I see how this somehow ties into the Lounge now defunct thread: assuming you would have a guaranteed positive impact in front of his investors, would you help him sell this -290dB BS against an X% partnership? If yes, what would be your minimum X?
Patrick, I think I did give him some suggestions how to proceed. Several times.
By the way as first poster he can change the title if he want to, no?
Jan
Then why not stop at -80 dB or so?
If there are people prepared to pay a lot of money for an amplifier with -290 dB distortion, that can be a good reason to make one, if feasible. It's just like 120+ dB dynamic range DACs: there is no reason why you would need such a dynamic range for domestic music listening, but as long as there is a market for it, who cares?
Whether the distortion is buried in background noise depends on how small you can make the bandwidth of your measurement.
Haven't even thought about that. The point is that he wants advice from us to get in touch with an investor or someone interested in his invention. I wouldn't do that unless I was convinced that his invention was worthwhile.
He doesn't seem to understand he needs to convince 'us' that his invention is worthwhile.
Suppose I know someone with a lot of money interested in the next audio thing. You think I want to be the fool that tries to sell him something I don't know about myself??
Jan
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> Then why not stop at -80 dB or so?
In the past 1.5 years, we built a series of headphone amplifiers of various topologies. Some with loop NFB, many without. THD varies from -90dB to -120dB at 1Vrms into 30R.
The best sounding one has only -95dB or so. But more than a few people considered this best sounding.
I do not have a scientific explanation. I just accept it as is.
Patrick
In the past 1.5 years, we built a series of headphone amplifiers of various topologies. Some with loop NFB, many without. THD varies from -90dB to -120dB at 1Vrms into 30R.
The best sounding one has only -95dB or so. But more than a few people considered this best sounding.
I do not have a scientific explanation. I just accept it as is.
Patrick
Or on how long you can afford to wait for time synchronous averaging.
The attached is an introduction for those interested in this technique. It is as old as dirt.
It's not about "knowing" (knowledge is, as clearly illustrated in this thread, totally irrelevant), it's about purposefully selling BS to ignoramuses with thick wallets. A common practice in the high end audio, I don't think you need examples.
He claims it is his way out of poverty. It’s all incredibly strange. It’s almost like he doesn’t realize that no one cares about the EC circuit he’s created and that HiFi products don’t usually sell on technical merits.
I think you misunderstand. The harmonics are already below the noise floor before I even apply the distortion magnifier. The screenshots I posted were the raw results of the QA401. The problem lies in when I make the EC extra potent and the distortion never rises above the noise floor of the analyzer, so the results cannot be seen without resorting to trickery.
Indeed you did, but those things I cannot do here and now because I don't have a working DM and probably won't for a couple of weeks. As far as starting over from scratch with the entire methodology and explanations, I can do that but there's no clean way to do it now that we are 11 pages in and I had hoped that at least you can Scott were keeping up with my meanings. I tried many times to explain. But you never gave any official indication that you were or weren't keeping up until you started to decide to mock me. There are also many other occasions where I was waiting for feedback and rebuttal and never received it though.
Also unfortunately it won't let me change title.
I think it would be accurate to say that I don't even know how to convince myself let alone the rest of you. I think you have a misunderstanding that I am trying to ask people here for anything other than methodology advice. I would not impose anything further in my own intentions.
Well there are a lot more distortion types than harmonic distortion. THD is practically meaningless for audio. There's a reason why high THD amps can sound good and low THD amps can sound bad. I've done several experiments to confirm this for myself.
IMO harmonic distortion and harmonic structure is like a symptom of other things rather than a diagnosis. I try to keep all harmonics below -120db at a minimum although I feel much more comfortable when they are below -140db. I feel like once this goal is reached the "symptoms" disappear which indicates the rest has fallen in line. Of course this needs to be paired with a detailed understanding of the workings of the circuit to find any potential hidden imperfections that can potentially conflict with this theory. I also think there is something to be said for euphonic distortion. IMO IME. Although in terms of audible performance this has only applied to my own designs. I find the vast majority of amps on the market to sound god awful which is part of the reason I'm interested in selling some of my own designs.
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While, perhaps, a bit off topic, it seems this perceptual phenomena occurs because humans must prefer some certain distortion profile. Perhaps, the proper behaving distortion profile is mimicking more the overtone behavior of live music? At any rate, I find it rationally disconcerting that gain stages having unquestionably inaudible levels of distortion are often perceived as not sounding musical. Or, said another way, they sound more artificial.
Obviously, there's been much published over the decades as to what the most musical distortion profile might be. It seems to me that this was determined because distortion was once at audibly high levels, so, one might as well make that distortion sound as pleasant as possible. The most commonly suggested profile is, of course, where the distortion is even order more than odd, although, not everyone agrees about that today. Even so, it seems that some other behavior of the distortion profile must be at work, else we would all simply utilize single-ended open-loop JFET voltage gain stages.
Victor Lamm has long hinted that the dynamic character of the distortion profile is critical toward the perception of musicality. As best as I can gather via published distortion measurements of his commercial gear, Lamm designs for a distortion character which is dominantly second harmonic, flat in percentage across the audio band, and which doubles in percentage with each doubling of of signal amplitude. So, distortion percentage is invariant versus frequency, while it varies linearly in percentage versus signal level.
Yet, all of the above seems that it should only be academic, because of the relatively low levels of total distortion anyhow. In Lamm's preamp's, for example, distortion is below that which should be perceptable. Certainly, it's not at an level where it would seem it could overtly alter perception of musicality.
As you indicate, it's interesting that of the headphone amplifiers you mention, the one most prefered had neither the highest or lowest THD. Makes me wonder how those amplifiers would compare on the relative dynamic behavior of their distortion profiles.
-95db thd is inaudible by any mean already.the AP has a headphones output that allows you to hear the THD only...Could anyone on Earth hear -90db THD? Anytime i see any discussion on lower thd than 90db i just skip it and consider it meaningless.
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I've heard distortions as low as 80db-90-db (can't remember exactly) very audibly through my headphones. Granted these weren't simple sinewaves but dynamic signals caused by a software glitch in my computer.
Now maybe that was some sort of fluke but there was a -80db-90dbish sine sweep that I could hear quiet easily and see on my distortion analyzer. One of the many reasons I think a simple harmonic distortion test is BS for audible performance.
Also I once did a test where I had two amplifiers of very similar distortion profiles that sounded quite differently. (one of them sounded really bad) That's why I perceive harmonic distortion as a symptom not a diagnosis and one of the reasons I don't trust NFB to handle all the work. There are other things happening that a simple sinewave harmonic distortion test does not show.
Now maybe that was some sort of fluke but there was a -80db-90dbish sine sweep that I could hear quiet easily and see on my distortion analyzer. One of the many reasons I think a simple harmonic distortion test is BS for audible performance.
Also I once did a test where I had two amplifiers of very similar distortion profiles that sounded quite differently. (one of them sounded really bad) That's why I perceive harmonic distortion as a symptom not a diagnosis and one of the reasons I don't trust NFB to handle all the work. There are other things happening that a simple sinewave harmonic distortion test does not show.
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i simply don't believe you...sorry! If nobody on Earth is able to hear a -84db dolby s reduced noise on tape , and that is the absolute limit dolby s provides , it can go lower than -60db at times depending on frequency and level, than claiming you can hear anything unless you live in a full proof anechoic chamber and you can hear your heart beating , it is simply a lie or an exceptional experience that very few might have.
I heard here guys claiming they hear -110db under the noise floor of a tape pretending they they were big s...t at Studer or working with DougSax, but you cannot find their names anywhere on a technical paper related ro Studer, Revox... Anytime i hear somebody claiming he was a big name in the industry i just make a quick google "DBS check" and the fact that Google never heard of them is enough proof that they are simply liars.
Just another BS...and this forum in full of it.
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Well, you can believe what you want. I'm just telling you what I saw and heard.
This plus a culmination of other experiences leads me to believe that THD measurements don't mean anything in the face of dynamically changing signals.
This plus a culmination of other experiences leads me to believe that THD measurements don't mean anything in the face of dynamically changing signals.
I have a friend who is an audiologist and "neck-nose-ears" medical physician for 40 years now and i specifically asked him: Can a guy in his 40's or 50's hear anything lower than -84db.He simply said : you cannot hear a damn thing below 80db in most over 50's male adults...
Should i believe him?
I personally cannot hear anything on a blank type 1 tape recorded with no signal in dolby s whose absolute limit is -84db.Can you?
I can hear dolby c faint hiss at -79db, but nothing in dolby s.
Should i believe him?
I personally cannot hear anything on a blank type 1 tape recorded with no signal in dolby s whose absolute limit is -84db.Can you?
I can hear dolby c faint hiss at -79db, but nothing in dolby s.
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I think the point I'm trying to make is I don't trust the THD analyzer specifically when it comes to displaying actual and complete distortion figures.
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I even bought a Pioneer cassette (ct w606)deck which has a digital noise reduction system that offers a min -82db and max -90db noise reduction specified in its manual and again...i can't hear anything and I am not the only one...Hopefully you and others understand why i consider this discussion completely irrelevant.
-90db thd is enough for any amplifier on Earth and they should aim for other parameters to be good, not thd after hitting this limit.
-90db thd is enough for any amplifier on Earth and they should aim for other parameters to be good, not thd after hitting this limit.
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Gunna have to respectfully disagree with you there. I think there are more variables to consider.
4.18 vrms into 100ohm resistor is 0.15 watts, any good amp with proper feedback can have 0.000... thd, Nothing new under the sun....
Any wire or case with a 60 hertz power cord will exhibit a -100db noise floor at 60 hertz. this is absurd to get to 250 db.... not even possible for atoms split in 4.
Also no one gives a damn anymore about THD, we all know they are just marketings.
plus, THD readings for error correction whatever feedback amp it is is absolutely inadequate to judge the quality of the sound... it is not even relevant 0.001%....
we need to see square waves at like 20 hertz at least at 20 watts into 8 ohm + some capacitance and reactant to mimic a driver....
Then we need to see a multiple signal with harmonics and the influence of a disturbing signal on the sawtooth or square wave to get the faintest idea of how this machine will deal with real world signals....
THD is OK to design an amplifier thats it.
Any wire or case with a 60 hertz power cord will exhibit a -100db noise floor at 60 hertz. this is absurd to get to 250 db.... not even possible for atoms split in 4.
Also no one gives a damn anymore about THD, we all know they are just marketings.
plus, THD readings for error correction whatever feedback amp it is is absolutely inadequate to judge the quality of the sound... it is not even relevant 0.001%....
we need to see square waves at like 20 hertz at least at 20 watts into 8 ohm + some capacitance and reactant to mimic a driver....
Then we need to see a multiple signal with harmonics and the influence of a disturbing signal on the sawtooth or square wave to get the faintest idea of how this machine will deal with real world signals....
THD is OK to design an amplifier thats it.
An important note you make implicitly: namely, an inherent sanity check before getting ahead of yourself. In a real sense, it's theoretically possible to have the claimed performance, but it's so far beyond the state of the art that it should come with healthy incredulity. My first reaction is the same as yours, "what of wrong with the setup?"
Not for audio, but, yes, I would be banging down doors for an amplifier with any sort of claim of -260 dB errors anywhere. It means I can almost forget about the pre-adc circuitry in an instrument. I doubt I'm alone in that, but you rarely see better than -150 dB, which is 100,000 times more than what's being tossed around in this discussion.
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