 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.37.197.123
In Reply to: Wait a minute Eli..... posted by Vinnie on May 2, 2007 at 03:47:49:
Vince,Your talking apples and oranges. What you did during breadboard checkout is not the situation in a working amp. Think about what happens at turn on in the real world. A surge of current occurs into ALL the cold filaments. However, no current flows in the rectifier winding. After 30+ seconds, the 6AU4s will SLOWLY start to conduct. You can bank on the signal tubes being fully warm and ready to conduct, by then. So, neither a voltage spike in the PSU filter, nor a current spike in the rectifier trafo will occur.
Eli D.
Follow Ups:
Need some clarification Eli.. are you talkiing about with everything on one switch where it all gets turned on at once? I was planning on having a filament switch and a plate switch. In that case would I have the power tranny and the 6au4 filament tranny on the plate switch?
Vinnie, you don't need two switches for power-on. The slow warmup of the 6AU4s eliminates the need to do that. What Eli said is correct - just throw the main switch. Power-down is a different matter. If you have a really long time constant in the HV bleed-down, you might want to keep the 845 filaments on for a few seconds after the HV supply is turned off. I'm not certain myself that this is necessary, but some people say it prolongs tube life.
It depends on the size of your reservoir capacitors. At some point I used two of those 550uF 385V JJ cans in a linestage and it took several minutes for voltage to drop appreciably, probably stressing the cathodes a lot more than a cold start. That was several "generations" of linestage ago, but with smaller caps it should be OK. A bleeder resistor is your best bet, one of those nice chassis-bolting aluminum power deals at Mouser probably. I forget how to calculate wattage, resistance and time to find a value but many people here can.
| ||||||||||||
| ||||||||||||
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
