Rectifier efficiency?

[tubeswell]

Hey all,

So, somewhere, sometime, I came across a listing of the various efficiencies of different rectifiers (diodes, 5AR4, 5Y3, etc..).

Can anyone point me in the direction of such a chart?

Hiya dehughes

Was this what you were thinkin' about (maybe)?

http://www.guitaramplifierblueprinting. ... fiers.html

[dehughes]

Hey all,

So, somewhere, sometime, I came across a listing of the various efficiencies of different rectifiers (diodes, 5AR4, 5Y3, etc..).

Can anyone point me in the direction of such a chart?

Hiya dehughes

Was this what you were thinkin' about (maybe)?

http://www.guitaramplifierblueprinting. ... fiers.html

tubeswell: Nah, that's what I have saved on my hard drive, but I thought I came across a chart that had the rectification efficiencies of the various tube/ss rectos.

Structo: Thanks for the link. I'll check them out.

dartanion: Thanks for clarifying. So the 1.3 factor takes into account the voltage drop from the tube plus all the miscellaneous losses?

[David Root]

Well yes, but it also depends on how many tubes you are hanging on the power supply and how heavily you bias the power tubes (assuming you're in AB1).

For example, you can bias the power tubes to match the OT's primary impedance by jacking up the cathode current if your initial plate/screen voltages are too high to match the OT's primary impedance. This will take down the plate voltage and all subsequent voltages in the PS chain.
This is generally a good idea unless you will exceed 70% of the plate's maximum dissipation by increasing the cathode current. Again assuming AB1 operation.

If you are separately controlling screen voltage lower, which some power tubes need, this gets to be an issue, and zener diodes clamping screen voltage becomes a good idea.

It can get complicated, but it doesn't have to if you pick the right PT and OT.

[David Root]

Double Post

[M Fowler]

Here what I have in a book. I loaded it into a xcel, then xml and then pdf to get it to load.

Mark

[dehughes]

Here what I have in a book. I loaded it into a xcel, then xml and then pdf to get it to load.

Mark

Mark, that's EXACTLY the info I'm looking for. THANKS SO MUCH!!!!!!!!!!!!!!!!!!!!!

David, I get what you're saying (I think), and my setup is a cathode biased pair of 6V6s that I'd like to run in Class A. I'm thinking I'll stick with a 270v PT for now and see if that gets me close....and I can always play with the cathode resistor if need be.

[dehughes]

Here is my contribution to the world of ampdom. Converted into Excell via iWork '09, so hopefully it will work for all you PC users. It ain't pretty, but then neither are my math skills or my amp work...

[Sonny ReVerb]

Worked fine on my PC. Thanks!

Maybe we could add some other (oddball) types - 5V4, 6X4/6X5, ...

[dehughes]

Worked fine on my PC. Thanks!

Maybe we could add some other (oddball) types - 5V4, 6X4/6X5, ...

Yes! If I knew their figures I'd put them in. Where does one find their "efficiency"? Is it on their data sheets?

[Sonny ReVerb]

Where does one find their "efficiency"? Is it on their data sheets?

It's there, but you have to know where to look. Here's a datasheet for a 5V4-GA.

Toward the bottom, it shows 'DC output voltage at filter input' as 410V and 'Tube voltage drop at 175ma' as 25V.

Voltage prior to the rectifier would be 410+25=435. Assuming 100% efficiency, the transformer would be producing 435/1.4=310 (or 310-0-310). So, the rectifier efficiency under these conditions (175ma load) would be 410/310=1.3.

Does that sound right?

Here's an example for one in the chart to check our math.

[img:610:345]http://img8.imageshack.us/img8/7421/5u4p2.gif[/img]

Looking at the 300ma numbers, voltage prior to the rectifier would be 290+54=344. Assuming 100% efficiency, the transformer would be producing 344/1.4=245 (or 245-0-245). So, the rectifier efficiency would be 344/245=1.18.


Looking at the 275ma numbers, voltage prior to the rectifier would be 460+50=510. Assuming 100% efficiency, the transformer would be producing 510/1.4=364 (or ~360-0-360). So, the rectifier efficiency would be 460/364=1.26.

Our 1.2 number in the chart is right in the ballpark.

[dehughes]

Very cool. I think I get it. Can anyone else verify these figures/methods?

[tonestack]

The voltage drop is already factored in with the 1.3 fudge factor.

Correct!

[tonestack]

Very cool. I think I get it. Can anyone else verify these figures/methods?

Si ~= 1.41 x secondary AC voltage
5AR4 ~= 1.3 x secondary AC voltage
5U4GB ~= 1.2 x secondary AC voltage
5Y3 ~= 1.1 x secondary AC voltage

[dehughes]

Very cool. I think I get it. Can anyone else verify these figures/methods?

Si ~= 1.41 x secondary AC voltage
5AR4 ~= 1.3 x secondary AC voltage
5U4GB ~= 1.2 x secondary AC voltage
5Y3 ~= 1.1 x secondary AC voltage

Nice. What other rectifiers might be handy to add to my spreadsheet?

I'd like to add the following, think:

EZ81
5R4
5V4

Having trouble finding the voltage drop info on the data sheets I have, though...for these three tubes, at least...

[10thTx]

I put together this one some yrs ago and have found it helpful as a starting place to consider designing a build.

With respect, 10thtx