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Old 19th Sep 2020, 3:36 pm   #1
Nuvistor
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Default PX4 valves?

My hearing is not that great, much worse since I have grown older. When I repaired amplifiers I relied on test equipment, decent AF gen, THD instrument, scope meter etc to confirm the amp was within spec.Perhaps that wasn’t enough but customers were happy with the results. Never heard or repaired an amp with PX4 valves.

So a simple (is it?), what is special about the PX4 that commands the price for valves many years old and may not be up to original spec?
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Old 19th Sep 2020, 5:05 pm   #2
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Default Re: PX4 valves?

In short, the PX4 is a directly heated triode; 3 words that get certain audio fans into a lather of excitement.

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Old 19th Sep 2020, 5:13 pm   #3
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Default Re: PX4 valves?

I think it is more like three symbols (and perhaps the shape a little) as there are directly heated valves, even triodes, which are a fraction of the price (although not generally power types).
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Old 19th Sep 2020, 5:19 pm   #4
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Default Re: PX4 substitutions

I remember reading that the pidgin-English phrase "Kerosene lamp bilong jesus christ him bu**er-up finish complete" meant total eclipse of the sun, in a group of remote islands.

This shows the sort of mess we get into if the concepts of one belief system are used to try to describe the concepts of another, quite different one.

There are people who believe that these valves have special properties, special enough to justify the prices to their minds. There are other people who do believe in these properties. Are they real? One camp thinks so, the other camp thinks not. Having watched for many years, I think there is no reconciling the two camps.

The devices being favoured seem to impart changes to the signal being listened to, so we are a long way from 'A piece of straight wire with gain'. If someone likes this, fine, go for it. However, it is making changes to what was recorded or broadcast, so saying that it is right seems to be on dodgy ground. Are they trying to reproduce the original music with the highest fidelity? or are they trying to make a different sound to their own preferences. I think they are doing the latter. Where I disagree is with claims that they are doing the former.

It would be easy to dismiss it as 'it's their money, and if it makes them happy...'. But I'm not sure they ever achieve happiness. Many of them seem to be stuck in perpetually upgrading equipment in search of an unattainable goal, like some accursed flying Dutchman. If they attained happiness, they could stop buying and sit back for many years and get on with listening to the music, not the equipment.

There are other inconsistencies. The greater disposable wealth needed to indulge in audio exotica tends to come in later life, as does degrading hearing. Is this one of nature's cruelest jokes?

A simple statement like "It sounds different, and I happen to like it!" is completely unassailable. I like Brie and Port Salut, but I do not like the taste of blue cheeses. I feel no need to justify this. I feel no need to try to convince others that they should come round to my opinions. My opinions are NOT right in any absolute sense, but they are MINE.

Of course the whole business explodes into a great gigglefest when the subjective audio people wheel out pseudoscience in an attempt to justify their preferences. If they'd only kept their gob shut they could have looked little different to a wine aficionado. But the moment the wrong science comes out, it can be attacked by objective and repeatable means. Science has had its share of not-quite-right ideas from N-rays to cold fusion and it has got quite good at testing for reality.

Where their universe impinges on ours is in it being impossibly expensive to repair a nice old radio. Seems a shame to me.

David
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Old 19th Sep 2020, 5:22 pm   #5
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Default Re: PX4 valves?

I recall a while back when sorting through some valves seeing a large ballon shaped 5 pin base pentode with a piece of fusewire strapping 2 pins together. Probably anode and screen. Certainly looked capable of a few watts of audio.
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Old 19th Sep 2020, 5:34 pm   #6
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Default Re: PX4 valves?

Thanks for the comments, I suspected as such but never having one to put through the test set I wasn’t in the position to comment.

I know my hearing is poor but I get a great enjoyment from listening to music of many types on my portable radios, not hifi but neither am I.
As David states, listen and enjoy the music, that is what I do and even if I don’t hear it all it's still good.
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Old 20th Sep 2020, 8:43 am   #7
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Default Re: PX4 valves?

It's only in the last 10 years if that that certain valves have reached cult status and price, probably due in part to Internet based spiel bigging up their supposed magic properties. most audiophiles wouldn't have touched a toob amp not that long ago, guitarists the same, someone comes along and says "this ere toob amp sounds wicked ", someone repeats it, soon everyone is saying the same thing.

A lot of humans behave like sheep following the trend, even better if the trend becomes exclusive, it becomes a self fullfilling prophesy. 10 years from now it might have changed, who knows by then there may be internment camps for audiophiles, TV/Internet pundits and wellness gurus.

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Old 20th Sep 2020, 10:28 am   #8
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Default Re: PX4 valves?

Oh, I don't know Andy. I bought my first pair of Quad IIs in the early 1990's and the valve hi-fi market was starting to swing upwards even then. Audio Note UK started around then https://www.audionote.co.uk/ and Audio Innovations preceded them (founded around 1984, I think). I'm looking at the June 1996 issue of Hi-Fi News and it's got a pair of new production Quad IIs on the cover, re-released as a limited edition to mark the 60th anniversary of the founding of the Acoustical Manufacturing Company. When I first joined this forum I seem to remember seeing 'Member of the PX4 owners club' as the footnote of at least one forum member. And I've just noticed that the day after tomorrow will be my 13th anniversary of signing up !

Cheers,

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Old 20th Sep 2020, 10:47 am   #9
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Default Re: PX4 valves?

Some of these valves have been silly money for a lot longer that 10 years

https://www.vintage-radio.net/forum/...read.php?t=622

Its just as the supply has dwindled they have outstripped inflation more like tracking house prices in the South East.

Even in the 1990's sets were regularly having their output bottles popped then dumped or sold on.

This problem has now been with us at least 3 decades.

I don't think it will ever change not when there are "tube rollers"

The PX4's are one problem but at least you can currently buy new ones. Valves like the 2P and 2XP are not to my knowledge being manufactured and this is leaving a lot of 30's and early 40's Cossors with empty sockets.

Crossed with GJ that's what happens when breakfast arrives when your in the middle of posting

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Last edited by Cobaltblue; 20th Sep 2020 at 10:49 am. Reason: Wot GJ said
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Old 20th Sep 2020, 10:49 am   #10
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Default Re: PX4 valves?

Well put, David: my thoughts exactly, though expressed better than I could.

One thing I've been trying to find out, and failed, is when did PX4s go out of routine production? According to to RMorg there was one set made with them in 1949 but I'd have thought some would be made after that for replacement purposes.
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Old 20th Sep 2020, 11:03 am   #11
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Default Re: PX4 valves?

It's always been there but it seemed to kick on in the 90's, a true valve revival for the Hi-Fi lot. It was the early 90's when I started building the odd valve amplifier, although none stretched to anything more than ECL86, El84,6V6. I was poor, couldn't afford things like KT's or 300B's. I remember saving long and hard for a pricey Goldring cartridge. It was lovely. Problem was just two weeks after buying it I was hankering after a cartridge that was twice the price. I kind of gave up after that and escaped from the psychological damage of always being thirsty.
Having said that it's the same with many other interests - cameras, musical instruments, sports equipment. There always seems to be someone making 'the ultimate' and if that doesn't satisfy, well we can find you another, different ultimate.
Then there was that Japanese valve amp with the silver output transformers, whatever that was called. Was that the Audionote?
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Old 20th Sep 2020, 11:30 am   #12
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Default Re: PX4 valves?

Quote:
Originally Posted by ThePillenwerfer View Post
Well put, David: my thoughts exactly, though expressed better than I could.

One thing I've been trying to find out, and failed, is when did PX4s go out of routine production? According to to RMorg there was one set made with them in 1949 but I'd have thought some would be made after that for replacement purposes.
PX4 (and PX25) are listed as replacement types, so still available, in the 1966 8th edition of the Iliffe "Radio Valve Data" manual.
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Old 20th Sep 2020, 11:55 am   #13
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Default Re: PX4 valves?

The setmakers dropped power triodes pretty quickly as beam tetrodes and kinkless tetrodes came on the scene.

Suddenly they could have plenty of power and plenty of stage gain.

The people who bought equipment in those days and the manufacturers development people as well as those they tried their new designs out on heard nothing wrong with them. In the quest for lower distortion, the ultra-linear circuit came along and became very popular at the upper end of the market.

No-one was complaining about how slow the bass was, the stifling lack of 'air' and 'authority' or that this end of the speaker cables must be fitted to the amplifier.

Were people so deaf and unsophisticated in those days that they were completely unaware of all the things now said to make major and life-changing differences?

Or did they just live in a better age before several major sorts of flim-flam were invented?

Thorens saw their change from idler to belt drive as an improvement!

In Yorkshire, we had the word 'codology', it had nothing to do with fish.

David
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Old 20th Sep 2020, 11:58 am   #14
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Default Re: PX4 valves?

I think it was the Audio Note 'Ongaku'

I don't think anyone noticed the date, everyone was just staring at the price.

David
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Old 20th Sep 2020, 12:00 pm   #15
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Default Re: PX4 valves?

Quote:
Originally Posted by Michael.N. View Post
It's always been there but it seemed to kick on in the 90's, a true valve revival for the Hi-Fi lot. It was the early 90's when I started building the odd valve amplifier, although none stretched to anything more than ECL86, El84,6V6. I was poor, couldn't afford things like KT's or 300B's. I remember saving long and hard for a pricey Goldring cartridge. It was lovely. Problem was just two weeks after buying it I was hankering after a cartridge that was twice the price. I kind of gave up after that and escaped from the psychological damage of always being thirsty.
Having said that it's the same with many other interests - cameras, musical instruments, sports equipment. There always seems to be someone making 'the ultimate' and if that doesn't satisfy, well we can find you another, different ultimate.
Then there was that Japanese valve amp with the silver output transformers, whatever that was called. Was that the Audionote?

The audio obsession game is an awful addiction - into which the perfectionists fall very hard. Generally, it's chasing rainbows as it never truly satisfies.
There's always that 'it could be a bit better' hankering that's hard to dismiss.
You might get an improvement or a 'difference' from one bit of kit to another, but most of it is related to what you paid - of course, very much on a 'law of diminishing returns' basis.
I have been there, done it and found it to be a costly waste of precious time, with the latter being the more regretted loss.
I have ended up more or less back where I started, with decent, but not overly expensive gear, and have decided to be content with that.
You can get 90% of the sound for 20% of the cost, I think...
One thing I did learn... buy equipment that is easily maintainable.. and for which parts are reasonably available/widely used.
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Old 20th Sep 2020, 12:09 pm   #16
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Smile Re: PX4 valves?

It is surprising to note that if you look in some of the 60's and 70's television magazines where they have advertisements with their valve stock list with price, some of the PX4/25's are cheaper than some of the then current production P series telly valves!!

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Old 20th Sep 2020, 12:11 pm   #17
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Default Re: PX4 valves?

Yes, I noticed that a while back when going through some old radio magazines.
I suppose at that point in time, they were actually quite unwanted.. !
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Old 20th Sep 2020, 12:20 pm   #18
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Default Re: PX4 valves?

That's why I was curious about the date. Given their supposed scarcity, and therefore value, I assumed they'd gone out of production long ago. Apparently not the case.
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Old 20th Sep 2020, 12:24 pm   #19
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Default Re: PX4 valves?

When I entered the world of vintage wireless in 1977 I was naive as to the standing and value of certain valves. As was the case in those days when you bought a radio you often were given a load of vintage parts and valves from an ex ham or even a deceased engineer or shop keeper. As such I had a number of PX4 valves in my possession. I never seemed to use them in anything so I decided to let them go. Mr Rees used to advertise for them so I tested them in my Mullard valve tester prior sending them off to him. However I didn't get paid for all of them as I was told some were soft. I think it was me who was soft.
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Old 20th Sep 2020, 1:30 pm   #20
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Default Re: PX4 valves?

When I was an apprentice TV engineer, "1963" one of our customers had a Mono amp with a pair of PX25's. The amp was a Williamson... apparently the bees knees at the time.. pre Leak, Radford etc. The output transformer primary went O/c on one leg.... obviously trying to locate another was impossible so we ordered and fitted a Gardners transformer.
It was returned to the customer who was also a friend of the business.... it came straight back.....with choice words to the effect it was "no good"..the transformer was removed and I was given the amplifier...... as it happened I had a Gardners transformer and it was duly fitted. Now me being "cloth eared" person decided it was ok to me..but eventually it was passed on to another...not because it was good/bad or indifferent.. I think the size had something to do with it. The original owner then started on the "merry go round"... trying this and that...probably never finding his "valhalla" .
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