160Hz Bump

[Diggar]

Hi all , I am not sure if this is the correct place for this question but if not please direct me to where I need to be.

I recently built a front ported 10" speaker cabinet for guitar and tested it by putting pink noise through it from my spectrum analyzer.

There is a spike at 160Hz and I am not sure why as I thought I ported it for 100Hz.

So my question is about this spike a 160Hz, is it the cabinet resonance, speaker resonance or something I am missing altogether.
Any help appreciated
Thanks

[rjbond3rd]

Can you try re-tuning the system by changing the port length?

Or if you don't have the internal volume to lengthen the port, you could go down to a smaller port diameter and get more tuning flexibility (at the expense of potential port noise).

[Diggar]

Thanks for the information. I closed off the port entirely and still had the bump at 160 hz. Can't figure where it is coming from

[chris661]

Your cabinet is likely too small, or it could be a room effect. If the back is removable, try running it open-backed. It doesn't suit everyone, but porting a cabinet for guitar use usually isn't recommended.

[rjbond3rd]

What are the dims of the cab? I hope it's not cube-shaped.

Chris661 may be right that the bump/resonance is caused by the cab being undersized. His suggestion to try it open-backed is right on. I've never personally come across a guitar speaker that wanted anything but open-back.

[chris661]

I've experimented with open backed vs sealed before now, using an Eminence Beta 12A (nice sound to it). Having the cabinet closed gave bassier sound (turned the bass down a bit, easier on the amplifier), but there was a serious resonance on the 5th fret of the E-string. There was lots of emphasis on it, and rolled off noticably the lower I went. Opened the cabinet, the resonance went, and the bass roll-off was much shallower. Not much fundamental output on drop C-sharp, but who'd want that anyway? (usually used with heavy overdrive, so bass isn't wanted)