Donald North Audio — Owners Thread

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Huxleigh, Aug 12, 2016.

  1. Donald North

    Donald North Friend

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    Thanks and yes
     
  2. Claud

    Claud Friend

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    Is this amp the same size as my Stratus? Mr North, is the 6CG7 a good input tube for Stratus? Any particular brand, vintage, etc?
     
  3. Donald North

    Donald North Friend

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    The Starlett is smaller than your Stratus; chassis measures 15x11” whereas your Stratus is 17x13”.

    I have not yet extensively compared the various NOS 6CG7/6FQ7 available. So far I’ve tried some Amperex and Sylvania units and they’re both good and better than the new production Russian version, IMO. I was hoping this wouldn’t be the case and the E-H would acceptable to use as the stock tube but it didn’t bring the magic. You’re welcome to try it in your Stratus. Gain will be 5dB less, so you’ll experience more initial range in the volume control which is beneficial with very sensitive headphones like the Utopia.
     
  4. ChaChaRealSmooth

    ChaChaRealSmooth SBAF Gearmaster

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    Joined the DNA Owner's Club. Shameless glamour shots with phone:

    20190926_123431.jpg 20190926_123817.jpg

    I don't perceive that I'll be buying another tube amp for a long time, if ever.

    As a side note, it might be appropriate to start new impressions threads for the DNA amps based on model.
     
    Last edited: Sep 26, 2019
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  5. ColtMrFire

    ColtMrFire Writes better fan fics than you

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    Redacted
     
  6. dubharmonic

    dubharmonic Friend

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    Any possibility of a Starlett loaner? I'm especially curious about how it pairs with the Utopia.
     
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  7. Donald North

    Donald North Friend

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    Yes, once I receive packaging and shipping cartons I can send out the prototype for demo
     
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  8. m17xr2b

    m17xr2b Friend

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    After playing around with the C3g, tubes that everyone raves about, I've pulled them out.
    Technically, they have sharper attack, deeper and better controlled low end, midrange is cooler and leaner, high end has increased presence but still extremely balanced across the frequencies, sharper to the point of loosing finesse, larger soundstage. Think of what the HD800 is to the HD650.
    I've tried different operating points from 2.5mA to 9mA by paralleling resistors to cathode ones to not have to unsolder anything.

    Over the past week I just didn't feel like listening to any headphones, music couldn't capture my interest and keep me engaged. I've reverted the Stellaris back to stock and using the 6N1P-E, everything came back. Romance, drama, excitement, every track can display its unique character. By comparisons it does sound like it's veiled coming from the in your face C3g. I know this will fade once my brain adjust to it but I will miss the technicalities.

    Now back to my tried and true combination, 422A AVVT 2A3 mesh and 6N1P-E.
     
    Last edited: Oct 3, 2019
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  9. Claud

    Claud Friend

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    Well, you did not know until you explored the extremes. Thank you for doing that so the rest of us do not have to do so.
    I will still try my ECC40s and 6CG7s I have purchased rather than sell them yet. They were just not that expensive.
     
  10. sorrodje

    sorrodje Carla Bruni's other lover - Friend

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    o_O .. Hugh. Soooo Tempting .
     
  11. m17xr2b

    m17xr2b Friend

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    Some eye candy:
    [​IMG]
     
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  12. Claud

    Claud Friend

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    All right I give!! What is the rectifier with the fancy coat of arms?
     
  13. m17xr2b

    m17xr2b Friend

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    Never try this tube in the stock amp unless there's a strong desire for a light show with sparks at startup.

    The tube is a mercury vapour rectifier, type 83. The blue glow is ionized mercury. Only 15V drop and holds it regardless of the current demand, closer to a SS diode in operation than a typical tube and not in a good way for DHT output tubes.

    A certain temperature is required to vaporise the condensed mercury and a delay circuit is mandatory before B+ is applied. Even 5 seconds would be enough but DHT output tubes heat up almost immediately, start conduction, the 83 is not ready yet and will arc.

    A cheap and cheerful fix is to add a 100K resistance between the transformer and rectifier plate shunted by a high voltage switch. This way I can let the heater warm up before applying HV.

    The advantage of a gas filled rectifier is very low resistance and voltage drop. Sound wise it's like an upgraded metal base GZ34. It isn't any more dangerous than a CFL tube but special care should be taken around pets or children.
     
    Last edited: Oct 17, 2019
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  14. Claud

    Claud Friend

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    The 64 thousand dollar question IS how does it sound in your Stellaris? Best sound so far? For some reason, I don't think you have any pets or children to worry about. You are too adventurous . And once again I thank you for exploring the outer limits of tube rolling the Stellaris.
     
  15. m17xr2b

    m17xr2b Friend

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    Best sound so far on a specific setup. I've came to terms there isn't any best, at this point it's just different flavours without compromised technicalities.

    I ran it only with AVVT 2A3 once. For AVVT it's the perfect tube, the synergy is there and will replace the 422A most likely.
    Yes, it is the best but only in my setup with AVVT 2A3. This is the problem with tube rolling and impressions, thinking it's that simple. It's all about synergy, and personal tastes. For PX4 output the 422A has better synergy, for Telefunken AD1 the U52 is ideal by far and I really dislike it with any 2A3 or 300B.

    As to the general sound, there is a strong solid state type feeling. If I didn't know it's a tube amp I wouldn't have guess, similar to a HPA4 with tube infusion, speed is uncanny with super fast transients, a refined GZ34m if you tried it. Need more time to evaluate it. Unlike any other rectifier I've tried, mercury really changes the behaviour, you'll also get more power from the amp.
     
  16. Claud

    Claud Friend

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    I am happy for you. You must be good friends with one or two English tube vendors. I reached another best sound Monday. Ruby Tiger gave me one of the 6N1Ps that are so special that he keeps them for himself. It was like the time when I changed the stock 6N1P for a Ruby Tiger Select I got from another member It was a big increase in dynamics and definition with a touch of bass boost.
     
  17. RAZRr1275

    RAZRr1275 Almost "Made"

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    I've been away for ages and its pretty much entirely because my rig hasn't changed at all and I don't really have any desire to. HD650/HD800>SFD-1 or MisterRogers DAC>Stratus is probably endgame for me. Especially with the U52 in. I like it most with a Mullard, Cryoset, or Pearl Cryo driver tube. Also dig a RCA 5AR4GY and Westinghouse driver. Such a great amp in terms of providing warmth while not losing out on detail, dynamics or speed.
     
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  18. MisterRogers

    MisterRogers Ethernet Nervosa

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    Glad to hear it's still bringing you enjoyment mate!
     
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  19. RAZRr1275

    RAZRr1275 Almost "Made"

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    For sure man! The bass response it can bring into the HD800s with the stratus is amazing
     
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  20. RAZRr1275

    RAZRr1275 Almost "Made"

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    Somehow there's a tube I like as much as the U52 in the Stratus and its $40. I had an RCA 5U4G but for some reason only used it once before during my 3-4 years or so that I've had the Stratus and with the SFD-1 its putting out the best bass I've heard from the Stratus and its pretty spacy and airy in tone with the Westinghouse in the driver slot. While the U52 is more thick and aggressive, this is super ethereal.
     

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