Porting cabinets

rpetersen · Post by **rpetersen** » 22 Mar 2004 4:46 am

I have a couple of small 15" cabinets that are open backed. I want to close the back and port them out the front - I don't have a lot of room - I can bore up to a 2 1/2" hole [up to 4 total]. - my question is how many do I need or what is the minimum amount of square inches I can get by with.
Thanx....Ron

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Ron Petersen &
The Keep'n Tyme Band

William Peters · Post by **William Peters** » 22 Mar 2004 3:18 pm

Ron,

Go to www.linearteam.dk and download WinISD. This is a free program that lets you design speaker enclosures. It will caculate the best port size and length to tune your enclosure to match your speakers. To use it, you have to look up the Thiele-Small parameters for your speaker. Peavey publishes this data for their speakers as do most of the other speaker manufacturers.

Bill

Joe E · Post by **Joe E** » 22 Mar 2004 6:35 pm

THe best thing about ports are they don't just have to be surface openings.

Meaning that if a baffle is 3/4" you may for example need a 6 square inches of port. BUt you can reduce the size by increasing the depth of the hole. You may have seen small cabinets with really deep tubes used to increase the depth of the port.

These are not really anything special, I was buying port rings that were 3" deep. BUt you can just use a cardboard tube like from wrapping paper as the port tube.

JOE

Dan Tyack · Post by **Dan Tyack** » 23 Mar 2004 12:16 am

One question I have is why do you want to close up the open backs? I have used open backs and a number of ported cabinets, and with the exception of the THD speaker cabinets, I much prefer the open backs. THe ported cabs can tend to sound a bit 'boxy' (IMHO).

David L. Donald · Post by **David L. Donald** » 23 Mar 2004 3:34 am

The ported cabinets can be louder, but it's a question of taste if it sounds better or not.

rpetersen · Post by **rpetersen** » 23 Mar 2004 4:37 am

Dan - Good question - I find with open back cabinets that whatever is behind them changes the sound - we have experimented by even just hanging a coat over the back of a chair that the speaker was sitting on and it changed the tone. If you were playing the same place all the time, it probably wouldn't matter, but we play the dance hall circuit and every stage is different.

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Ron Petersen &
The Keep'n Tyme Band

Scott Appleton · Post by **Scott Appleton** » 23 Mar 2004 8:58 am

Ok Marrs and Sterio Steel both use a small cabinet with 4 it looks like 2" ports with eather JBL or black widow 15's. closed back. Every one i see with these riggs swears by them and they sound great. so whats
the issue?
I am building a cab with a closed back and 4 2" ports
to use with another amp that has an open back 12'
in it. Hi Fi is what i would call it. 19 by 24 by 11 deep.

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Mullen S12
Acoustic 165 100W tube
71 Tele, Regal 45, Gretch
Lap, Columbia Lap, Line 6

rpetersen · Post by **rpetersen** » 23 Mar 2004 11:35 am

Thanx for the reply Scott - I think that is about what I decided on also - I see your cabinet dimensions are real close to the peavey 115E - - 181/2 x 221/2 x 141/3.

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Ron Petersen &
The Keep'n Tyme Band