Magnavox SVT Tubes

bassboysam · #1 01-24-2012, 07:08 PM

My SVT is in the shop, screen resistors blew, tubes and some caps need replacing so I have been doing some research. I'm pretty sure my amp is from between 1978-1980. As far as I can tell the pre (top half)consists of:
1 x 6C4
3 x 12DW7
1 x 12AX7

On the bottom half there seems to be a 12DW7 between the two 12BH7 driver tubes. This seems wrong to me, should the 12DW7 PI actually be in the pre and the 12AX7 be the phase inverter?

coreyfyfe · #2 01-24-2012, 07:29 PM

Nope that's how it should be. The 12ax7 is either for channel 2 or the mid range circuit. 12dw7 splits to the two 12bh7 drivers.

bassboysam · #3 01-24-2012, 07:31 PM

Since the 12DW7 is half AX7 and half AU7 does that mean each 12BH7 gets a different "feed"?

coreyfyfe · #4 01-24-2012, 07:45 PM

No the two halves have different functions. IIRC the first half amplifies the signal from the preamp and the second half splits the signal to the 12BH7s.

bassboysam · #5 01-24-2012, 07:49 PM

Good to know, thanks!

**B-string** · #6 01-24-2012, 07:56 PM

Quote:

Originally Posted by coreyfyfe

No the two halves have different functions. IIRC the first half amplifies the signal from the preamp and the second half splits the signal to the 12BH7s.

This correct the "AU7" half is the phase splitter.