Are the reasons the same for having a stand by switch with a SS rectifier as it is with a tube rectifier?
Thank You
Stand By. SS rectifier vs Tube rectifier
Moderators: pompeiisneaks, Colossal
Re: Stand By. SS rectifier vs Tube rectifier
A lot of older tube rec'd amps didn't even have an SB switch.
Due to the slow warm up time of the rec tube.
SS rectified makes the switch necessary.
Too much inrush current kills the rest of the tubes in the amp.
Not to mention cathode stripping.
HTH.
Due to the slow warm up time of the rec tube.
SS rectified makes the switch necessary.
Too much inrush current kills the rest of the tubes in the amp.
Not to mention cathode stripping.
HTH.
Re: Stand By. SS rectifier vs Tube rectifier
I guess that is my real question. ^^^^^ I was just reading a post on TAG about where to locate the stand by switch in relation to the first filter cap. The amp in question had a tube rectifier. For some reason I have always thought that a tube rectifier negated the need of a stand by.
My thinking is getting a little convoluted, but how "real" is the problem of "cathode stripping"? When your power tubes fail, or loose strength, how would you know if it was from cathode stripping?
My thinking is getting a little convoluted, but how "real" is the problem of "cathode stripping"? When your power tubes fail, or loose strength, how would you know if it was from cathode stripping?
Re: Stand By. SS rectifier vs Tube rectifier
I'm no expert on cathode stripping, but, from what I've gathered, this issue might be somewhat overblown. It is probably more important to operate the filament at the proper voltage.
If you err on the conservative side, which is the right thing to do, IMO, you'll get a softer start if you put the first filter cap on the hot side of the standby switch. And, since it certainly doesn't hurt anything to build in a standby, you should do it. Also, it doesn't cost much to put that switch in, another reason in favor of doing it.
If you err on the conservative side, which is the right thing to do, IMO, you'll get a softer start if you put the first filter cap on the hot side of the standby switch. And, since it certainly doesn't hurt anything to build in a standby, you should do it. Also, it doesn't cost much to put that switch in, another reason in favor of doing it.
Re: Stand By. SS rectifier vs Tube rectifier
Just to add to what Phil said, some rectifier tubes have directly heated cathodes and others indirectly heated cathode.
The direct heated rectifiers such as a 5U4GB use the heater as the cathode, these heat up quickly and so they can benefit from a standby switch.
The indirectly heated rectifiers such as GZ34 are said to be able to function without a standby switch.
But as mentioned, a switch and wire is cheap insurance that will make the tubes last longer.
When choosing a rectifier be sure to check out the specs as there are different current draws and voltage drops on the various tubes.
Here is some info on rectifier tubes.
http://acruhl.freeshell.org/mga/main/rectifiers.html
The direct heated rectifiers such as a 5U4GB use the heater as the cathode, these heat up quickly and so they can benefit from a standby switch.
The indirectly heated rectifiers such as GZ34 are said to be able to function without a standby switch.
But as mentioned, a switch and wire is cheap insurance that will make the tubes last longer.
When choosing a rectifier be sure to check out the specs as there are different current draws and voltage drops on the various tubes.
Here is some info on rectifier tubes.
http://acruhl.freeshell.org/mga/main/rectifiers.html
Tom
Don't let that smoke out!
Don't let that smoke out!
Re: Stand By. SS rectifier vs Tube rectifier
Once again, thanks for the info. I appreciate it.