this is my friend Tubalu's 805 SE amplifier .25kg each
An externally hosted image should be here but it was not working when we last tested it.
I hope Tubalu has no children (human or pets) in the same home. Those are what I classify as "electric chair amplifiers". 805's really need to be inside a protective housing.
It looks like they are running with about 20 mA too much plate current.
805's sound very good in SET. I have an 805 SET amp myself and absolutely love it. It sits on the floor between my speakers. The 805's are safely enclosed and I have children (cats).
It looks like they are running with about 20 mA too much plate current.
805's sound very good in SET. I have an 805 SET amp myself and absolutely love it. It sits on the floor between my speakers. The 805's are safely enclosed and I have children (cats).
astouffer said:
Your valid concern has already been presented Stouffer. See post #2.
I observed the same plate color as visible in the picture presented above which I though excessive when Chinese 805's are placed in my amp with the same bias setting that the good old North American stock 805's like RCA and Westinghouse operate without color while proviiding full power. It may just be that these Chinese repro tubes need to rev faster to develop rated horsepower.
This amplifier is being debugged, I am experimenting two kind of different parameters
I think it is photographic prolonged exposure results ,Indeed, the plate is not red .
Finally, my 805 tube work in 850V plate voltage and plate current is 100mA, Shuguanag products are used, the quality has been very good , In addition, improved version of the 805A I am also prepared to try!
I think it is photographic prolonged exposure results ,Indeed, the plate is not red .
Finally, my 805 tube work in 850V plate voltage and plate current is 100mA, Shuguanag products are used, the quality has been very good , In addition, improved version of the 805A I am also prepared to try!
tubalu,
You certainly are not overheating 805's with only 85 watts PD. Yes, it must be a photohgraphic effect we see.
I have had good luck with my limited experience with Shuguang tubes. The 805's I tried that got a bit red were Shuguang and they sounded good. I have no need to purchase any other 805's as I am fortunate to have 6 pairs of old stock American type 805's (i.e. RCA, Westinghouse, GE) as ready spares.
It is up to you to provide a safe environment in your home. All I can do is urge you to reconsider the safety hazard that an open transmiting tube can pose in a home environment. That large, very hot tube could explode if water dripped on it, or burn someone, or electrocute anyone touching tube cap. Accidents happen and in this case can be prevented. Death is permanent.
You certainly are not overheating 805's with only 85 watts PD. Yes, it must be a photohgraphic effect we see.
I have had good luck with my limited experience with Shuguang tubes. The 805's I tried that got a bit red were Shuguang and they sounded good. I have no need to purchase any other 805's as I am fortunate to have 6 pairs of old stock American type 805's (i.e. RCA, Westinghouse, GE) as ready spares.
It is up to you to provide a safe environment in your home. All I can do is urge you to reconsider the safety hazard that an open transmiting tube can pose in a home environment. That large, very hot tube could explode if water dripped on it, or burn someone, or electrocute anyone touching tube cap. Accidents happen and in this case can be prevented. Death is permanent.
In addition, I would like to tell you £º
The 805 that china produced is good than the other imports£¨Including RCA, Westinghouse, GE£©, is unique in the world. It is the security of the guaranteed .
Shuguang tube's manual said: the 805 tube is made of graphite and it's plate do not allow to send the red light.
This is a common sense!
rgds
tubalu
The 805 that china produced is good than the other imports£¨Including RCA, Westinghouse, GE£©, is unique in the world. It is the security of the guaranteed .
Shuguang tube's manual said: the 805 tube is made of graphite and it's plate do not allow to send the red light.
This is a common sense!
rgds
tubalu
The Chinese 805 has a different characteristic and it's plate mustn't be a bit red according to the datasheet.
Moreover,the chinese 805 has a good linearity at 75W-85W P.D.
In 1970s,China improvemented the 805 which has a better characteristic than American types.It can be driven more easily,thus reduce the T.H.D largely.
Moreover,the chinese 805 has a good linearity at 75W-85W P.D.
In 1970s,China improvemented the 805 which has a better characteristic than American types.It can be driven more easily,thus reduce the T.H.D largely.
ttan98 said:
The original 805 design (1930's RCA?) is a carbon plate triode with a continuous PD of 120 watts and a max VP of 1500 volts. It has a plate cap on top. These tubes can make 40-45 watts RMS with 1050 volts on the plate in SE and sound very good. The 845 can only make half this amount of power from a single tube. I have not heard an 845 or 211 so I cannot comment on comparative sound quality, and so much of that will depend on operating point and quality of the output xfmer employed.
the datasheets, i've found at frank's....display anode voltage vs. GRID current in Ma....
maybe that explains the very high voltage....and, ofcourse, it was a transmitting tube, so it will be in the ballpark of 800-1000v indeed (max. 1500v dc...)...
could someone point met to a Va-ia sheet???
maybe that explains the very high voltage....and, ofcourse, it was a transmitting tube, so it will be in the ballpark of 800-1000v indeed (max. 1500v dc...)...
could someone point met to a Va-ia sheet???
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