Fender Bassman 300 Pro Schematic Confusion

[theiceyman]

Hey guys --

I was looking over the schematic that I received with my Fender Bassman 300 pro.

The drawing number on the bottom is 0057736000.. it's a rev A.. and it says it was plotted 05-Nov-01.

Very clearly on sheet 1 of 4 it shows four 12AX7A tubes in the input section, and very clearly on sheet 3 of 4 it shows two more 12AX7A tubes and two 12AT7 tubes in the output section (in addition to the six 6550C tubes).

This is a total of 14 tubes... however the users manual and every other source (including some old fashioned counting) suggests that there are actually only 3 12AX7A tubes and 1 12AT7 tube.

Is my schematic out of date ? Is there a newer version?

Is it possible that some of the tubes shown in the schematic are actually not populated in the real design? And if so, does anyone know which ones? Are there other changes in the actual design not shown on the schematic?

Thanks for any help.

[johnk_10]

AFAIK there is only one incarnation of the 300 pro. every one that i've serviced/repaired had a total of 10 tubes (6-6650s, 3 12AX7's and 1-12AT7). sounds like you're getting confused by the schematic since it shows the preamp tubes as each half of the tube. for example, V1 shows V1a and V1b.

[theiceyman]

John,

What a silly mistake on my part.

Thanks for the clarification... I guess that's what happens when you let embedded design engineers read schematics with tubes on them