• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

russian6c33b

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passes current like a motherflucker, so its good for OTL.

but due to the design slight variances can cause a big bias shift over time, and screw it up.

heavy on the heater..

in se or pp (with output tranny) you need something with low Z and a lot of current handling.

edit: i sure hope you didnt pay $40 USD /ea. thats highway robbery.
 
Well,

There could be pluses and minuses with this tube, although I have never used them.

The bad news is that the life, from my understanding, is around 600 hours. I would guess the seals are the main culprits. But if one were to cool the seals, one might get much longer life.

The good news is the plate resistance is very, very low. This means the high frequency response with a good OPT could extend into the stratosphere.

Wish I could be of more help.
 
Hi

I have used this tube in a SE amp earlier and now use them in an OTL. The SE amp had a transformer with 600 ohm primary, (Tango).

There can be differences in characteristics between tubes as Gm is very high, 40mA/V but it is not a big problem, I dont use matched tubes in my OTL and it is not a problem.

The rumours about life time of 600 or 1000 Hours is due to that this is the guaranteed life time when used in military applications at full data, I have used my OTL with same tubes now several years without any change in bias current or any signs of aging so I would say that lifetime is at least the same or better then for other power tubes.

BTW the lowest price I have seen is 11 USD each...

See more on my homepage http://www2.gol.com/users/tube/tubeamplifiersindex.html

Regards Hans
 
Advice

Hello ,
These valves need a bit of care and attention . Due to the very high gm , it is 'safer' to use these at slightly lower dissipation , about 40-45W . Run them close to dissipation limit and you're looking for trouble ! I found this out the wrong way . Sockets need to be considered carefully , I have found problems with Chinese and Russian ceramic B7a . Use a Johnson or British teflon b7a socket . As 6C33 have a glass base , most of the heat is transferred via the filament pins which can cause problems with the socket contacts , use as thick a cable as possible for the filaments which also acts as a 'heatsink' . 6C33 also get VERY hot , I find it preferable to use the teflon sockets which provide a bit of chassis clearance . To date I have successfully used 6C33 arranged in a stacked parafeed 'SRPP' setup , running conservatively at about 250mA . Driver valves need to be considered carefully , due to the low mu , plenty of grid swing is required . 6SN7/7N7 sounded very flat and dull , something along the lines of 6BL7/5687/2C50/6BX7 is preferred . The good news is that after checking a few weeks ago , the bias in the amp is virtually spot-on what it was when the amp was built a year ago so I would expect these to have a long life . :nod: A hairy-chested valve , not one for the 12AU7 pre-amp building 'boys':att'n:

316a:)
 
Hi,

Is it a headphone amp? the reason I ask is that the output capacitor seems very small so maybe it is assumed that the load impedance is high.

As this circuit only goes in class A the ouput power is very limited, for any useful power for speakers you have to run in class AB which is not possible with this circuit.

Using 200 mA idle current and 2 6C33C I put out 25W in 8 ohm class AB, tubelife is very long and no longterm problems so far.

Regards Hans
 
tubetvr said:
Hi,

Is it a headphone amp? the reason I ask is that the output capacitor seems very small so maybe it is assumed that the load impedance is high.

As this circuit only goes in class A the ouput power is very limited, for any useful power for speakers you have to run in class AB which is not possible with this circuit.

Using 200 mA idle current and 2 6C33C I put out 25W in 8 ohm class AB, tubelife is very long and no longterm problems so far.

Regards Hans

yes i was thinking the same thing

how about this
 

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