Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: hesamadman on November 04, 2015, 06:55:54 am

Title: switching SS/Tube Rectification
Post by: hesamadman on November 04, 2015, 06:55:54 am
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.
Title: Re: switching SS/Tube Rectification
Post by: sluckey on November 04, 2015, 07:36:24 am
There are several methods that should work well. I've used this method...
Title: Re: switching SS/Tube Rectification
Post by: hesamadman on November 04, 2015, 10:13:32 am
That's awesome Sluckey. Thanks!
Title: Re: switching SS/Tube Rectification
Post by: Paul1453 on November 04, 2015, 04:29:09 pm
That is a really clean/clear solution sluckey provided.   :worthy1:

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.
Title: Re: switching SS/Tube Rectification
Post by: jjasilli on November 04, 2015, 04:43:41 pm
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!
Title: Re: switching SS/Tube Rectification
Post by: Paul1453 on November 04, 2015, 04:54:57 pm
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?
Title: Re: switching SS/Tube Rectification
Post by: Willabe on November 04, 2015, 05:05:18 pm
The tube can short 2 different ways, 1. open, 2. through.

Read this; 

http://www.premierguitar.com/articles/the-immortal-amplifier-mod-1 (http://www.premierguitar.com/articles/the-immortal-amplifier-mod-1)
Title: Re: switching SS/Tube Rectification
Post by: Paul1453 on November 12, 2015, 12:36:55 pm
The tube can short 2 different ways, 1. open, 2. through.

Read this; 

http://www.premierguitar.com/articles/the-immortal-amplifier-mod-1 (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.   :sad2:
Title: Re: switching SS/Tube Rectification
Post by: Willabe on November 12, 2015, 03:52:53 pm
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. 
Title: Re: switching SS/Tube Rectification
Post by: Colas LeGrippa on November 12, 2015, 04:02:46 pm
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
Title: Re: switching SS/Tube Rectification
Post by: Fresh_Start on November 12, 2015, 10:28:58 pm
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
Title: Re: switching SS/Tube Rectification
Post by: 2deaf on November 12, 2015, 11:20:49 pm
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.