Port design help on bass guitar enclosure.

[ianhall]

Hi all,

I have recently built a 1x15" bass guitar cabinet using an eminence deltalite driver. I followed their box specs, which calls for two 4" ports, and the results seem to be good so far.

I would like to use a front ported design, so the cabinet can be pushed all the way up against the wall in my room when practicing (I have a very small room). There is not reasonably enough room on the front for two 4" ports, but I do have some 5.5" ID tube stock, which would fit if a single port was used. The other option is slot porting, which I would like to avoid to save weight and loss of internal volume.

So, the question:

What are the advantages/disadvantages of going from two 4" ports to a single 5.5" port?

I calculated that the 5.5" port would have to be about 3-4" long for my tuning, would the length being less than the diameter cause any strange effects?

[Pete Schumacher ®]

> Hi all,

> I have recently built a 1x15" bass
> guitar cabinet using an eminence deltalite
> driver. I followed their box specs, which
> calls for two 4" ports, and the results
> seem to be good so far.

> I would like to use a front ported design,
> so the cabinet can be pushed all the way up
> against the wall in my room when practicing
> (I have a very small room). There is not
> reasonably enough room on the front for two
> 4" ports, but I do have some 5.5"
> ID tube stock, which would fit if a single
> port was used. The other option is slot
> porting, which I would like to avoid to save
> weight and loss of internal volume.

> So, the question:

> What are the advantages/disadvantages of
> going from two 4" ports to a single
> 5.5" port?

> I calculated that the 5.5" port would
> have to be about 3-4" long for my
> tuning, would the length being less than the
> diameter cause any strange effects?

It should work, and remarkably well. There would likely not be much turbulence either. It's worse when the length is in large excess of the diameter if there's lots of air to move. That can cause compression. But a short port is just fine.