Just take it slow. Worry more for your hearing. 😉

Here's something you don't see, a %THD v. power plot for a pair of MC30s.  The output tubes are new make, matched pairs from JJ (6L6GC), rectifier is also new make JJ 5U4GB.  The small signal tubes (preamp 12AX7, phase inverter 12AU7, voltage amp 12BH7 and driver tube 12AX7) are all vintage.  The amp pair is shown.  Load is 8 Ohm non-inductive power resistor.  Plot shows that both amps produce about 30W RMS with <0.4% THD.   

What photo format do you guys use on this forum? JPG? PNG? HEIC? Zipped file? I can't seem to get my Klipschorn photos uploaded even at 1 MB.

I've been reading an old (1972) book (How To Build Speaker Enclosures by Badmaieff and Davis). A topic that I found to be of interest was how the area of the mouth of an exponential horn determines the lowest frequency that the horn can reproduce. I tried applying the logic to my vintage La Scalas, but the answers I get don't seem to be very satisfactory.    I measured the area of the mouths of:    a) the lens used with the K-77M tweeter (4" x 1.5")    b) the K-400 horn used by the squawker (16.75" x 5.75")    c) the La Scala bass bin (22.25" x 22")   I then used those areas to figure out what the circumference of a circle with the same area would be (i.e., Radius=sqrt(Area/pi) and Circumference = 2pi*Radius). The thinking is that the lowest wavelength the horn can support should match the circumference,   I divided the speed of sound (1125 ft/s) by the wavelength to get the frequency (in Hz).   Here's what I came up with for the lowest frequencies supported by the different horns:    a) lens used with the K-77 tweeter ---> 1555 Hz    b) the K-400 horn used by the squawker ---> 388 Hz    c) the La Scala bass bin ---> 172 Hz   I thought the the K-400 got its name because it was intended for use down to 400 Hz, so the figure for it (i.e., 388 Hz) seems reasonable. However, from what I've read on this forum, I thought that the La Scala bass bin was supposed to be good to about 104 Hz, which is well below the 172 Hz that I calculated.   I'd be grateful if anyone would care to help me understand this better.

I'll see if one of my relatives would like to pick it up.

I’m looking for a grille for my RB5 II, only need o e but if you have two and don’t want to separate I will buy both. Thank you Brian Fogelman  

Thank you JRH, not sure why the pics didin't send but I will try again to attach. They re heavily compressed because 2MB isn't much... Third attempt maybe a zip file

Cost? Location? Am I missing it?

I'll give you $1.86 for it!