might have lost my mind. thinking of building a7 cabinets

[Audio_by_Goodwill]

......the back of each panel will get undercoated.

Undercoated? If you mean the stuff used on cars, why? Unless you've got some professional use stuff, that you know is good, I wouldn't bother, or risk the mess.

the box seems to be sealing well, the test will be covering the speaker hole and seeing if the box will hold a vacuum.

Wow that's getting serious! I've never heard of anyone pulling a vacuum on a cabinet. How do you do it....... use a shop vac, or do you install a port and use a vacuum pump for refrigeration use?

[GM]

But air at high speeds does not flow smoothly over smooth surfaces.

This is true and why ?those in the know? quit micro polishing intake manifolds decades ago and began adding reversion ?lips? or other means of providing the right amount of back pressure to ?time? exhaust systems due the extreme difference in the SoS of each sub system; but sound is AC, so we?re dealing with a vibrating air mass ?plug? [piston] that in a horn is also expanding/contracting under pressure at the SoS. Consequently, any airflow impediments affect its sound quality [factor], though whether within or outside our acute hearing BW there?s much dispute as to which, and how much, distortion is required to become an issue.

All that said, there is a point where what you?re referring to comes into play in that when the expansion in WLs has ?shrunk? in size to approximately 1 WL of the horn?s expansion it begins to narrow up [beam], so it?s necessary to increase the expansion enough to keep it from happening [mouth end correction] unless the horn is only going to be used below this point.

I?ve always taken the racer?s view that ?God? is in the details, so while no single one may seem to make a difference, a whole bunch of them might add up to something and smoothing out a horn?s surface is easy/cheap enough and looks nice to boot.

GM

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i went ahead and used the closed cell foam.

i went ahead and tried stress testing it and yes i can stand on it with 1 foot (tomorrow i could probobly jump up and down on it) without any flex

i have more pictures, but i seem to have used my 1 mb limit. ? and i'm not sure if i can delete some of the pics in the attachment box

OK, was there a question we missed?

Cool! Looking good! Much nicer woodworking/attention to detail than mine too. Now if there was only a way to make those flares cheaply without having to get them from China???..

Go into your ?settings? listed at the top of the page, then scroll down and click on ?miscellaneous/attachments? to bring up the list, then check off /delete as desired.

GM

[Phil-G]

Wow that's getting serious! I've never heard of anyone pulling a vacuum on a cabinet. How do you do it....... use a shop vac, or do you install a port and use a vacuum pump for refrigeration use?

i'll just have to figure it out when i get there.

This is true and why ‘those in the know’ quit micro polishing intake manifolds decades ago and began adding reversion ‘lips’ or other means of providing the right amount of back pressure to ‘time’ exhaust systems due the extreme difference in the SoS of each sub system; but sound is AC, so we’re dealing with a vibrating air mass ‘plug’ [piston] that in a horn is also expanding/contracting under pressure at the SoS. Consequently, any airflow impediments affect its sound quality [factor], though whether within or outside our acute hearing BW there’s much dispute as to which, and how much, distortion is required to become an issue.GM

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OK, was there a question we missed?

Cool! Looking good! Much nicer woodworking/attention to detail than mine too. Now if there was only a way to make those flares cheaply without having to get them from China………..GM

you know i had considered the difference between ac vs dc since we're dealing with vibration and not flow.

i have been accused of "turning japanese" but not chinese.
i had to repair my form after the first one. i should have done a better job with the mold release compound. but i have the lefthand flare almost laid up.

[Cal Weldon]

Wouldn't it be easier to pressurize and measure the cabinet instead of a vacuum?

On top of that, is there a need to?

[Phil-G]

On top of that, is there a need to?

probly not i would just be showing off.

[Audio_by_Goodwill]

Wouldn't it be easier to pressurize and measure the cabinet instead of a vacuum?

On top of that, is there a need to?

Vacuum would likely be better for the cabinet.......less likely to break something when the force is into other cabinet pieces than out towards space.

[bowtie427ss]

Vacuum would likely be better for the cabinet.......less likely to break something when the force is into other cabinet pieces than out towards space.

Railroad tank car vacuum implosion - YouTube

[Altec Best]

That's what measurements are for.You can tell if the cabinet is leaking with measuring.Unless you don't have the means to do so.

[bowtie427ss]

That's what measurements are for.You can tell if the cabinet is leaking with measuring.Unless you don't have the means to do so.

A pressure or vacuum "leak down" test is certainly a measurement.

Just maybe not one we'd normally associate with speaker cabinets, and probably marginally useful at best. I'd advise anybody considering such a test to limit their testing to a scale of less than 30 inches in a water column, not Hg(mercury) and NOT PSI.

[Phil-G]

you know. i was kinda kidding about the vacuum test guys. it's a wood cabinet.
will be tight boxes though.