Finished the headphone amp and have it on my desk at work now. I love the way it fits in the case and shows off the tube and the rest of the workings.
I'm just running it off a dragonfly black and into Sennheiser ear buds so I'm probably not taxing it much but I largely got it for the look and to add an easy to reach volume control on my desk. That and I'm addicted to soldering things.
I could throw out lots of neat words to try to describe the sound but I'll skip that and just say that I've had it on for hours and haven't tired of listening at all. Running just off of the dragonfly I'd tire after an hour or so.
As CoM mentioned the regulator gets quite hot. I can't touch it for longer than a second so I'll be adding a heat sink. With no music playing I do notice a lot of microphony but I don't notice it with the music playing.
I'm just running it off a dragonfly black and into Sennheiser ear buds so I'm probably not taxing it much but I largely got it for the look and to add an easy to reach volume control on my desk. That and I'm addicted to soldering things.
I could throw out lots of neat words to try to describe the sound but I'll skip that and just say that I've had it on for hours and haven't tired of listening at all. Running just off of the dragonfly I'd tire after an hour or so.
As CoM mentioned the regulator gets quite hot. I can't touch it for longer than a second so I'll be adding a heat sink. With no music playing I do notice a lot of microphony but I don't notice it with the music playing.
Tried out the buffered 6P1 and love it! Thinking about building the hp amp.
And if you offer the Nutube ClassD amp, I will be very interested.
😉
I'm now selling the "official" Korg evaluation board for the 6P1 online. You can find it in my eBay store (Nutube.US Store | eBay Stores), and there is info (like the schematic / manual) at NuTube. Only $100 🙂
Pete
Pete
I think I am missing the point of this Nutube. It seems to be 1/10 of a 12au7a. What advantages over a common 12au7, 12at7 does this thing have?
The point is primarily that it uses far less power. The filament is 700mV at 17mA. And it can operate on plate voltages below 12V. So it can easily be battery powered.
I tell people to think of it as a signal processing element, not an amplifier. It is a real triode, and sounds like one.
A high power tube will provide lower distortion amplification. But if that's your goal, you should be using opamps, not tubes.
Pete
I tell people to think of it as a signal processing element, not an amplifier. It is a real triode, and sounds like one.
A high power tube will provide lower distortion amplification. But if that's your goal, you should be using opamps, not tubes.
Pete
Hi Pete,
I was wondering what is the gain of this preamplfier, (if it could be called like that)? I was thinking if it would be possible to use this preamplifier to drive a small Mosfet follower amp (no voltage gain). Imagine a circuit that mr. Pass posted (this tube sandwitched between two jfet buffers), driving a, say , 3-5w Mosfer follower. The idea would be to build a small class-A hybrid amp, using easily obtainable parts, being powered by 19v supplies (think of laptop psu-s). The end result would be an amp that sounds very similar to a tube SE but does not use high voltages. What do you think? 😉 🙂
I was wondering what is the gain of this preamplfier, (if it could be called like that)? I was thinking if it would be possible to use this preamplifier to drive a small Mosfet follower amp (no voltage gain). Imagine a circuit that mr. Pass posted (this tube sandwitched between two jfet buffers), driving a, say , 3-5w Mosfer follower. The idea would be to build a small class-A hybrid amp, using easily obtainable parts, being powered by 19v supplies (think of laptop psu-s). The end result would be an amp that sounds very similar to a tube SE but does not use high voltages. What do you think? 😉 🙂
It's surprised me that I've had several requests for that. Easy enough to do, one Nutube as a diff amp per channel, with LSK389 FET followers in and out, maybe?
Pete
I'd buy one certainly if its compact enough. I've been curious about this thing since first seeing it.
Hello Peter,
regarding the headphones amp, you wrote:
If used with 300 ohm (HD580/600) headphones could it then be ommited? Any mods for use (exclusively) with high imp headphones?
S.
regarding the headphones amp, you wrote:
If used with 300 ohm (HD580/600) headphones could it then be ommited? Any mods for use (exclusively) with high imp headphones?
S.
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Nope. Without the buffer the output impedance of the nutube is very high (like 100k). You need the buffer.
With high Z phones you might want to change R8 and R9 to something bigger. It really depends on your taste. You could go as high as 100 ohms. This will affect the damping factor of the headphones, and will alter the bass sound primarily. Higher resistance will soften the sound a bit, but may make the bass sound a bit loose.
Pete
With high Z phones you might want to change R8 and R9 to something bigger. It really depends on your taste. You could go as high as 100 ohms. This will affect the damping factor of the headphones, and will alter the bass sound primarily. Higher resistance will soften the sound a bit, but may make the bass sound a bit loose.
Pete
Pete,
I'm hoping you build portable headphone amp (battery) with this tube.
any plan for selling this ?
I'm hoping you build portable headphone amp (battery) with this tube.
any plan for selling this ?
No plans for this at the moment, though its not a bad idea. I wonder what kind of batteries would be best... I think the DIY ones I've seen in Japan used a pair of 9V batteries.
Pete
Pete
i would suggest rechargeable battery like 14500 or 18650 with charger build in, all you need i plug the mini usb to charge without taking off the battery.
I just ordered the nutube buffer from Pete and am curious what kind of power supply is being used. I have a 12V switcher with 1 amp and was wondering if this would be adequate.
How does this nutube compare to a regular triode? I would like to hear some listening opinions of it 🙂 I wonder if this would make a good fit with the tpa3255 I own?? I have a pentode tube amp that does voices and instruments really good, but it doesn't have the power that the tpa3255 has. Therefore I'm looking into making a hybrid amp with the tpa3255. With the lifetime of the nutube and the clean tpa3255 it could be an interesting mix.