An amp, including OPT, needs to be designed for triode or pentode output. Having a switch means that it will be misdesigned for at least one switch position.
While make a sense ( not for me) to have a switch for UL to triode, the pentode to triode in not a good idea.
The charateristscs of the tube is completely different starting from Rp. So the OT trafo need to be different.
Walter
The charateristscs of the tube is completely different starting from Rp. So the OT trafo need to be different.
Walter
In fact, it is possible with an appropriate output transformer. Philips made one in the fifties with 2K5, 3K5 and 5K impedance (at 5 ohm sec.). It's a scarce unit, so you'll probably have to have one made for you. Fidelity could be better though because of the compromises made.
Not really, except the possibility of damage from high voltage transients caused by operating the switch with the amplifier on.
original 807 SE its UL??? the best
in triode mode your psu should be very good filtered and steady and you loose dynamics and power anyway
pentode good for guitar player
Looking at the data sheet it depends on the operation point of this particular amp. The Pentode loads read from 2k5 to 4k5, Triode mode uses 5k.
I say try it and see if you like it, it won't destroy anything.
Cheers.
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Upstream of the output tubes as well. My recollection is the increased Miller capacitance of some home brew Dynaco ST70 triode conversions overtaxed the phase splitter, with audible results interpreted as improvement.
I think at the OPT the Triode/Pentode winding is one and the same. (?)
OK OK, thats os a fine explanation Thanks;
Thanks for inform that. I think I will stick w/Triode due SQ, there is a Hammond 5K prompt avaliable. I wonder like to know how many W I will get w/a 5K OPT in a conservative Bias for 807?
> how many W I will get
807 is 6L6 with top-cap and higher ratings. 6L6GC has similar ratings.
http://www.mif.pg.gda.pl/homepages/frank/sheets/093/6/6L6GC.pdf
See page 2: Class A1 Triode
250V is the limit on G2 for 807 and original 6L6, so the published value as Triode is for 250V supply: 1.4 Watts output. This is a conservative 10 Watts dissipation, far below the dissipation rating.
807 as Triode is allowed 400V supply. This will raise dissipation to 25.6 Watts, real near the limit. Sine audio output may rise to a whopping 3.6 Watts.
807 is 6L6 with top-cap and higher ratings. 6L6GC has similar ratings.
http://www.mif.pg.gda.pl/homepages/frank/sheets/093/6/6L6GC.pdf
See page 2: Class A1 Triode
250V is the limit on G2 for 807 and original 6L6, so the published value as Triode is for 250V supply: 1.4 Watts output. This is a conservative 10 Watts dissipation, far below the dissipation rating.
807 as Triode is allowed 400V supply. This will raise dissipation to 25.6 Watts, real near the limit. Sine audio output may rise to a whopping 3.6 Watts.
3.6W!! I cant believe it so small😱
And for 1625? this have dissipation=40W.
With 30W dissipation Triode how many output W I sill get?
Many thanks,
And for 1625? this have dissipation=40W.
With 30W dissipation Triode how many output W I sill get?
Many thanks,
In a s. e. config, in theory , you can have on the load the 25% of the anode power dissipation
Walter
Walter
Yes, but there is more to a circuit than the wires. Gain and impedance will be different.FullRangeMan said:
The 807 tube is tetrode, not a pentode. Would you mind sharing your schematic showing your switch? Once you have decided on a certain design, why would you use a switch?
RA
The switch aims just having more power.
There any more opinions on the 1625 in Triode in SE?
(with a Hammond 16xx series 5K OPT)
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