Tube Amps for Dummies

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David Matz

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I have never owned a tube power amplifier, and I understand it is a "hobbyist" proposition. One of the biggest dealers in Chicago, who has been in the audio business for 40 years, does not sell them because of "clear disadvantages" to SS. What are the disadvantages? How can they be overcome, remedied, or mitigated? What knowledge, tasks, or activities are required to own and be satisfied with a tube amp? Are certain brands more user friendly?


Thanks!
 
The only disadvantages to tube amps is that tubes have to be replaced from time to time and they tend to run hotter than non-class A SS. Tube amps tend to be heavy, all that iron in the transformers and have lower power at equivalent prices to SS.

As far as a hobbyist proposition, tube amps may require biasing, keep in mind that biasing a modern tube amp is not difficult. I rebiased mine yesterday and it took all of a half hour to complete for both amps. At two to three times per year that is a total of one and one-half hours. Some don't even require that. Prima Luna, et.al. amps have an auto-bias circuit so you put in the tubes, turn on the amp and voila, the tubes are automatically biased for you.

Tube amps can be fine tuned sonically by the judicious choice of tubes and bias point to give you a customized sound if you're so inclined. I'm not, but many roll tubes to get just this level of sonic refinement. Try that with SS.

IMO the real benefit to tubes is a closer approximation of the tonal balance, sound stage recreation and life of the real thing, though many will differ.
 
David, there's not much I can add to risabet's post. My McIntosh is so user friendly, I can't think of anything to do except dust it! Your choice of speaker does have some bearing though. Unless they're very large (lots o' tubes) and high powered (lots o' heat) tube amps tend not to provide the best bass control over cone woofers. But individual needs and musical taste may mean that's not an issue.

Of course you can bi-amp, using a modest ss amp for the bass, or buy a powered subwoofer, OR, if you are about to buy a (MartinLogan) speaker, I suggest either a Vantage or a Summit. Both come with their own ss-powered bass section(s) making a (minimum 100W/ch) tube amp a no brainer IMO. Why? Because stats in general are so accurate that few other speakers are so suited to bringing out the subtleties of which tube amps are capable.

There are ss amps today that (I understand) can rival a tube amp's qualities. But they are few and very expensive. The darTZeel is one example. From that point of view, tube amps are an excellent dollar value.
 
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David, there's not much I can add to risabet's post. My McIntosh is so user friendly, I can't think of anything to do except dust it! Your choice of speaker does have some bearing though. Unless they're very large (lots o' tubes) and high powered (lots o' heat) they tend not to provide the best bass control over cone woofers.

You can bi-amp, using a nodes ss amp for the bass, or buy powered subwoofer, OR, if you are about to buy a (MartinLogan) speaker, I suggest either a Vantage or a Summit. Both come with their own ss-powered bass section(s) making a (minimum 100W/ch) tube amp a no brainer IMO. Why? Because stats in general are so accurate that few other speakers are so suited to bringing out the subtleties for which tube amps are capable.

The are ss amps today that (I understand) can rival a tube amp's qualities. But they are few and very expensive. The darTZeel is one example. From that point of view, tube amps are an excellent dollar value.

If you get a chance, I would check out the newer Plinius amps, or even the ones that Dan, Dave, and Joey own (SA-102 -?).

Awesome class-A biased amp.
 
I just started down the road with tubes and so far I love it. I’m running all glass now and what a difference. The music is warm and more engaging. My 55watt tube may lack the slam of the 250 watt Sunfire ss amp that I used to use. However, the tubes make up for this with detail and soundstage. To me this is what HiFi is all about.

Next step for me is to bi-amp.
 
Listen to a high-quality tube amp on Summits or Vantages and you will understand. BTW - it's worth all the effort. (not as much as you've been lead to believe.)
 
Plain and simple: Tubes sound better! If you have speakers that are too difficult for a tube amplifier to drive, change speakers.
 
"My 55watt tube may lack the slam of the 250 watt Sunfire ss amp that I used to use. However, the tubes make up for this with detail and soundstage."

A-bleeping-men!
 
There is yet another way to get the "best of both worlds"... pair a tube Pre with a SS amp! You'll still get most (if not all) of that tube "magic", yet still have the simplicity, reliability, and bass control of SS. Also, if so inclined, you can still try tube-rolling with the Pre. Another advantage is that Pre tubes need NO bias adjustments, and tend to last a lot longer than tubes in amps.
 
There is yet another way to get the "best of both worlds"... pair a tube Pre with a SS amp! You'll still get most (if not all) of that tube "magic", yet still have the simplicity, reliability, and bass control of SS. Also, if so inclined, you can still try tube-rolling with the Pre. Another advantage is that Pre tubes need NO bias adjustments, and tend to last a lot longer than tubes in amps.

That's what I am doing. I got an ARC LS MK2ii coming soon. Can't wait to try it out.
 
Valve amps do have "Clear limitations", but so do solid state amps! It's all about preference - that's why there is a market for both.

You'll have to listen to both to understand.

Risabet is spot-on, and add to that the fact that tube amps are driving your speakers through an output transformer - not an insignificant limitation!

Agreed that you can get "almost" the best of both worlds by combining a tube pre with a SS amp - that is exactly what I do - Copland CTA305 --> Classé CA-101.
 
There is yet another way to get the "best of both worlds"... pair a tube Pre with a SS amp! You'll still get most (if not all) of that tube "magic", yet still have the simplicity, reliability, and bass control of SS. Also, if so inclined, you can still try tube-rolling with the Pre. Another advantage is that Pre tubes need NO bias adjustments, and tend to last a lot longer than tubes in amps.

Not all IME, the tube pre/SS amp combo will give about 70% of the tube magic but to get it all you have to go all the way. That final 30% is the full package, the reason that tubes are the way is the sound of the amp.

You can get tube amps w/o the output transformer, which may not be as much of a limitation with current t-former technology as previously. OTL amps may be the Ne Plus Ultra of tube sound but have their own issues not to mention they won't work with low impedance speakers like MLs.
 
get your feet in the water and see how it feels....

Personally, I'm in the tube preamp and solid state power amp category because I listen to my system 10 hours a day and that wears tubes out in a hurry!

There are a lot of great tube amps out there and if you buy used, a number of great values as well. Most modern tube gear really isn't any trouble, though current Chinese tubes aren't always as reliable as they could be.

Let us know what your search reveals....
 
This comparison brings to mind the other tube vs. SS discussion:

CRT vs. digital projectors

While I'm seriously in the SS camp on audio, for video, I've been running a big-a$$ CRT projector (Sony G70) for seven years and love the image. Three huge ‘tubes’ in that thing ;)

It is 'softer' than digital PJ's, definitely not as sharp but oh does it have outstanding color and black levels. Black is so black, you cannot see your hand if you hold it between the screen and your face.

But just like tube amps, this puppy requires registration tweaks every six months and if you ever move the screen, a full-on focus and alignment session that can take six hours.
Oh, and they heat up the room something fierce.

I'll be crossing over to the digital side sometime next year, as those are finally getting close enough in all areas (they are ahead in some) to CRT to make the jump.

The preference for a tube amp on audio I find to be parallel to using a CRT, softer, less sharp, but somehow more pleasing to the eye or ear.
Whether it's because it masks flaws in the sources or just interacts better with the speaker is debatable. But many of you seem to like the effect.
 
"Tube Magic" ???? No such thing. There is nothing "magic" about it, just marketing BS developed over the years. Tube sound is the sound signature of the amp and tube combo, change tubes change the signature (usually). Either you like the sound of tubes or not. But there is no magic about it.

"Tubes sound better" ????? A VERY VERY subjective statement with no truth to it at all, just someones opinion. Again, either you like the sound of tubes or you do not. The only better in audio is what the end user thinks.

David: You need to get out and listen for yourself to see what you think these amps. As you have read here before, try to get one home to audition, and again see what you think. I am not going to sit here and tell you what is better, because I am not you. You need to decide this, so read all the posts here realizing there is a bunch of biased statements being presented to you. And it is expected for people here to show some bias towards their gear.

Keep a very open mind with what ever amp you decide to audition either Tube or SS.

Take detailed notes of your experience to remember your sessions.
 
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Folks,

Thanks for all of the spirited replies. I think this has evolved into a tube/ SS discussion, while my original question was about maintenance, since I am a pretty lazy guy...

How does one bias? Is this the same as measuring tube strength? How does one know which of the X tubes in the amp went out? How many tubes does one have in the drawer in case of an emergency? How does one know where to reliably purchase tubes? Upscale Audio advertises unit re-tubing - if this is so easy why mail it to them and let them do it?

I have not done much auditioning of tube amps because the Ascents needed power, and my Bryston threw a lot of power at the speakers (and was an amazing value at the same time). Now that I own the Vantages and the Bryston has become the new weak link, I am curious to experiment.

By the way, I have listened to some solid state amps on the Vantages and my impression is that they still love power, but power is relative to price point levels. My impressions: Ayre V1-Xe 200 watt/ channel - $9k amp >>>>>> Mac 400 watt/ ch >> Bryston 250 watt ch ($2400) >>> Ayre 150 watt/ ch ($4500). After hearing the Ayre V1, I was blown away - I left the dealer emotionally moved, but it's $9K!

My experience with pre-amps is that at the higher price points people would find it hard to distinguish tube gear and SS products blind folded - it just becomes great emotionally conveyed music regardless of the technology under the hood. There may be differences within a brand family, however. Listening to BAT SS vs tubes, the tube product does have a slightly more seductive quality, as if one was feeling a fine cloth with their fingertips. The SS was no slouch either and had slightly better bass. Victor Khomenko of BAT told me he prefers the sound of his tube products to SS, although he is very proud of his SS stuff.


Thanks again for your advice.

David
 
Biasing an amp is basically setting the point where the signal waveform switches from one tube to the other in a push-pull pair. Depending on the tube and the amp the bias can be set to class A, AB1, AB2, or B. Each type of tube has a certain maximum limit of current that it can conduct (dissipate) and the bias must be set appropriately e.g. EL34/6CA7 35-40ma, 6550/KT88 65ma, etc.

Some amps are autobias and you'll never have to set the bias. Some use LEDs and a bias pot that you turn until the LED lights up or goes out depending on manufacturer. In my case I need to use a DMM and measure the current flow while adjusting the bias pot to the correct reading. All of this is done away from the circuit board. The final type requires you to measure the current across the tubes load resistor which does expose one to the lethal voltages (>500v) inside a tube amp. Be careful with these types as they can kill you. You are unlikely to see any current amps with this setup.

Check out the link for a more detailed explanation.

http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#bias
 
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This discussion could get ugly so I will not fuel the fire. I have three amps one tube and two SS. My main listening is with the tube amp. The two SS are for the center and rear spears for home theater.

As Dan (DTB300) has so eloquently stated it is a matter of choice. There is an expense involved, there is a " little bit" more time involved in regards to maintenance and possible issues with heat dissipation. it comes down to preference in sound, a budget and after that requirement is satisfied then you can move forward.

The difference is "sound" has a lot to do with the design of each type of amp. There is the difference based on even and odd harmonics which is more pleasing to the ear (odd typically). A tube when it does distort does it in a more gradual way where a SS distorts (clipping) tends to be very noticeable and painful a times.:eek:

I would listen to the manufactures you like and ones which are in your budget. No one can tell you which will sound better that is your choice alone. The best thing is to listen to a few then see if you can get a demo for the weekend. Then listen to your setup again and then the following weekend do it again with different equipment.

This is trial and error until you find the sound you like. It may be you end up keeping everything because it is the best for what you desire at this time. There will always be time to change again and I think this is where some of the fun of this hobby, it is always changing and evoling.

Jeff:cool:
 
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"Tubes sound better" ????? A VERY VERY subjective statement with no truth to it at all, just someones opinion. Again, either you like the sound of tubes or you do not. The only better in audio is what the end user thinks.
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But then isn't pretty much everything stated here subjective? Even though I am very definitely in the tube camp I agree wholeheartedly with your last statement quoted.
 

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