OK to run a 5V4GA recto in a 6G9 Tremolux?

[Randall]

The 6G9 Tremolux takes a 5AR4/GZ34 recitfier. The PT in this one is over 20% hot, and the customer wants to try a 5V4GA that he has to see if it drops the B+ and gives the amp a bit of a less stiff feel. The filament draws are the same, so the PT should not care, and the other parameters are lesser for the 5V4GA. Question is, this is only two EL84s and three 12AX7s, so my gut feeling is it wouldn't hurt anything to try it and see how he likes it, would it? I don't have any experience with this tube.

Oh, and will run it at 115v.

[nosaj]

The 6G9 Tremolux takes a 5AR4/GZ34 recitfier. The PT in this one is over 20% hot, and the customer wants to try a 5V4GA that he has to see if it drops the B+ and gives the amp a bit of a less stiff feel. The filament draws are the same, so the PT should not care, and the other parameters are lesser for the 5V4GA. Question is, this is only two EL84s and three 12AX7s, so my gut feeling is it wouldn't hurt anything to try it and see how he likes it, would it? I don't have any experience with this tube.

Oh, and will run it at 115v.

Here's a cheat sheet, i think it will be fine.PS Tube Data cheat sheet.pdf
nosaj

[Chuck H]

I typically use a 5v4 when I want to INCREASE voltage. Not the right tube for this. The 5ar4 doesn't drop a lot of voltage but the 5v4 will drop less. I might just add a sag resistor or try a 5u4. I think a 5y3 would be ok in this circuit too, but you'll need to be sure it's a proper 5y3 as some Rusky models apparently act more like 5v4's.

[The Dude]

For reference:

[Helmholtz]

For reference:

[ATTACH=CONFIG]51854[/ATTACH]

Are the DCV drops in this table specified all at the same current?

[eschertron]

Are the DCV drops in this table specified all at the same current?

Good catch! I would suspect the voltage drops to be measured at the nominal max current. Which for the 5AR4 and the 5R4G, happen to be the same. Not so for some others.

[Justin Thomas]

The voltage drops for rectifiers on the data sheets are secified assuming the tubes are used at close to or at max current. Since not many amps are using our rectumfriers that harshly, the voltage drops we get are usually less...

Justin

[Randall]

"I typically use a 5v4 when I want to INCREASE voltage. Not the right tube for this. The 5ar4 doesn't drop a lot of voltage but the 5v4 will drop less."

I don't understand. According to the chart 5AR4 drops 10 volts, the 5V4GA drops 25 volts?

[Chuck H]

"I typically use a 5v4 when I want to INCREASE voltage. Not the right tube for this. The 5ar4 doesn't drop a lot of voltage but the 5v4 will drop less."

I don't understand. According to the chart 5AR4 drops 10 volts, the 5V4GA drops 25 volts?

And according to the chart that Jason linked the 5ar4 drops 30V and the 5v4 drops 25V. You can check charts all day until you find the figure you like apparently At least some of the voltage drop from the rectifier tube is due to it, uh, rectifying. Forward voltage drop due to internal spacing, etc. That's one reason why resistors don't accurately emulate tube rectification. IIRC there are other factors too, but I can't remember what now. The point is that the rectifier tube drops what it drops with some being due to current and the tubes internal resistance, but that's not the whole picture.

[g1]

Oh.
Well, better throw this one into the mix then. Says 17V for the 5AR4 and 25V for the 5V4.

[nosaj]

Oh.
Well, better throw this one into the mix then. Says 17V for the 5AR4 and 25V for the 5V4.

Electrically speaking I think he's fine to try those choices but I wouldn't try the 5u4. Try them and see what he likes.
nosaj

[Randall]

The 5V4GA provided 6 volts B+ less than the 5AR4, so results ended up being insignificant in this amp.

[pdf64]

What’s the heater and mains voltages?
I’m wondering whether the root cause of the excessive HT may be a higher than intended mains voltage. In which case a bucker may be s much better way forward.

[Chuck H]

Try a 5y3.

[Justin Thomas]

Or a 5R4. I chose a 5R4WGB in my last build because the AC was a little too high (as well as I could figure) for a 5Y3. But both listed the same voltage drop.

Justin