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8950 tube ??

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Old 08-23-2011, 05:05 AM
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Default 8950 tube ??


I have been doing some researce,and I see if not mistaken. I can take a 8950 tube and exchange the heater pins 1 & pin 12 from the socket,and place a 6lf6 in and use it in place of the 8950! 6LF6 is just a broke down verson of the 8950 but at 6 volts........any thoughts


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Old 08-23-2011, 05:10 AM
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6lb6 works fantastic for replacing the 8950, of course heater voltage is different.

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Old 08-23-2011, 06:56 AM
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2057 will work with no changes,and more output...73s de JW
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Old 08-23-2011, 10:22 AM
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Quote:
Originally Posted by wavrider View Post
6lb6 works fantastic for replacing the 8950, of course heater voltage is different.
Are there any changes to be made to use the 6LB6?

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Old 08-23-2011, 10:32 AM
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Quote:
Originally Posted by n0zna View Post
2057 will work with no changes,and more output...73s de JW
Indeed they will but good luck finding a 2057 at a reasonable price. They are probably the only sweep tube to cost more than the 8950.

Better to do the 6lb6 conversion.
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Old 08-23-2011, 10:56 AM
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Quote:
Originally Posted by Atlasta View Post
Indeed they will but good luck finding a 2057 at a reasonable price. They are probably the only sweep tube to cost more than the 8950.

Better to do the 6lb6 conversion.

Yep

The 8950's are going for around $100 or so when you can find them. I don't do cheap tube amps at all myself but all the guys around here are only going with the common cheaper tubes either by design or the above conversions.
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Old 08-23-2011, 11:16 AM
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Quote:
Are there any changes to be made to use the 6LB6?
Yes.
The heaters ( filament ) on the 8950 are 12 volt.
the heaters on the 6LB6 are 6 volt.
If it has an even number of tubes, you can feed two of the 6LB6 heaters in series and do it, or else supply a 6 volt filament transformer.
How many tubes does it have?

73
Jeff
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Old 08-23-2011, 12:58 PM
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Keep in mind that although the 6LB6 will work as a replacement for an 8950, your power output will drop a little bit, as the 6LB6's are around 33W plate dissipation per tube, vs. 40W plate dissipation for an 8950.


Just tie the filaments in series with the 6LB6's, and you should be good to go. Most of the inter-electrode capacitances are fairly close, so you shouldn't have too much trouble tuning up the amp. Just keep your input wattage down so you don't over-drive the tubes. Good luck!

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