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Old 13th January 2009, 09:21 PM   #1
steevo is offline steevo  United Kingdom
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Default Minimum Detecable Distortion

I have a read a lot post about one particular ampifier sounding great
and better than another design, for example an amplifier with a Mosfet ouput stage and maximum distortion at 20Khz of 0.04% say and an amp with a bipolar output stage with max of 0.01% distortion at 20Khz, do people realy think they can tell the difference between these microscopic figures and also audible difference in designs with Mosfet ouputs and amps with a bipolar output stage. If the amps have been designed correctly and are linear having low distortion figures then we cant tell the difference. Unless there are some super
Human Bat eared people on here.

Steevo
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Old 13th January 2009, 10:07 PM   #2
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Default Minimum Delectable Distortion

Quote:
Originally posted by steevo
0.04% say and an amp with a bipolar output stage with max of 0.01% distortion at 20Khz,


Coming out of a time machine?



I thought it was known for over 30 years that audiophiles don't care much for distortion specs and seldom give ultra low distortion amps any preference. To the greatest disappointment of engineers. And trolls.
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Old 13th January 2009, 10:50 PM   #3
syn08 is offline syn08  Canada
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Default Re: Minimum Delectable Distortion

Quote:
Originally posted by analog_sa
I thought it was known for over 30 years that audiophiles don't care much for distortion specs and seldom give ultra low distortion amps any preference. To the greatest disappointment of engineers. And trolls.
And to the greatest satisfaction of GEB charlatans, charging $150,000 for a 10% distortion tube amp. And trolls.
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Old 13th January 2009, 11:23 PM   #4
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Default Re: Minimum Detecable Distortion

Quote:
Originally posted by steevo
I have a read a lot post about one particular ampifier sounding great
and better than another design, for example an amplifier with a Mosfet ouput stage and maximum distortion at 20Khz of 0.04% say and an amp with a bipolar output stage with max of 0.01% distortion at 20Khz, do people realy think they can tell the difference between these microscopic figures and also audible difference in designs with Mosfet ouputs and amps with a bipolar output stage. If the amps have been designed correctly and are linear having low distortion figures then we cant tell the difference. Unless there are some super
Human Bat eared people on here.

Steevo
or, just maybe...
THD alone does not measure everything
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Old 13th January 2009, 11:51 PM   #5
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0.04% can be hearable, still numerous amps have higher distortion.
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Old 14th January 2009, 01:21 AM   #6
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Quote:
Originally posted by darkfenriz
0.04% can be hearable, still numerous amps have higher distortion.
If it is high order. 1% at low order (2nd) is probably inaudible (at least with music). Geddes is showing scientific results that lumped THD of >10% is immaterial in loudspeakers.

The numbers given for lumped THD are completely meaningless... far too much context has been tossed out.

dave
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Old 14th January 2009, 04:28 AM   #7
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Ignorant and inexperienced engineers.
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Old 14th January 2009, 04:52 AM   #8
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Measurements just gives you an indication of the performance....

I once read a paper about the distortion created in the human ear (can't find the paper right now though), that clearly indicate that we all have special preferences regading the quantity and kind of distortion we accecpt in music reproduction.

This could some of the explainations to why we DIYers can create circuits that we find performing better than commercial.
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Old 14th January 2009, 05:18 AM   #9
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Default It is interesting the way we use to fool ourselves with those things


Performance numbers are everywhere.

We measure automobile power using horsepower, and this is measured coupling the engine into a dinamic brake, or magnetic brake... and there are several tests to allow precision into those measurements.

Automobile power should be measured into the wheels, so transmission losses and different types of transmissions could be compared...but they do not publish the horsepower into the wheels...in the U.S. there are an Institute that controls the fool in numbers... the guy goes to the factory to inspect the engine into the break.

Amplifiers also do not works alone.... depends from audio source and worse than that, depends from the speaker... amplifier distortion by itself does not mean too much for human ears.

There are people more sensitive...more trained ears... in my case i turn bothered with distortion above 0.2 percent...but is see that i have friends that feels sound good when reaching 1 percent that do not bother them... and some chip amplifiers shows power specifications made into 10 percent of distortion, also some cheap micro systems too.

You see tubes... they measure very badly, but even this way produces a pleasant sound to many friends into our communitty.

I have learned, those last monthes, better to adjust speakers and room acoustics to reproduce good sound.... this may result better than reduce distortion numbers.

This is what makes some micro systems tollerable...they have matched speakers (some of them have... Sony for instance)...in the correct room can be pleasant too.

No one has bat ears i think..but for sure there are experienced, skilled, trained ears...... and this is a tragedy to the ones can listen such ammount of details.... sadly they feel bothered with something i cannot even perceive...their threshold is different.

regards,

Carlos
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Old 14th January 2009, 12:47 PM   #10
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Default friend of mine ....

owns a medioum size club something like 300pax

previously this used to work as disco club .... equiped with huge 80's style double 15" boxes +drivers all of them original JBL units ...the boxes though were sealed no bass reflex ...extremelly big and greek made ..... they sounded very nice but totally out of style for use now days

so the club owner thought about changing something to the club but also to the sound .....since disco times and big speakers are gone now ...

so we actually copy the constraction of the box of JBL from SRX series , then used the existing units JBL inside and created 12 speakers that was almost identical to the SRX .....( we also put big JBL stickers on them )

soundwise nothing changed ...give or take the same amps same xovers same eq almost same tuning

the sound was more or less good and the same as before only looks changed .....


costumers though congratulated the owner for such a good sound .......

do you know what made the diference to the audience ?????
the big JBL stickers !!!!!!!

you know greece is a small country .....the first disco club in greece was eqiuped with JBL... now days you have babies 18 years old, that JBL blood flows in their vains ....JBL is a legend in greece ....nice ....
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