LETS COMPARE TUBE AND SS AMPS. TECHNICAL


I am seeking some very technically minded people to chat about differences in sound quality, dbs, and power ratings. I have not dived into this much yet but in my past study, I find that some SS amps are uniquely rated (lie about it). Maybe there is special "sound watt" used when comparing input fusing and wire size to rated output. When looking at tubes, their rating for power is much lower. 50-120wpc seems about right. However, I hear people say it comes down to "current" BUT, current and watts are directly related. Since the voltage or wave amplitude depends on the sound to be reproduced, it only makes sense that the only variable is the current, thus the wattage. I run a Rotel RB1080 on my RF-7s at 400wpc. I have to wonder the difference in dbs from a comparable tube amp.



Sure sounds like tube is way more expensive but can really give some nice sound. My experience with tube is only on guitar amps and I would not touch a SS guitar amp now!



Has someone compared tube with SS directly for dbs, accuracy, THD, etc??
viper6383
There has been a debate in audio- tube vs transistor- for the last 50 years. The results of the debate are unimportant. What *is* important is understanding that the debate arises from a deeper conflict as described in the links to the Atma-Sphere site in T_bone's post.

As others have already pointed out, matching between amps and speakers is paramount. The equipment matching conversation also arises from the Voltage vs Power conflict.

I personally feel that the important thing here is the rules of human hearing. I think we can all accept that these rules are going to be violated by equipment that is not perfect (IOW all equipment), but that some will come closer to following those rules than others. I contend that the Rules of Human Hearing are in fact the most important thing in audio- without ears, we would have little interest in audio equipment :)

So what is the most important Rule, IOW what is the thing that is the most important to get right? IMO/IME it is the way we perceive loudness. This is done by the ear/brain system by sensing the presence of trace amounts of odd-ordered harmonics in the sound. The louder these harmonics (5th, 7th and 9th of the fundamental) the louder we will think the sound is.

If these harmonics are unnaturally enhanced, the sound will loose its natural quality. Many things can cause this enhancement, or distortion, but the 2 chief culprits are transistors and loop negative feedback. In fact, loop feedback is the bigger offender. It is possible to build zero-feedback transistor amplifiers to avoid this distortion, and those that have done so successfully are at the leading edge of the art of transistors. However, its a lot easier to do it with tubes (which, for the record, can have full power bandwidth as wide as the best transistor amplifiers).

This why I say the results of the old debate are unimportant- because either technology can be successful if we only know what it is that we are supposed to do (which is obey the rules of human hearing rather than meet an arbitrary set of specs that are meaningless to the human ear).

The objectivist vs subjectivist debate is nearly as old as the tube/transistor debate, and for the same reason. It too arises from the conflict of the Power and Voltage paradigms. The Voltage paradigm is responsible for a set of arbitrary specs that I referred to earlier; we know from listening that they are not important. The Power Paradigm attempts to follow the Rules of Human Hearing.

Don't feel bad if you go into a dealership and get a blank stare when you ask about this stuff, but any dealer worth his salt will invite you to audition the equipment. Until someone has developed a set of specs that if followed, will guarantee that the Rules are being followed, audition is about the only game in town.
Atmasphere, there's one important detail missing on your link mentioned by T_bone and which you perfectly might know as engineer is meaning of ideal source vs. non-ideal. It can also be explained in simple language to the public.

Tube or even transistor output devices can't be ideal by default: What device is closer to ideal source tube or transistor? The total impedance including impedance of the source should've been mentioned as part of the integrated source --> load circuit. There figures will come quite different especially in terms of current passing through the load.
Marakanetz, true enough- but since this **is** the real world, an ideal source exists in dreamland only- we can safely ignore it as a result.

So, what is, is tubes and transistors. Either can have a high or low source impedance, and a price is paid either way, and both (high and low source impedance) have very distinct advantages.

IMO/IME, there is no such thing as an ideal source, and I am not even sure that there is even a good consensus about what that even is. Keep in mind, the reason I used the word Paradigm in the way I did is that those who operate inside one Paradigm will by definition be unable to accept any way of thought that exists outside of that Paradigm. So what is an 'ideal source' for the Voltage Paradigm is very different from that of the Power Paradigm, and if you re-read the paper, you will see the issue clearly addressed.
Watts is Watts, at least into a resistor, which NO load is, as far as I know.

One major difference is the delivery of power into reactive loads, which to a greater or lesser extent includes ALL speakers. Huge phase angles at low impedance will take the wind out of many amplifiers sails.
Transistors typically do better. I don't remember which, but tubes don't like either Capacitive or Inductive loading, again as a general rule.

The articles ref'd to in an above post are a good read. Thanks! Also, Nelson Pass has at least 1 article on the web concerning Current Source amplification vs Voltage Source along with extensive testing of some single driver systems.