B15N, single baffle vs. double baffle

[BadHairDay]

In mid 1965, Ampeg switched their B15-N from a double baffle cabinet design to a single baffle design.

I don't have the two amps to compare side by side.

What little I know about cabinet design tells me this is a not insignificant difference. Can anyone comment? Are my instincts right, or am I just making a mountain out of a molehill?

When they did this switch, they changed the name to B15-NF and also gave it fixed bias tubes (not sure what exactly that means, but it's just another thing that can affect tone I suspect). The previous model was named the B-15NC (the one with the printed circuit board starting around 1963/64).

 

[coreyfyfe]

You can check out the portaflex wiki up at the top for the various revisions and ask this question in the portaflex thread if you want, might bring in some more opinions.

The circuit revisions between cathode and fixed bias, turret board and pcb, double and single baffle were all around the same time but not necessarily related. Also worth considering the change in circuit arrangement from tone stack > volume to volume > tone stack was I think sometime in 64.

I’ve had a 66ish single baffle fixed bias and a 65 cathode biased double baffle. The single baffle had the original CTS, the double baffle I tried about 5 or 6 speakers but settled on a reconed CTS before selling the amp.

The number of differences between amps so close in manufacture can complicate direct comparisons some times, without trying the same amp into multiple cab styles it’s hard to make definitive statements.

For me, the 65/cathode/double baffle was a bit darker and more compressed than the 66/fixed/single amp that I had, but again, a lot more to the differences than just the cab there.

Check out some videos of the heritage B15 amps where they switch cathode vs fixed bias into the same double baffle cab.

 

[beans-on-toast]

They are different designs and have subtle sonic differences. Adjusting the EQ can help but how a cabinet breaths is important.

I wouln't say no to either but given the choice, I'd want a double baffle. The double baffle involved more labor to produce and they wanted a more cost effective porting solution. The next step was the thiele based design in late '67. There have been revisions over the years. They love to change things. The current Heritage revision has gone back to the double baffle.


If you want a new double baffle, check out Vintage Blue.

TalkBass Portaflex Wiki: Ampeg Portaflex Wiki

Cabinet details start here:

Double Baffle Cabinet

 

[DJ Bebop]

I just got an empty double baffle.
Time for a speaker swap and see.