|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
63.246.183.22
In Reply to: RE: Standby switch...pros and cons? posted by DAK on August 18, 2016 at 13:52:01
It's not clear why you want to add a standby switch. If the only issue is the surge of current drawn from the AC line, a larger fuse will remedy that. If you're concerned about the surge of current into the filter caps, the standby switch won't help. What is it exactly that you want to fix or prevent?
--------------------------
Buy Chinese. Bury freedom.
Follow Ups:
Yeah, i am worried about the surge on the caps. I thought if the tubes were warmed up there was no high voltage surge when all the tubes were at operating temperature.
Even if the standby switch is located at the transformer CT, it won't solve this problem. The filter caps won't charge until the switch is closed. What Eflow said about solid state supplies is correct. I have several old HKs that use solid state rectification in a high-current voltage doubler configuration. None has experienced a PS failure despite more than 50 years of service.
--------------------------
Buy Chinese. Bury freedom.
In 1968 I purchased a used HK Citation. As you may know few amps ran the output tubes any harder or had higher under chassis temperatures than a Citation II. Seeing the handwriting on the wall for tube availability in 1974 I replaced the output tubes. When I did a McShane rebuild about a dozen years ago, every resistor and capacitor was still original. This amp had literally several thousand on/off cycles. What I think this illustrates is that if one picks the correct parts for the duty and environment where they are used. a solid state rectifier does not place life shorting stress on amplifier parts. That said an inrush current limiter make sense to increase the safety margin for components and allow a smaller power fuse for quicker protection against excessive current draw.
FWIW... most amps I've seen with standby switches, have the SB after the first stage filter cap(s). The rectifier "sees" this first stage, regardless of the position of the SB switch. Therefore, the rectifier still feels a lot of the current rush on cold starts. The first stage many times being the largest mfd section of all the filter stages.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: