The Amp Garage

Hey.
I'm trying to put together a sort of 2x12 slant cab.
I think I read some posts, where people mentioned that a closed back cabinet should be airtight to work correctly.
I wonder how true this is, since there will be holes through the jacks, plus other places?

Very important if this is a closed box design. Not so much if it's a ported, or open back design. Speaker jacks should be air proof design to keep the plug from being blown out also. Use the Neutrik airtight jacks.

arjepsen wrote: ↑Sat Jul 15, 2017 9:46 am I think I read some posts, where people mentioned that a closed back cabinet should be airtight to work correctly.

In this area I'm going to recommend you do what you think you need to. Without good test equipment I'm not sure you can tell the affect a 100% sealed vs. a 99% has on cone movement. If there is scientific / engineering data regarding this on GUITAR cabs I'd love to see it - HiFi is a whole 'nother critter. I've never sweated the need to 'seal' a closed back cab and not noticed anything a miss on 14 cabs so far. I am a fan of tight fitting joints - more from woodworking snobbery than anything. I use the standard 1/4" jack and never had one come out - though I tend to play very loudly.

Russ

I use sealant on all the joints, does it help, I don't know!
I don't worry about the jacks, though I have seen plugs for sealing them. Once, (at a very loud venue), I did blow the 1/4 plug out of a bass bin!

Not sure being totally airtight is a good thing. I've seen plugs blow out of jacks with high volume and they needed to be duct taped in to stay! That's something to watch for, as you can leave the output tranny unloaded and it could fry if it's the only cab hooked up to the amp.

I'm not sure there is data for guitar applications.
I've played lots of "sealed" cabs with 1 to 3 open phone jacks.
Sometimes they whistle with no plug.
Switchcraft used to make a phone plug with a threaded ring to lock the plug in.
And spring loaded soft rubber covers for the other ones.

Bob

If your cab is designed based on modern theory, most of the available formulaes and software for closed box design is based on an airtight box. If the cabinet is based on random or haphazard design, it doesn't matter too much - you need to test for a final result. Copying an existing design without using identical drivers can also give you a random result. The problem with traditional guitar speaker elements is that the T/S parameters needed for a proper and predictable design are often not available, and production spread is also sometimes highly variable.