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el34 [message #8331] Wed, 21 July 2004 18:17 Go to next message
valvetrain is currently offline  valvetrain
Messages: 4
Registered: May 2009
Esquire
what are the hi points and low points of the el34? how does it compare with other tubes?

Re: el34 [message #8336 is a reply to message #8331] Fri, 23 July 2004 15:51 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
HI,
I think a lot would depend on the overall circuit, and the parts used. If the circuit is right, most tubes will be pretty linear. If the parts are good quality, the amplifier should be more transparent and control frequencies better.
In other words, it may be better to go for the best implementation, rather than go for any particular tube.
Just my 2 cents.
-akhilesh


Re: el34 [message #8339 is a reply to message #8336] Sat, 24 July 2004 21:54 Go to previous messageGo to next message
metasonix is currently offline  metasonix
Messages: 103
Registered: May 2009
Viscount
If I may, past tests done by myself and others indicate that EL34s enjoy about 2-3 times more distortion than 6550s or KT88s in the same circuit.


Re: el34 [message #8340 is a reply to message #8339] Sun, 25 July 2004 04:06 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18792
Registered: January 2001
Illuminati (33rd Degree)
Do they have the same pinouts and voltage requirements? Can 6550's or KT88's be used as a direct replacement for EL34's in a circuit so equipped?

Re: el34 [message #8341 is a reply to message #8340] Sun, 25 July 2004 17:04 Go to previous messageGo to next message
metasonix is currently offline  metasonix
Messages: 103
Registered: May 2009
Viscount
Yes, except for grid bias voltage. Also, the 6550s would be more reliable than the EL34s because 6550 screen grids don't draw as much current. Screen overheating is a major cause of EL34 premature death. Ask any guy who plays metal thru a Marshall amp.


Re: el34 [message #8342 is a reply to message #8341] Sun, 25 July 2004 19:09 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18792
Registered: January 2001
Illuminati (33rd Degree)
How much difference is there in bias voltage?

Re: el34 [message #8343 is a reply to message #8342] Sun, 25 July 2004 20:35 Go to previous messageGo to next message
metasonix is currently offline  metasonix
Messages: 103
Registered: May 2009
Viscount
It is not a fixed ratio. 6550s need about 20-50% more negative bias voltage than EL34s in the same circuit. Depends on plate voltage, screen voltage and even the brands of tubes involved.


Re: el34 [message #8344 is a reply to message #8343] Sun, 25 July 2004 20:55 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18792
Registered: January 2001
Illuminati (33rd Degree)
Thanks, Eric, that's the kind of information I was looking for. It's enough difference that they definitely shouldn't be considered drop-in replacements. A person could easily modify most circuits, some with as simple a change as a resistor or two. Others might need power supply mods or an entirely new supply. But either way, it isn't something that a tube roller could do without a soldering iron and some understanding of electronics.

Re: el34 [message #8345 is a reply to message #8331] Mon, 26 July 2004 07:13 Go to previous message
valvetrain is currently offline  valvetrain
Messages: 4
Registered: May 2009
Esquire
thanks for all your replies!

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