Tubed Power Amplifiers. Are the disadvantages too great ?

Joseph R.

Joseph R.

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Had a thought yesterday about tubed power amps. I have many friends who will never consider a solid state power amplifier. I am not one of them. I certainly understand the fluidity and “beauty” of tube gear. Nevertheless, considering the great solid state amps out there, the question stands.
 
jdandy said:
Joe.......What specific disadvantages do tube amplifiers present that you might consider too great to own one?
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Just simple ones, like tube degradation, low power, limited ability to handle less than 8 ohm loads, bass overhang, rolled off high frequencies, quality tube availability, high cost of power tubes, need for a vacuum tube tester, tube biasing, tube matching, sound variability dependent on tube brand or date of manufacture, total tube failure, high heat and overall reliability.

I understand that all of these rarely apply. But every one can be a possibility and therefore a trade off. Oh, and I forgot that sometimes the tubes needed go out of production. The stock pile of NOS is not going to last forever.
 
Joseph R. said:
Just simple ones, like tube degradation, low power, limited ability to handle less than 8 ohm loads, bass overhang, rolled off high frequencies, quality tube availability, high cost of power tubes, need for a vacuum tube tester, tube biasing, tube matching, sound variability dependent on tube brand or date of manufacture, total tube failure, high heat and overall reliability.

I understand that all of these rarely apply. But every one can be a possibility and therefore a trade off. Oh, and I forgot that sometimes the tubes needed go out of production. The stock pile of NOS is not going to last forever.
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Joe.......That's some serious tube phobia. . :rolleyes:
 
Joseph R. said:
Dan: You kinda get the feeling I’ve lived with them for quite some time ?
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Joe.......I understand where you are coming from. I have been a tube amp aficionado for over five decades. Yes, I am certifiably old! My very first tube mono amplifiers were a pair of McIntosh MC30 mono tube amps that I bought in 1968. Since then I have owned tube based tuners, preamplifiers, and power amplifier. I can't say they have all been trouble free, but most of the issues were minor, nothing a schematic, a few parts and a soldering iron couldn't repair. Things have improved dramatically with modern tube amplifiers, now sporting protection circuits that shut down an amp in the event of a short at the terminals or a power tube failure. Manual biasing has been made simple with the advent of meters installed on power amplifiers. Some manufacturers have developed sophisticated auto bias circuits that allow you to replace or roll tubes without concern for bias settings.

Power isn't really an issue any longer, either. If you want high power in a tube amplifier, there are quite a few prestigious manufacturers offering some amazingly powerful tube amps, ARC, McIntosh, and VAC to name just a few. The SET crowd will always be shackled to esoteric tubes, low power, and mediocre specification, but they will be quick to point out how wonderful the midrange is. Personally, I prefer full range amplifiers.

Tube availability is not an issue to be worried about. There are quite a few tube manufacturers around the globe making excellent vacuum tubes of all varieties. If NOS is your thing then be prepared to spend some cash for tubes that have taken on transcendental reputations with corresponding prices. Yes, the sources for exotics are drying up, but there are still stashes to be found if one knows where to search and willing to pay.

Yes, test equipment is an essential element to being a tube enthusiast. Modern well designed tube testers are available and should be considered a requirement for those who enjoy tube amplifiers. I have two that get used annually to check the state of the tubes in a preamp and four tube power amps. Knowing the state of your tubes helps avoid future problems, helps to identify problem tubes when an issue comes up, and offers owners peace of mind. Knowledge is power.

Sound variability is not a shortcoming of tubes, it's an asset that can be capitalized on. If an amplifier is the main dish, consider tubes as the spice that brings it all together. Tube rolling is great fun, but it can become addicting and expensive if not held in check by some common sense. Unfortunately, common sense doesn't seem to be so common these days.

You mentioned heat. Yes, tube amplifiers radiate heat, some more than others. Heck, light bulbs radiate heat, sun coming through the window, and your body radiates heat, typically between 250 and 400 BTU's. We are walking furnaces. A room full of people can raise the temperature quickly unless air conditioned. Ventilation is important for tube amps and must be factored in if you wish to play in that world.

And finally, reliability. Tubes are still made by hand. Even with highly skilled assemblers using the finest parts available the occasional tube failure will occur. The same can be said about everything made by the hand of man. Damn near everything fails eventually. Fortunately the overall quality of the more established tube manufacturers is quite good. It is not uncommon to get 4,000 to 5,000 hours from premium power tubes, and between 8,000 to 10,000 hours from small tubes. Think about it. If you listen to music 4 hours a day 7 days a week, you can expect to get approximately 3.4 years of service from power tubes before replacement becomes necessary. Small tubes can last over 5.5 years listening 4 hours a day 7 days a week. That's a lot of listening for a home sound system. When you own tube based audio gear it is always wise to have spare tubes on hand. Buy some each year as the years go by and you will always be prepared when it is time to re-tube your gear. I have about 60 tubes standing by. It makes sense to be prepared. Buying them over time spreads the cost out to where it isn't a big deal.

Then, of course, there's the sound, that glorious tube sound that creates such accurate and believable musical timbre, fully fleshed male and female voices, strings and brass reproduction to die for. There is much to enjoy from tube amplification. Yes, it is a bit more involved and eccentric than simply placing a solid state integrated amp on the shelf and calling it a day. Only you can decide if the commitment to the sublime musical experience of tube gear is worth it. I'm in, but don't misunderstand, I also enjoy solid state amplifiers. I have owned and enjoyed my fair share of them, too.
 
Dan: I can appreciate your love of tubes. I have also lived with tubes for many years. My first being a Bogan PA head amplifier and a 25 watt Lafayette guitar amplifier. My first hifi piece was a McIntosh 240 stereo power amplifier. Every single disadvantage I’ve mentioned, I have experienced first hand. Like solid state amplifiers, I have heard great tube gear and not so great tube gear. But like omnidirectional speakers, I am ready to holler “uncle”. I think of all the distortion I have experienced, not even realizing it was slow tube degradation. Not to mention all the power fuses I have blown due to deteriorating rectifier tubes. So unlike you, I am not sure it is all worth it. As my components grow old, I am replacing them with solid state gear. I am not ready to go quite as far as an integrated amplifier, but I love the consistent sound of high quality solid state. When I flick the switch, I know I will hear exactly what I have worked so hard to achieve.
 
I've never owned a (home audio) tube amp so I can't speak with any authority on them. However, I have owned many hand made (boutique) tube guitar amps. I would not own a ss guitar amp, but that's just me and my ears. The only ss guitar amp I owned was a Thomas Organ era Vox Royal Guardsman (2x12" speakers and a midrange horn). It actually sounded OK as long as you kept things clean, tone wise. As you might expect from an early ss amp the distorted tones were terrible.

I know we're talking guitar amps and not home audio. Distortion is often a very desirable thing to have with a guitar amp...not so with a home audio amp. But I can say I never had to replace a tube in any of my guitar amps except when I wanted to. It was usually because I wanted to experiment (roll) with tubes for a different tone.

However, I would still be hesitant to own an all tube home audio amp for reasons already stated by others above. Ironically, it's still mostly a reliability issue with me. Even though I've had pretty good experiences with tubes. NOS tubes are continuing to age and they are gradually becoming picked over, making finding high quality NOS tubes a challenge. In ten more years there will be far fewer to pick from. Not to mention the cost, especially for power tubes. The last set of RCA NOS power tubes cost me $200 for two. That was almost ten years ago. When you're dealing with four to eight power tubes and the same number of preamp tubes reliability can become an issue. JMHO, but, there are currently just too many far more reliable, ss amps with outstanding sonic performance to make me want to go back to tubes. Something's wrong if we can't find a great sounding ss amp at a reasonable cost. Especially these days.

Now that I've said all that, I'll be auditioning several amps to go with my Harbeth speakers next month. One of those amps will be a VAC integrated, if it's available at the time. I'll try to keep an open mind regarding sonic quality. Who knows? I could end up with tubes...again.
 
I've owned both tubes and SS. I've had issues with both, but like anything made, it will break one day and depending on the maker and their customer service repairs are usually painless and supported. I say, enjoy what you have got, Also this subject reminds me of the subject Digital vs LP's, there is never a winner in opinion. One thing about this great hobby, its personal. I don't buy gear based on what someones likes or dislikes. , I buy what I like.
 
Joseph R. said:
Just simple ones, like tube degradation, low power, limited ability to handle less than 8 ohm loads, bass overhang, rolled off high frequencies, quality tube availability, high cost of power tubes, need for a vacuum tube tester, tube biasing, tube matching, sound variability dependent on tube brand or date of manufacture, total tube failure, high heat and overall reliability.

I understand that all of these rarely apply. But every one can be a possibility and therefore a trade off. Oh, and I forgot that sometimes the tubes needed go out of production. The stock pile of NOS is not going to last forever.
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Yeah, but why not start a thread bashing tube gear anyway?
 
Dan, what a great answer. The only issue you did not address what what happens when a transistor fails in your SS amp. I have seen SS amps fail and when they do they get thrown away at times. Other times they can not be brought back to original spec so they sound different after repair. What do you think is going to happen to your First Watt amp when those not in production parts are gone. I bet, don't know for sure, but I bet tube amps are found to last a lot longer than SS amps. They may require upkeep and maintenance, but there are a lot of tube amps from the 50s still doing just fine.
 
Kingrex said:
Dan, what a great answer. The only issue you did not address what what happens when a transistor fails in your SS amp. I have seen SS amps fail and when they do they get thrown away at times. Other times they can not be brought back to original spec so they sound different after repair. What do you think is going to happen to your First Watt amp when those not in production parts are gone. I bet, don't know for sure, but I bet tube amps are found to last a lot longer than SS amps. They may require upkeep and maintenance, but there are a lot of tube amps from the 50s still doing just fine.
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Kingrex.......Thank you for the compliment. I thought about digging into solid state amplification in last night's post but it was 12:30 AM, I was getting tired, and the post was getting lengthy. You bring up a good point about solid state failures. They are not as uncommon as people tend to believe, and often can result in catastrophic damage to the output stage and power supply. Like you said, matching critical parts like outdated output transistors can be a challenge when repairs are made, with some repairs ultimately altering the sonic signature integrity. I have owned many solid state amplifiers, Hafler, Dynaco, Adcom, Kenwood, and at least 10 McIntosh solid state power amps, as well as 10 McIntosh tube power amplifiers. I have been fortunate that only a couple components caused repair issues. The majority have been reliable performers.

There is no guarantee that audio equipment will not fail at some point. Being a solid state component doesn't make it immune to failure. If it were a given that all audio components would last a half century there would be no such thing as a factory warranty. Who would need one. Then again, there is no reason not to believe well designed and built audio gear can't last an indefinite period of time. I have a 50+ year old McIntosh MA230 integrated amplifier (solid state preamp/tube power amp) that still sounds marvelous. Listening to it, you would not have any thought of its age. I had the power supply rebuilt with new caps, but beyond that the MA230 integrated amp is still making sweet music after all these years. This is my YouTube video of the McIntosh MA230 playing in the studio.


 
CPP said:
I don't buy gear based on what someones likes or dislikes. , I buy what I like.
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Like you Chris, I do too. When I go to audio shows like RMAF, Axpona and now the Florida Expo, I am amazed at how many power amplifiers are super impressive. Soulution, Constellation, Roland, Pass, Nagra, VAC, Quicksilver and Van Alstine, to name a few. Some are SS, some are tube. There is so much quality gear out there, I wonder if those little glass bottles are buying anything ? One disadvantage I forgot to mention is the tubes that don’t work straight out of the box. I have retuned a good number of tubes.
 
I've read this thread with interest, and Dan has provided some really exceptional background, information and context.

Here's my perspective, having used tube power and preamps now for 10 years, since getting back into high-end audio: today's tube components are excellent quality, provide superb performance across the audio spectrum, and per some of Joe's concerns, are both reliable and durable (which are different quality attributes). Tubes today have excellent spec to spec consistency and little to no unit-to-unit variabilty. and excellent tube durability.

Last, and this point may be a bit controversial, but in my personal view, you have to spend considerably more on a SS amp to obtain or match the performance of a well-designed and manufactured tube amp.

So, while I am in agreement with the points of concern Joe raised in his first post, from any practical (that is, real-world rather than hypothetical) perspective, the concerns or problems raised are non-issues.

Just my 2¢. Cheers,
 
Tube versus solid state really is a personal preference. I have gone through the gamut since getting back into this hobby a few years back.

I have had tube amps; ARC, Quick Silver, Audio Mirror; and solid state; McIntosh, First Watt, Wyred 4 Sound, PS Audio, Job, SST, and T+A. I might have forgotten one of two :)...

I had tube pre-amps; ARC, Dennis Had; and solid state; W4S STP-SE, W4S STP-SE Stage 2, McIntosh, Benchmark (DAC pre), NuPrime (DAC pre), T+A (DAC pre), etc.

I have had a tube go bad... startled the crap out of me, and had to bias with built in meter and even bias using a multi-meter. I have had a tube amp that acted very flaky, had SET mono-blocks, etc. None of that would stop me from getting a tube amp again. The ones I had sounded great and were satisfying. Tube rolling is the devil :). I constantly thought maybe this other tube would sound better. I bought NOS tubes, Sylvania Bad Boys, CBS Brown Base, Black Treasures, Golden Lions, etc. I dealt with a lot of heat... ALOT OF HEAT... that still didn't turn me off to tubes, and at some point, depending on what comes along I might try another.

However, I found that I never felt settled... always feeling like a need to try a different tube, every time I heard a little noise I would think, is another tube going bad. I finally felt that the tubes were stopping me from really getting into the music... I keep worrying too much about the gear, about tube rolling, heat, looks... etc. I never would listen to my tuner because I always felt I was wearing out tubes listening to background music.

And then I found the Wyred 4 Sound Stage 2 pre-amp and the T+A amplifier. They sound as good as any tube I have ever heard, but most importantly, I felt like I no longer worried about the gear and could just listen to the music. I could just turn on the equipment and listen to music. I didn't worry about the gear any more. The convenience and ease won out. Music won out for me.
 
Joseph, I guess I don't truly understand the basis for the thread. It is kind of like starting another Cable Thread.
Anyone that has been around or owned tube equipment clearly understands the possibilities of amazing sound and catastrophe of failed tubes and taking out resistors and capacitors. Not to mention the cost of new tubes.
When one purchases tube equipment you come to grips with in a not to extend period whether they are for you.

Just my .02 and personal feelings burning aprox. 50 tubes at any listening moment.
 
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