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General questions about Tube amps...

post #1 of 4
Thread Starter 

So is it true that any tube speaker amp, with a headphone output will be optimal, and preferable over an OTL amp design powering low impedance headphone loads?

 

Furthmore in such a design with a headphone plugged in and speakers disconnected, Where does the unused power go? Being that speakers need several watts and headphones need only a fraction of that.   Do the output transformers behave like a power soak coil for the power tubes?

 

thanks in advance

post #2 of 4

The headphone out on a speaker tube amp has a lower voltage and thus lower power ( depends on load ).  Most amps are constant voltage sources so looking at a speaker or headphone amp as a power source can be a bit misleading.  Think of them as a voltage source.  That said the voltage is lowered from the voltage needed for your 4 or 8 Ohm speakers by a transformer, voltage regulator, some resistors, and hopefully some caps to filter out the DC.

post #3 of 4
Quote:
Originally Posted by kramer5150 View Post

So is it true that any tube speaker amp, with a headphone output will be optimal, and preferable over an OTL amp design powering low impedance headphone loads?

 

 

 

I think that may be too general a question to give a definitive yes or no answer to.  The general head-fi consensus is that OTL tube hp amps are best when used with higher impedance headphones.  Whether the hp-out of a tube speaker amp is a better option for a low impedance par of cans would likely depend on the amp in question and the circuit used for it's hp-out.

post #4 of 4
Quote:
Originally Posted by kramer5150 View Post

So is it true that any tube speaker amp, with a headphone output will be optimal, and preferable over an OTL amp design powering low impedance headphone loads?

 

No, that's an untrue generalization. Some tube amps have an output impedance which is too high for low-impedance headphones. Some non-tube amps have sufficiently small impedance.

 


Quote:
Originally Posted by kramer5150 View Post

Furthmore in such a design with a headphone plugged in and speakers disconnected, Where does the unused power go? Being that speakers need several watts and headphones need only a fraction of that.   Do the output transformers behave like a power soak coil for the power tubes?

 

There's no "unused" power. The speaker connections, when disconnected, are open circuits; no current (and thus no power) flows through them.

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