After agonizing over parts and biasing and countless PSU simulations I am enjoying sweet success with my new SE 5687/EL34 amp. Diana Krall is crooning in my ear as we speak and she is sounding quite lovely. I can also say that the Magnequest transformers (TFA-204s) are proving to be every bit as good as their reputation alleges. I will post pics and schematics as soon as I can tear myself from my listening position long enough. Cheers.
Hey-Hey!!!,
Choke input, instead of a Pi-symbol looking arrangement of a capacitor, choke and capacitor, the choke is directly connected to the rectifier's cathode(s).
Requires a minimum curent drawn to operate properly, and this is dependant on input voltage and the choke's inductance.
The output voltage is about .9 times the RMS input voltage and less the resistive losses in the copper coil and drop across the diodes if tubes are used.
Benefits are a constant load on the power transformer, as the choke passes DC and presents an impedance to AC. Since the Harmonic content of a half of a Sine wave has a DC content of magnitude ~90% of the RMS value, this is what the choke seeks to output. The resulting AC component is at 120 cps and is also a sine wave. Sine waves are fairly easy to filter out with energy storage devices like capacitors ( and Inductors for that matter...).
Anyway, there are many details that I went over with only a bare mention, look to follow-ups and ask more questions.
regards,
Douglas
Choke input, instead of a Pi-symbol looking arrangement of a capacitor, choke and capacitor, the choke is directly connected to the rectifier's cathode(s).
Requires a minimum curent drawn to operate properly, and this is dependant on input voltage and the choke's inductance.
The output voltage is about .9 times the RMS input voltage and less the resistive losses in the copper coil and drop across the diodes if tubes are used.
Benefits are a constant load on the power transformer, as the choke passes DC and presents an impedance to AC. Since the Harmonic content of a half of a Sine wave has a DC content of magnitude ~90% of the RMS value, this is what the choke seeks to output. The resulting AC component is at 120 cps and is also a sine wave. Sine waves are fairly easy to filter out with energy storage devices like capacitors ( and Inductors for that matter...).
Anyway, there are many details that I went over with only a bare mention, look to follow-ups and ask more questions.
regards,
Douglas
arnoldc said:hi g, is this PP, SEP, or UL? PPP? can i pull you out of your listening chair?
btw, you remind me of holy man
I apologize. THe sound and the alcohol prevented any further transmissions. It is a SE EL34 amp using a 5687 as the driver. It is triode strapped using no feedback. The output transformers are Magnequest TFA-204s. The rectifier is a GZ34. I will draw up an "as built" schematic with the part numbers listed. I'll even try for a pic or two but I may have to have someone host the images as I don't think I can get it to upload to the site due to the resolution. As far as being Holy goes I'm afraid you have the wrong guy. I have been accused of much worse though. So thanks. I think.
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