A friend has asked me to build him a tube amp for his three headphones that are 25 ohm (AudioQuest Night Owl), 110 ohm (Audeze LCD3), and 300 ohm (Sennheiser HD650).
He loves Lundahl iron so I thought about the LL2765 OPT (30mA, SE) with its configurable secondaries for 32 ohm, 150 ohm, and 600 ohm.
Are those OPT impedances close enough to my friend's phones? I worry about matching the 300 ohm Senns.
He loves Lundahl iron so I thought about the LL2765 OPT (30mA, SE) with its configurable secondaries for 32 ohm, 150 ohm, and 600 ohm.
Are those OPT impedances close enough to my friend's phones? I worry about matching the 300 ohm Senns.
https://www.lundahltransformers.com/wp-content/uploads/datasheets/2765.pdf
3:1
that means, if you hook 300r hp, primary will look 2k7. not 5k4....
opt impedance ratio stay same.
3:1
that means, if you hook 300r hp, primary will look 2k7. not 5k4....
opt impedance ratio stay same.
Looking at the data sheet and the connection diagrams, looks like it would be pretty complicated to wire switches for all three outputs, you'd be better off picking two of them.
I'd use the 32 and 150 ohm connections (a and b) and would expect 150 to work fine with 300 ohm cans.
EDIT: You'll lose some power, but Senns are efficient enough so it won't matter. You'll need some power to drive the LCD3's, so should have plenty for the Senns.
I'd use the 32 and 150 ohm connections (a and b) and would expect 150 to work fine with 300 ohm cans.
EDIT: You'll lose some power, but Senns are efficient enough so it won't matter. You'll need some power to drive the LCD3's, so should have plenty for the Senns.
Last edited: