You learn a lot about what they like, what they'll spend money on. You see clear lines that transcend price. And most importantly you learn how they speak another language most of the time, that just isn't what you'd find around engineer types.
You left out third monkey, sellers, a.k.a. shills.
To see what it's like to sell audio electronics? No need to because I can already see that on this forum.
You mean like the people selling cables that are dressed up super cheap wire? I guess... I don't think they represent the majority by any means. And sometimes what people think is a joke isn't.
This forum is DIY. It shows you nothing about what actually sells at high end shops and online.
If anyone here was truly interested in objectionism irrespective of sales, they'd only be talking about designing recording, mixing, and mastering gear.
It's already been shown. It can be demonstrated that if a 24 bit sourced CD recording was prepared without dither the effect of trucation is audible to some people at down around -96dBFS.
Further, I was reading a review of the latest greatest dac yet at ASR and the guy that does the measurements said the dac distortion came at around -130dB, IIRC, and since the limit of audibility is -116dB the dac distortion is therefore inaudible.
Needless to say I was surprised at the number -116dB, not -117dB and not -115dB, but exactly -116dB! None of the other objectivist guys jumped in to complain either.
Regardless of wherever that number came from, I think the actual number is probably a bit lower for at least a few people. Nothing amazing about it to me, maybe you are more easily amazed, I don't know. Human hearing is an interesting thing and we haven't learned or proven everything it can do yet, IMHO.
Last edited:
He's done that alreadyWhat kind of evidence do you consider as sufficient?
Good, I was not planning to read 93 pages of discussions, ending abruptly as expected.
My answer quote, for your perusal, is below, looks pretty clear to me. Unless "hearing the grass growing" doesn't contradict your prior beliefs, sorry.
Last edited:
Do-you mean damping factor is to be avoided ?
With a good amplifier, measuring the distortion with a speaker load does not show a lot of added distortion. So, as the speaker ignore that feedback is at work, it is just powered with a good signal AND a high damping factor. Am-I wrong ?
If I am, we are back to the current drive.
Last edited:
In the amplitude domain a reverb tail is identical to a fade-out. Using them for evaluating low-bit linearity and dither spectra is a valid technique. Of course, so is playing special-purpose recordings made at -60 to -80 dB re: FS. I have a Denon test disc with tracks like this, and they really showed up limitations of early DACs...on my Auralic Vega tracks recorded like this sound almost normal other than a higher noise level, and they just smoothly fade to noise floor.
Of course you could be pulling our leg, and in this case I would advise that any noise emanating from near a tail is not a good one!
Cheers,
Howie
In general I see your point, but please don't group any single individual, I'm like Groucho Marx in that "...I don’t care to belong to any club that will have me as a member."
Cheers!
Howie
Did you find that out through your marketing research?
Thank you for acknowledging that third monkey was left out in your previous reply.
But this is "lounge" where anything is brought up.
Do you have a link? Again you use a known flawed way of digitizing a signal to prove some point.
Let me add a bit of historical perspective: until the 60's, tube power amps had less than 20dB of GNFB, mostly limited by the output transformer, and produced about .1-.2% THD at mid-band. Life was good if you had the money: good output transformers are not cheap.
in 1961, Tobey & Dinsdale published their SS power amp: 2 gain stages and a quasi-complementary output stage, Germanium In order to approach the THD numbers of the tube amps, they had to apply 34dB of GNFB; they used a cap-coupled booststrap in the VAS to get the extra gain. Hey, it was an OTL topology, they could get away with it, right? Bad idea, but at least it could be produced cheaply!
We had to wait until the Marantz Fifteen by the end of the decade before we had something at least listenable. The topology was different: diff amp input, VAS with a current source, and a complemetary output stage, all silicon; not so borring at its time. (OT: I still have one in my basement, I blew it twice, now I'm wondering if I should fix it or totally revamp it? Any expert opinion will be appreciated)
We had to wait well into the 70' before we got more insight into the internals of a SS amp.
Zung, I agree with you that the Marantz 15 was pretty good for its time (1969), I even bought one, BUT I returned to tubes fairly quickly, and then to my solid state prototype comp differential power amp, because the Marantz 15 gave me listening fatigue. It measured pretty good too, caused me to wonder, almost 50 years ago, what the problem was. Now, I think I have covered most of the bases, and can make a pretty good power amp.
The CD example only makes clear than one particular effect has been demonstrated and accepted as non-controversial. Doesn't prove anything beyond what it says. It does illustrate at least one kind of correlated high order distortion can be audible at low levels.
Regarding what I recalled seeing at ASR, looking at it again maybe I was misinterpreting what they were trying so say. Could be. Picture below. Link: Review and Measurements of Okto DAC8 8Ch DAC & Amp | Audio Science Review (ASR) Forum
Attachments
Be very careful about taking what was said, known and done about feedback in audio amplifiers (and especially solid state) in the 1950’s, ‘60’s, ‘70’s and ‘80’s.
Few really knew what was going on (Bart Locanthi was the exception in the late 1960’s - but he came from a servo and analog computing background in military guidance systems). Most others from what I have gleaned did not fully understand what was going on - just look at the circuits and the compensation networks to get the picture. As mr tinned above, tube designers were used to dealing with c 20 dB feebsck because of the large phase shifts in the OP transformers. Sure, designers of the day thought feedback was a cure-all, but that was 50 years agoe and we have actually moved on. Otala raised the specter of TID/SID but misinterpreted his findings, blaming feedback rather than poor compensation design.
Compensation design is not a ‘small design issue’ - it is key to getting stable, high performing circuits.
See Bruno’s ‘The F- word’ for an in depth discussion on the subject.
For some lighter reading, here is Bart Locanthi’s masterpiece Amplifier History: The JBL SA-600
Here is an article on feedback and why we ended up with ‘feedback is bad’
Feedback: A Short History
Few really knew what was going on (Bart Locanthi was the exception in the late 1960’s - but he came from a servo and analog computing background in military guidance systems). Most others from what I have gleaned did not fully understand what was going on - just look at the circuits and the compensation networks to get the picture. As mr tinned above, tube designers were used to dealing with c 20 dB feebsck because of the large phase shifts in the OP transformers. Sure, designers of the day thought feedback was a cure-all, but that was 50 years agoe and we have actually moved on. Otala raised the specter of TID/SID but misinterpreted his findings, blaming feedback rather than poor compensation design.
Compensation design is not a ‘small design issue’ - it is key to getting stable, high performing circuits.
See Bruno’s ‘The F- word’ for an in depth discussion on the subject.
For some lighter reading, here is Bart Locanthi’s masterpiece Amplifier History: The JBL SA-600
Here is an article on feedback and why we ended up with ‘feedback is bad’
Feedback: A Short History
Last edited:
Ah the confusion and lack of common ground.
What is distortion? What is THD or IMD? If you have THD in an amplifier must you also have IMD? Does the same hold true for a loudspeaker driver?
What is the effect of masking? Hint low frequencies can mask higher frequencies.
What is the musical perception of THD, IMD?
What are the perceptable limits of dispersion? (What does dispersion mean in acoustics?) How does that relate to phase shift versus frequency?
Just a few of the basic issues that are well researched and applicable to much bouncing around here.
What is distortion? What is THD or IMD? If you have THD in an amplifier must you also have IMD? Does the same hold true for a loudspeaker driver?
What is the effect of masking? Hint low frequencies can mask higher frequencies.
What is the musical perception of THD, IMD?
What are the perceptable limits of dispersion? (What does dispersion mean in acoustics?) How does that relate to phase shift versus frequency?
Just a few of the basic issues that are well researched and applicable to much bouncing around here.
- Status
- Not open for further replies.