GU50 SE Amplifier class A , with 6SN7 Full construction details

[eeyore]

Reading this thread, it seems that the maximum voltage of the screen on datasheets being 250V and 4W is conservative, and running it at higher voltages, say up to 400V, is okay, as long as the 4W dissipation is observed and respected?

 

[Joshua_G]

can anybody tell me what the output power [w] of a gu 50 in triode is?
bob :thnx for the value of the condensor,this is the condensor ofer r12?? ,did you build this amp?
wich schematic you are using or can you recomend me
kind regards ko

I'm also interested in replies to those questions.

 

[soundbrigade]

Have you seen the triode curves I have somewhere on my site(s)?

Triode curves

 

[TheGimp]

100mA at 400V with a 3500 ohm load looks pretty nice. It looks like what, around 17W to the load? Lots of drive voltage needed though, near 50Vrms.

 

[Arnulf]

100mA at 400V with a 3500 ohm load looks pretty nice. It looks like what, around 17W to the load? Lots of drive voltage needed though, near 50Vrms.

Is this peak power ? RMS should be 10W or less.

 

[Svein_B]

About 10W sounds about right, unless you can drive it into A2.

... or sell in on Ebay from China

Svein.

 

[TheGimp]

Peak, sorry. RMs is less than 12 and that is assuming you drive to 0v g-a which you probably wouldn't do over concerns of A2 operation. G1 is rated for 1W (although no positive grid lines are in the plots), but I expect distortion would go up considerably once G1 current starts to flow.

 

[Joshua_G]

For 12 Watt output in SET, I see no reason to use this tube.

 

[eeyore]

I did some curves at various operating points here. Seems that 350V @100mA @ 5k is a good operating point giving around 11W output power. Need an input swing of 100Vpp, or 35Vrms to limit to A1.

 

[Arnulf]

Can you introduce me to your maths ? What I see is 80 mA peak to peak (28 mA RMS) and 400V peak to peak (141V RMS) swing. How does that equal 10+W RMS out ?

 

[eeyore]

Hmm... At lower end of 0V at grid, 145mA @ 130V, and at the other end of -100V at grid, 65mA @ 530V. The current difference is 80mA and the voltage swing is 400V. P=IR, P=400x0.08 => P=32Wpp => Prms = P / 2 / 1.414 => Prms = 11.3W

Have I got it the wrong way around?

 

[eeyore]

My bad, I did not quite understand P equations is with Vrms and Irms, but now I do! Thanks Arnulf. It should be 3.9W.

 

[Globulator]

For 12 Watt output in SET, I see no reason to use this tube.

The GU50?
Why not?

 

[Joshua_G]

The GU50?
Why not?

Because of there are better tubes for such OP power, like EL156.

 

[Globulator]

Because of there are better tubes for such OP power, like EL156.

Are they really any better though?
Also the EL156 is not very obtainable, but the GU50 is peanuts per truck-load

 

[Joshua_G]

Are they really any better though?
Also the EL156 is not very obtainable, but the GU50 is peanuts per truck-load

There are current production Chinese EL156. I heard this tube and like its' sound very much.

 

[Globulator]

There are current production Chinese EL156. I heard this tube and like its' sound very much.

Ah! I'll have to look out for those, the Chinese really are making everything we should be!! I should move there soon

 

[soundbrigade]

I bought my EL156 for 60 €, while I can get 10 GU50 for that sum.

GU50 is a great tube, though EL156 is slightly more powerful. If more power is needed two or three GU50 can be parallelled.

 

[pre65]

I have just read through this thread, and I would like to try a GU-50 SE amp.

Having tried 832a (P-P), 829b (PSE) and GM-70 (SE) GU-50 seems a good place to go next.

However I am not a "designer" so I am looking to see who has actually built a GU-50 (triode mode) single ended amp and use an existing design as my basis.

Not worried about the PSU as I have an existing PSU that should do, it already powers two other SET amps (300b and PT15) but not at the same time.

 

[fpelleti]

I do that !!!!!!!

work perfekt without any problems ..
best regards
mario

I'd like to build Mario5000, May 2006 diagram but I'm left with a simple remark. The title of this section says "... full construction details". Does anyone has detailed specs for capacitors and resistors voltage and power ratings? These info would be very helpful! Thanks.