Help with these Russian GU50 tube amplifier

[kmtang]

Go Albert go,

Wishing your GU50 SE amp will become the champion of the forthcoming competition. CP just finished his direct coupled 2A3 with paralleled 6SL7 as driver and Lundahl LL1623AM amorphous output transformer. Wanna a match, DING!!!!!

Johnny

 

[albertli]

Go Albert go,

Wishing your GU50 SE amp will become the champion of the forthcoming competition. CP just finished his direct coupled 2A3 with paralleled 6SL7 as driver and Lundahl LL1623AM amorphous output transformer. Wanna a match, DING!!!!!

Johnny

My intention is to learn more and try more on different designs.

 

[Wavebourn]

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An externally hosted image should be here but it was not working when we last tested it.

 

[albertli]

It's a pp ??

 

[Wavebourn]

It's a pp ??

Yes. It is a high-end PP.

 

[TonyTecson]

hi Wavebourn,

do you think the 6LX8 and 6BN11 can work here?

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[Wavebourn]

hi Wavebourn,

do you think the 6LX8 and 6BN11 can work here?

Not directly, some adjustments will be neded. I have unfinished project where I am going to use 6F1P tube.

Here is schematic of previous version.

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[TonyTecson]

so which one do you like better?

changing from differential pentodes(6P15P) to differential triodes(EF184) lowered you open loop gain isn't it?

 

[Wavebourn]

so which one do you like better?

Both.

Previous version had too much gain. Last one needed 10-pin socket for ECF200. I think 6F1P will be right in ballpack.

 

[Junm]

Both.

Previous version had too much gain. Last one needed 10-pin socket for ECF200. I think 6F1P will be right in ballpack.

Hello sir , i'm planning to build your driver for my GU-50 using 6F5P, will this be okay without any adjustment, as far as I remember i had a your schematic of this one using this tube.

 

[Wavebourn]

I am afraid 6F5P wants more current than tubes I use. It may be not as linear as you want on that place.
Use 6F1P, it is better there. And it is dirt cheap, as many other sleepers.

 

[albertli]

You could also try building it MJK-style, but without DC-connection. There is a thread somewhere about it http://www.diyaudio.com/forums/tubes-valves/165221-most-linear-triode-strapped-pentode-7.html#post2204502 . Will probably measure better than the 6E5P but don´t know about sound.

I have the PSU write up for the one with 6e5p, please do give advise. I also have my chassis made up and almost already to cut he top plate if the lay-out is no problem.

 

[Wavebourn]

You need quite powerful Zeners. And if you put hot toobs so close to transformers I would add a mirror behind them, in form of Г

 

[Junm]

I am afraid 6F5P wants more current than tubes I use. It may be not as linear as you want on that place.
Use 6F1P, it is better there. And it is dirt cheap, as many other sleepers.

Sorry my mistake, I'm referring to your tower III hybrid driver which use 6f3p. is it okay to use 6f5p?

 

[Wavebourn]

Sorry my mistake, I'm referring to your tower III hybrid driver which use 6f3p. is it okay to use 6f5p?

They are different tubes, require different bias.

In last Tower I used 6N1P and triode strapped 6P15P. Both loaded on gyrators.

 

[Junm]

They are different tubes, require different bias.

In last Tower I used 6N1P and triode strapped 6P15P. Both loaded on gyrators.

okay thanks...

 

[albertli]

You need quite powerful Zeners. And if you put hot toobs so close to transformers I would add a mirror behind them, in form of Г

Is 5w zeners good enough ??
Is the 200v on my design good to feed 2 locations? - G2 of 6e5p, and the ccs.
I'll leave more room in between the power tube and the OPT. I'll take your advise to put a mirror there too.
Thanks

 

[TonyTecson]

In last Tower I used 6N1P and triode strapped 6P15P. Both loaded on gyrators.

i think i missed your triode strapped 6P15p, can you post links or pics please?

 

[Wavebourn]

i think i missed your triode strapped 6P15p, can you post links or pics please?

I did not post it. I even did not draw it on a napkin.

 

[Wavebourn]

Is 5w zeners good enough ??
Is the 200v on my design good to feed 2 locations? - G2 of 6e5p, and the ccs.
I'll leave more room in between the power tube and the OPT. I'll take your advise to put a mirror there too.

Let's calculate. 250V on Zeners, 200V on 15K resistor. Current is 200/15k. Power dissipated on Zeners = 250 * 200/15 in miliwatts, that means about 3 Watt on all 3 Zeners. But total current is 13 mA. If your tubes draw 13 mA that means Zeners will not work.
I usually start from requirements, how much current should supply your power supply, then decide how to stabilize the voltage.

If say when tubes are cold all current flows through Zeners, it must not be higher that causes 5W dissipation on 100V Zener. That means no more than 50 mA. So, according to current consumption of yout tubes you may now calculate value of resistor, instead of 15K.