has anyone got a schematic for a headphoneamplifier with 12AU7 (ECC82) or 12AX7 (ECC83)
preferrably output-transformerless !
preferrably output-transformerless !
Shut up about my sweetheart! 😛
12AU7 can push a bit of current, it's pretty much a miniature 6SN7 (which makes me wonder why AU is so maligned here, yet the SN praised), say a White CF from 300V B+, two AUs per channel (if you want the extra headroom 🙂 ). Parallel the triodes, get like 40mA peak output. No problem...
Additional NFB can be applied globally if you want to reduce distortions, making the output stage electrically disappear, literally.
AX is no good for current, so wouldn't work worth a dang for output, however it has a lot of gain so use it for that.
Tim
12AU7 can push a bit of current, it's pretty much a miniature 6SN7 (which makes me wonder why AU is so maligned here, yet the SN praised), say a White CF from 300V B+, two AUs per channel (if you want the extra headroom 🙂 ). Parallel the triodes, get like 40mA peak output. No problem...
Additional NFB can be applied globally if you want to reduce distortions, making the output stage electrically disappear, literally.
AX is no good for current, so wouldn't work worth a dang for output, however it has a lot of gain so use it for that.
Tim
AX.
Hi,
Keyword: a bit.
Keyword: electrically maybe, sonically no.
Advise: don't // unless necessary.
Nope, you can avoid global FB, the worst kind IMO, too by clever choice of topology and valves.
Said it before, say it again, unless you're desperate for high voltage gain..forget it.
Here, you don't need such high at all.
Come to think of it Joel's circuit is not so bad after all for this kind of application, is it?
Numerous variations are possible here none would be nec plus ultra but a AX and a AU for a headphone amp?
Not me,😉
Hi,
Keyword: a bit.
Keyword: electrically maybe, sonically no.
Advise: don't // unless necessary.
Nope, you can avoid global FB, the worst kind IMO, too by clever choice of topology and valves.
Said it before, say it again, unless you're desperate for high voltage gain..forget it.
Here, you don't need such high at all.
Come to think of it Joel's circuit is not so bad after all for this kind of application, is it?
Numerous variations are possible here none would be nec plus ultra but a AX and a AU for a headphone amp?
Not me,😉
hey, guys!
..it was not my intention to start a war here.. there´s one too much already..
yep, i know that the beloved (and very much hated) 12AU7 isn´t that sonically perfect, but i have a lot of those in my junkbox, so therefore i want to reduce the amount in the junkbox building a headphoneamp with'em.
thanks for the input, i will hopefully find some suitable transformers somewhere!
what impact does the B+ do to the sound, +250V or +300V or whatever it´s stated in the schematics??
i run a preamp with 12AU7 for the moment and i found that the best sound is with about +250V atop is best for me, but i guess that there would be other numbers given the other conditions a headphoneamp has to work with.
Cheers, and thanks for the input!
..it was not my intention to start a war here.. there´s one too much already..
yep, i know that the beloved (and very much hated) 12AU7 isn´t that sonically perfect, but i have a lot of those in my junkbox, so therefore i want to reduce the amount in the junkbox building a headphoneamp with'em.
thanks for the input, i will hopefully find some suitable transformers somewhere!
what impact does the B+ do to the sound, +250V or +300V or whatever it´s stated in the schematics??
i run a preamp with 12AU7 for the moment and i found that the best sound is with about +250V atop is best for me, but i guess that there would be other numbers given the other conditions a headphoneamp has to work with.
Cheers, and thanks for the input!
a 12AU7, both sides paralleled, single-ended will work quite nicely and drive most headphones out there. Although if you ever anticipate using 8 ohm grado's or other crazy gear - you might want to consider 30-40mA as opposed to the 16mA from 6J5/6F8/6SN7/12AU7/6CG7.
Same situation here, I built Hept'AU7.. PPP triode amp! All of 7W output, but 1W per AU ain't bad! 😉
Testing different supply voltages isn't fair because as you change the voltage you change the operating point; the biasing resistors have to be recalculated for each voltage step for this to be valid.
Tim (has a preamp running from +200V with 12AT7 front end and 12AU7 CF output, sounds fine)
Testing different supply voltages isn't fair because as you change the voltage you change the operating point; the biasing resistors have to be recalculated for each voltage step for this to be valid.
Tim (has a preamp running from +200V with 12AT7 front end and 12AU7 CF output, sounds fine)
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