tube rectifier Vs solid rectifier

[grtamp]

if you use the same Power trafo and to use two different rectifier type, with which of the two has more output voltage?

Thanks

[ChrisM]

The SS will have a higher output voltage. Diodes drop almost no voltage across them. Tube rectifiers have a significant voltage drop.

[tubeswell]

... and the voltage dropped is different for different rectifier tubes.

SS rectification is a 0.6V drop (from the peak AC voltage swing), and rectifier tubes drop even more volts in this regard - see attached chart

[grtamp]

thanks a lot for the good info

[TheGimp]

Implicit in the voltage drop is the effective resistance of the tube. The higher the voltage drop, the greater the effective resistance, and the softer the output will be. This means you get more sag under load with tubes that exhibit greater voltage drop.

For instance the 5R4 and 5U4 both are rated at the same 250mA load current, however the 5U4 has only 44 volts drop compared to the 5R4 66 volt drop. Under similar transient load conditions, the 5R4 supply will sag more.

[PCollen]

Implicit in the voltage drop is the effective resistance of the tube. The higher the voltage drop, the greater the effective resistance, and the softer the output will be. This means you get more sag under load with tubes that exhibit greater voltage drop.

For instance the 5R4 and 5U4 both are rated at the same 250mA load current, however the 5U4 has only 44 volts drop compared to the 5R4 66 volt drop. Under similar transient load conditions, the 5R4 supply will sag more.

When I blew the GZ34 recto in my JTM (admittedly my own fault), I went with the Weber Copper Cap WZ34 equivalent:

(http://www.webervst.com/ccap.html).

It's solid state, and has a resistor inside as well to emulate the GZ34 tube resistance characteristics. I honestly can not tell the difference between the GZ34 tube and the WZ34. Going on 4 years now with no problems whatsoever.

[dorrisant]

... and the voltage dropped is different for different rectifier tubes.

SS rectification is a 0.6V drop (from the peak AC voltage swing), and rectifier tubes drop even more volts in this regard - see attached chart

I don't see an attached chart. I would love to see it though...

Tony

There it is... Wouldn't show up until after I made this post... sorry about that and thanks for posting it.

[rsi]

Here's the rectified voltages for Magnetic Components PT40-18054 (from the datasheet).

Rectifier Voltage
1N4007 456V
5U4GB 395V
5Y3GT 409V
5AR4 424V

Obviously these would be different for other PTs, but the idea is the same.

[Super_Reverb]

When I blew the GZ34 recto in my JTM (admittedly my own fault), I went with the Weber Copper Cap WZ34 equivalent:


It's solid state, and has a resistor inside as well to emulate the GZ34 tube resistance characteristics. I honestly can not tell the difference between the GZ34 tube and the WZ34. Going on 4 years now with no problems whatsoever.

One thing I have added to recent builds with silicon diode power supplies is a series power resistor between diode cathodes and the first PS capacitor. Typical values for my amps are 47 Ohms for a 50W 2x6550 output or 82 Ohms for my SE 6L6 rig. The way I see it, it does two things: 1) improved filtering because the first (large) filter cap has a larger series resistance from rectifiers, making a more effective LP filter and 2) can tailor sag to final design/power tubes, etc.


cheers,

rob

[Gaz]

You can also add the resistor from center tap to ground to simulate tube recto sag - puts less stress on the resistor that way.

[azatplayer]

So would it be a smaller value to use the centre tap?

[profgoop]

Kind of an old thread but thought it matches what I am looking for. I am building a fender 5c1 clone and my PT doesnt have the 5v filament winding. So, that leads me down the SS rectifier road.

I have never used a SS rectifier. However, instead of using a 5y3 tube it looks like I can use 2 1n4007 diodes. I have seen that some people use a pretty high wattage resistor in series with it. What are your thoughts and any ideas on the best schematic for this?

Thank you so much!!

[rdjones]

Kind of an old thread but thought it matches what I am looking for. I am building a fender 5c1 clone and my PT doesnt have the 5v filament winding. So, that leads me down the SS rectifier road.

I have never used a SS rectifier. However, instead of using a 5y3 tube it looks like I can use 2 1n4007 diodes. I have seen that some people use a pretty high wattage resistor in series with it. What are your thoughts and any ideas on the best schematic for this?

Thank you so much!!

You can use one of the 6V rectifiers that have an indirectly heated cathode.

The octal 6AX5 has very similar ratings as the 5Y3.
There are others with 7pin and 9pin bases that are similarly spec'd.
http://www.nj7p.org/Common/Tube/SQL/Tub ... ype=6AX5GT

Voltage drop is not going to be exactly like a 5Y3 but it would be a whole lot closer than SS.
Either way (SS or tube) you can make up the difference in voltage drop by using an appropriately sized resistor.


reddog