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Once you have the CNC files, turning a kit of parts out would be pretty straightforward - I'd probably buy a set.
Do keep in mind that to go commercial would require permission from Mark, i'm sure he would give that readily, and a one-time commercial licence fee to MJK.

dave
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Old 11th October 2011, 04:23 PM   #94
chrisb is offline chrisb  Canada
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Originally Posted by Studio Au View Post
This was the idea, keeping the pencils, internal dimensions, port size etc.

Simply a starting point, if anyone has any suggestions I'm all ears.

Click the image to open in full size.
elegant shape


echo the points on registration via dowels, randomization of internal surfaces, etc.

also - at least part of front baffle needs to be removable for builders' access to install / adjust damping fill levels (threaded insert fittings?)

consider a few bracing struts

dare I say, don't use MDF?

this will be far more costly to machine, package and ship than you might think
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Old 11th October 2011, 06:12 PM   #95
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Does the effort warrant a fresh design, anyone wishing to collaborate.

The pencils seemed a great starting point, perhaps improvements can be made?
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Old 11th October 2011, 06:29 PM   #96
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Have you considered building a Pensil 7 on top of a box with the woofer? That would leave the Pensil 7 in tact, raise the driver to above ear level (my personal preference) and give you a chance to add some bass reinforcement (with the right crossover).
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Old 11th October 2011, 08:17 PM   #97
chrisb is offline chrisb  Canada
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Does the effort warrant a fresh design, anyone wishing to collaborate.

The pencils seemed a great starting point, perhaps improvements can be made?

Keep in mind that the Pensil format was intended to be easy for a DIY to fabricate with a minimum of elaborate tooling.

I can assure you the author has penned more complicated designs, and wouldn't be surprised if their operating principles or critical features had been misunderstood and second-guessed by builders' modifications, with possible deleterious results.
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Old 11th October 2011, 08:27 PM   #98
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If you are considering the A7 as the mid-tweet over a real woofer, then you sure don't want to do a MLTL for the A7. You will want to cross the A7 anywhere between 100-300Hz. I like 120Hz (partly room related), I hear 160Hz. Perhaps you will finally choose something else. In any case, the simplest solution is a small (4L) sealed box. The downside of a sealed box is the impedance peak is in the XO range making a passive XO a nightmare. If active, no big deal. For passive, a better choice might be an overly large box, say 10L and then put a 20Ω resistor in parallel with the driver.

Bob
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Old 11th October 2011, 09:03 PM   #99
jimbro is offline jimbro  United States
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Consider that there might be some times when you want to listen fullrange without the woofers so the pensil (or ?) would be nice to have. You may try a special amp you want to hear on it's own for example.
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Old 11th October 2011, 09:18 PM   #100
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Quote:
Originally Posted by Bob Brines View Post
If you are considering the A7 as the mid-tweet over a real woofer, then you sure don't want to do a MLTL for the A7. You will want to cross the A7 anywhere between 100-300Hz. I like 120Hz (partly room related), I hear 160Hz. Perhaps you will finally choose something else. In any case, the simplest solution is a small (4L) sealed box. The downside of a sealed box is the impedance peak is in the XO range making a passive XO a nightmare. If active, no big deal. For passive, a better choice might be an overly large box, say 10L and then put a 20Ω resistor in parallel with the driver.
For the A7 FAST i am designing, i am using an aperiodic TL. It will be active, but the ATL does a good job of reducing the impedance peak. My XO will be 160-250 Hz (200 Hz is the target based on current box dimensions).

Here is the impedance of an unboxed FF85, and in the ATL we used in Tysen

Click the image to open in full size.

dave
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