Otala did call attention to some previously neglected factors. But the solution he proposed was totally unnecessary. Bob Cordell debunked it nicely.
Jan
Jan
Yes - agree. Otala blamed feedback for TIM - something Martin Coloms for example still clings to along with a number of other reviewers. I wrote about this here for those that are interested
Feedback: A Short History
Feedback: A Short History
That article of yours is a must-read for anyone who wants to form an opinion on audio amplifier design and performance!
Jan
Jan
in this case the PDF files from post #82 under
The best audio amplifier books - Overview (Google books)
are of interest
The best audio amplifier books - Overview (Google books)
are of interest
open loop gain that corners to 20khz, what is wrong with that?
low open loop gain not more than 60db, fully complimentary from input to output,
low open loop gain not more than 60db, fully complimentary from input to output,
From an historic perspective, the rather unknown fact that two transistors NPN-PNP push-pull input stages were already known in 1965 shoud be mentionned :
James J. Davidson JAES "Low noise transistorized tape playback amplifier" January 1965 volume 13, Number 1.
distortions? why is it that many are drawn to the sound of tubes with higher THD?
@forr, you mean small signal tranies? power pnp came a bit later for silicons...
@forr, you mean small signal tranies? power pnp came a bit later for silicons...
any way, i like very simple topologies now, a single gain stage, no complications, the ACA fits this bill...
Harmonics give a 'warmer' character to the sound, I think that is no secret.
Nelson Pass sells an 'H2' kit which, when included in an amp, increases the 2nd harmonic content. People love it!
Jan
as NP said in one of his interviews, this audio business is one big entertainment business....
i looked at Matti Otalla's amps schematic, and right there i told myself, why go thru all the trouble, when simple sounds as good?
i looked at Matti Otalla's amps schematic, and right there i told myself, why go thru all the trouble, when simple sounds as good?
Yes, small tranies. Here is the Davidson's circuit of 1965.
Attachments
Last edited:
I don't have any criticism for folks that like low feedback amps/zero feedback amps (maybe in the dim distant past 🙂 ). I've heard some of Nelson's big amps at dealers and at shows (one of them was around 40k GBP for a pair of monoblocs over here) and they sounded fantastic.
What I don't think we should do is claim that any one type of approach or design is better. 'Better' in audio is in the ears of the listener and nothing else - it is entirely subjective. Talking about measurable parameters is another subject. We've beaten this thing to death along with VFA<>CFA, DAC's, JFET vs bip, IC vs discrete etc over the years on this forum. No good came out of it. But, engineering measurements are facts and that is that - debating whether they indicate a more pleasurable aural experience or not is a waste of time IMV.
Each to his own, and enjoy the music!
What I don't think we should do is claim that any one type of approach or design is better. 'Better' in audio is in the ears of the listener and nothing else - it is entirely subjective. Talking about measurable parameters is another subject. We've beaten this thing to death along with VFA<>CFA, DAC's, JFET vs bip, IC vs discrete etc over the years on this forum. No good came out of it. But, engineering measurements are facts and that is that - debating whether they indicate a more pleasurable aural experience or not is a waste of time IMV.
Each to his own, and enjoy the music!
I agree that people should listen to the music and enjoy it as it is, but I see no reason to "improve" the music by adding distortion.
I listened to a huge Pass amp some years ago and I was extremaly dissapointed, the amp was very noisy and distorted like ****.
In my opinion if it's so that people dont like the music as it is meant to be by the artist, the sound engineer and the producer, but are meaning that it sounds better if they introduce noise and distortion, maybe they should listen to another artist instead of using an effectbox to improove the music.
NP is ofcourse laughing all the way to the Bank.
In my opinion the EC amp is in a whole different division.
Stein
Lets stick to the engineering discussion stinius. I'm not going to get into what is right and wrong with the sound - I just want to there to be an honest debate without erroneous claims either way.
🙂
Peace.
🙂
Peace.
Hi Jan,
There is a similar answer that I think is in play. While people are able to hear harmonics of tones, I think the bigger issue may be that what people are hearing from distortion is the intermodulation products created, which often occur at lower frequencies.
Different frequencies in the program can combine (mix) in the nonlinearity to create IM products down in the listening band even if those frequencies themselves are at high frequencies. This simplest example is difference frequencies created by 2 tones and an even order nonlinearity. Like a beat frequency effect.
This has multiple implications. First, in real music there are a plethora of different frequencies and bursts at different frequencies involved, and the nonlinear mixing that can occur as a result can be highly complex. Triple-beat distortion is a simple example. IM products are usually dissonant with any component of the music, and are perhaps poorly masked by the music.
Second, higher loop gain in the audio band, resulting from the 6-dB/octave rolloff of typical compensation, provides more suppression of the IM products because they are usually at the lower frequencies where loop gain is greater.
Finally, the question of the sound of even and odd harmonics also has a caveat. While it is generally accepted that second harmonic distortion may be pleasant, we have to remind ourselves that we do not listen to symmetrical sinewaves or music waveforms. Many, if not most, music waveforms are asymmetrical. If we want to stick with the harmonic distortion model, as opposed to IM, we need to bear in mind that an asymmetrical waveform passed through and even-order nonlinearity will often result in odd-order products.
Cheers,
Bob
At any given time, there is always the most optimal approach for a given set of technical specifications. Establishing this optimal approach must be underpinned by measurement and not by ear for the elementary reason that human hearing is the least reliable way of determining the quality, or lack thereof, of a unit of audio electronics.