[JohnR]

Very quickly from the Australian distributor Dan Archer.

I was bemused to discover that not only is there an extra magnet, an extra front cover bezel, but also an extra pair of terminal lugs. Not really sure how to describe that right now. The extra front cover, I really do not understand the point of. It's plastic - what advantage is there to using it? If used, should it be recessed fully?

I do have to say, I wonder at times if any fullrange manufacturer has ever considered proposing a set of standard frame sizes. it would certainly make it easier for many DIYers. Some of us would likely buy more drivers if the same nominal-size driver fit into the same actual-size hole...

Alpair 7s next to a CHR-70 (Gen 1):

[jeffh]

This may help answer some of your questions about the A7:

http://www.diyaudio.com/forums/markaudio/197071-glueing-alpair-front-trim-rings.html

http://www.diyaudio.com/forums/markaudio/190401-alpair-7-gen-3-coming-soon.html

[JohnR]

OFGS.

Do you have these drivers yourself?

[jeffh]

Yes, I have some A7's and plan to build a Frugel-Horn Mk3 over the Christmas holidays for them.  I also have some of the new CHP-70's I am using in a Pensil build that I should complete this week.

p.s. I am loving the Virtue amp you sold me.

[JohnR]

Well, I fail to understand the purpose of pointing me to a 22 page thread that may or may not answer my question... Never mind though, your post prompted me to send an email to MA directly.

I'll be interested to hear how you go with the FH3 

J

[JohnR]

Sorry, I missed the PS. I'm listening to one of the others now, albeit on tweeters.

[jeffh]

The first link is only two pages with 15 posts where the actual designer explains why he has the extra bezel in post #6.  The second link is full of details from the designer on the A7 that would probably answer many of your question.  Sorry, I was just trying to help and point you to the facts from the actual creator of the speaker.

[JohnR]

Where practical, please use the front covers. They add to the mass damping of the driver.

Well, the cover weighs about 18gm as far as I can tell. I don't see how this adds to "mass damping."

[chrisby]

Well, the cover weighs about 18gm as far as I can tell. I don't see how this adds to "mass damping."

John - I've been a fan of Mark's drivers for several years now, and generally don't like to second guess any designer's reasoning,  but I'm certainly inclined to agree with you on this.  I avoid the extra rings on the new  Alpair7s for the practical reason of required mounting depth - since I happen to use BB plywood for all my speaker projects and recess drivers for flush fit, the extra 1.5mm or so makes things pretty skinny in the area of mounting screws.  Going thicker than 18mm on the baffles might deal with that, but only creates another issue of choking the rear-wave output.

The easiest compromise I've found is to scallop a chamfer around the area of the 4 support legs (seen here with a beater A7 G1 mounted on FH3 removable baffle)



Not a fan of the slip-on terminals, as I use #24 wire, a quick solder is easy - I do love the hex head screws (M3 key required) - just remember to use the cardboard liner to protect the very delicate cone when installing and don't overtighten  - the beater A7 above is direct result of a glancing blow. 

[planet10]

John,

I've sent you an email (based on the diyA thread) on the bezel covers, as Chris said we avoid them when we can. As Bob Brines' said about my stiffening and damping of Fostex bezels "how much difference does it make once you have the driver bolted to the baffle?" -- that treatment is now optional.

The extra set of terminal thingys are so that those who insist on using welding cable don't melt the plastic baskets. They are the MA equivalent of crimp-on connectors.

As Chris said, with a max of 2 strands* of 24g CAT5 wire to be soldered, we have no issues soldering direct to the terminals.

*(on the ground terminal, when we are emulating Louis'  trick of double the wire on the ground)

dave

[JohnR]

Cool, thanks for the info. I'll ponder on the covers. Looks like I'll need to get a chamfer bit then. Another Chrissy present for myself!

[chrisby]

Cool, thanks for the info. I'll ponder on the covers. Looks like I'll need to get a chamfer bit then. Another Chrissy present for myself!

a high quality carbide bit will pay for itself here - the amount of material to be taken off on these chamfers is small enough that a laminate trim router is more than adequate horsepower, and much easier to handle

just be careful to set the depth of cut so at least 2mm of the bearing is running on the interior of driver cut-out, and clearly mark the start and stop lines if scalloping around the the support legs - there's not a lot of visibility inside the router base to see where you're going