Bad tube in home stereo - happy Friday

[Madkrafter]

My morning started with coffee and music. Brew the coffee, start the stereo. I took a sip of coffee, looked at the glowing KT88’s in my PrimaLuna ProLogue Five rig, looked down to hit play in my BlueOS app... and nothing. I look back up and no glow! The PrimaLuna was off. Ok, blown fuse, but why? Disconnect, open up just to make sure there’s nothing strange happening inside (and to look at the beautiful innards). If you guys aren’t familiar with PrimaLuna or home audio tube gear, let me share my audio joy.

Meanwhile, I have to swap tubes and figure out which one is bad. Wish I had a tube tester. I did a quad tube swap a while ago after a bad tube, so I have three known ~good tubes. This may require beer after I get home from work... or, do I begin start up procedures with my new build which I finished last night (Blackface Deluxe Reverb) 

[bmccowan]

That's a nice amp! My audio amps are vintage tube equipment (Fisher and Grommes) that I've restored; and a couple of pre-amps I've built. Since you do not know the cause of the blown fuse - do you have a light bulb limiter, or a variac? If not, either or both would be useful for both the PrimaLuna and your new build. And congrats on finishing building a BFDR.

[Madkrafter]

Well, I put in the three known good tubes and put the Genalex Gold Lions in one by one. It fired up no problem each time. I then put all four Genalex back in and it lit up. Listening to the system, the left channel sounds weak. I’m thinking it may be a preamp tube. It uses two 12AU7 & two 12AX7. That will be another time...

I built my limiter last night and I have a Variac that I added a current meter to. The Blackface is coming alive today!

You can’t beat that old gear. My Reverb feed has old stereo gear in it that I keep an eye on. If anyone is looking for new home audio tube gear, I love my PrimaLuna. They make great stuff. Here’s two pieces that I sold 17 years ago and regret. The Sound Valves is a Dynaco ST70 clone (you can still find the Dynacos). The preamp is an N.E.W. - killer preamp.

[bmccowan]

Not familiar with that preamp. Looked it up - seems similar to a Decware preamp that I fixed after UPS had its way with it. I have a pair of Mark IV Dynaco monoblocks I bought in a Maine pawnshop. They are waiting for me to stop building/fixing guitar amps for a bit. I'll probably sell them after I get them going, as I have too many audio amps. As we all know, you can't have too many guitar amps