I have some 5672's, and I'm planning on making a headphone amp project (after a pentaboost and possibly a bass overdrive/distortion). Could something like a pentaboost possibly drive headphones? I have LM386 and NE5552 opamps, but I'm hoping I can keep the circuit all-tube. I also have some 12AU7s and 12AX7s if anyone out there has seen a headphone amp circuit with these inside. I'm aware there's an issue with the output impedance of tubes... so would an output transformer be absolutely necessary?
Sorry for all the beginner questions, but I'm dying to learn more about my options here.
You can use tubes into a non-ideal load, but the output and performance will be terrible. A transformer will be best.
Quote from: Ripthorn on April 03, 2009, 10:55:47 AM
You can use tubes into a non-ideal load, but the output and performance will be terrible. A transformer will be best.
Thanks! I don't mind buying a little transformer. The saturation/distortion of an output transformer is responsible for some of that classic tube amp mojo anyway. Any ideas where I can do a little research to learn how to choose the right transformer? I'm a little rusty on the concept of impedence.
My "Murder One" submini tube amp uses a 5672 as a power amp into a Fender reverb transformer #22921, the Hammond equivalent is the 1750A. It works nicely as a headphone amp (though I suspect there is some impedance mismatch), and gives a good range of clean and overdriven tones.
http://www.diystompboxes.com/smfforum/index.php?topic=73222.0