Why do Tube Amps sound more romantic v SS amps


Question newbie on tube amps, why are tube amps according to people who own them say the sound is more say romantic sound vs SS amp ? 

What is better to own cost wise sound advantage single ended and push pull ?

Thanks guys excuse my inexperience on the tube issue.

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I just purchased a Bryston 2.5 cubed amp (for small 14’ x 12’ x 8’ room) I can’t quite wrap my head around this amp. For example, I have two or three go-to female vocalist tracks (one is- Sam Brown’s solo on PF’s live (“The Great Gig in the Sky”) that literally gives me goosebumps or makes the hair on my arms stand up every time I play it, with the tube amp. I’ve yet to experience the “hair on my arms stand-up” playing this track on the Bryston ss amp?

@keeferdog 

In your case, the simple answer is the tube amp is sounding more real.

not really, AB imbalance does contribute directly into third (odd) order harmonic increase. Perfectly balanced second (even) only order harmonics distortion, AB designs “distort" A and B the same way only if tubes are perfectly matched, which NEVER happened. it is very hard to pick matched tube replacement, which will age at the same pace to the <1% point.

Good designed SS amps have many AB transistors in parallel, which reduces imbalance problems. SS amps I have all are “maintenance free”, and there is no need to change any transistors due to aging degradation in 100 000 hrs life time.

@westcoastaudiophile 

We’ll have to agree to disagree since my experience is different from yours! FWIW transistors rarely match at that well, often being quite a bit further apart than tubes. But they are a lot cheaper so you can afford to go through a few to find a decent enough match, a hidden cost in case anyone is wondering why high end solid state amps might cost more than their mid-fi brethren.

Our tube amps parallel of a lot of output devices as well, since they are lower power tubes and a lot are needed to drive speakers directly without a an output transformer. So we have the same advantage of the differences ironing out in the wash as you suggest happens in the output section of a traditional A or AB solid state amp. As these tubes age they tend to drift towards a common value; if tested a few months down the road they tend to test extremely close to each other! As a result (and also because of how the bias is controlled by a very low impedance circuit) the Bias and DC offset of the OTL is thus quite stable and not prone to drift. That kind of stability is part of why we’ve been able to stay in business nearly 50 years.

You may not get 100,000 hours on the equipment before corrosion has had a chance to damage the semiconductors, depending on how long it takes to log that much time. So there may well be a need to replace a device well before that. Just FWIW.

 

@atmasphere agree with you on tubes could match better than PMOS/NMOS or N/P BJTs. Please try to measure distortion of tube amp while adjusting bias/balance of the output tubes, and you’ll see how sensitive it is. Then please repeat the same after 50+ hrs. If you are luky, and your AB tubes are aging the same pace, then distortions will not increase much. There is a lso big issue with output transformers in the tube amp, depending on core magnetics, resistance of coils, symmetry etc you will get variety of imbalance/distortion/FR problems, which does not exist in SS> 

"You may not get 100,000 hours on the equipment before corrosion has had a chance to damage the semiconductors"

-good point on corrosion! In my experience corrosion hits tube amp sooner than SS! Just look at the power transformer, capacitors, output transformer inside the 20yr old tube amp.

Please try to measure distortion of tube amp while adjusting bias/balance of the output tubes, and you’ll see how sensitive it is. Then please repeat the same after 50+ hrs. If you are luky, and your AB tubes are aging the same pace, then distortions will not increase much. There is a lso big issue with output transformers in the tube amp, depending on core magnetics, resistance of coils, symmetry etc you will get variety of imbalance/distortion/FR problems, which does not exist in SS

@westcoastaudiophile 

We've done that plenty of times. No measurable difference. You can avoid a lot of the imbalance issues in output transformers by using a Circlotron, since the issues in the transformer are usually related to DC components, which are minimized in a Circlotron. This is so successful that Circlotron amps made in the 1950s were class B and had no crossover distortion at all. However such amps are rare.

IME tube amps suffer less from corrosion than solid state. I've serviced literally thousands of amplifiers over the last 50 years. You can have a well preserved solid state amp that shows no signs of corrosion but its semiconductors are failing on that account. If a tube amp is given the same treatment its likely the only service it will need (in time) is filter capacitors.

About the only place I see your age argument holding any water has to do with filter capacitors. Because tube amps run warmer, the filter caps have a shorter life than in solid state amps. So 30 years instead of 35, unless the designer placed the filter caps in such a way that they really ran too warm.