What is wrong with op-amps?

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Here I disagree. If my amp has 0.1 % THD in the audio band, and your amp has 0.001 % THD at 100 Hz and 0.1 % at 10 kHz, I would like to think that an instrument with a fundamental at 5kHz, would sound more natural with my amp. [snip].

But you never listen in isolation to an instrument with only 5kHz fundamental. You listen to a full spectrum of music. And if both amps have 0.1% at 10kHz, both will reproduce the 5kHz instrument equally well. But the 0.001% at 100Hz (which probably has 0.01 at 1kHz) reproduces the lower fundamental instruments better, more uncolored.

Anyway, I note that you say 'I would like to think' which is of course your personal prerogative.

jd
 
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But you never listen in isolation to an instrument with only 5kHz fundamental. You listen to a full spectrum of music.

Fully agreed.

And if both amps have 0.1% at 10kHz, both will reproduce the 5kHz instrument equally well.

Partly agreed, what about higher harmonics?

Anyway, I note that you say 'I would like to think' which is of course your personal prerogative.

jd

I have designed amplifiers with no global feedback and amplifiers with global feedback with an open loop bandwidth greater than 20 kHz (Class A all over).
To me, these amplifiers have a similar way of reproducing music. I also must add: THD is quite low also for the amplifiers with no global feedback. But as everybody(?) know, all amplifiers sound different. It is all about design philosophy and personal preferences, I am afraid.
 
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Partly agreed, what about higher harmonics?
[snip].

It was your argument that amps with the same hf distortion reproduce the hf signals (exacmple 5kHz fundamental) equally well, in this context, so I don't understand your question.

[snip]But as everybody(?) know, all amplifiers sound different.[snip].

It's what everybody BELIEVES. The repeatable, reliable and well controlled tests that have been done about this fail to uncover this difference.
But as you say, it's all about personal preference and as anyone knows, personal preference has an overwhelming impact on what you perceive.

jd
 
Look at my MPP thread, there i posted several buffer designs with different types of distortion profiles. Unfortunately that thread got rather long and complex but i could post 3 types with different profiles that where measured and auditioned. I found like others before me that a small amout of low order harmonics can be benefical for subjective sound quality. The intesting thing is that for example 0.1% second harmonic does not sound distorted but full and dynamic. I usually design for lowest distortion posible and add distortion ( if i want ) in that buffer stage. So i can keep the amplification chain clean and modify the signal at only one place in the topology. I thought for a long time to develop a modern version of a tone control that is able to add "designed" amounts of distortion, has a parametric equalizer to tame problems in the recording and loudspeaker - room interface and is of cause a total seperate module that can be bypassed.
 
OP-Amp
- we can not generalize, as there are 1.000 of different op-amps
with their very own mix of different transistors inside
One op-amp can be almost as different to another
as one Tube can be different to one Silicon Transistor

When we tell one op-amp 'sounds' like this or that compared to something
we should always tell WHAT op-amp we refere to.

My opinion
is that for a gain of 4 (+12dB) at very high performance
there are at least a handful 5-10 'audio op-amps'
that would do as good a job so no discrete circuit
could make you noticable improvement soundwise.


Several such op-amps has already been mentioned.


Finally.
op-amp vs. (discrete) transistors circuit for same use

There should not be much difference, basically.
- An op-amp is a bunch of fet/silicon transistors attached as a circuit.
- The discrete transistor circuit will be a bunch of fet/silicon transistor
attached in another way as a circuit.
 
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I can't speak for anyone else here, so I won't - just for myself. This statement is not true. I have no beliefs in regard to amplifier sound - but I do hear differences between differently wired amplifiers. A well grounded amp (star earthing) sounds more transparent, more 'musical' than one with poor grounding.

I agree with your post, but the thing you don't agree with is not what I meant - it was taken out of context.

The poster said: "everybody KNOWS that etc..." to which I said: "everybody BELIEVES that etc.".

But we agree basically I BELIEVE ;)

jd
 
I can't speak for anyone else here, so I won't - just for myself. This statement is not true. I have no beliefs in regard to amplifier sound - but I do hear differences between differently wired amplifiers. A well grounded amp (star earthing) sounds more transparent, more 'musical' than one with poor grounding.

Very Truth.

I think one can truly have much more influence in sound with proper PCB design and very good grounding, rather then picking components. Components are just Tool's (like paint for a painter) the designer is the Artis, and the end product will be as good as the tools are used. I think people focus way to much on components alone.

With kind regards.
Bas
 
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