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  1. #1
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    Tube-phobia - founded or unfounded?

    I believe many folks are afraid to move to tube amps due to their percieved danger, reliability, concern over DIY biasing and the belief that tubes will introduce hum into one's system. Let's examine these concerns.

    Yes there is lethal voltage in tube amps but unless you're going inside the case it's not a problem. On many newer models biasing, if required at all, is accomplished with top adjustment screws. If you're using matched tubes you may never need to change the bias. You can not get shocked with changing tubes or the routine handing of a tube amp. Tube amps are more resistant to electrical storms and power surges as they don't have transistors to blow.

    All my amps except for the Rotel/Martel from the 1960's are self biasing. Most single ended triodes amps are self biasing. Biasing is not rocket science and only requires a screw driver and $5
    multi-meter. There are many tutorials online and a tube tech will check and adjust the bias for a small sum if you don't want to learn this simple process. .

    I currently own six tube amps, two tube preamps and one tube phono preamp. I'd like to go on record as stating that I've never experienced audible tube hum with any of these. I certainly would if there was any as my HE speakers range from 93dbs to 98dbs. I've only had one mirophonic tube which I quickly replaced. With over 5 years of daily listening I've only had two tubes to blow ( one EL84 and one small signal tube ) and zero repairs.

    I have also had many higher power push pull amps in my home for extended periods. These included a Primaluna Prologue, Fisher 500, HH Scott, HK Citation, and Dynaco ST70. These were all in various condition levels yet none gave any noticable hum.

    I see so much interest from many on this forum with "rolling speaker cable and IC's" it would be startling for these same folks to hear the level of change and sound customization one can achieve with rolling tubes. Tube rolling and collecting is an audio hobby in itself. When I'm checking out flea market vinyl I'm also looking for that old ham radio guy's tube stash.

    I've tried solid state preamps with tube amps, tube amps with solid state amps and tube preamps with tube amps but for me all tube is just better. Saying you'd rather have a solid state amp and tube preamp when increased power is not required is like saying you don't want too much of a good thing ( IMO ).

    You can buy lots of tubes for the price of boutique IC's yet there's no comparison to the audible improvement good tubes offer vs IC's or speaker cables.

    If you stay in this hobby long enough and aren't encumbered by hard to drive low efficiency speakers a tube amp is probably in your future. So don't fear it, look forward to it!

  2. #2
    Can a crooner get a gig? dean_martin's Avatar
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    I agree with ghostchicken. Do not be afraid. I'm the world's worst at hands-on diy and was reluctant to get a tube amp, especially one that required manual biasing, but pretty quickly, I found that the rare times I have to bias are ritualistic much like the process or routine I go through in turning on my amp and components. In my integrated amp, I've had two power tubes and several preamp tubes die. It's not a big deal and the problem is much easier to solve than going into the internal workings of the amp.

    When one of those two power tubes blew, it took out the $1.00 fuse. Again, not a big deal.

    Now, I have tubes in both my separate phono preamps and my cd player. Sometimes when I place an order for vinyl from music direct or some other place that carries tubes, I order an extra pair of 12AX7 preamp tubes so I can roll and I'm not caught without replacements. I have a pair of NOS preamp tubes that I run regularly and a few single nos I swap out in my Bellari phono stage (only has one tube), but most of the new production tubes are good, reliable and easy to find. For no particular reason other than I went through that phase, I don't search eBay for NOS tubes anymore, but it was fun when I did.

  3. #3
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Poultrygeist View Post
    I believe many folks are afraid to move to tube amps due to their percieved danger, reliability, concern over DIY biasing and the belief that tubes will introduce hum into one's system.
    The relevant challenge is matching. The very high source impedance of tube amps is a poor match for many speakers causing pretty significant tonal changes. The Advents sound fat and overly dark with the VTLs. With the stats, however, they amps are very neutral. The Advents sound much better driven with the Stasis. The difference has to do with the severity of the speaker's impedance curve. Those with roller coaster curves are poor candidates for using tube amps.

    Tubes do fail and require replacement. Retubing the eighteen tubes in the VTLs costs about $900 which I need to do every four years or so and I keep a complete backup set. Last night, one of the 6550s failed. Fortunately, the (expensive) B+ fuse opened up instead of taking out components on the board requiring repair. This failure wasn't as spectacular as the last time when the output went supernova and glowed brightly before dying. It took me four more $5 fuses to figure out the culprit.

    Some folks just want plug n play.

  4. #4
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    I'd agree that tube equipment is not the black and white situation some perceive. I've had many pieces over the years, building kits from scratch back in the late 60s and 70s and rebuilding quite a few amps the past 10 years or so as a hobby.

    The odds of a problem with a tube amp are a bit higher than with solid state equipment. I had an output tube failure take out a 100 ohm resistor about a year ago. That's an incredibly cheap fix if you can do it yourself and a more expensive hassle if you have to take it to the shop, but it still cost me another $160 for a new quad of output tubes.

    If a person just wants to test the waters with the lowest risk possible, a preamp is a good choice. Preamp tubes last a long time and rarely damage things when they go bad - you just end up with extra noise or no signal passing until you pop the new ones in.

    Equipment using the smaller wattage outputs (EL84, etc.) also tend to be more forgiving than an amp with KT88s or 6550s. It also doesn't hurt to see what people have to say about the reliability of various brands. Some are more notorious than others.

  5. #5
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    E-Stat, If I were spending $900 on re-tubing I'd be getting rid of some gear. Sounds like your power hungry electrostats are taking their toll on your tube amp. I'm running original tubes in one SE amp from the 60's but that amp has always driven easy loads. In 5 years I've had one power tube failure and it was a brand new but defective EL84.

    I agree the relevant challenge is matching and in your case solid state may be a better match.

  6. #6
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Poultrygeist View Post
    E-Stat, If I were spending $900 on re-tubing I'd be getting rid of some gear. Sounds like your power hungry electrostats are taking their toll on your tube amp.
    Getting 4000 or so hours out of a power tube is pretty much standard fare with the best Russian stuff these days. Audio Research claims about 3000 hours for optimum use. Quite a few manufacturers (VTL and ARC among them) use the same SEDs (the original Svetlana produced in St. Pete) which are very rugged.

    As for power, more is better still. Hearing HP's Scaenas driven by Siegfrieds sure made a believer out of me with his phenomenal system.

    Quote Originally Posted by Poultrygeist View Post
    I'm running original tubes in one SE amp from the 60's but that amp has always driven easy loads.
    How many hours do you reckon you'll get from them?

    Quote Originally Posted by Poultrygeist View Post
    I agree the relevant challenge is matching and in your case solid state may be a better match.
    Only for the Advents. Don't get me wrong. I was seduced by tubes early in the game. Hearing tri-amped Tympani IIIs driven by Audio Research amps on the mids and tops with a workhorse Crown DC-300a on woofer panel was a revelation to me at age 17. Everything changed.

    I bought my first Audio Research preamp when I was 24. At the time, I was running Acoustat X speakers which were actively and direct driven by (horizontal video output) tube amps. When I upgraded those to the 2+2, I couldn't afford a reasonably powerful tube amp that could handle the load.

    Sidebar: I am a fundamentally a speaker guy. Yes, everything matters, but that's where I always start. If I could get the same kind of resolution, coherency and image size realism out of more efficient designs, then I might follow that path.

    Back to tube amps. Eventually replaced using the Stasis in the main system with an Audio Research VT-100 MKII. Since the Acoustats also had a forgiving impedance curve, that amp worked well with them. Finally, I understood what HP had been talking about for decades - it's all about the midrange where it was superior to the Stasis - even if it sacrificed a touch of extension at the top. Getting the MB-450s ten years ago made a profound change in dynamic capability and resolution. If I want to snuggle up to a solo piano or guitar, vocal or other smaller venue then I run the amps triode. For larger works, I switch to tetrode.

    It will require a really special speaker to woo me away from the U-1s. Have you ever heard a Sound Lab electrostat? Ray Kimber put on a really special show a couple of years running at RMAF where he used his own four channel recordings through an array of a dozen 922 (nine foot tall - 22 degree radiation angle) Pro-Stats. Since there is a single diaphragm used full range, you choose the controlled radiation angle, frame construction and build arrays for greater power. Mine have but a fourth the panel area of triple 922s but have a wider 90 degree angle intended for single use in homes using a 100 lb steel frame to improve first octave response. You can see pics of mine by clicking the "Systems" link in my signature.
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  7. #7
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    Speakers always dictate the amp. High efficiency full range speakers would not be the best match for a high power solid state amp and a powerful push pull tube amp wouldn't be much better.

    The best scenario for me is the simplest and oldest of all amp circuits, the single ended triode which is low powered and it's tubes don't run at insane temperatures. Heat kills tubes and the more they are stressed by difficult loads the more heat they generate. But it's not uncommon for low output Telefunken radios from the 50's to still have their original working tubes. Power doesn't come cheap as E-Stat can well attest. $900 to re-tube, holy triple micas!

    I find Electrostas interesting but their power needs dictate Frankenstein amps that I don't find as appealing.

  8. #8
    Music Junkie E-Stat's Avatar
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    Quote Originally Posted by Poultrygeist View Post
    The best scenario for me is the simplest and oldest of all amp circuits
    I gathered you were an amp man. To each his own.

    Quote Originally Posted by Poultrygeist View Post
    I find Electrostas interesting
    Which ones have you heard?

    Quote Originally Posted by Poultrygeist View Post
    but their power needs dictate Frankenstein amps that I don't find as appealing.
    Yes there is significant energy storage with a 250 joule amp, but unless you're going inside the case it's not a problem. The first VTLs I heard were Wotans running triode at Sea Cliff driving the big Nolas. 500 watts of triode power impart an authority that is difficult to match.

  9. #9
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    Sometimes noise issues with tube amps may not be the amps fault. When I switched my CJ amp to the Van Alstine (technically a hybrid) I began to hear sort of a ringing noise, after talking with Frank and experimenting the issue was an IC which was only grounded at one end, a quick swap of interconnects fixed the problem.

    Also, any one who may be new to tubes and following this thread should realize that tube amps vary in sound and quality as widely as solid state, so avoid putting stock in blanket statements and generalizations regarding either.

    The Van Alstine hybrid brought my system more toward neutral but if I won the lottery my dream system is Octave Audio, the best tube gear I have ever heard personally, I've never heard tubes sound so transparent and have so much control while giving that live presence of certain good tube gear. My second choice in amplification would be Levinson, I know they get bashed around but I've had opportunity to listen to a couple including the brand new "H" series and they are very good, solid state yet musical IMO. So I guess what I'm getting at is listen to gear for what you like despite what's under the hood.

  10. #10
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    It's no generalization to say there's no such thing as a bad sounding 2a3 SET.

  11. #11
    AR Newbie Registered Member
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    hello all out there im from sweden and im about to make and write a Little hifi Collection
    and looking to find a few Pictures maby if people could show of their hifi stuff from real home

    like those down below im looking for



    Luxman MB3045

    Brook 12A

    WE124

    WE350B tubes

    HK Citation 2

    Eico HF-81

    and the most rare McIntosh mc3500

    hope for some help

    kind regards Robert

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