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Thread: Korg NuTUbe dataseet

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    "Thermionic Apocalypse" -JT nickb's Avatar
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    Korg NuTUbe dataseet

    I see these Korg 6P1 Nutubes are showing up at distribution at around US$50 each (ouch) for rather dismal performance. I pity the guys who buy into these and have to replace them. Expensive glass part soldered to the PCB is likely an $80 bill to replace. Anyway, here is the datasheet in case you were wondering.

    0900766b815db1b5.pdf

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    I misread your opening as "for rather digital performance."

    About the only thing I know how to interpret is the amplification factor... How you gonna get a 5150 out of effectively is a 12AU7?

    Justin

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    Wow, Anode Power Dissipation = 1.7 mW! Less than a tiny SMD transistor.
    Also I wonder what is the unit of gm (according to Barkhausen for a vacuum triode must equal gm*Ra, Ra being the internal plate impedance).
    And what means "resonance frequency" 5.8kHz?

    Hard to think of a useful application.

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    "Thermionic Apocalypse" -JT nickb's Avatar
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    Quote Originally Posted by Helmholtz View Post
    Wow, Anode Power Dissipation = 1.7 mW! Less than a tiny SMD transistor.
    Also I wonder what is the unit of gm (according to Barkhausen for a vacuum triode must equal gm*Ra, Ra being the internal plate impedance).
    And what means "resonance frequency" 5.8kHz?

    Hard to think of a useful application.
    Quite awful isn't it? I take it the resonace frequency is a mechanical thing i.e the frequnecy at which is internals vibrate. Not suitable for use in a combo I'd say.

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    I take it the resonace frequency is a mechanical thing i.e the frequnecy at which is internals vibrate.
    That's what I thought, too. But it is listed under "Electrical Characteristics".

    Also I think the device might not even be well suited for high impedance inputs. Maybe with some bootstrapping.

    What is the target market/application field?

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    "Thermionic Apocalypse" -JT nickb's Avatar
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    Quote Originally Posted by Helmholtz View Post
    That's what I thought, too. But it is listed under "Electrical Characteristics".

    Also I think the device might not even be well suited for high impedance inputs. Maybe with some bootstrapping.

    They do need to be surrouded by buffers to work.

    What is the target market/application field?
    Guitar amps! https://voxamps.com/en-gb/product/mv50-boutique/



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    Quote Originally Posted by nickb View Post
    Guitar amps!
    Any amp with a tube like that would definitely qualify as "disposable." Onward to the future!

    5.8 KHz resonance sounds like it's a set up to make an awfully annoying whistle. Maybe some genius at Korg thinks guitarists will like that feature.

    Gain like a 12AU7? Well heck just cascade stages as necessary to get the gain you want. Uses more Nutubes, and owners of the amps can boast about how many tubes are in 'em. Everybody wins.

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    It's existence is just to get a marketing handle on having a tube fitted. The relationship to some venerated technology implying timeless virtue. I had a Chinese combo for repair with a tube in a little window that when removed made no difference to the sound at all. It was backlit, lit from underneath and changed colour when you switched channels. It's got a tube in it so it must sound good. Maybe the Nutube can be pressed into shaping an already distorted signal. I suspect plenty of supporting SS circuitry that does all of the heavy lifting.

    It's a bit like food where the marketing spin is on an ingredient that amounts to less than 2%. Like almond milk. Principal ingredient - water, and in some cases more sugar than almond. They don't sell it as sugar-water with almond flavouring.

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    Guitar amps!
    So it's just meant as an "alibi" or "excuse" tube in a SS amp for marketing purposes.

    Surely no decent successor to the excellent Nuvistors.

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    Has anyone ever made a guitar amp with nuvistors?

    Justin

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    Quote Originally Posted by nickb View Post
    From their ad copy:
    "... An ultra-compact head amp that you can easily carry in one hand.
    In spite of its size, monster-class sound power with 50W output.
    The ... amp features vacuum fluorescent display technology...
    Analog circuitry based on a pure design philosophy."

    Funny, my 67 Bassman has all that AND I can still carry it easily with one hand...

    Justin

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    "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
    "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
    "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

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    Quote Originally Posted by Helmholtz View Post

    What is the target market/application field?
    The original application was fluorescent displays. I have a feeling this was a way to try to extract some money out of some old machinery that was otherwise going to be scrapped.

    https://audioxpress.com/article/r-d-...org-nutube-6p1

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    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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    Excellent article and answers both my questions. Gm is very low at 54A/V (around 30 times lower than a 12AX7). And it's the filament wire mechanical resonance.

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    I thought the idea was to mass produce "tubes" cheaply using existing flourescent display technology. If it's costing $60 plus for a low quality tube I predict they will disappear soon.

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    Quote Originally Posted by dmeek View Post
    I thought the idea was to mass produce "tubes" cheaply using existing flourescent display technology. If it's costing $60 plus for a low quality tube I predict they will disappear soon.

    I bet it doesn't cost them $60. Maybe $3.

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    Quote Originally Posted by Justin Thomas View Post
    Has anyone ever made a guitar amp with nuvistors?

    Justin
    I haven't, but I have several set aside for a couple of projects. The first time I ever saw one, it was years ago in an old tektronix plugin type module like this:



    I thought they were some kind of weird power transistor I hadn't seen before. I compiled a file with all the transfer characteristics of the ones I have.

    As for the NuTube, I had high hopes in anticipation of it's release. But after getting a hold of the datasheet, I wondered why they bothered ever going into production. The gm, gain, and input impedance blooooooooooow, compared to any other discrete amplifying device I can think of. Even in the miniature class of tubes, Nuvistors and Subminiature tubes perform so much better. I like the idea of what they were going for in the physical package design, but what a let-down.

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    Last edited by SoulFetish; 01-08-2020 at 03:45 AM.
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