John Curl's Blowtorch preamplifier part III

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#27,401
scottjoplin said:
Distortion figures aren't often published. But measuring at the listening position is very informative. Who can or wants to listen nearfield?
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It is possible to measure distortion at the listening position, it is measured, but it is not easy to interpret the results. Why? Because of speaker directivity and room reflections, you get "all in one" in your measurement, but the ear makes difference between the direct sound, early reflections and later reflections.
 
#27,403
Yes, we have yet to find proper interpretation and method of measurements of the sound reaching the ears. Seems that we seriously lack proper understanding and left too many confounders in forming a robust opinion. This thread has admittedly a few of valuable tips for audio but the bulk of it is mostly entertainment to bored grumpy old men. 😀
 
#27,404
PMA said:
It is possible to measure distortion at the listening position, it is measured, but it is not easy to interpret the results. Why? Because of speaker directivity and room reflections, you get "all in one" in your measurement, but the ear makes difference between the direct sound, early reflections and later reflections.
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I now have a miniDSP 2x4, a Umik-1 calibration mic, and a copy of REW. It will take me several months to learn and understand the software, and probably a lot longer to implement it. I am a great believer in making the very best of what you have - it is often more than we think.
 
#27,405
PMA said:
It is possible to measure distortion at the listening position, it is measured, but it is not easy to interpret the results. Why? Because of speaker directivity and room reflections, you get "all in one" in your measurement, but the ear makes difference between the direct sound, early reflections and later reflections.
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Yes, I was thinking more purely of the driver distortions.

@ToS Be very wary of room eq, easy to do more harm than good. Why Can't I Fix All my Acoustic Problems with EQ?
 
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#27,409
PMA said:
It is possible to measure distortion at the listening position, it is measured, but it is not easy to interpret the results. Why? Because of speaker directivity and room reflections, you get "all in one" in your measurement, but the ear makes difference between the direct sound, early reflections and later reflections.
Click to expand...

Quite true, the Haas effect was a subject I was interested a while back. But I have noticed that acoustic distortion measurements seem to have gone out of style. Perhaps the degree of difficulty has something to do with it. If measuring individual drivers, distortion has to be done fairly close-field and largely ignore the response, just measure the distortion (this is what John 'Zaph Audio' does if you look at his measurements). Maybe a case of 'you have to choose between response and distortion and not do both at the same time? Do you have a view about that?
 
#27,412
Markw4 said:
It probably seems more petty the more one likes Sy, misses him, and wishes for his return. If one has been ridiculed by Sy, then pointing out Sy's imperfections may seem much less unfair.
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billshurv said:
Whilst I am only human I think quoting something someone does elsewhere on the internet is poor form in general. This is my personal view. I may have been guilty of it in the past, but we should all strive to be better people despite others.

I have been ridiculed by SY and I deserved it at the time.

I'm not quite sure why people don't bother to understand what is written though. The trolls on here I get, they want to cause trouble and I they can be ignored. You used to be so much better. This thread has not been good for you as a person looking at how your tone has changed in the last couple of years.

But I'm out. bad music to find and threads which are not as toxic.
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I've been noticing the increased resemblance of his posts to those who are in audio business and yet he claimed not to be in such business. The level of persistence in pushing his narrative is hard to miss. What I'm suspecting is, he is prepping to start one soon, likely selling DAC or modification to DACs. :radar:
 
#27,413
scottjoplin said:
ToS Be very wary of room eq, easy to do more harm than good. Why Can't I Fix All my Acoustic Problems with EQ?
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Scott, I have been reading through the REW Manual for most of the afternoon. It is going to take me quite awhile to understand the conceptual basis of modelling sound. But, as a know-nothing, I have to start somewhere. Methinks it is time to build yet another cathedral of knowledge, I’m at the front door, I’m going to knock, if there is nobody there, I will push the door open myself ..... OK ..... here we go! :yes:
 
#27,417
indra1 said:
I was responding to Scott Joplin about speaker distortion measurement at listening position. Seems anechoic chamber would help wrt room reflection problems Pavel mentioned.
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Yes it helps. windowing helps also... removes the reflections.

Measuring up close to drivers gives unrealistically low distortion. Up close a 1/10W can generate 80-90 db spl. But we dont listen that way and further back in the room requires more power for same spl.

Measuring up close makes distortion seem a lot better than we perceive it to be when listening further back in the room for same spl (10W+).

THx-RNMarsh
 
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