Hello,
I saw i had a 6as7g NOS in my collection and it's honestly just beautiful, might be my favourite looking tube. Definitely at least my favourite looking double triode. So I wanted to use it for a headphone amplifier. Then I saw I had a 6c8g which is the same base so I thought why not put these together? One is a medium mu double triode and one is a low plate resistance double triode, should add up to one headphone amp, right? 😁
Looked around and found this on the Web and was thinking I'd adapt it for an autotransformer volume adjuster and obviously redoing the input stage along with larger value caps to get a better low frequency response. Also want to do a different PSU.
https://www.gammaelectronics.xyz/ax_06-08_tube-headphone-amp.html
Not sure if there are any other glaring flaws in the design i am missing. The input signal to the 6c8g should be around 0.5V(but obv has no drive or I would need an amp 🙂 ) at max volume and the load will be my 50 ohm headphones.
I'm thinking 300V B+ for the 6c8g and 150V for the 6as7g so I can use OA2s(I'd use OD3s for the looks but I've only got two octal sockets and I have a lot of BG7 sockets and equally huge piles of both tubes 🙂 ).
Not sure if I want to do tube rectification or solid state, I'll have to look through my tubes but I don't think I have any that would really be up for the task. I remember having four 6x4 tubes but I think they would be a bit weak for this, right?
Anyway that's what I've got for now, suggestions welcome as I've probably overlooked a few things!
I saw i had a 6as7g NOS in my collection and it's honestly just beautiful, might be my favourite looking tube. Definitely at least my favourite looking double triode. So I wanted to use it for a headphone amplifier. Then I saw I had a 6c8g which is the same base so I thought why not put these together? One is a medium mu double triode and one is a low plate resistance double triode, should add up to one headphone amp, right? 😁
Looked around and found this on the Web and was thinking I'd adapt it for an autotransformer volume adjuster and obviously redoing the input stage along with larger value caps to get a better low frequency response. Also want to do a different PSU.
https://www.gammaelectronics.xyz/ax_06-08_tube-headphone-amp.html
Not sure if there are any other glaring flaws in the design i am missing. The input signal to the 6c8g should be around 0.5V(but obv has no drive or I would need an amp 🙂 ) at max volume and the load will be my 50 ohm headphones.
I'm thinking 300V B+ for the 6c8g and 150V for the 6as7g so I can use OA2s(I'd use OD3s for the looks but I've only got two octal sockets and I have a lot of BG7 sockets and equally huge piles of both tubes 🙂 ).
Not sure if I want to do tube rectification or solid state, I'll have to look through my tubes but I don't think I have any that would really be up for the task. I remember having four 6x4 tubes but I think they would be a bit weak for this, right?
Anyway that's what I've got for now, suggestions welcome as I've probably overlooked a few things!
Nothing better than a "pretty" amp... 🙄
Anyway I made my own like this years ago. 6DJ8 gives enough gain and can be split between channels.
Headphone amplifiers don't need gas tubes - that's for small signals like in a phono amp. (simplified)
Also, the coupling cap to headphone is pitiful IMHO. I don't want 20Hz to be -3, I want it to be flat. -3 then is 2Hz.
Based on 32R not 300R. Of course the above will work fine with high-Z cans
Anyway I made my own like this years ago. 6DJ8 gives enough gain and can be split between channels.
Headphone amplifiers don't need gas tubes - that's for small signals like in a phono amp. (simplified)
Also, the coupling cap to headphone is pitiful IMHO. I don't want 20Hz to be -3, I want it to be flat. -3 then is 2Hz.
Based on 32R not 300R. Of course the above will work fine with high-Z cans
It's a silly reason yes, but my enjoyment is more in the build and design than using the final product 🙂
Yep the coupling caps are awfully specced, I'm going for either 2Hz or 0.2Hz for the breakpoint. As for the 6DJ8, I mean yeah I could use one but I want to stick with these tubes if possible.
It's easily possible. I just find the 6SL7 / 6N9S makes too much gain in this circuit. All the action on the volume knob is in the first 1/4 of rotation. With a couple of resistor changes, 6SN7 can plug in (if you have a PSU that can make the extra current).
Oh you're looking at the schematic, I'm not using those, I'm looking to use the 6c8g which I belive should have a lot less gain than those tubes
Downloading too much the frequency response will cause coupling of low frequency variations into the earphones Line, heaters, etc.) and also make to flow during a larger time a DC current through them until coupling caps voltage becomes steady. It may damage your phones.
And now looking at the datasheet, the 12AT7 seems close. Still too much gain IMHO
bananasplit_00,
Please look at my Post # 26 on the thread: "Learning by dissecting circuits" in Tubes / Valves.
It has lots of things that apply to your circuit in Post # 1 of this thread.
Thanks!
Please look at my Post # 26 on the thread: "Learning by dissecting circuits" in Tubes / Valves.
It has lots of things that apply to your circuit in Post # 1 of this thread.
Thanks!
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