French omni15 vintage bass cab

[michel_olivier]

Hello, here in France we are some bassmen who have done BFM cabs…
And after about 25 hours, my omni15 vintage bass cab is completed.
Mine is without tweeter. Grill cloth is old Marshall cab style.
Some pics of my new stack!!

To resume my point of view :
very sensitive (like my old Marshall 1982B loaded with four G12h30 at 102db/1w/1m),
very clean and very smooth (like HIFI cab) ,
and big low end (like no other one)!
I use it with vintage tube amps : Marshall Superbass 100W, Ampeg SVT 300W… mosfet amps : Tube Works, Gallien Krueger, Yamaha… and different e-basses : Musicman, Fender, Ibanez… and with double bass too.
It’s always very transparent : you know what amp you use (or don’t know with a transparent one like the Yam or GK) and which bass is plugged in your amp (or double bass too).
In my mind maybe could-it be a little bit so straight and cold with modern amp (with the double-bass for example) but with vintage one’s it’s really good.

[LelandCrooks]

Very nice

[Mark Coward]

It looks very good....not to be picky but I'd try to straighten those stripes on that lovely checkerboard grill cloth

[wallywally]

Nice looking build. Just a word of caution. The Ampeg SVT needs a MAXIMUM 4 ohm load hooked to it. Running 8 ohms is hard on your tubes and your output transformer. The SVT(original) has only 2 taps on the output transformer 4 ohms and 2 ohms.

[michel_olivier]

Thank you for your answers!
Yes I know it's not the good choice to have the amp at 4ohms & the cab at 8 but in this case it's only bad for the tube's screen grids (and in the case the impedance the cab is less than this the amp it might kill the output transformer primary).
I prefer to change the tubes instead of the output transformer...
The best will be I do an other BFM cab to complete the rig... I was thinking about a OT12 single driver or 2*O10.5 ??? I have the plans for the two but I can't chose one...

[Bill Fitzmaurice]

Thank you for your answers!
Yes I know it's not the good choice to have the amp at 4ohms & the cab at 8 but in this case it's only bad for the tube's screen grids

In this case, not a problem. With single driver cabs that run full range the rising impedance in the midrange is a bit of a problem, but since the O15 crosses over to the midrange driver below the point where the woofer impedance goes up it actually will present a lower broadband load than the average commercial 4 ohm box. One must also keep in mind that impedance is not a constant with frequency, that even a two ohm cabinet will show impedance peaks well over 20 ohms. In short, don't worry about it.

[michel_olivier]

Thank you for the answer Bill. I wasn't so worry but it's better to have the opinion the BOSS