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Author Topic: What hapenned to HiFi  (Read 16348 times)

Offline syhprum

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What hapenned to HiFi
« on: 09/04/2009 20:54:38 »
In the sixties enthusiasts were always fretting about how to reduce the harmonic distortion of audio amplifiers from .01% to to .001% at 20 KHz and the necessity of using 100 Amp cable to connect their 15 Ohm speakers.
Now days people seem content with MP3 and other distorted forms of recording, do HiFi fanatics still exist?.
« Last Edit: 09/04/2009 21:18:53 by syhprum »


 

Offline Soul Surfer

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What hapenned to HiFi
« Reply #1 on: 15/04/2009 19:23:50 »
Most definitely they still do exist but are rather rarer than they used to be with digital recording there are fewer opportunities for ensuring the best quality but really good loudspeakers do make a vast difference to what you can hear in complex orchestral music.
 

Offline Bored chemist

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« Reply #2 on: 15/04/2009 19:37:56 »
There's a simple test to see if there are any  hi-fi addicts reading this. I just mention "Peak music power output" and wait for them all to come out screaming and ranting.
 

Offline LeeE

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« Reply #3 on: 15/04/2009 20:25:48 »
There's a simple test to see if there are any  hi-fi addicts reading this. I just mention "Peak music power output" and wait for them all to come out screaming and ranting.

Lol - who cares about what the power is as long as it's enough?

Actually, getting good loudspeakers is the last thing you should worry about; you should start with the sound source and work your way back through the pre/power amps to the speakers.  With a flawed sound source, all that good speakers will do is show how bad the source is.
 

Offline syhprum

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« Reply #4 on: 15/04/2009 21:33:56 »
I am always amused when people talk about putting 200 Watts into a speaker, a small coil of wire that might be capable of dissipating 5 Watts without burning out!
Do they believe 200 Watts of electrical power can be converted into 195 Watts of acoustic power.
 
 

Offline RD

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« Reply #5 on: 15/04/2009 22:12:44 »
Stereo buffs will love this field recording.

(click on the play triangle on the top left of the waveform)
 

lyner

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What hapenned to HiFi
« Reply #6 on: 15/04/2009 23:25:35 »
I am always amused when people talk about putting 200 Watts into a speaker, a small coil of wire that might be capable of dissipating 5 Watts without burning out!
Do they believe 200 Watts of electrical power can be converted into 195 Watts of acoustic power.
 
For most high power Hi Fi speakers, I think the majority of power is dissipated in the crossover / equalisation circuits and the internal damping - pretty low efficiency. A large speech coil has a very low resistance, I think and it will be able to dissipate a fair bit of heat. The units in the back of the lads' motor cars (thump thump thump) have very big speech coils and I bet they get quite hot.
But 200W means at least 200+ each. That's what people hear.
 

Offline Don_1

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« Reply #7 on: 16/04/2009 09:31:13 »
I think the problem with the finest digital recording played on the finest Hi-Fi separates system was the background noises which were being picked up, like the second violinist's thunderous clapping eyelids every time he blinked. OK, so I'm exaggerating a bit.

Then there was the complaint of the purists who claimed that without a little hiss and crackle, as heard on good old vinyl, the recordings sounded flat.

Without a totally sound proof room, I could never see the point in recording/playback perfection.
 

Offline Chemistry4me

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« Reply #8 on: 16/04/2009 09:32:30 »
What hapenned to HiFi?

FOG
 

Offline Soul Surfer

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« Reply #9 on: 16/04/2009 10:49:37 »
Good CD recordings are pretty good (OK not perfect) but most people are not able to detect the failings.  All the problems nowadays lie in the reproduction system.  Amplifiers are very good although some obsessives would like to go back to valved for certain obscure technical reasons.  The weakest link by far is the speaker system and most speaker systems are only moderate in their quality.  I say this with some authority.  I worked almost my entire working life in EMI Central research laboratories where we had definitive variable geometry listening rooms, anechoic chambers and tested out the standard and the very best speakers in the world.  We had also "golden ears" who were real experts at listening to music and could identify the both recording and performance failures.  I was not directly involved myself in this work but had plenty of time to listen and compare results and counted the real experts as my friends.   I am often amazed by the quality that can be achieved with some small speakers today but they tend to suffer a bit more from intermodulation distortion on complex music  because of the large speaker cone movements needed to generate the volume of sound. Listening to a large symphony orchestra played at concert hall volume performing a large complex piece for example the conclusion of Elgar's enigma variations through a top class listening system can be a true revelation (can you her clearly when the organ comes in?).  Most pop music is totally synthetic and precisely distorted for effect and often designed to be performed on less than perfect equipment so is not a true test.
 

Offline Don_1

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« Reply #10 on: 16/04/2009 18:07:29 »
What hapenned to HiFi?

FOG

According to the on-line OED it is Hi-Fi, but I think either spelling is considered acceptable.




BTW I don't know, what ***hapenned***, but I might know what happened!!! Return FOG!
 

Offline Bored chemist

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« Reply #11 on: 16/04/2009 20:58:00 »
There's a simple test to see if there are any  hi-fi addicts reading this. I just mention "Peak music power output" and wait for them all to come out screaming and ranting.

Lol - who cares about what the power is as long as it's enough?

Actually, getting good loudspeakers is the last thing you should worry about; you should start with the sound source and work your way back through the pre/power amps to the speakers.  With a flawed sound source, all that good speakers will do is show how bad the source is.
Let's assume that I'm listening to Kraftwerk. The signal from the output of the synthesiser is "correct" more or less by deffinition.
They are perfectly capable of ensuring that the levels are properly set and that they use good equipment. So they should send a near perfect copy to the CD recorder. That should do a pretty good job. Not perfect, of course, but the THD should still be low and the frequency response adequate for my ears (which tend to lose anything above about 17KHz anyway). As far as recall they are 16 bit which isn't really up to recording the whole dynamic range that the ear can cope with, but most of the time I'm not listening in a reasearch grade anechoic chamber, nor am I playing it anywher near the threshold of pain.

My CD player can probably pretty much do justice to the distortion figures that were written on the box it came in; I can't remember them but I think it was a case of counting the zeros after the decimal point. The signal has gotten all the way from the original signal generator to my amplifier without picking up much distortion.
I built my own amp about 20 years ago. The specification was something like 60 parts per million THD, frequency response flat from 10Hz to 20KHz and 200 Watts (and I checked that by how fast it could boil a cup of water using an 8 ohm resistor and a sig gen).

Then I feed this, so far, uncorrupted power into a loudspeaker with distortion figues over 1% and a frequency response (in a real room) that looks like a cross section of the Alps.

(end of rant)
 

Offline techmind

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« Reply #12 on: 16/04/2009 22:36:09 »
Actually, getting good loudspeakers is the last thing you should worry about; you should start with the sound source and work your way back through the pre/power amps to the speakers.  With a flawed sound source, all that good speakers will do is show how bad the source is.

Obviously the sound is no better than the weakest link in the chain. However with digital recording technology and solid-state (integrated circuit) amplifiers these components can be made extremely good at very low cost. Barring any silly/schoolboy design faults or software/firmware errors in the former, loudspeakers and the room acoustics really are the weakest link.

i.e. wot Bored Chemist said.


The plots on my webpage http://techmind.org/audio/#freqres
show the frequency response and indicate speaker and room-resonances (red bits) for a setup of el-cheapo PC speakers and microphone.
In contrast, if I use a lead to plug the PC sound output back into the line input entirely in the electronic domain I get a completely flat response...
« Last Edit: 16/04/2009 22:41:24 by techmind »
 

lyner

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« Reply #13 on: 17/04/2009 10:02:38 »
Could it be that people have actually started listening to the MUSIC?
 

Offline Don_1

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« Reply #14 on: 17/04/2009 10:15:38 »
Could it be that people have actually started listening to the MUSIC?

Good point..... unless it was The Bay City Rollers, or some such pile of dung.
 

lyner

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« Reply #15 on: 17/04/2009 10:34:32 »
Are you dissin my plaid trousers?
 

Offline Don_1

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« Reply #16 on: 17/04/2009 11:24:59 »
Are you dissin my plaid trousers?

Perish the thought!


*Mumbles under breath* Plaid trousers!!! OMG!!!
 

lyner

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« Reply #17 on: 17/04/2009 18:45:50 »
I actually did have a pair but that was in around 1969 and were a touch of the Rupert Bear. The BCRs were hardly even toddlers then, I think.
Moving on . . . .
 

Offline LeeE

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« Reply #18 on: 18/04/2009 00:21:29 »
...As far as recall they are 16 bit which isn't really up to recording the whole dynamic range that the ear can cope with...

This is actually one of the major objections that some audiophiles have with digital sound; vinyl can actually have a higher resolution.

As to just how often, in practice, this higher resolution is realised is a different issue; most people don't have audio equipment capable of achieving the max performance possible, which tends to be extremely expensive, let alone have ears that are highly trained enough to hear it.
 

Offline RD

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« Reply #19 on: 21/04/2009 00:10:20 »
I suspect the inertia of the speaker diaphragm would smooth a discrete 16 bit digital signal so it would be indistinguishable to the ear from a continuous analogue one. (Bear in mind the sample rate for audio is typically 44.1 KHz). As Bored Chemist has pointed out if you are over 40 the high frequencies (above about 16KHz) will be lost on you.

http://en.wikipedia.org/wiki/Presbyacusis
« Last Edit: 21/04/2009 00:18:36 by RD »
 

Offline Don_1

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« Reply #20 on: 21/04/2009 08:36:53 »
Judging by the vibrations felt at 50ft from the thumping bass of a hot hatchback full of teeny boppers, I should think most frequencies will be lost by the age of 20!!!

I think Hi-Fi lost out to Hi-Vol. (High Volume).
 

lyner

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« Reply #21 on: 21/04/2009 19:42:04 »
I suspect the inertia of the speaker diaphragm would smooth a discrete 16 bit digital signal so it would be indistinguishable to the ear from a continuous analogue one. (Bear in mind the sample rate for audio is typically 44.1 KHz). As Bored Chemist has pointed out if you are over 40 the high frequencies (above about 16KHz) will be lost on you.

http://en.wikipedia.org/wiki/Presbyacusis
Actually, the quantisation noise is a function of the quantisation step size and the sample rate.  Increasing the sample rate will spread the noise over a larger and larger range of ultrasonic frequencies and achieve a better SNR for the listener. (Hence the fashion for one bit DACs, at one time)
 

Offline LeeE

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« Reply #22 on: 22/04/2009 22:38:33 »
I suspect the inertia of the speaker diaphragm would smooth a discrete 16 bit digital signal so it would be indistinguishable to the ear from a continuous analogue one. (Bear in mind the sample rate for audio is typically 44.1 KHz). As Bored Chemist has pointed out if you are over 40 the high frequencies (above about 16KHz) will be lost on you.

http://en.wikipedia.org/wiki/Presbyacusis

Loudspeaker drivers don't ever have to deal with a digital signal - that's not how it works.  The power-amplifier (whether just a stage in an integrated amplifier, or as a discrete power amp) only amplifies analogue signals.

Off hand, I don't know of any pre-amplifiers that incorporate their own DACs but I imagine that someone, somewhere probably does make such a thing.  Usually though, digital sources incorporate their own DAC, or you feed a digital output in to a stand-alone DAC.  It is the analogue output from the DAC that goes in to the amplifier and from the DAC onwards everything is analogue.

The issue of resolution doesn't just limit the highest frequencies that can be reproduced but has an impact across the frequency range, where it contributes to timbre and phasing, so although our hearing may not be up to hearing the highest frequencies, we can still hear the difference in resolution at lower frequencies.

You really do have to train your ears/hearing to be able to notice the tiny differences this can make though, and for the most part the majority of people just won't hear the difference.
 

Offline Bored chemist

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« Reply #23 on: 23/04/2009 20:12:12 »
The heavy loudspeaker cone might limit the frequency response (though it shouldn't) but it won't do anything to regain the data that was lost when a signal was comressed from the range of human hearing (about 120dB which is equivalent to roughly 20 bits (assuming no oversampling and dithering for those who car about such things)) down to 16 bit (equivalent to about 96 dB).

BTW, LeeE,  at least some DC players had digital outputs and so I presume that there must be something with a digital input. IIRC there was even an optical version called "Tosser" or something.
 

lyner

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« Reply #24 on: 24/04/2009 01:12:57 »
There is always a low pass filter after a DAC, to avoid overloading any audio amplifier with unwanted ultrasonic frequencies.
A loudspeaker will respond to the frequencies for which it was designed so the 'boxcar' waveform from the DAC would not be of any consequence.
 

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« Reply #24 on: 24/04/2009 01:12:57 »

 

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