The VALVE THREAD reboot!

[Friesiansam]

All new vacuum tubes are produced in only a handful of factories world wide (they are located in Russia and China).
The largest factory in China (Shuguang) closed down in 2019. The vast majority of all new tubes today are now manufactured in the Expo-Pul factory in Russia, regardless of the brand printed on them - even the revived British 'Brimar' brand are made there.
Guitar amplification is the main driving force for the need for new vacuum tube manufacture and during covid there was a massive demand for musical equipment (including tube amplification) that created a world wide tube shortage (not helped by the closing of the Shuguang factory). Prices skyrocketed, but have since come down a bit.
Interestingly, Western Electric set up a factory in the USA to produce only 300B Hi-Fi power tubes and they sell for $1,500 for a matched pair.
McIntosh uses all Russian made tubes in all of it's amplifiers.

The Global Supply of Vacuum Tubes: What Happens Now?

Several weeks back, Jay Jay French discussed in his article, “Nero Fiddles while Rome…” (Issue 158), that the atrocities still taking place in Ukraine make our pastime of audio seem frivolous in the shadow of greater existential threats. He is correct, and I’m sure many of us feel the same...

www.psaudio.com

Brimar Thermionic Products Ltd say they are working towards UK valve manufacturing.

 

[My2Cents]

even the revived British 'Brimar' brand are made there.

Indeed they are. They found the machinery required in a junkyard in the Western Balkans. Based on the price of the USA manufactured 300B's I wonder what the cost will be if it ever becomes a reality?

 

[SallyB]

Very nice...
What does 'Reverse' nmode do??

As far as I was concerned it swapped the left and the right channels, but according to WHF: “there’s also a two-step Bass Boost and a stereo reverse function that inverts the signal phase 180 degrees. In some systems, the inverted phase could give more focused results.”

Didn’t do much for me if I’m honest!😀

 

[Al ears]

As far as I was concerned it swapped the left and the right channels, but according to WHF: “there’s also a two-step Bass Boost and a stereo reverse function that inverts the signal phase 180 degrees. In some systems, the inverted phase could give more focused results.”

Didn’t do much for me if I’m honest!😀

Interesting, just curious, it's not something you see everyday...

 

[SallyB]

Interesting, just curious, it's not something you see everyday...

Any thoughts as to when such a feature might be useful? Cheers

 

[Al ears]

Any thoughts as to when such a feature might be useful? Cheers

No, not really.... Don't understand 'inverted phase could give more focused results....'

 

[My2Cents]

It's more likely that this switch reverses the polarity of the left and right channels, it doesn't just swap left and right and it's got nothing to do with the focus of the sound. It's basically the same as you swapping the + and - connections around on the back of each speaker.
It was a common feature on early stereo amplifiers back in the early days of stereo vinyl because many master recordings got mastered out of phase.
This resulted in the sound-stage of the orchestra being switched - you would notice this on playback because the placement of the instruments would be reversed.
If you have such a recording and you switch it to 'mono' any sound common to both channels will actually cancel each other out and therefore be inaudible.
Many early Capitol stereo records in particular suffered from the problem of being mastered out of phase, but they were not alone. Early Decca and DG discs did also. By the late 70's most companies were complying with RIAA standards which helped to solve the problem.

 

[SallyB]

It's more likely that this switch reverses the polarity of the left and right channels, it doesn't just swap left and right and it's got nothing to do with the focus of the sound. It's basically the same as you swapping the + and - connections around on the back of each speaker.
It was a common feature on early stereo amplifiers back in the early days of stereo vinyl because many master recordings got mastered out of phase.
This resulted in the sound-stage of the orchestra being switched - you would notice this on playback because the placement of the instruments would be reversed.
If you have such a recording and you switch it to 'mono' any sound common to both channels will actually cancel each other out and therefore be inaudible.
Many early Capitol stereo records in particular suffered from the problem of being mastered out of phase, but they were not alone. Early Decca and DG discs did also. By the late 70's most companies were complying with RIAA standards which helped to solve the problem.

That’s absolutely fascinating, thanks for enlightening me

 

[SallyB]

It's more likely that this switch reverses the polarity of the left and right channels, it doesn't just swap left and right and it's got nothing to do with the focus of the sound. It's basically the same as you swapping the + and - connections around on the back of each speaker.
It was a common feature on early stereo amplifiers back in the early days of stereo vinyl because many master recordings got mastered out of phase.
This resulted in the sound-stage of the orchestra being switched - you would notice this on playback because the placement of the instruments would be reversed.
If you have such a recording and you switch it to 'mono' any sound common to both channels will actually cancel each other out and therefore be inaudible.
Many early Capitol stereo records in particular suffered from the problem of being mastered out of phase, but they were not alone. Early Decca and DG discs did also. By the late 70's most companies were complying with RIAA standards which helped to solve the problem.

Also surprising is that Leben included this feature when the amp first came out in, I believe, 1992!

 

[Gray]

It's more likely that this switch reverses the polarity of the left and right channels

But if it reversed the polarity of both channels, then the channels would still be in phase with each other.

I can only say that the 'reverse' switch on my Harman Kardon amp swapped the channels.

 

[Gray]

....many master recordings got mastered out of phase.

Precisely what was out of phase with what though?
All mics? Some mics? Both channels? One channel?

If it was some, but not all mics, apart from being an unforgivable situation, no amp switch would cure that.

 

[nopiano]

But if it reversed the polarity of both channels, then the channels would still be in phase with each other.

I can only say that the 'reverse' switch on my Harman Kardon amp swapped the channels.

You may have encountered it as absolute phase. I remember a Meridian CD player I owned having a phase or invert switch. It reverses phase of both channels so they stay in phase with each other. It is based on the idea that a more realistic sound arises if when say a bass drum is hit, both speakers cones move outwards. If they both move inwards then absolute phase is inverted. Historically some studios tended to invert phase, and others didn't. Some amplifiers invert too; Hifi News reviews mention this.

(I think of it like blowing instead of sucking. Imagine trying to suck a pingpong ball across a table -v- blowing it!)

 

[SallyB]

You may gave encountered it as absolute phase. I remember a Meridian CD player I owned having a phase or invert switch. It reverses phase of both channels so they stay in phase with each other. It is based on the idea that a more realistic sound arises if when say a bass drum is hit, both speakers cones move outwards. If they both move inwards then absolute phase is inverted. Historically some studios tended to invert phase, and others didn't. Some amplifiers invert too; Hifi News reviews mention this.

(I think of it like blowing instead of sucking. Imagine trying to suck a pingpong ball across a table -v- blowing it!)

Just trying it now!😂😂

 

[Gray]

You may gave encountered it as absolute phase. I remember a Meridian CD player I owned having a phase or invert switch. It reverses phase of both channels so they stay in phase with each other. It is based on the idea that a more realistic sound arises if when say a bass drum is hit, both speakers cones move outwards. If they both move inwards then absolute phase is inverted. Historically some studios tended to invert phase, and others didn't. Some amplifiers invert too; Hifi News reviews mention this.

(I think of it like blowing instead of sucking. Imagine trying to suck a pingpong ball across a table -v- blowing it!)

Yes, some people say they can tell whether they're hearing a positive or negative reaction to the positive sound wave.

You'd certainly have the evidence on an oscilloscope - and it makes sense that it might be more audible than the difference between..............say.............cables 😏

 

[Gray]

You may gave encountered it as absolute phase.

Yes and I can understand how the incorrect absolute phase could pass unnoticed.

What @My2Cents is describing in post #57 must be relative phase difference(s) - though I'd like to know just how any amp switch could cure them.

 

[Al ears]

That’s absolutely fascinating, thanks for enlightening me

And me...

 

[Al ears]

Yes, some people say they can tell whether they're hearing a positive or negative reaction to the positive sound wave.

You'd certainly have the evidence on an oscilloscope - and it makes sense that it might be more audible than the difference between..............say.............cables 😏

...steady on there....

 

[Friesiansam]

Yes, some people say they can tell whether they're hearing a positive or negative reaction to the positive sound wave.

You'd certainly have the evidence on an oscilloscope - and it makes sense that it might be more audible than the difference between..............say.............cables 😏

I'm sure there must be some people out there, that claim polishing the outer cover on all their cables, makes an audible difference...

 

[nopiano]

Just trying it now!😂😂

When I could easily switch it, there was definitely a change. But I could never really decide which I preferred. In the end I forgot it!

 

[nopiano]

Yes and I can understand how the incorrect absolute phase could pass unnoticed.

What @My2Cents is describing in post #57 must be relative phase difference(s) - though I'd like to know just how any amp switch could cure them.

TBH I didn’t recognise that description. There is an extended explanation here:-

Absolute Phase: Fact or Fallacy?

Natural sounds produce different waveshapes during their positive and negative phases, and playback-system polarity reversal often changes the reproduced sound. Does this mean our ears are phase-responsive, or is there something else here we've been overlooking?

www.stereophile.com

And since we’ve moved on from valves, I gather some amps invert phase between each channel to reduce load on the transformer. Further in the signal path it’s all corrected, so the output matches as you’d expect. Fascinating!

 

[AJM1981]

Maybe I will get a decent valve amp in the future. Till that time I will fake my way through with the Sansui au101

 

[nopiano]

Maybe I will get a decent valve amp in the future. Till that time I will fake my way through with the Sansui au101

I only found out quite recently that Sansui made valve amps in their early days!

 

[jjbomber]

Just trying it now!😂😂

I believe it's to get a ping pong ball out of a bottle. If you suck, it gets jammed. If you blow the air forces the ball out from behind.

 

[AJM1981]

I only found out quite recently that Sansui made valve amps in their early days!

They indeed did. : ) I also didn’t know that till a few months ago when I went looking around for solid state amps that sounded like valves sounded.