I’m way over my head in this discussion, but concerning CD players, I noticed that someone mentioned the D/A converter. This really can affect the sound. My ex-roommate did custom installations for people on the order of 5k and up, and just for kicks he did an A/B comparison between using the built-in converter and a separate component.
I knew I was not a trained ear, but on switching back and forth, it was rather evident that the separate component gave a more pleasing, warmer sound.
Please don’t shoot too hard if I’ve gotten something wrong here.
Randy Slone may well be right, but let me explain why I condemned negative feedback. (By the way, we apparently agree that Bob Carver is a charlatan.)
In the late 70’s, the Audio Critic and several other high-end publications were in love with the NAD 3020, a 20-watt integrated amplifier that sold for less than $200.
According to NAD, the secret was in the high-current design, the amplifiers ability to make 20 watts into any sort of load, even two ohms or less.
NAD also stated that they used less negative feedback leading to less TIM. The audio press, and dealers (like me) believed the story. We believed it because the NAD absolutely sounded better than anything else anywhere near its price. It would even drive Dahlquist DQ-10’s.
Our belief in the NAD cost us a lot of money (instead of selling a $1000 amp we were selling a $200 one) but it was way more FUN to sell an NAD.
Anyway, no one at the time bothered to build a high-current amp with higher levels of negative feedback, so there was no way to test NAD’s assertion.
Other amps did eventually come along that sounded as good as, or better, than the NAD, and all claimed ‘high-current’, if not low TIM.
Michael, I “briefly” discuss the concept of TID (or TIM), that is, transient intermodulation distortion, on pages 19-21 of my High-Power Amp book. In retrospect, I recognize that I should have spent just a little more time on this issue, since the concept seems to be somewhat rampant within the audiophile community (although often described in different terms, such as “memory distortion” by one manufacturer).
TID is literally a misunderstanding regarding several known distortion mechanisms when analyzed in their “cumulative” effect, and it also represents a portion of misguided thinking on the part of some individuals. Allow me to explain.
Hypothetically speaking, suppose you were analyzing the overall performance of a power amplifier suffering from several types of higher-frequency distortion problems, such as “input stage current starving” and “inadequate slew rate.” Such an amp could measure out pretty well in conventional 1-KHz THD analysis, but distortion would rise in extremes of 12 to 18-dB/octave above the P1 frequency of the amp. Such distortion components would be the most extreme when the amp was attempting to process “transient” information (which is virtually always high-frequency, high-level information). The distortion of such transient information creates a rise in harmonic coloration and imitates the properties of some type of intermodulation distortion. It has been suggested that such distortion is created by a type of “out-of-sync” action of the global negative feedback loop, insinuating that the “error” has to occur “before” the negative feedback loop can correct for it. Thus, the higher the negative feedback levels, the higher the level of TID will be.
We might then argue that conventional flashlights are inappropriate for nighttime use, because the light has to be emitted from the flashlight, strike a visible object, reflect from that object, and be received by our eyes. Heck, by the time we actually “see” the object, maybe it isn’t really “there” anymore. After all, light is just as “slow” as electricity.
In truth (all humor aside), TID is an acronym that should never have been coined. What it really boils down to is a form of “SID” (slew-induced distortion), and relates to frequency and level handling capabilities of the amplifier - negative feedback levels are irrelevant. Thus, to eliminate all traces of the elusive TID phenomenon, it is necessary to incorporate a good input stage design and insure the VA stage quiescent current levels are high enough to provide the necessary slew rate for the maximum frequency/amplitude characteristics of the amplifier/application.
I hope I’ve adequately answered your question - let me know if I can be of any further assistance. Till later, take care and God bless.
Till later, take care and God bless.