Split from Bob Cordell Interview:
This noncence again may be explained in technical terms. Distortions of tube amps create "effect of compression", so while loud sounds sound subjectively louder because of distortions they are in reality have less power. It means, subjective dynamic range is wide, objective dynamic range is narrower, that's why you hear reverberation better, it's power against direct sounds is more. And it sounds natural, because class A tube amplifiers add coloration on high power, that sounds natural.
Distortions which level increases on low power and spector widens on low power level (so called crossover distortions) kill the "air", distortions which level increases with power add the "air".
I don't argue, I explain. When I need "air and space" on concerts I use reverberator.
PMA said:
This noncence again may be explained in technical terms. Distortions of tube amps create "effect of compression", so while loud sounds sound subjectively louder because of distortions they are in reality have less power. It means, subjective dynamic range is wide, objective dynamic range is narrower, that's why you hear reverberation better, it's power against direct sounds is more. And it sounds natural, because class A tube amplifiers add coloration on high power, that sounds natural.
Distortions which level increases on low power and spector widens on low power level (so called crossover distortions) kill the "air", distortions which level increases with power add the "air".
I don't argue, I explain. When I need "air and space" on concerts I use reverberator.
I don't think you can blame compression for the lack of "air" in a reproduction.
I have both tube and solid state amplifiers that I enjoy listening to and neither one suffers from compression within their power ratings. Often, single ended tube amps are said to have an "airy" quality to them. This would seem to contradict Wavebourn's preceding statement.
-Chris
I have both tube and solid state amplifiers that I enjoy listening to and neither one suffers from compression within their power ratings. Often, single ended tube amps are said to have an "airy" quality to them. This would seem to contradict Wavebourn's preceding statement.
-Chris
anatech said:
Chris,
you did not understand me.
Crossover distortions are distortions that "cut off" very small portions of signal when it "goes through the null". As the result, fading signals fade faster, less proportionally than in the nature, and in process of attenuation level of distortions becomes higher, their spectrum extends. It is what kills "air and space" distorting reverberation, this is what kills fading sounds of piano strings when you listen to Beethoven.
Crossover distortions are generated by common transistor amplifiers with abused emitter followers. They may be generated by transformer cores of push-pull tube amps, also under-biased push-pull tube amps generate such distortions.
Well biased class A tube amp, especially single - ended one - do not generate crossover distortions. It generates different type of distortions that indeed highlight reverberation, i.e. "air and space", what I explained in my previous post.
Hi Wavebourn,
In this day and age, I think most amplifiers would be free from crossover distortion, older Exposure excepted. The lack or presence of "air" is still discussed in the absense of crossover distortion. I won't even consider that case.
I was responding to your earlier statement .......
-Chris
In this day and age, I think most amplifiers would be free from crossover distortion, older Exposure excepted. The lack or presence of "air" is still discussed in the absense of crossover distortion. I won't even consider that case.
I was responding to your earlier statement .......
-Chris
Chris,
the problem is, they present but are greatly underestimated. And as I see from this discussion, are underundestanded.
the problem is, they present but are greatly underestimated. And as I see from this discussion, are underundestanded.
anatech said:Hi Wavebourn,
In this day and age, I think most amplifiers would be free from crossover distortion, older Exposure excepted. The lack or presence of "air" is still discussed in the absense of crossover distortion. I won't even consider that case.
I was responding to your earlier statement .......
-Chris
PMA said:When this "Ayry"
Come in captain "Hansen Solo"..
Anyhow, to ya all,
let's take a word from Papa and then lets move on, the distortion and harmonics stuff has been covered quite well in the past here on diyaudio.
Cheers Michael
MikeB said:
Presence of "lack of air and volume" is a well audible indicator of how well is it designed.
Sometimes power amplifiers are innocent, when crossover distortions are created by mixers, microphones, even... contacts!
Mixers contain operational amplifiers. For example, currently TOA RX-216 mixer is on my surgery table. It contains a lot of BA4558 chips, much more than needed. All of them contain differential inputs and symmetrical emitter follower output, both are sources of small crossover distortions. It may be Ok if you use one such opamp in signal path, but if you use more, and some of them in non-invertion connection, resulting crossover distortions kill "the air and volume".
My main console Yamaha MX400-24 has OpAmps too, but they are different, used mostly in inverting connection, and much less number of them in signal path. As the result, Yamahe sounds more "airly".
One more example is modern Marshal MXL 770 condencer microphone, on the same surgeon table. It has couple of emitter followers that working on cable capacitors generate "broken glass" distortions, they are different from crossover distortions, but anyway are unnatoral. Another the same mic I already modified contains output transformer and no emitter followers. As predicted, it sounds very clean.
In my life I played a lot not only with amps trying to squeeze less distortions from some standard topology, but generated distortions developing analog synthesizers and guitar pedals. You know, when you have experience in creating effects you better understand how to avoid them when you hear similar to what you already heard many times experimenting.
So, if you hear "lack of space and air", always look for crossover distortions. Probably, even hysteresys loops may present on very low powers. The less them you have, the finest will be the effect, but anyway it will sound innatural. Especially, when their level is higher on top end of audible spectrum.
moamps said:Yes, mortuary table stories of fifty-dollar mikes and 30-year-old consoles are indeed a step in the right direction.
I don't see any principial difference between cheap console and mic in my examples and huge money spent on fashionable parts for DYI, if to refuse to understand roots of the problem...
Good luck!
anatech said:Hi Wavebourn,
That's a good title. As always, my pleasure sir.
Done.
-Chris
Thanks, sir!
Now if you will again use your favourite trick asking provocing off-topic question in order to blame those who answer, I will report to Moderators.
Ok, here is what the discussion started from:
It may be easily translated on the technical language: crossover distortions may be very small and not audible on human voices, but they kill naturality of reverberation. Reflected sounds have different coloration because of frequency-dependent damping of surfaces that reflect it. Crossover distortions screw down the picture.
Reverberation is what creates imagination of air and space.
So, no witches, no snake oil, just old well known racks in the pool...
Wavebourn said:
I really like that the thread has been split so I may now ask you questions that have nothing to do with the Cordell thread.
For instance, you say that opamps in non-inverted connection cause crossover distortions. However, in my experience, high-quality professional broadcasting/recording consoles use opamps in non-inverting connection just as often as in inverting connection, depending on the function of a particular block within the channel strip. I'd appreciate it if you could elaborate what you meant.
Regards,
Milan
moamps said:
I'd tell you that by my own experience high-quality professional broadcasting/recording consoles contain less opamps in signal path in common, and in non-inverting connections particularly, and opamps are different than in low-quality-30-years-old-cheap consoles that contain opamps of low quality when needed and when not needed. Also, cheap consoles don't have switches to bypass channel strips and equalizers, to avoid unneeded noises and distortions.
Milan, I did not get your point, do you have some different explanations of "lack of air" phenomenon and want to share it with us?
Wavebourn said:
Could you please tell me how many opamps are there in the TOA console on your workbench and which mode they're in? I'll count the number of opamps in the Soundcraft Vienna and B800 consoles so we can compare them (tomorrow morning, that is, I have to go to bed now).
Regards,
Milan
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