^^ Nice! Make sure you fuse the cathodes. That tube can fail with hard shorts that can fry a speaker in an instant.
thanks, i have made provisions for that....
my main concern is that i only have 6 pcs of 6336 for matching,
not enough tubes to go by....
btw, i am sticking to the output capacitors,
with provisions for taking it out of circuit as option...
i am also making a speaker matching, 64/32 ohms to 8 ohms speakers....
Hi,
Used to have some 50 of these 6336 (A) and could not match any.
Do you put the two triodes per valve in parallel ?
Cheers, 😉
Used to have some 50 of these 6336 (A) and could not match any.
Do you put the two triodes per valve in parallel ?
Cheers, 😉
Sort of- you have to provide some current limiting to prevent current hogging. A cathode resistor does the trick. And a cathode fuse!
yes, individual cathodes with resistors and a fuse...btw, i now have 8 tubes and looking to get more...i have 3 6528's and also looking for more...
You will have to tell us what you were expecting to hear and what really are the differences when you get a chance to compare yours and the original
Looks good!
Regards
David
Looks good!
Regards
David
i am not even sure if this will work to my satisfaction....
originally i wanted to do a pp 6336 amp, but then i thought, less two opt's...
why not?....will keep you posted....
originally i wanted to do a pp 6336 amp, but then i thought, less two opt's...
why not?....will keep you posted....
Driver tube choice
And what about the EF184?
This was the driver tube of choice in the Graaf GM20 OTL which also makes use of 6C33 tubes. Used there in triode mode connected and not as a pentode.
Compared to the EF86 it has more gain and can deliver more anode current although much much lower than your recommended 6AQ5. But on the other hand amplification factor of the 6AQ5 is quite low compared to EF86/EF184. Isn't that not a disadvantage in order to reach enough output voltage swing on the grids of the 6C33 or doesn't that matter?
Your opinion?
Thank you very much
And what about the EF184?
This was the driver tube of choice in the Graaf GM20 OTL which also makes use of 6C33 tubes. Used there in triode mode connected and not as a pentode.
Compared to the EF86 it has more gain and can deliver more anode current although much much lower than your recommended 6AQ5. But on the other hand amplification factor of the 6AQ5 is quite low compared to EF86/EF184. Isn't that not a disadvantage in order to reach enough output voltage swing on the grids of the 6C33 or doesn't that matter?
Your opinion?
Thank you very much
Burn in
Ok and thanks for the tip.
So if B+ has already been applied once to the tube for instance for a short functional test does it make then no sense to do this?
And do all other connections i.e. anode, grid and cathode of the 6C33 need to remain open respectively not connected during this time frame?
Thank you very much.
Ok and thanks for the tip.
So if B+ has already been applied once to the tube for instance for a short functional test does it make then no sense to do this?
And do all other connections i.e. anode, grid and cathode of the 6C33 need to remain open respectively not connected during this time frame?
Thank you very much.
The difference of mu of the tube isn't going to affect things much. However, if the power tube arcs it can damage its driver tube and the 6AQ5 is common and inexpensive and also is far more likely to survive the arcing event.
If B+ gets applied the preconditioning is over. In preconditioning jigs the other elements of the tube are traditionally tied to one side of the filament circuit.
i am looking at 12by7, 12hg7, 12gn7, 12hl7
and the other video pentodes....
the thing with drivers is the plate ratings,
a pentode that can do 300 volts plate
as voltage amplifier is it imho....
the russian 6P15P is also cheap...
and the other video pentodes....
the thing with drivers is the plate ratings,
a pentode that can do 300 volts plate
as voltage amplifier is it imho....
the russian 6P15P is also cheap...
not yet tried as i still have a lot of other things on my plate, will update soon...
Driver tube damage due to arcing
Ok, I can imagine that a 6AQ5 is a more robust tube when it comes to arcing of the 6C33 but I wonder if part of the problem for this in case of the Tim Mellow design is also due to it's circuit topology.
In this design the anode of the EF86 is directly connected with the grid of the 6C33 with nothing in between as opposed to the Graaf GM20 schematic where there is a 220 Ohm grid stopper and a 1uf capacitor bypassed with a 470k resistor in series between the EF184 anode and the grid of the 6C33.
As such I could imagine that the Graaf GM20 EF184 driver tube then is prone to a much lesser degree to damage in case of arcing if at all.
Is that right or would you disagree with my assumption.
Thanks
Ok, I can imagine that a 6AQ5 is a more robust tube when it comes to arcing of the 6C33 but I wonder if part of the problem for this in case of the Tim Mellow design is also due to it's circuit topology.
In this design the anode of the EF86 is directly connected with the grid of the 6C33 with nothing in between as opposed to the Graaf GM20 schematic where there is a 220 Ohm grid stopper and a 1uf capacitor bypassed with a 470k resistor in series between the EF184 anode and the grid of the 6C33.
As such I could imagine that the Graaf GM20 EF184 driver tube then is prone to a much lesser degree to damage in case of arcing if at all.
Is that right or would you disagree with my assumption.
Thanks
^^ I think a grid stopper is an extremely good idea and something to add to the design of the amp!
Such a device would reduce the chance of damage to the driver tube during an arcing event. 1K might do it- but it should be a 3-watt device...
Such a device would reduce the chance of damage to the driver tube during an arcing event. 1K might do it- but it should be a 3-watt device...
