DirtyErnie

90% chance: loose speaker, or loose speaker baffle plate. make sure all screws are installed, tight, not stripped. 10% chance: bad driver or bad glue seam on the back of the speaker box.

Big Sugar: Turn The Lights On Better Get Used to It Sleep in Late <-- my alarm clock. Gone for Good <-- Reminds me of The Who, only heavier

If you want low-frequency extension and quality, 'Dare' by Gorillaz goes all the way down. there's an 'E' subharmonic that is in the neighborhood of 20Hz.

I have some well-recorded Acoustic music by Michael Gulezian that has some great transients and clarity. Soundgarden 'Superunknown' album is very well recorded, as is 'Everybody loves a Happy Ending' by Tears for Fears. Daft Punk "Random Access Memories" might be one of the best recorded pop music albums of all time.

Probably not a bad idea, but I had to order some more stuff from Eurotubes anyways. The JJ's do sound great with those voltages. They're not magic like the vintage RCA or Telefunken, but definitely livable for a broke-arse honky like me. 😀

Found pix of my rectifier and bias board. I don't remember what size the 10-turn pots are, but they work well. somewhere between 10K and 50K, I'd guess. the 10uF IC cap is on the screen grid line, which I lowered to ~315v or less by substituting the 1.2K series resistor with a 3.3K. Every 6BQ5 or EL84 datasheet I've seen suggests 24W through an 8K P-P transformer with 400v on the plates and 300v on the screens; screen grid V is the more important of the two.

Raw rectified DC, without the tubes in their sockets. If you put the tubes in, you'll get the ~48v. You're both right. 😉

If they sound great, does it really matter? There are some decent frequency sweep videos on the YouTubes, running those seem a little more practical for in-room checks.

^^^ This first. Electrolytics, selenium rectifier, clean & tension sockets. Don't worry too much about voltages being 'over' as long as the heaters are 7v or less. I'll look up what I did to make the bias voltage variable. I think it was a couple of 10-turn precision resistors, will check the value.

I changed the 1.2K series resistor (screen grid voltage, with the 8K/20w shunt resistor) for 3.3K, lowered my screens to ~315v. The stock ~360v made the JJ EL84 have a 'harsh/busy' kind of sound, now they're smooth.

Mine has a black cable running front-to back by the selenium rectifier. gotta get back to soldering on that one.

There is the notion that an amplifier is a modulated power supply. From that perspective, everything from the power plant to your speakers has an effect.

I think the surface temp limit referenced in most of the spec sheets I've seen is something like 250*C. Capacitors should be at least 85*C. That's a lot hotter than you can handle.

Toy Hauler? aim them out the back and enjoy the closest thing to perfect acoustics.

With? Con: More Gear. Pro: can tune the system and the room to something resembling 'perfection'. Without: The opposite of that ^^^^^^^^^.

8-ohm drivers, should meter out about 6.3 or so. maybe a bit more...

Yup, that would do it. used to play bass for a guy that gigged with one. the bar would let us turn it up to 0.8-1.1. Mesa V-Twin pedal for tone. Apocalyptically loud. 😁

If you were doing it right, they got hit so hard they broke in instantly. 😉

Did you notice both the lows AND the mids cleaned up?

Some of them. Then you get the older-school stuff with naked paper cones and tiny motors. Few things are black-n-white. Most things are closer to 'on a scale of 1-to-10...'

I'll go with 'Yes.' Whether that's due to equipment or ears adjusting is open to debate. I've definitely heard new vacuum tubes 'open up' after a few hours of use. Guitar speakers are quite well known for loosening up after several hours, I don't see why any other cone speaker should be different.

Duke: I hope you meant 16K. 6K upper limit is some pretty bad hearing loss. After all the rock-n-roll and firearms I'm still good to around 14K in my mid 40's.

The RCA tubes are both made by RCA in the US. Tube ID in the elongated octagon was RCA's mark. GE did the multi-line text with the dots after it.

If its ABS, Actone will melt it back together, and flow down into the cracks to seal that back up.

Get the titanium diaphragms for all three and then they'll match. 😉