Fender Bassman Ten insulation or not?

[Axtman]

I have an early 70's Fender Bassman Ten that I am restoring. I removed the speakers and chassis to clean the cabinet and noticed there is insulation stuffed in the cabinet. I don't remember Bassman Ten amps having insulation. Did they?

[bob p]

No.

[Randall]

No.

Shortest quote ever from the usually loquacious bob p!

[Tom Phillips]

Let's re-consider.
The 1970's Silverface "Bassman Ten" model that I am familiar with looks like a combo from the front but the speakers are in a closed back section of the cabinet. In that case, I would expect the beast to have insulation like other Fender closed back speaker cabs.
Can you show us pictures of your amp?
Tom

[Justin Thomas]

I don't "Like" that's because I doubt bob, but just because I'm curious... insulation is easily removed. At the same time, Fender never made a separate 4x10" cabinet, did they? They were all 1x12", 2x10", 2x12", or 2x15"... maybe because it was a combo amp they just left it off the Bassman Ten. Maybe they thought it was too wooffy with insulation... I would also think the Bassman Ten was subject to the same kinds of "evolutions" as other Fenders, and the occasional lazy or hungover employee who "just didn't feel like it that day..."

Justin

[bob p]

I was commenting on this one:

It's not a sealed cab. It's ported.

It's an oddball design in that it uses an empty ported cab with very small ~1" circular ports, which in practice are too small to be effective. The cab exhibits an odd behavior where the holes don't allow enough air passage for the vents to properly perform their duties, so the speakers pressurize the cabinet faster than the holes can depressurize it. The result is that the cabinet exhibits a pumping sound when used for bass. It's not a problem with guitar. This is why this version of the amp has never been all that popular with bass players.

I've never seen one of these with insulation. If one has insulation I'd bet that somebody was trying to fix the pumping problem. Axtman, are your portholes still there or were they plugged? Plugging the holes is a common mod to fix the pumping problem.

[stokes]

I've only worked on 2 of these amps and both were as Tom described,closed cab with insulation.

[Tom Phillips]

Axtman,
In another thread you asked about sources to purchase a new baffle board for a Bassman Ten amp. I assume that this thread is about the same amp. In that case you can have a baffle board made without the small ports. You can also replace the solid back with an open back if you would rather have the sound performance of an open backed cabinet. Things to consider anyway...
Tom

[bob p]

Leo has serviced a lot of these amps over the years. He probably knows more than any of us.

FWIW I've never seen one that wasn't ported. I've never seen one that had filler. And I've never seen a 70W "UL" version. Mine was built in 74-75. It was totally stock when I bought it on consignment from the first owner. It still has the original hang tags.

IME you CAN NOT trust the Fender Amp Field Guide about this amp. The Bassman 10 page contains a lot of errors. Whoever did the write-up on this amp appears to have just copied most of the specifications from the SF Bassman pages.

For example: they claim that the Bassman 10 is just like the regular Bassman series of amps, in that they were originally 50W amps and were later upgraded to 70W ultralinear [sic] amps. That's not right. The Bassman 10 is built on the Bandmaster chassis and it uses the Bandmaster / Pro Reverb / Super Reverb power transformer # 022798. That's a 40W transformer, not a 50W transformer. When running full-tilt, mine produces 20VRMS sine waves in to a 10R resistive load. It uses a much smaller OT than the 50W Bassman, and the amp circuit is totally different.

FAFG also claims that the B10 had a sealed back cab. Another error. It's ported.

I can't explain why the FAFG is so wrong on this amp, other than to guess that whoever wrote-up that page didn't actually have experience with the amp and just assumed because of it's name that it was your garden variety Bassman, and as a result, filled-in all of the information on that amp with generic Bassman data. The iron compliment and the circuit are nothing like the real Bassman amps, so I'm not sure why Fender even gave that amp a Bassman derived name. There isn't much that's "Bassman" about it.

I tried contacting the FAFG to have these errors corrected but the page has been wrong long enough that everyone thinks it's right. It's too bad that such wrong information has become sticky.