Whats on your turntable tonight?

@mammothguy54 

Yep Joel, what I was thinking too, but, the two NOS Brimar 12au7’s were matched from Upscale. So I have a good feeling they were sold as a good matched pair.

As I understand, a preamp typically isn’t as sensitive to matching or bias as an amp would be. Thus, unless there is a catastrophic failure, or an extreme mismatch, as far as I know, there should not be a significant difference.  

Curious.

Hey Brian,

Are you able to take any measurements of the 12AU7 tubes or check cartridge azimuth?  

Weird it didn't follow channels though...

@boxer12 

Tim, I have no equipment to measure tubes. Thought about azimuth, but again, after swapping the two 12au7’s, everything seems to back to ‘normal’. Haven’t checked in a while though, so could not hurt regardless.

I wonder if the Hagerman has some type of self-biasing circuitry and just flipping them allowed to be ‘readjusted’. I dunno.

Could be self biasing, but then again you would think both channels would have it.