The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Dynaco VTA tube amp kits, all products and all products




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    Post by t8ter on Wed Nov 30, 2011 11:13 pm

    Every so often I read where someone is talking about tube watts being different than SS watts or one being more powerful at say 50 watts than the other. Can someone explain this to me.


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    Post by GP49 on Thu Dec 01, 2011 2:56 am

    t8ter wrote: Every so often I read where someone is talking about tube watts being different than SS watts or one being more powerful at say 50 watts than the other. Can someone explain this to me.

    Although this will confuse the guys with the umpteen-inch woofers in carpet-covered boxes in the back of their Cadillac Escalades, there is more to an amplifier than just its "watts."

    Various amplifier designs have different distortion characteristics, and there can be an especially large difference between the distortion products of a tube amplifier, as compared to those of a transistor amplifier.

    Another factor is behavior under overload. ANY practical amplifier will clip, i.e., exceed its maximum output, at some point. If an amplifier clips "softly" (characteristic of tube amps), that is if it overloads gradually at first, producing lower-order distortion products, it will sound "different" from an amplifier which clips abruptly and "hard" (characteristic of transistor amplifiers).

    Captain Coconut

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    Post by Captain Coconut on Thu Dec 01, 2011 10:48 am

    There's an ongoing million page thread on this topic on Canuck. It's exhaustive. I'm sure you'll find everything you need on the topic.


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    Post by tubes4hifi on Thu Dec 01, 2011 11:21 pm

    yeah, got to love those 500watt car stereo amps, that if measured like hi-fi gear might be about 25watts.
    For t8ter, actually HEARING a tube amp will make you a convert. Most 15 watt tube amps will sound better and about as loud as
    a high quality 100w SS amp. Most often you will hear the "equivilent" power of a tube amp is about double that of an SS amp.
    But if you like your music loud, an SS amp will clip at full power and produce ***-awful sound and probably trash your $100 tweeters in your $2000 speakers. A half decent tube amp run at full power and clipping is sometimes even hard to tell it's clipping or distorted (better if it's got a tube rectifier, no SS diodes!)
    Way back in the day (early 70s) when 200w power amps first came out, I worked in retail hi-end hi-fi selling Marantz and JBL gear.
    400w of SS power was never enough. At that time JBL warrantied their speakers unconditionally. We tried to blow a pair up
    running 350 watts per channel (Phase Linear) and we blew our ears out and had the speakers mechanically hitting the inner and outer
    limits of travel and audiby "hitting" both ends, and it was clean until the amps distorted fairly cleanly. The worst SS amps are the ones under 100 watts. That's not enough serious power for a serious listener who wants to feel the sound and bass. They distort hard and rough and sound like a really bad car stereo. My 35 watt/channel VTA modified (well hey, that's me!) sounds better than just about ANY power amp I've ever heard, and other than not breaking the speakers with sub 20Hz power, it's got enough power to make the neighbors a block away complain, all the while sounding sweet and clean. If you need serious power, Bob's got our M125 tube monoblocks available!


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    Post by j4570 on Mon Dec 05, 2011 7:32 pm

    Well, it seems the bases are covered here. Clean power is way better.

    Just as a fun note, my first job outside the family was installing car stereos (and CB's, cellphones-when they were a lot of work, etc.). And of course I installed the good, the bad, and the ugly. We would install stuff you brought us (it was a fledgling business in the mid 80's, and we took whatever).

    And some of the best amps were moderately rated for car stereo, but just sounded great. About the best bang for the buck was the A/D/S PQ10 (40Wx4) and is just about right for a small car. There are other good amps, but there was a lot of junk too.

    And car stereos were notorious for clipping. You needed a lot of headroom.

    But it all came down to quality, just like we are talking here. I think tube amps avoid some pitfalls as most weren't "cheap" made (and most tubes used were excellent quality, regardless of whatever brand was considered "the best"). Some were cheaper than others, but even my Bogen AP-35 here in the office sounds sweet compared to some new junk.

    A Dynaco is not a cheap amp. Sure the kit is not too bad (but more expensive that most peoples entire entertainment system), but if you pay yourself a decent wage while building it, figure in taxes, overhead, profit, etc. that a business needs, you see it's a bargain!

    My ST70 is plenty loud in the house.


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