Let me end the Premp/Amplifier sound debate ...
I'm old enough to remember Julian Hersch from Audio magazine and his very unscientific view that all amplifiers sounded the same once they met a certain threshold. Now the site Audio Science Review pushes the same.
I call these views unscientific as some one with a little bit of an engineering background as well as data science and epidemiology. I find both of these approaches limited, both in technology used and applied and by stretching the claims for measurements beyond their intention, design and proof of meaning.
Without getting too much into that, I have a very pragmatic point of view. Listen to the following three amplifier brands:
If you can't hear a difference, buy the cheapest amplifier you can. You'll be just as happy. However, if you can, you need to evaluate the value of the pleasure of the gear next to your pocket book and buy accordingly. I don't think the claim that some gear is pure audio jewelry, like a fancy watch which doesn't tell better time but looks pretty. I get that, and I've heard that. However, rather than try to use a method from Socrates to debate an issue to the exact wrong conclusion, listen for yourself.
If you wonder if capacitors sound different, build a two way and experiment for yourself. Doing this leaves you with a very very different perspective than those who haven't. You'll also, in both cases, learn about yourself. Are you someone who can't hear a difference? Are you some one who can? What if you are some one who can hear a difference and doesn't care? That's fine. Be true to yourself, but I find very little on earth less worthwhile than having arguments about measurements vs. sound quality and value.
To your own self and your own ears be true. And if that leads you to a crystal radio and piezo ear piece so be it. In my own system, and with my own speakers I've reached these conclusions for myself and I have very little concern for those who want to argue against my experiences and choices.
Music is a sequence of fundamentals rich in harmonics. The OTL - Output TransformerLESS - is off topic. The images are for "tube amplifier output transformer". Let’s take it as written that atmasphere makes fine amps. The question was about current and voltage. The current and voltage cannot be the same if the harmonics are temporally shifted relative to the fundamental. |
@ieales
Are you saying the voltage is proportional to something other than SPL? You say that the ear is sensitive to phase. Which speakers are you using and are they providing some well behaved phase response? |
@holmz If a single frequency SPL is measured with the same terminal voltage, that SPL should be the same for any amp. Since almost agree that tubes sound different than solid state, then what makes up the ’voltage’ must vary. So if you measure 1kHz 2.83v at the speaker, an SS amp could be 99.999% 1kHz. A tube amp may be 99.5% 1kHz, 0.25% 2kHz, 0.05% 3kHz, etc. Additionally, depending on the amp and system, there could be PSU or loop components. An FFT of the captured output could be revealing. There fore, depending on the equipment and pertaining to the suggestion to measure the terminal voltage to match levels, is that the program SPL may not be the same with the same measured voltage assumed to be made at a reference frequency. Since the early 70’s I’ve had time coherent speakers: Dalhquist DQ-10, KEF 105 MkII, BiAmp Magnepan Tympany IV. From 1987 to 2020, I used Spica TC-50, which were the speakers I carried around to studios. The TC-50 was the first box speaker I heard that more correctly presented the phase coherence that I first heard on Quad 57s. and were able to correctly produce what I heard on time corrected BIG monitors in recording studios. I bought the TC-50 without asking the price or knowing anything about them as they were the first small monitor I’d heard that came close to presenting the recorded sound field. Since 2020, I’ve used Eminent Tech LFT8b’s, triamped with time alignment via miniDSP. The speakers can produce a tolerable facsimile of a square wave. And then I screw it up with tubes. |
If you put a solid state amp and a tube amp on the bench, both might measure quite flat- the H/K Citation 2 is a good example. One amp might sound bright while the other does not. But if you measure the output at the frequencies where the bright amp sounds that way, you'll see that the power can be the same as the amp that is not bright (likely the tube amp). The difference in sound is higher ordered harmonics which tend to be audible with most solid state amps (audiophiles have been hearing this problem for the last 60 years, which has kept the tube industry alive), and the ear is both keenly sensitive to these harmonics (it uses them to sense sound pressure) and assigns a tonality (as it does for all forms of distortion) of 'bright and harsh'. Yet at any given frequency, for a given amount of power into a given load (8 Ohms for example) the voltage and current will be the same on account on the power formula (1 Watt= 1 Amp times 1 Volt). This is a simple fact that cannot be undone. The difference you hear isn't on account of power! Its on account of the distortion signature, which is simply too little energy to show up when measuring voltage and current. The big reveal here is that distortion is always audible! The ear has over a 120dB range and since it uses higher ordered harmonics to know how loud a sound is, its sensitivity to those harmonics is paramount, but poorly understood by audiophiles and engineers alike. Yet that is the main difference you hear between tube and solid state. |
