Hi,
trying to make it clear.
In one of my posts in this thread,I wrote,that all technologies and components have their plus and minus points.We MUST use each one where it is better.
Speaking for me,I use everything that sounds good to my ears.There are times that my rig ,makes me take a hammer and smash it.Other times it is pure bliss.
I do not blame anything on the basis of technology,since I know that the main distortion and alteration to the whole thing is my room.And not only mine.
If you are interested in further readind on the subject of sound quality and accuracy,an excellent read is the words,of one of the most influential audio designers ,contempo,Stan Curtis. Just click, Stan Curtis.com,and read what this man says on the subject ( pdf articles in Audio Critic)
I use all kinds of technology too, but the point was that article was implying that a starved plate tube had less harmonic distortion than an op amp. That's not true.
Also your room does not add distortion, that's not possible, but it will cause phase cancelation.
Also I don't need to read someone else's opinions on "sound quality and accuracy". I'm already well versed on the subject, and actually build the stuff, not just critique it.
The bottom line is modern op amps are very low in harmonic distortion and have excellent audio characteristics.
I know that this give and take could go on forever.
1.Phase alterations ARE distortions
2.Room modes,peaks and nulls ARE distortions.
3.Furnitures and all the paraphernalia ARE distortions
4.We,being in the room ARE distortions.
and as tubes(valves),transistors,and op amps go,the biggest distortion that alters the signal AUDIBLY is not the harmonic distortion up to a level,but the often "forgotten",intermodulation distortion.The sumperimposing of multiples plus or minus of the original signal ,ON, the signal.Something that rooms do agressively,too.
By design, op amps, unless propeply implemented,and by saying properly I mean without the slightest mistake,something that is not possible,-no design is faultless-,are more easily prone to annoying audible distortions,of the IMD kind,compared to the others. Not because discreets and thermionics are less faulty in use,but because with discreets and tubes you can engineer up to your satisfaction, actively.With op amps,you are restricted to their pros and cons without futher choices. Op amps are in the market,not for sound quality reasons,but for ease of design and construction,aka, lower cost.
B.L
Out of phase wiring? Out of phase to what? What are you smoking?
So a cheaply implemented transistor is better? All electronic devices have their limitations.
No, the reasons are well known. It's physics. You pick a certain devices based on what your goals are in the design. I use JFETs for some things and op amps for others, often in the same circuit.
That didn't even make sense. If your recording has distortion or hiss, that's part of the recording. Recordings get better all the time. But then some people want to listen to vinyl gramophone records, and that's not accurate at all! The recording amp mangles the sound, the high frequency reproduction at the outside of the disk is better than the inside, overlapping left and right channels, etc. But people still swear by them. I don't even own a turn table anymore.
The sound of the recording. Personally I often dislike live room recordings. Too much mush introduced in the recording. Unless you are listening with headphones, why bring one acoustic environment into another?
Accuracy means the signal at the input exactly matches the signal at the output. You don't want to round off your waves (slew rate), you don't want to add harmonic distortions, etc. Tubes for instance have a transfer curve. They are linear only for small signals. But unlike solid state devices clip in a more pleasing manner. But you are adding artifacts to the recording that weren't there originally. People find the tube distortion tone pleasing though, which is why most guitar amps use tubes.
That's nonsense. You are making all this mystery out of nothing mysterious at all. If you record the event, you have a recording of the event. It might be a certain aspect of the event, but you have recorded it. I'm a musician. I've been a musician for almost 45 years.
In fact the only way to relive a live event is by recording it. Otherwise it's gone when you finish. Studio recording are something all together different. You attempt to create an atmosphere with the recording. To say that the recording is flawed makes no sense because the recording defines itself. It's not like there is some "pure" sound that gets mangled in the recording process. Sound is a perceived event. Everything in the process is in a way inaccurate. Your ears surly are.
But what you hear, is what it is. That's part of the reason tone controls and EQ were invented. Besides trying to even out acoustic responses you also alter things to your own liking.
The bottom line is there is no right or wrong. It's personal preference. But when someone makes blanket statements that op amps are the "dark side" or cause all this distortion, well that can be proven wrong. If anything they can be too clean. People use JFETs and tubes to introduce a sound inherent in those devices. Let's be honest, unless you are sitting and listening to a live acoustic instrument, everything else is electronic, and in some ways sounds like it.
Last edited:
Well that's room acoustics, and that has nothing to do with signal processing or op amps. No active device will change your room. The room will alter your frequency response, but not distort the wave forms. It's comb filtering. If that bothers you, treat your listening room, or use headphones. 😉
Now if the tops of waves are flattened, or the corners are rounded over, or you add unpleasant harmonics or artifacts, that's distortion in the audio path. That kind matter most in music reproduction.
The addition of noise or other extraneous signals (hum, interference) is not considered to be distortion, though the effects of quantization distortion are sometimes considered noise.
It's not that hard or mysterious to make a good clean sounding audio circuit. And it's even easier using op amps. All playback systems are flawed, as are microphones, and even our ears.
And please, learn to punctuate.
How do you vary the frequency response and NOT distort a waveform (pure sine wave excepted)? Take a square wave as a simple example. Reduce the third harmonic 10%, increase the seventh harmonic 10%. Is it still a square wave or is the wave shape now altered?
When one adds non-minimum phase phenomena as well (e.g., room reflections), of course the waveforms are also altered from the original (which can certainly be termed "distortion").
I have a sneaking suspicion that it is becoming personal,and since I am not in the mood for this kind of dialogue,I am leaving the building. Bye
Because you are dealing with a composite signal. If you turn down the treble on your amp, you are not distorting the signal, you are filtering part it out. Room acoustics are not going to add or subtract harmonics from a square wave. It wont make a fuzzy guitar sound like a flute.
Yes, you can get some phase stuff going on, which will notch some frequencies and reinforce others, but room acoustics is not the same as phase distortion in an amplifier.
And none of that has anything to do with op amps, so it was irrelevant to the discussion. It's like saying "op amps suck because I have crappy speakers", or "I don't like the sound quality on this CD because my walls are too reflective." Right?
Last edited:
No, unless one or more of the harmonics happen to fall into an infinite notch. But they will definitely alter their relative intensity and phase, thus altering the waveform. You may not like to call that "distortion," but it is- the original waveform is changed.
Agreed, it has nothing to do with opamps.
Yes, but only for that one root frequency. As the frequency changes, the harmonics do too. But that's normal for how we hear sound, and why we like things like reverberation and early reflections.
I'm not trying to sound like a hard head either. But I see this blanket statement about op amps from people who should know better, and it's annoying. You get the same thing filtering down to pro audio and musical instruments. Guitar and bass players will prefer passive instruments and claim they sound more pure, even though the cable capacitance and loading from the potentiometers are altering the tone of the pickup.
Then I see the whole tubes are better thing for amplifiers, and, you know what? I have a big Mesa 400+ all tube bass amp... 16 damn tubes in the thing. It sounds very nice, but it's slower feeling than a solid state amp, and everything has that warm tube tone. It's a nice tone, but sometimes I like the sound of my bass DI into a mixer better. It's more like what the bass sounds like.
So they all have their place, but we need to get rid of the voodoo. 😀
It's not better or worse, it's different.
"It's not better or worse, it's different. "
Bravo! This is the best statement on the op-amp, discrete, tube debate I've heard in a long time.
Bravo! This is the best statement on the op-amp, discrete, tube debate I've heard in a long time.
Back to: what is wrong with op-amps?
To me op amps are always better than tube amps.
But:
There are differencies between op amps. I think BB's OPA(2)134 sounds best in most applications. For an I/V-converter the LT1028 is very good (see my website (by-rutgers.nl).
Always use heavy feed back!!!! (> 40 dB)
To me op amps are always better than tube amps.
But:
There are differencies between op amps. I think BB's OPA(2)134 sounds best in most applications. For an I/V-converter the LT1028 is very good (see my website (by-rutgers.nl).
Always use heavy feed back!!!! (> 40 dB)
Because no active element is free of distorsion, so feed back is a must! However Baxandall prooved already 50 years ago that little feed back (some 6 dB) makes things worse.
Feedback is a must but heavy feedback gives the same lousy sonical results as (too) light feedback isn't it ?
IMO (we can not discuss taste) discrete circuits with only local feedback and no global feedback sound the most natural with little to none listening fatigue. Certainly when compared with opamp circuits.
IMO (we can not discuss taste) discrete circuits with only local feedback and no global feedback sound the most natural with little to none listening fatigue. Certainly when compared with opamp circuits.
Last edited:
This is a bit too broad a generalization. Baxandall showed that low amounts of NFB would cause spectral growth distortion in a simple circuit dominated by second-order nonlinearity (a single-stage JFET). I show in my book that this is not representative of the real world. For more complex distortion to begin with (example: crossover distortion), even the application of small amounts of NFB decreases distortion of all orders.
Many, many people have read too much into what Baxandall demonstrated, and he himself would probably be the first to agree.
Cheers,
Bob
I'm very glad to hear! Please give me the article or book title in which you show this.
Are we mixing feedback issues in power amp and pre-amp (small signal)? Assuming large amount of feedback in power amp creates problem. Does it also happen in pre-amp?
Shall we separate feedback issue in power amp and in opamp (pre-amp)? Power amplifier reactive load will affect its feedback behavior. But we don't have this in pre-amp. Correct?
Shall we separate feedback issue in power amp and in opamp (pre-amp)? Power amplifier reactive load will affect its feedback behavior. But we don't have this in pre-amp. Correct?
- Status
- Not open for further replies.