Double Bass Up firing PJB Double Four

[madbanjoman]

After reading about the new Upshot speaker cabinet from AI in another thread, I got to thinking of trying this out with my PJB Double Four. At first I used a couple of books to put a little space between the passive rear speaker and the floor without blocking it. I liked what I was hearing. The sound was more focused and I wasn’t reaching for my HPF pre to tame the lows. I happened to have a spare set of 1/2 thick amp feet, so I installed them on the back of the amp. While I love this amp, prior to making this change I felt wasn’t loud enough for my outdoor street gigs. Now I have been using it exclusively completely happy with the volume and sound.

I wanted to pass this on to any PJB Double Four owners as possible modification.

Of course I have added pics for proof

You can hear it in action with my EUB in this youtube video.

 

[Earl]

I have also tried this with my double four and it works well in some rooms, in others though the bass radiator facing the floor can make it too boomy.

 

[Walter Folly]

If I may ask, how did you do it precisely? Did you just use the stock bolts?

 

[madbanjoman]

I used wood screws and drilled a guide hole first to attach the feet.

 

[Walter Folly]

Okay, thank you! There seem to be two versions of the double four. Older ones don't have screws on the back. Newer ones do have them. So does mine.

I checked the screws and they seem to be reasonably long. Perhaps I have to use something longer but I try to make it work with the stock ones.

 

[madbanjoman]

Much better to use the screws you have than drill holes

 

[bassically_eli]

For the ones with screws on the back, does anyone know where to find screws with the same threads and diameter as the originals? I have looked multiple times at hardware stores and cannot find suitable screws anywhere.

Edit: the feet I have need screws that are flat on the underside of the head.

 

[Ric Vice]

Reading this thread, I’m reminded of a rig that bassist Major Holley once had. He somehow attached a 12” driver inside a the bottom of his bass stool
pointed upward. I’m not sure how it sounded but it was a creative solution. My fix is either of these handy items. Rick Jones (R.I.P.) had custom Eminence drivers designed to work in a UP Firing orientation. Just flipping a cabinet isn’t quite the same, but if it works for you then, great! I’ve put cabs in all kinds of weird spaces and unusual places.