# Hybrid tube rectifier question

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#### indaco

I'm tryning to make out the right design of a hybrid bridge rectifier, according to the old formulas where there is a R(lim) before the diodes. The tube is 5V4-GA e the other specs are in the photo. In particular, is it useful for the tue life to limit current when the C(out) is rather low , as 22uF?

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#### kodabmx

What is the voltage of the secondary?

Your drawing looks fine. Depending on the voltage of the secondary, you might need to add resistors in series with the secondaries (between coil and bridge).

#### Brice

That's interesting. What is the advantage of doing so?

#### Osvaldo de Banfield

With those values of trafo resistance and the low cap value, these resistor is unnecessary.

#### kodabmx

I see now that the voltage is written on the drawing and I'm just blind. It'll work as is.

#### indaco

I see now that the voltage is written on the drawing and I'm just blind. It'll work as is.

Ok, perfect. Just to know, it's an old and quite big transformer but well built..

#### Eli Duttman

That's interesting. What is the advantage of doing so?

Good, bad, or indifferent the hybrid bridge's character is dominated by the vacuum rectifier. Pluses to the arrangement include PIV limit avoidance and (most significantly) no double forward drop penalty.

#### 6A3sUMMER

Advantage of two solid state rectifiers and one tube in a bridge rectifier circuit:

For a hybrid solid state plus tube bridge rectifier . . .
You only need one 5V filament winding.

You would need three (3) individual independent 5V filament windings, for a three (3) tube (all tubes) bridge rectifier.

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#### TonyTecson

I'm tryning to make out the right design of a hybrid bridge rectifier, according to the old formulas where there is a R(lim) before the diodes. The tube is 5V4-GA e the other specs are in the photo. In particular, is it useful for the tue life to limit current when the C(out) is rather low , as 22uF?

https://frank.pocnet.net/sheets/127/5/5V4G.pdf

the datasheet says total effective plate supply, meaning the secondary resistance is 65 ohms per plate...

if you want longer tube life, this is what to observe...
and if you notice, 4 or 8 ufd is recommended...

if you are using chokes, you can go high capacitance after the choke...

#### indaco

https://frank.pocnet.net/sheets/127/5/5V4G.pdf

the datasheet says total effective plate supply, meaning the secondary resistance is 65 ohms per plate...

if you want longer tube life, this is what to observe...
and if you notice, 4 or 8 ufd is recommended...

if you are using chokes, you can go high capacitance after the choke...

Thanks Tony. Indeed I'm going to use a Pi filter CRCRC as I mentioned but if I have room inside the amp I can consider a choke, maybe a better solution

#### TonyTecson

if your primary voltage is 240 and your secondary voltage is 155, then you have a turns ratio of 240/155 or 1.54,

now the total impedance looking from the 5v4 plate is 15 x 2.37 + 22 ohms or 57.5 ohms, close, but you can do better with a 47 ohm series resistor...

many diyers look beyond this, they can get away with none anyway, but as a matter of good practice, i would say this is a good thing...

#### TonyTecson

Thanks Tony. Indeed I'm going to use a Pi filter CRCRC as I mentioned but if I have room inside the amp I can consider a choke, maybe a better solution

a choke is always a good solution...

CRCRC is also a good solution, each RC stage is -6db of ripple attenuation, but downside to this is you may not have enough high voltage legroom, thus a choke..

you can have say 4ufd at the 5v4 filament, then as high as 470ufd after the choke, i do this all the time..

remember than ripple voltage is a function of load current and inversely the value of the filter capacitor...

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#### appme

I'm tryning to make out the right design of a hybrid bridge rectifier, according to the old formulas where there is a R(lim) before the diodes. The tube is 5V4-GA e the other specs are in the photo. In particular, is it useful for the tue life to limit current when the C(out) is rather low , as 22uF?

Hi Indaco!
I recommend it with the diodes in parallel with 1-1 10nF to tie a capacitor. On a domestic forum pave for this recommendation, his amplifier hummed with the hybrid nutriment because somebody did not succeed.
He has to work if somebody does the hybrid one well.
Good luck!

#### indaco

Hi Indaco!
I recommend it with the diodes in parallel with 1-1 10nF to tie a capacitor. On a domestic forum pave for this recommendation, his amplifier hummed with the hybrid nutriment because somebody did not succeed.
He has to work if somebody does the hybrid one well.
Good luck!

Yes, I heard about bypassing the diode bridge with small ceramic caps and it could be a good hint from you...Besides, it's the first time I'm opting for a hybrid rectifier and I'd like simply to experiment if it affects the sound somehow or not. Otherwise I'm fine with SS rectification that I happily used until now.

#### appme

Thank you for your answer. His what kind of strengthening power-supply unit will he be?

#### indaco

Thank you for your answer. His what kind of strengthening power-supply unit will he be?

It's for an OTL headphone amp, based on the 6H13S with an overall wattage about 25W

#### appme

It's for an OTL headphone amp, based on the 6H13S with an overall wattage about 25W

I wait for the result!

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