6AN8 question

[gui_tarzan]

The Pioneer stereo I just finished freshening up has something I haven't seen before and the owner just asked me what their purpose actually is. They are in the circuit between the 12AX7s and the 7189s, but each side of the output on the 6AN8s goes to one 7189 on each channel, sort of like a split signal something or other. Does that have something to do with phase canceling or stereo separation? Schem attached.

[g1]

but each side of the output on the 6AN8s goes to one 7189 on each channel, sort of like a split signal something or other.

I'm not seeing that, the only thing in common are the power supply connections. Can you specify component designations?

[gui_tarzan]

Oh never mind, I was looking at the B+.

[g1]

I do prefer when they keep the positive supply "up top" so to speak. Down below just doesn't seem right.

[R.G.]

The 6AN8 is a combo pentode/triode in a single glass envelope. It's often set up exactly like this, with the pentode providing voltage gain and the triode being a phase splitter for the entire front end of a power amp. This is the setup that was used in most of the low power Dynacos, although I believe the Dynas used a different pentode/triode tube. Same function.

[gui_tarzan]

That's what I thought, R.G., I just wanted to make sure. Thanks.

[Jack Hester]

The 6AN8 is a combo pentode/triode in a single glass envelope. It's often set up exactly like this, with the pentode providing voltage gain and the triode being a phase splitter for the entire front end of a power amp. This is the setup that was used in most of the low power Dynacos, although I believe the Dynas used a different pentode/triode tube. Same function.

Both my Oliver PA-100X and G-300 use a 6AN8 for this purpose.

Jack