DIY stereo tube amp

Discussion in 'Archived Threads 2001-2004' started by Todd Beachler, Feb 4, 2002.

  1. Todd Beachler

    Todd Beachler Stunt Coordinator

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    I'm looking for a project to occupy my time. I'm wanting to build a stereo tube amp and use it for music listening through a set of Acoustic Research AR-1s. Has anyone had experience with a purchased kit and all of the parts or building an amp from purchased plans? Please give list vendors, tips or how-to sites.
     
  2. BrendanL

    BrendanL Agent

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    Check out www.bottlehead.com
    Aimed squarely at the DIYer who wants great results for cheap. The owner is a great guy, and his products really do sound phenomial. You may need new speakers though, as his gear is single ended tube, making about 3-4 watts.
     
  3. Ken Shiring

    Ken Shiring Agent

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    BrendanL, the Bottlehead site is cool, but I would have to say that DIYaudio is the mecca for amplifier design.
    DIYaudio was started with the avid support of Mr. Nelson Pass of Pass Labs. His commercial amplifiers are highly sought after, and there is a forum there for every taste, including Tubes, Solid State, and the newer digital amps. There are many people over there with a scary amount of experience building amps.
    Todd, I highly reccomend it.
     
  4. Brian_Lko

    Brian_Lko Auditioning

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    OK, I'm very intrigued by the tube amp kits, but I have a question.

    Why are the watt ratings so small? Any current receivers output 100W no problem. These tube amps (bottlehead)are putting out 8W. What gives? Obviously, you can't compare the two, as the bottlehead site states their 8W amp will make a 'Straight 8 sing', something I really don't think my 100W Yamaha receiver can do.

    I'm looking for something for music amplification, my Yamaha RX795 just doesn't cut it for music. A friend of mine who is into DIY likes Bryston ($), but it looks like I can get these tube amps for more or less the same $, even if I have to buy one for left & right channels...

    Anyways, hope these aren't awfully stupid questions (like the woman at the local DVD store returning a 16:9 DVD because it had those 'black bars'...)

    Thanks

    Brian
     
  5. Dustin Haug

    Dustin Haug Agent

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    Unless you've actually heard and like the sound of a tube amp I'd suggest that you stick to solid state amps. You'll almost certainly get more power and less distortion (unless you build it wrong) than a tube design.
     
  6. Colin Dunn

    Colin Dunn Supporting Actor

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    Brian_Lko:

    You are correct that tube amps don't rival the power of current solid-state receivers and power amps. However, many solid-state receiver power specs are exaggerated. When measured RMS, full-bandwidth, all channels driven, many "100W" receivers actually supply 60-70W per channel at acceptable distortion levels. Most high-end tube amps are more conservatively rated for power (RMS, full bandwidth, all channels driven).

    Eight watts per channel doesn't seem like much, but you can actually get a lot of volume even with that little power. Most speakers have efficiency ratings of 88-92 dB/1W/1m. You get an additional 3dB of output when you double your amplifier power. So here's how output scales up from 1W to 100W.

    1W / 88 - 92 dB

    2W / 91 - 95 dB

    4W / 94 - 98 dB

    8W / 97 - 101 dB

    16W / 100 - 104 dB

    32W / 103 - 107 dB

    64W / 106 - 110 dB

    100W / 108 - 112 dB

    This isn't quite THX reference level, but plenty sufficient for many two-channel music applications. Going up from 8W to 100W just takes you from 'dangerously loud' to 'ear-bleed' levels.

    This is somewhat of an oversimplification, since volume declines from that 1m location to the listening position.

    Many people are willing to trade away an extra 11dB of volume capability for the subjectively 'warm' and 'smooth' sound of tube amplifiers. That, however, is a matter of your own taste and priorities.
     
  7. Nathan_M

    Nathan_M Extra

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    Well, I was surfing through the posts on tube amps at DIYaudio boards and ran across this post:
     
  8. Eric S

    Eric S Agent

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    Have a look at Andrea Ciuffoli's web site. Lots of great DIY tube amp plans. Andrea is a very well respected amp designer.
     

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