The RTA has a 61-band graphic display and I can watch the noise floor portrayed on the display change in real time as I move the power cord around. This doesn't take an act of genius or any real training to observe the display and I assume that as it goes down, so does the background electrical noise level.Originally Posted by Ian Mackenzie
The Behringer has a noise floor of -113 dB and I was observing a noise floor of ~-100 dB, so it was within the Behringer's claimed range.
I am entirely in agreement on the single listener at a time seated in the listening position, any others will be asked to be out of the room or at least out of eye sight to avoid any unintentional signally cues.
Regarding level matching, the digital pre/pro that will be under test has 0.1dB output adjustments so getting a very close level match should not be an issue.
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Have you had others operate the switching without you knowing which cap is in the circuit at a given time?
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I do it in the dark and don't know the orientation of the switch. On some things it is pretty obvious. Others, not at all. It depends on if that spot on a track is highlighted by the minute differences or not. That's why you need to be able to instantly go back and forth between the two at any point in time as many times as necessary.
You may hear a specific spot on a track that "bugs" you (e.g., glare) and do the comparison at that spot to see if there is improvement or not.
But the question is level matching to what noise source? I have found that when comparing my tube amp and solid state amp, pink noise may not be the best way.
Why??? Because the tube amp rolls off, so to match the levels to pink noise the midrange is increased relative to the bass and treble on the tube amp. So if the track that is to be played is, say bass-heavy, it will be louder on the SS amp. If the piece caters to the midrange, it is louder on the tube amp. The same thing occurs to some extent to any equipment that has a differing roll-off.
So, the reality of the situation is that to match levels you would need to play the entirety of the track to be auditioned and match the Leq levels of the track.
Or...???
We use a 1khz tone (not warble) +/- .005 volts. Comparing transformer coupled tube amplifiers with solid state is always going to show obvious differences in frequency response.
Since I am comparing line level devices that are flat plus or minus fractions of a dB from below what my speakers can recreate to way above what any of us can hear, I doubt the frequency I pick will matter, but I was planning on checking a couple of mid band frequencies (sine waves). I don't think it'll be a big deal. The hardest part will be the record keeping. For each participant's test to be useful we need to repeat it at least 10 times.
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Seems like this would be even worse than pink noise. If a piece of equipment has a peak/dip at this frequency, it is penalized/accentuated across the rest of the spectrum.
No, probably not for what you intend to do.
That’s not a necessarily valid statement either.
Is your Lyndhorf processor better ? Of course you think it is? But is it?
I’m betting your bottom dollar if you were the distributor and your sales team took the unit home and compared and there was a consensus it’s improved you’d be jumping all over it.
Your posturing conjecture.
The notion that your RTA is actually going to prove anything either way is myth.
Those measurements on Stereophile unless l am wrong are of a AP525 analyser which is looking at the electrical signal versus noise with a specific filter.
That in itself isn’t necessarily an indicator of what the audible differences are btw.
That is common sense if you’re technically astute. Stereophile are just looking for a reaction from you. They have succeeded.
The pertinent point is do you really think Naim are stupid enough put something to market if it’s a hoax? They aren’t going tell you how it works. The comments are pure speculation.
What l can tell you is that eliminating all forms of power supply noise or mains noise interference ultimately have an impact on the purity of the audio signal in one form or another.
Most people can audibly detect 2nd order (H2) when it’s -80 db and amplifiers with different distortion profiles. When noise gets mixed inside complex audio circuits the result is often unpredictable because models don’t accurately inform us of physical phenomena in a practical circuit layout.
So then, you don't think that as the display drops, the signal that drives the display drops? And when I turn on the air conditioner and watch the noise floor increase, that doesn't mean that the line is actually getting "noisier" even though the display goes up?
Kind of contrary to the whole idea of the display isn't it?
Hi Ian... how are you doing? Haven't heard from you in a while.
Of course I think my Lyngdorf processor is better? Better than what?
Please try to restating your post. I have no idea what you are trying to say.
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Why would someone even go to the effort of a double blind test if one piece of equipment in the test had an obvious peak or dip in its frequency response at 1khz? Voltage matching at 1khz is the only method for comparing equipment in listening tests I've seen used. I've not compared equipment of radically different specifications. We're usually trying to compare things that measure similarly (as Mr Widget is planning) to see if we can hear a difference between them, or as in the Stereophile example, if an 'upgraded' power supply can have an audible difference in a component.
To respond to your recent post.
I find your post is without sufficient technical understanding between measurements and what people are actually able to discern.
That’s why l made the comment about your Lydorf processor. If l replaced it with another processor without you knowing it would you realise it?
Psycho acoustics isn’t an exact science and Nelson Pass has stated there is still a long way to go before we can rely on measurements alone to validate what we hear.
If you look at some THD measurements versus amplitude of preamps in Stereophile test reports the distortion rises very rapidly at low levels below 100 - 200 mv.
But it’s not distortion. It’s the residual noise because the analyser doesn’t discriminate between noise and distortion. At low amplitudes which are often the nominal listening levels in a room the noise is significant in relative terms.
In layman terms l’m referring to soft passages or sounds between subtle transients such as a flute in the background while a piano is playing. This is where the fidelity can suffer. That is because those subtle sounds are much closer to the noise floor. The human ear has more difficulty translating certain sounds as the level drops.
All this happens very quickly with recorded music so the ear - brain is working hard to pick up everything. If the sounds closer to the noise floor aren’t accurately made out then the perception of what’s heard will change. This is because most of the dynamic range in recorded music sits below your normal listening level. If these subtle sound aren’t as pin sharp as the louder sounds then Houston we have a problem.
Of course this is just one facet of high fidelity sound reproduction but one that is constantly overlooked.
To support the above :
In numerous reviews of Pass Labs preamps using separate power supplies there is a consensus that separate power supplies make a difference. I have called this out when talking about low noise design of active crossovers. Still the sceptics remain.
Wayne Colburn at Pass Labs in this clip.
https://youtu.be/6UzoQGTqOQA?si=Uv09oAzxbDaDq0hX
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