Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Williamblake on November 24, 2022, 09:36:45 am
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Hello!
This must be the quadrillionst time this topic is coming up, begging your pardon.
I just got my hands on four identical OT from Telefunken Magnetophon 85. They are push-pull for two EL95s with 2.25 Ohm and 4,5 Ohm Output with RAA 10k (this is nicely printed on the transformer).
However i would like to use an 8 Ohm speaker.
I measured the turns ratio to be 1:44 and 1:61. So with an 8 Ohm speaker RAA is 15 kOhm.
What would you expect? Is this usable? Don`t guitar amps want to pass below the knee rather than above it anyway? Should i raise the supply voltage to better fit 15k? Maybe i should just try it with 4 Ohm and 8 Ohm load and see what happens?
Yes, it sucks being too stupid to draw a load line.
Regards,
Jens
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... OT from Telefunken Magnetophon 85. They are push-pull for two EL95s ...
Stuff I find online says this model record player uses single-ended ECL82/6BM8.
Anyway, yes, you can probably use your 8Ω speaker load. The expected impact could be higher screen current, which you might be able to offset with a (larger? added?) screen resistor. The tradeoff will be a part-watt less output power, and maybe a touch more compression at high signal level.
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Thanks. There is a SE and a push pull version.