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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Transformers for valve headphone amps

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#41
Take a look at the LL1630, a better choice

kevinkr said:
If you look at the lundahl data sheet you will see that the performance is specified into a 10K load on the secondary side. (The secondary is not 10K, it is the source impedance divided by the square of the turns ratio ignoring the effects of the shunting inductive reactance of the primary at low frequencies) These transformers are tiny and can't handle an appreciable amount of power.. Note the application. They do not specify the load impedance for the distortion measurements which probably means solely into the input impedance of the measurement setup which would typically be at least 100K ohms based on my experience.

http://www.lundahl.se/pdf/1930.pdf
Click to expand...
 
#42
kevinkr said:
If you look at the lundahl data sheet you will see that the performance is specified into a 10K load on the secondary side. (The secondary is not 10K, it is the source impedance divided by the square of the turns ratio ignoring the effects of the shunting inductive reactance of the primary at low frequencies) These transformers are tiny and can't handle an appreciable amount of power.. Note the application. They do not specify the load impedance for the distortion measurements which probably means solely into the input impedance of the measurement setup which would typically be at least 100K ohms based on my experience.

http://www.lundahl.se/pdf/1930.pdf
Click to expand...

Thanks Kevin. Though dsavitsk/ECP Audio has used them in parafeed with 32 and 300 ohm headphones (few other posts from Lundahl's AA forum which gave me the idea to use them).
 
#43
Based on your comments I'd recommend you check with Kevin Carter over at K&K Audio, if there is precedent and they perform decently they certainly are reasonably priced. Their performance might possibly be acceptable even mis-applied with a low rp tube driving them? He will steer you towards the right transformer for your application even if that does turn out to be the LL1930 in the end.
 
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