GU50 SE vs 300B SE tube amp??

[matejsirk]

One of my version:

power more than 10W with THD around 3% (LTspice sim)

 

[costis_n]

In any case, I would keep the trashcan, it reduces microphonics a lot (not that a GU50 is as microphonic as an EL34). Just get the soviet-made ones.

 

[multi]

Were is the best place to get the Russian, GU50? All the sites I have tried don't have them.
FU 50 are easy to find. Are the Chinese ones OK?
Phil

 

[costis_n]

Really? They are all over ebay? Look for big Ukrainian e-stores, too. Also, sites like sovtube.com.

On the other hand, I rarely see any FU-50 for sale...

 

[multi]

Costis;
THANKS.
I tried Sovtube, out of stock, but good price.
I have GU 50's on Ebay,world wide search, so far all that has come up is Polish, sockets and one GU 50 in 3 months.
Maybe I need to try a different search terms or Maybe Should search Russia & Ukraine, not world wide.
Phil

 

[DrRoyal]

ebay from Russia

Regards

 

[andyjevans]

Has anyone considered using the 813 instead of the GU50? Good tube and not expensive. Rod - did you ever look at those curves?

 

[Rod Coleman]

Some triode curves 813 published here earlier. They are better than IDHT curves: far less compression at high voltage - which is the big advantage of DHTs.

http://www.diyaudio.com/forums/tubes-valves/128516-813-trioded-datasheet-curves.html#post1591957

The Chinese FU-13 is the recent equivalent, but I would Prefer the Russian GU-13

http://hamradio.online.ru/ftp/gu-13.pdf

But other transmitters, like 211 are probably even better.

 

[artosalo]

I have made some tests with GU-13. My opt was 5k Hammond 1628SEA.
Once again the UL-connection was better than triode. The THD was lower and output impedance almost as low as with triode. I don't have my memos available now, but some 20...25 W is available below 3 % THD with 700 V +Ub.

 

[Globulator]

SRPP not the best schematic for driver GU50 or 300B.

Why do you say that? I tried many topologies for that driver and that was by far the best sounding - so ironically it _was_ 'the best schematic for driver GU50'.

BTW it's an SRPP+(tubelab) now, not an SRPP.

For a good driver you need something active pulling up for large voltage swing and A2 operation as required. You also need gain, so something active on the bottom too.

That narrows the field down to what most people would mistake as 'the wrong type'.

 

[artosalo]

One of my version:
power more than 10W with THD around 3% (LTspice sim)

One of mine:

Fixed bias and DC-coupled cathode follower to make A2 drive possible, or actually to avoid negative effects of grid current when overdriven.

 

[matejsirk]

Another one:

9W in triode, THD (simulation) 1.5%

 

[Wavebourn]

I found the main problem with the GU50 was buying valve bases that didn't crack the tubes if you turned the chassis on it's side (so the tubes where horizontal). I lost 4 GU50's this way - they just cracked at the base.

Some naked sockets are ok - I have some that work fine, but I think the ebay variety stress the pins radially and the loading change finishes them off.
The official GU50 holders are available and look rather military but are very safe for the tubes.

I painted them in black, and they look sexy.

 

[anilkumarbn]

schematic diagram request

Can you please share schematic diagram. Thank you