switching SS/Tube Rectification

[hesamadman]

So far, every single amp I have built, I have done a SS rectifier. Im about to do a Fender Deluxe. On my breadboard I would like to have both solid state and tube rectification (switchable). Does anyone have a method they like for the switching? I really need to be able to A/B the difference of these two types of rectification.

[sluckey]

There are several methods that should work well. I've used this method...

[hesamadman]

That's awesome Sluckey. Thanks!

[Paul1453]

That is a really clean/clear solution sluckey provided.   

I might like to try this on my breadboard too, just to see if I can hear any difference.  It would also give you a backup if you blew your tube.

[jjasilli]

Is it possible to put the SS diodes in series with rectifier tube plates, with a SW to bypass the tube? 


If the tube fails by way of an internal short, the diodes will still protect and run the amp.  With the tube in the series circuit, it will still provide its effects of impedance, etc.


EDIT:  Synchronicity!!! this form of diode tube protection is posted in the thread below!

[Paul1453]

If the tube fails by way of an internal short,
EDIT:  Synchronicity!!! this form of diode tube protection is posted in the thread below!

If the tube shorts we're going to have PT issues, and probably a blown PT.  But not if in series, right?

[Willabe]

The tube can short 2 different ways, 1. open, 2. through.

Read this; 

http://www.premierguitar.com/articles/the-immortal-amplifier-mod-1

[Paul1453]

The tube can short 2 different ways, 1. open, 2. through.

Read this; 

http://www.premierguitar.com/articles/the-immortal-amplifier-mod-1

So with sluckey's layout, if we are using the tube and it shorts through we are still looking at a possibly blown PT, right?
Or can we hope that if we have the correct fuse installed (maybe non SLO-Blow is better?), that it will blow before we kill the PT?

Nice PTs are very expensive.   

[Willabe]

So with sluckey's layout, if we are using the tube and it shorts through we are still looking at a possibly blown PT, right?

Yes.

Or can we hope that if we have the correct fuse installed (maybe non SLO-Blow is better?), that it will blow before we kill the PT?

You can hope but........   You can't use a fast blo fuse on the PT primary because the heater current at start up will pop it. 

[Colas LeGrippa]

You should be aware that the ss recto will give you more voltage and will raise the bias of the output tubes. So, if you have biased the tubes with the recto tube at their limit, switching to ss will supply too much voltage to the power tubes thus reducing their life. You chould bias the p tubes with the ss rectifier. Then you'll run safe with the recto tube.

Colas

[Fresh_Start]

You should be aware that the ss recto will give you more voltage and will raise the bias of the output tubes. So, if you have biased the tubes with the recto tube at their limit, switching to ss will supply too much voltage to the power tubes thus reducing their life. You chould bias the p tubes with the ss rectifier. Then you'll run safe with the recto tube.

Colas

This is a good point. Cathode bias might help some by having the tubes self bias for different plate voltages.

Chip

[2deaf]

So with sluckey's layout, if we are using the tube and it shorts through we are still looking at a possibly blown PT, right?

Use sluckey's example AND put diodes at the plates on the rectifier tube.