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Old 16th May 2023, 11:44 am   #3101
emeritus
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Default Re: The Audiophoolery Thread.

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Exercise for the student:

Calculate the phase difference at 15kHz introduced by 3.5ns of delay, both electrically and acoustically.
And then calculate how far you have to move your head to achieve the same effect. Students may assume 330m/second velocity of sound waves.

Added merit for comparing this with the stiffness of those wooden braces which victorian photographers used to keep their subjects still for the very long exposures they took, and derive the associated size of forces.

David
Back in the days before the BBC broadcast 24/7, they used to play a sequence of test tones after shutdown on FM, presumably to allow you to check for things like stereo balance. I had fallen asleep on the sofa while listening and was woken up by the tones. As I got up to switch the radio off, I could hear the change in volume as my ears moved through the standing waves in the room (then bare walls covered with emulsion-painted woodchip wallpaper). I found I could find positions where the sound in either ear could be completely nulled out by moving my head a few inches. It was a dramatic demonstration of the effect of room acoustics on the sound produced by loudspeakers
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Old 16th May 2023, 12:11 pm   #3102
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Default Re: The Audiophoolery Thread.

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Exercise for the student:

Calculate the phase difference at 15kHz introduced by 3.5ns of delay, both electrically and acoustically.
And then calculate how far you have to move your head to achieve the same effect. Students may assume 330m/second velocity of sound waves.

Added merit for comparing this with the stiffness of those wooden braces which victorian photographers used to keep their subjects still for the very long exposures they took, and derive the associated size of forces.

David
Back in the days before the BBC broadcast 24/7, they used to play a sequence of test tones after shutdown on FM, presumably to allow you to check for things like stereo balance. I had fallen asleep on the sofa while listening and was woken up by the tones. As I got up to switch the radio off, I could hear the change in volume as my ears moved through the standing waves in the room (then bare walls covered with emulsion-painted woodchip wallpaper). I found I could find positions where the sound in either ear could be completely nulled out by moving my head a few inches. It was a dramatic demonstration of the effect of room acoustics on the sound produced by loudspeakers
Indeed. And when you visit some of the audio groups, you'll see uber-$$$ systems installed in concrete bunkers, with plenty of glass, minimal diffusion and sharp angles everywhere. But at least they have nice mains cables. That's important!
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Old 16th May 2023, 1:50 pm   #3103
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Default Re: The Audiophoolery Thread.

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Noting how some colours of markings on valves denote sonic superiority...
...and even the shape of the getter ring, Lord help us.
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Old 16th May 2023, 2:24 pm   #3104
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Default Re: The Audiophoolery Thread.

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...does this apply to transistors too?
If you've looked at the 'Diy audio' group, you'll see plenty of amp building threads where people debate the sonic merits of transistors. I recently found an inspiring 10-page thread where, over a period of months, a member honed a design that used Hitachi MOSFETs. It was fascinating, as he updated it every few days, nibbling away at noise and overshoot until it looked like a good commercial design. On page 10, having dedicated weeks of time to it, another member came along and posted a diatribe against lateral FETs, saying how cold and lifeless they were subjectively, and how he'd wasted his time on the project. The OP (obviously a learned engineer), has never been seen at the group again...

You have to be thick-skinned to post at groups. That's probably why so few of the academically-inclined design engineers I know go near them. I take my hat off to Mr Stenning and his mods for keeping the cabbage throwing at a minimum here. It shows!

edit - to quote the great audio engineer Tim de Paravincini: 'electrons have no memory'.
Cold and lifeless, a jibe I've heard directed towards Peter Walker's great Quad 11 amplifiers more than once, perhaps we're back where we started, where designers go to great lengths to eradicate all trace of distortion but so called audiophiles then complain because their chosen super amp isn't adding anything, probably second harmonic distortion which is easy on the ears.
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Old 16th May 2023, 4:06 pm   #3105
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Default Re: The Audiophoolery Thread.

I've seen it. Post and get pilloried. It isn't only cabbages or renaissence faire (Yuk!) wet sponges. There is real malice.

But these people like distortion. It makes the sound they get so much realer than reality. They are adding artefacts to the sound which weren't there in the concert hall. Words like 'fidelity' go into hiding. While the uneducated loons gibber about the flavour of distilled water, forgetting that the task was to faithfully reproduce the flavour that already existed in the recorded music.

The professional design engineers I know would as soon publish a hifi amp as leap into a snake pit.

David
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Old 16th May 2023, 4:43 pm   #3106
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Default Re: The Audiophoolery Thread.

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Back in the days before the BBC broadcast 24/7, they used to play a sequence of test tones after shutdown on FM, presumably to allow you to check for things like stereo balance. I had fallen asleep on the sofa while listening and was woken up by the tones. As I got up to switch the radio off, I could hear the change in volume as my ears moved through the standing waves in the room (then bare walls covered with emulsion-painted woodchip wallpaper). I found I could find positions where the sound in either ear could be completely nulled out by moving my head a few inches. It was a dramatic demonstration of the effect of room acoustics on the sound produced by loudspeakers
It was for lines testing - known as "step tone".
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Old 16th May 2023, 4:45 pm   #3107
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And then calculate how far you have to move your head to achieve the same effect. Students may assume 330m/second velocity of sound waves.

Added merit for comparing this with the stiffness of those wooden braces which victorian photographers used to keep their subjects still for the very long exposures they took, and derive the associated size of forces.

David
Back in the days before the BBC broadcast 24/7, they used to play a sequence of test tones after shutdown on FM, presumably to allow you to check for things like stereo balance. I had fallen asleep on the sofa while listening and was woken up by the tones. As I got up to switch the radio off, I could hear the change in volume as my ears moved through the standing waves in the room (then bare walls covered with emulsion-painted woodchip wallpaper). I found I could find positions where the sound in either ear could be completely nulled out by moving my head a few inches. It was a dramatic demonstration of the effect of room acoustics on the sound produced by loudspeakers
Indeed. And when you visit some of the audio groups, you'll see uber-$$$ systems installed in concrete bunkers, with plenty of glass, minimal diffusion and sharp angles everywhere. But at least they have nice mains cables. That's important!
Heresy I know... but shouldn't they be listening to the performance, not their systems?
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Old 16th May 2023, 4:58 pm   #3108
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Added merit for comparing this with the stiffness of those wooden braces which victorian photographers used to keep their subjects still for the very long exposures they took, and derive the associated size of forces.
Errr... there was another reason for those braces;

Post-mortem photography
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Old 16th May 2023, 7:48 pm   #3109
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Default Re: The Audiophoolery Thread.

More phoolery - anybody else seen the valve power supplies for the Sony Pro Walkman? Available at your local auction site for a king's ransom...
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Old 16th May 2023, 8:32 pm   #3110
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Default Re: The Audiophoolery Thread.

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Noting how some colours of markings on valves denote sonic superiority...
...and even the shape of the getter ring, Lord help us.
Yes, I recall seeing that in the earlier days of eBay and wondered what all that nonsense was about. I guess audiophoolery has been going on for many years and not just a fairly recent thing.

Regards,
Symon
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Old 16th May 2023, 8:42 pm   #3111
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Default Re: The Audiophoolery Thread.

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Noting how some colours of markings on valves denote sonic superiority...
...and even the shape of the getter ring, Lord help us.
Yes, I recall seeing that in the earlier days of eBay and wondered what all that nonsense was about. I guess audiophoolery has been going on for many years and not just a fairly recent thing.

Regards,
Symon
Afik the yellow coloured chalk lettering on mullard valves simply denoted manufacturer in the year of their anniversary, nothing more, apparently reading the manufacturing and date codes has become something of a cult following.
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Old 16th May 2023, 9:23 pm   #3112
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Default Re: The Audiophoolery Thread.

[QUOTE=Cathovisor;1558550]
Quote:
Originally Posted by emeritus View Post
Back in the days before the BBC broadcast 24/7, they used to play a sequence of test tones after shutdown on FM, presumably to allow you to check for things like stereo balance. /QUOTE]

It was for lines testing - known as "step tone".
Thanks for that info, I always did wonder what they were really for.
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Old 16th May 2023, 10:08 pm   #3113
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Default Re: The Audiophoolery Thread.

The valve Walkman PSU is particularly daft, but we ought to remember that some of the big UK OEMs have been on the PSU upgrade gravy train for decades... You have a PSU for 500 quid, one for a 1,000 and a deluxe for 2,000. What does it say about the PSR of the electronics, assuming the 'improvement' isn't placebo? Do they deliberately make the circuits susceptible to junk?

(I'll go with placebo. Even cheap opamps have decent PSR these days)
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Old 16th May 2023, 10:18 pm   #3114
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Default Re: The Audiophoolery Thread.

Plug and play valves vs. soldered in transistors. I see a huge can of worms being opened here on the audible merits of traditional solder vs. lead free.
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Old 16th May 2023, 10:41 pm   #3115
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Plug and play valves vs. soldered in transistors. I see a huge can of worms being opened here on the audible merits of traditional solder vs. lead free.
...and what grade of flux you use.
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Old 16th May 2023, 10:47 pm   #3116
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Default Re: The Audiophoolery Thread.

It looks like you've found a yawning gulf of a marketing opportunity for audiophile solder.

So someone has to buy a pundit approved amplifier and get an approved guru to remove all the solder and redo it with the audiophile stuff. You'll soon revel in a fast soundstage and wide bass.

David
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Old 16th May 2023, 11:57 pm   #3117
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Default Re: The Audiophoolery Thread.

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The valve Walkman PSU is particularly daft, but we ought to remember that some of the big UK OEMs have been on the PSU upgrade gravy train for decades... You have a PSU for 500 quid, one for a 1,000 and a deluxe for 2,000. What does it say about the PSR of the electronics, assuming the 'improvement' isn't placebo? Do they deliberately make the circuits susceptible to junk?

(I'll go with placebo. Even cheap opamps have decent PSR these days)
Most of the PSU upgrade stuff is BS in my view - it reflects poorly on the original design of the amplifier, does it not? The rot started with the Naim SNAPS, if memory serves - a power amplifier supply for two two-transistor preamps! As it happens, there is a market for a decent WM-D6C supply - the motor control chip is a delicate thing and not well protected. The unit is centre-pin negative with no reverse polarity diode, and doesn't seem too happy with SMPSs either. That said, try making a compact linear which meets preset efficiency standards...
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Old 17th May 2023, 12:25 am   #3118
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Default Re: The Audiophoolery Thread.

Much better if superior solder is certificated to have been applied in an oxygen free atmosphere. Certificates are everything, they can be displayed.

Dave
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Old 17th May 2023, 12:56 am   #3119
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Default Re: The Audiophoolery Thread.

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Plug and play valves vs. soldered in transistors. I see a huge can of worms being opened here on the audible merits of traditional solder vs. lead free.
Could be a whole new market for oxygen free cryo treated solid gold pin transistor sockets, perhaps there already is!.
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Old 17th May 2023, 4:59 am   #3120
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Default Re: The Audiophoolery Thread.

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...and even the shape of the getter ring, Lord help us.
Yes, I recall seeing that in the earlier days of eBay and wondered what all that nonsense was about. I guess audiophoolery has been going on for many years and not just a fairly recent thing.

Regards,
Symon
Afik the yellow coloured chalk lettering on mullard valves simply denoted manufacturer in the year of their anniversary, nothing more, apparently reading the manufacturing and date codes has become something of a cult following.
Greg.
If you haven't got the gear to test valve gain or emission, you might assume that two unused valves of the same type made around the same time in the same factory are a good match. But it would be a wild guess, wouldn't it? I usually test valves from the same factory for emission if I want a likely match, but that's because I can't test for gain.
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