first thanks for the input on Ralphs amp, speakers likely the dead ESL-63 I mentioned in another post. I am away from them but I am assuming with ago all the panels are toast, the limited fault tree look I have done so far indicates EHT power supply issues. I am away from them so do not know on panel color, will check that when home next. Thanks all for inputs on rebuilders.
The fault tree should have the panels at the top and EHT at the bottom.
The EHT power supplies are usually NOT the problem in the 63's. The problem is dried out contact cement. All the panels fail over time and temperature cycling is their worst enemy. My friends died in a hot room one summer day. There are many videos on YouTube that show how the glue lets loose and how to rebuild them. Its not for the faint of heart. It is indeed sad that the 57 panels last forever and the 63 panels have a very limited lifetime due to.... GLUE!
I am away from my toolbox also but I will get DMM peak voltages measured today, SPL at 1 M
fun, real data will set you free was our mantra at work for 30 years..
As I listened to the modified and unmodified OTLs the other day on the 57s (that story is told in an earlier post of 11/26), I had the 57 terminals hooked up to the scope. I was constantly monitoring voltage. Music is fun to watch and anyone can get a good scope on eBay for under $100 and learn to use it if nothing else to look at music, look for oscillations, look for offset drift Its really not hard, really. I suppose I sould make a video.
I could see certain things the amps were doing. It takes a lot of experience to see and hear music and correlate, but indeed I could see current clipping and hear the mud is produced. I could see bass peaks due to low damping (that took a oscillator or sweep CD). I could hear that the low damping amp produced a boomy one note bass while the one with 4x the damping produced actual bass tones.
Years ago in the Stereophile "As we see it" column the writer asked several people what they listen for. His daughter said she listens to the "beat". Someone else the tonality, someone else the separation of instruments, someone else the soundstage, yada yada yada.
I think this is important for listeners to think about what they listen for when they judge a system. If his daughter puts on a recording where she likes the beat it might not reveal any of the other things. But she just wants the system that gives her the "beat"
I particularly wanted to hear high level high frequencies where the low impedance of the 57 would tax the amplifier. If I had Miles Davis I would have used him, but I dont have Miles. I do have Bach organ works with trumpet enchmade. Thats even toughter. https://en.wikipedia.org/wiki/En_chamade
I could see and hear the current clipping. More hear than see. But I also knew I was in the 3% and over distortion area of the amp and 12 dB of simple feedback made a big difference in the clairty of this organ stop. I had a brief experience of being mentored by an old German organ builder so I knew and was facinated how organs worked. This music was chosen precisely to provide an audible test. It was done with levels matched by pink noise and immediage A/B switching.
BTW the 57 has a dc resistance of 0.5 ohms. If an amp has even 50 mV of offset that is 100 mA of output current which is also similar to the bias of most SS amps so at idle either the top or bottom transistors are turned off. This is not good for the speaker or amp. The 57 was meant to be driven by an amp with an output transformer where there is never any offset.
This is the stuff I think people should know that is never talked about. If you doubt me go measure it for yourself.