Alpair 12 - Damped Air Coupler box design

[zman01]

Thanks Dave. 18mm it will be.

[zman01]

Found another thread which answered many of my concerns - First timer - desperately confused with the options...

Chris thanks for being vocal on Baltic Birch... it pointed me in the right direction. Great inputs from Dave, Chris and other forum members. Though the thread is on BIB, the discussion is useful for other projects too. And I am building a BIB too besides the Pensil 12 .

Got my marine grade hardwood ply! Still waiting for drivers...

[zman01]

Scott,

What are the characteristics of the "Nessie" cabinet for the Alpair 12? I came across the plans on Dave's site.

-Zia

[superpat]

Hi

My first post here, on a very interesting forum, and a steep learning curve. but I have been reading, (and learning) for some time.

I am constructing a pair of Super Pensil 12's. I have the BB plywood panels cut, and am practicing routing circles on scrap wood at the moment. I have the drivers on periodic gentle break-in as per Mark's instructions.

I have three questions to which I have not found the answers on this forum.

1. Cone excursion?

I need to protect the driver cones from little granddaughters' inquisitive fingers, therefore I need to put a grill over the driver area. I cannot find a figure for the forward cone excursion above the front rim of the driver chassis. It would be helpful to know this so I can make a slim grill but with a safe clearance.

2. Polyfill stuffing, I have read various posts regarding this and am a bit confused. If I use hollow core Dacron loose fiber (as is used in pillow filling), what are the limits of fill? i.e. should I fill from just above the bottom vent to the top of the inside of the case or to just below the driver?
What is the approximate weight of fiber required per cabinet? I note that the figures shown in the Super Pensil plan are the same as the Pensil 12 plan and have not been updated. by my calculation they should be 1.8 - 2.7 lb of fiber for the Super Pensil, or is the figure the same for both models? The reason I am a bit picky about this is I have to buy a bag of fiber, and I don't want to suffocate in a truck load of leftover material!

3. Rodent filter.

We live out in the country and have a considerable problem with small rodents coming into the house when the patio and house doors are open during the warmer months and we are not looking! For example, last summer a rat took up residence inside the insulation lining in the carcase of our C.H. boiler. It was a horrible job removing it and clearing up the mess it had left.
When I showed 'the one who must be obeyed', pictures of the Pensil cabinet, her immediate response was, "How are you going to stop rats, mice, voles, shrews, etc. crawling up that hole at the bottom of the cabinet". "No problem", I said "there is a grill across the hole to stop them!" Now of course. I have to make good that statement, so my last question is, Would a bit of speaker grill material stretched across the port affect the performance very much, what material would you suggest? Don't say "get a cat", we have one and he adds to the problem by catching these pests and bringing them in to show us, unfortunately they are mostly still alive when he drops them at our feet and they immediately run and hide. A pair of Pensils would be super bolt holes for them.

Many thanks for any advice!

cheers

P

[planet10]

Originally Posted by superpat

3. Rodent filter.

We live out in the country and have a considerable problem with small rodents coming into the house when the patio and house doors are open during the warmer months...
Don't say "get a cat", we have one and he adds to the problem by catching these pests and bringing them in to show us, unfortunately they are mostly still alive when he drops them at our feet and they immediately run and hide.

We have some 10 cats, 1/2 of which are more or less permanently outside so we have no issues. We have had the issue of live rodents being brought into the house (including rabbits), but the more aggressive cats at least keep us informed of where to look for them, if not deal with the problem. Cats do like to play with their food.

A rodent will just eat thru speaker grill if determined. I'd recommend door screen material.

dave

[andb]

Thats an interesting design requirement
Normal door screening is a good idea, but I'd be concerned that something might be able to gnaw even through that, however with no experience with rodent-proofing I could be wrong. What about something like chicken coup wiring, with perhaps 3 staggered layers to reduce the hole size? Stronger wire, larger holes than door screening, but small hole size enough when layered to keep out rodents. Paint it black and use a dark finish on the cabinets and it should be just about invisible. Superpat, make sure you post pics of your final solution!

[doorman]

Luckily, I have a Cairn Terrier. They're bred as "ratters"
Guess I should put him on patrol!!
don

[GM]

Originally Posted by planet10

A rodent will just eat thru speaker grill if determined. I'd recommend door screen material.

Agreed, though it needs to be the pet resistant kind as I've had racoons and stray dogs eat through the standard metal screening, but not the other in repeated attacks plus after years of assaults, its mounting has held up much better when they use it as a climbing wall.

It just stretches a bit whereas the metal screen shears at the joint, though a particularly large tomcat's weight did bend/crimp the large/cheap sliding glass door's screen frame, so had to add some bracing after straightening/squaring it back out as best I could.

GM

[jimbro]

I'd use hardware cloth which is available in 1/2, 3/8, and 1/4" squares, welded and strong. Just spray it black and it should look fine with a strip of wood across the top. I think they'd give up and look for someplace more convenient. Don't feel too bad - we've had snakes in the house 3 different times. I really need to make sure that door stays closed.

[doorman]

Originally Posted by jimbro

I'd use hardware cloth which is available in 1/2, 3/8, and 1/4" squares, welded and strong. Just spray it black and it should look fine with a strip of wood across the top. I think they'd give up and look for someplace more convenient. Don't feel too bad - we've had snakes in the house 3 different times. I really need to make sure that door stays closed.

Yes, hardware cloth occurred to me too. t would work very well.
don