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.
Very nice to hear. I still remember the first time I got my amp up and running. The sweetest sound imaginable gently flowed from my speakers. There truly is something very special about tubes.
The longer it plays the better it gets!! I am a believer of a choke in the PSU now. The difference is readily apparent. The EL34 sounds nice in SE triode mode. Very punchy and smooth. It purrs!!!!
G.,
It can get better. Try a choke I/P filter some time. Reasonably tight regulation with little fuss.
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
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 😀
btw, you remind me of holy man 😀
arnoldc said:
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.
Mikael Abdellah said:
Thanks Mikael. I use demo version of a program called ISIS by Labcenter Electronics. It has served me well. How do you like the sound of the 6N1P? It has a lot in common with the 5687.
I don't have anything to compare my 6N1P too, but I do love my amp. My previous amp was an old DENON receiver so I guess anything would be better than that.
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