Vented cab design question...

[zebrostripe]

I'm building a guitar cabinet using a Jensen P12N speaker. I have a question regarding vent placement. The cab will be a about 19" wide by 11" deep by 17" tall. How would the sound of the cabinet be affected by placing the vents on any other face af the cab other than the one with the speaker? I'm particularly interested in placing the vents on top for visual reasons, but if putting the vents on any other surface than the speaker diminishes the sound, albeit perceived volume or tone quality, then I'll redesign the cab.

I don't know much about the science behind cabinet design other than pulling ideas from existing designs that sound good and trying my own little twists. Any links to any cab design info or pointers would be greatly appreciated.

Thanks!

[Geek]

Hi,

Vented cab design for guitar speakers is a little bit of 'black magic', as they don't lend themselves well to vented cabs - the Qts/Qms/Qes just isn't in the right places or consistent. They are made for open back (open baffle) or sealed.

Smaller speakers, like 6" to 8" lend themselves well to horn designs, though.

Bass drivers however, many of them were designed specifically for vented cabs.

Cheers!

[Hotsauce]

If you do go vented try to design it so the vent can be easily replaced with another one of different tuning, or covered over altogether.

I find that open back cabs sound great at lower volume, but have issues as it starts to get really loud.

John C.

[nyazzip]

...some hi-fi speakers have "rear-firing" ports, and proximity to a wall is alleged to be somewhat important in these designs. i own a pair of Klipsch rf-52, and they are rear ported.
most speakers(especially guitar cabs) are going to have something placed on top of them eventually, so this is reason enough alone to stay away from a "top-firing" port i would think...

[zebrostripe]

Thanks for the responses.

What led me to the idea of creating a vented cab for guitar was that my guitar player in my band sometimes uses a Sovtek-branded vented cab with a Celestion Vintage-30 12" speaker (the vent is located in the lower right corner as you face the front of the cab). Set beside my open-backed P12N, the sound is more compressed, uni-directional, and focused (not necessarily to my liking, but I see the draw...), and I thought I might experiment with creating a vented-cab combo amp that would create a similar sound, meshing my beloved P12N with the tightened sound of the Sovtek.

I've got the design pretty much finalized, but as I was toying with the look on the front of the amp, I wondered if the vents could be placed anywhere or if I was limited to keeping them on the same face as the speaker.

Once again, I appreciate your help!

-z

[zebrostripe]

nyazzip-- good point!! my luck the vent would be mistook as a cup-holder! : )