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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 16th Feb 2019, 11:01 am   #21
PJL
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Default Re: "Audio" Valves

The hype about double triodes has come from the guitar amplifier fraternity where they are driven to distortion to add colour to the sound. It is quite reasonable that differently constructed valves of the same type might have different behaviour at these limit conditions.

Plug & play with valves for hi-fi use may show differences in performance but it is more likely to be related to the circuit they are plugged into than the valve itself. For example ECC82 and ECC83 are not interchangeable and using a different type will alter bias positions and present different gains and impedance that could easily result in an apparent change in tonal quality. Also the valve is 60 years old with unknown history so there is no assurance that the sample you plugged in is in good health.
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Old 16th Feb 2019, 11:11 am   #22
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Default Re: "Audio" Valves

I am getting a bit confused how the posting system works here - seemingly random order, anyway...…………….

Swapping ECC82s and ECC83s - no - the ECC83 are in the MM phono stage so provide RIAA correction as well as amplification. The single ECC82 is what I am told is a cathode follower which will have a gain of around unity. That being so, my CD signal will only pass through the ECC82, while the record deck will pass through both. And yes, changing the ECC82 changes what the CD sounds like, and it changes what the phono stage sounds like too.
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Old 16th Feb 2019, 11:18 am   #23
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Default Re: "Audio" Valves

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I am getting a bit confused how the posting system works here - seemingly random order, anyway...…………….
As a new member your first few posts required moderator approval, so later posts in this thread may have appeared first.

However, as can be seen from the time stamps, all posts are in the correct order.
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Old 16th Feb 2019, 11:23 am   #24
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Default Re: "Audio" Valves

Thanks Graham - I had realised that, but some shuffling seems to have taken place, although now back into date/time order.
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Old 16th Feb 2019, 11:23 am   #25
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Default Re: "Audio" Valves

Please be more specific. Apart from this thread being moved into this section, no other editing by moderators has taken place and I know of no way in which the order of posting can be changed.

Is it possible someone posted a reply in the thread while you were still typing yours?
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Old 16th Feb 2019, 11:30 am   #26
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Default Re: "Audio" Valves

I think military rated components, valves, transistors and IC's do have some advantages.

To meet the contract specifications I think there was a lot more supervision & testing of the product during & after manufacture at the factory.

One example of this applying to IC's (though I'm sure the principle is the same for valves) is the difference between 54 series and 74 series logic IC's. They are essentially the same part, but many people who worked with them back in the 1970's reported that 1/100 new 74 series types were faulty. However, if one tries to find a new old stock 54 series IC that is faulty, good luck. I have been trying my whole life (as an ongoing experiment) have tested literally thousands of NOS 54 series IC's and I still can't find a single one faulty from new.

Also other mil spec parts (if genuine) transistors, capacitors, resistors are less likely to be DOA. For my projects using vintage parts, I often go for mil spec parts (if they are affordable).

I don't know if many of the valves out there such as ECC83's that are being said to be mil spec parts are genuine mil spec conformity, but if they were genuine NOS mil spec parts, you could probably quite sure they will be well made & working. Whether they "sound" any different (in an audio application) that is a whole other story.
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Old 16th Feb 2019, 11:31 am   #27
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Default Re: "Audio" Valves

I have a quantity of "NOS" JAN 12AT7WC of USA manufacture in the 1980s. Packed in sleeves of 5. Barcoded labels affixed and marked NAMSA. (NATO supply agency).When I tested some, they have a far wider spread in characteristics than consumer brand 12AT7. Don't know what equipment they were purchased for originally, but obviously thought as essential spares to buy in the 1980s.
I think I will try "ageing" a sample and see what happens. When I get time of course, as I am retired!
I must admit, some descriptions in sales text are I think dubious. "Tested GOOD" with emission of about 60% quoted. "Strong" is another often used term you see.
Doing a search for 12AT7WC like those I have, I just found some like mine, but used, advertised as a "Matched Quad". There is one shown with white coating within the top section that is described as "One getter has been depleted, but the tube is in very good working condition".
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Last edited by robinshack; 16th Feb 2019 at 11:41 am. Reason: spelling!
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Old 16th Feb 2019, 11:31 am   #28
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Default Re: "Audio" Valves

Sorry Graham - a misunderstanding I think - my screen showed a "random order" as it updated the thread, which now appears logical. Blame the www

Caveat emptor Rob - a little common-sense helps too.

The whole testing thing is a can of worms, or so I read. Actual valve testers do not generally measure any valve in an operating condition, and many people just measure heater resistance and say all is OK based on that.

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Old 16th Feb 2019, 11:53 am   #29
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Default Re: "Audio" Valves

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Originally Posted by Diabolical Artificer View Post
Where are these NOS ECC8*'s? Links? Every big valve toob seller I've come across in recent years have only new Russian or Chinese made valves or when you look up NOS ECC83 you get N/A. Of all the NOS valves I have, I've never seen a ECC83 in it's original box, though I am lucky enough to have a few NOS 81's and 82's in original manufacturers boxes.
Contact Lorenz Tang at Wi Wi Tubes Andy http://www.wiwitubes.com/en/product....d=ECC83&page=1 (there are NIB Mullards on pages 2 and 3). But make sure you're sitting down before you ask him for a price. He was one of the folks buying pallet-loads in the surplus market in the 70's and 80's.

Cheers,

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Old 16th Feb 2019, 11:56 am   #30
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Default Re: "Audio" Valves

If there is a noticeable difference when you change the type of ECC82 used for a cathode follower it is more likely to be a design error, component fault, or a matching problem with your other equipment.

What is the equipment we are discussing? If it is vintage and you want best audio performance then I would start by replacing every resistor and capacitor.
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Old 16th Feb 2019, 12:05 pm   #31
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Default Re: "Audio" Valves

The amp' is a Croft Micro - probably about 20 years old and it was OK'd by Glenn Croft about a year ago.

I feel that I must emphasise, differences are subtle - far too subtle to be aware of unless doing consecutive listenings using the same source.

I was curious and sceptical until about 12-18 months ago, so decided to spend not too much ££ to find out and if you are curious and OCD enough to do back-to-back listening, you can hear differences. When my partner, completely oblivious to what has or has not been changed, describes what I hear, I am happy that it is not all imagination.
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Old 16th Feb 2019, 12:27 pm   #32
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Default Re: "Audio" Valves

The clueless outnumber the clued-up.

The clued-up know when to keep their gob shut, and that leaves the clueless making most of the noise. There is an effect whereby if something is repeated a lot, then others start to take it as the truth.

In this way a self-supporting mass of folklore has arisen around all sorts of spurious beliefs. Some of them may have a basis in fact, but are taken out of all proportion. There is also an attitude that if you can't prove something untrue, then it must be true! and the standards for proof are rather dodgy as well.

Add in human nature that no-one wants to be seen as gullible or foolish.

Season with a generous supply of shysters prepared to make a quick buck out of anything. Misrepresentation, faking, false information, hyping equipment like they hyped records up the hit parade, you name it.

And you have a perfect storm.

On car fora it seems that a majority in America believe that a car battery will self discharge faster if it is stored stood on concrete than it it is stored on wood. Not in other countries, folklore demography. It's a self-supporting belief. Maybe it makes a difference in temperature which makes a real difference, but it is the wood which is seen as the defining thing, not the thermometer. Similarly, we see valves offered for sale with the unstated assumption that having been tested on as late a model AVO as possible makes them better.

It a tube roller keeps plugging ECC81/ECC82/ECC83 into the same socket and doesn't notice a difference then he may be better investing in a hearing test. The characteristics and bias points are intended to be very different.

But it's all a matter of belief systems.

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Old 16th Feb 2019, 12:35 pm   #33
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Default Re: "Audio" Valves

Quote:
Originally Posted by Dave1000 View Post
I was curious and sceptical until about 12-18 months ago, so decided to spend not too much ££ to find out and if you are curious and OCD enough to do back-to-back listening, you can hear differences. When my partner, completely oblivious to what has or has not been changed, describes what I hear, I am happy that it is not all imagination.
That's the indicator that what you're hearing is real - That the differences, in reasonably designed equipment, are not large.

Valve circuitry is usually quite simple and that leaves the characteristics of the valves that are plugged in capable of making discernible differences.

You aren't imagining things. The problem is that many other people are!

How did it go? "In the country of the blind, the one eye'd man is king" No, not quite. Stoned to death as a heretic is more likely!

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Old 16th Feb 2019, 12:53 pm   #34
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I have seen a picture and it is very simple and point to point wired using modern standard parts available from RS including 2W resistors. That leaves circuit design, matching, and of course valve condition. It claims 300ohm output impedance so matching issues are improbable. I can't find a circuit diagram.

You are unlikely to get much sympathy on this site of largely engineers.
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Old 16th Feb 2019, 12:58 pm   #35
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Default Re: "Audio" Valves

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You are unlikely to get much sympathy on this site of largely engineers.
LLOL - I was after information rather than sympathy - I was curious about what valves were used for in their heydays.
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Old 16th Feb 2019, 1:09 pm   #36
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Default Re: "Audio" Valves

The ECC82 was used a lot in TV's, eg: timebase oscillator.

Lawrence.
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Old 16th Feb 2019, 1:13 pm   #37
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Quote:
Originally Posted by Dave1000 View Post
... When my partner, completely oblivious to what has or has not been changed, describes what I hear, I am happy that it is not all imagination.
The cynics who test pharmaceuticals for a living would say that if you and your wife meet during the testing process then the results are compromised. That's the difference between blind testing and double-blind testing - in the latter case not only are the test subjects unaware of what change, if any, has been made but so are the test managers (doctors, nurses etc) with whom they interact. Otherwise, they'd claim, your wife, who knows what features you like in your music, will subconsciously pick up whether you're more or less satisfied after a change and will replay your expectations/disappointments back to you. Double-blind testing costs the pharma people a lot of money. They wouldn't spend it if they didn't have to.

I'll be interested to learn what a calibrated mic makes of the differences. Provided these are set up with reasonable care they can detect changes much smaller than we can perceive with our ears. If yours doesn't show a clear difference then there will be a conundrum to explain.

Incidentally if you're ever going to raise this subject on an audio forum you might want to get other listeners in to confirm your better half's experience. "Even my wife can hear it" is such a cliché in those places that I'm afraid sniggering has now become the most common response. This is a shame because often our partners really are the people who know our systems (nearly) as well as we do. The feeling seems to be, though, that their closeness to us is outweighing their closeness to the kit.

Cheers,

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Old 16th Feb 2019, 1:18 pm   #38
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Default Re: "Audio" Valves

GJ - I am more than well aware of blind, double-blind etc., and subconscious influences, so I did all that I could to do as best that I could.

My question was about valve usage, the hifi thing came along with it, for better or worse.
So far as the mic' goes - I will compare the chalk and cheese valves judged by ear (modern Tung-Sol and old Mulard) and go from there, when I have a chance.
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Old 16th Feb 2019, 1:27 pm   #39
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Default Re: "Audio" Valves

I expect with a lot of this is let the buyer beware. I remember years ago when with someone I kew. We were amused when we bought a valve from a local supplier, as these were often supplied in plain white boxes (I still have two ECC83's from then). There was never any issue with quality, but there was often traces of dust on the top lol. I suspect nowadays though that there are a lot of people out there selling valves that they know little about (or worse NOS fraudulently). In recent times I first wondered about buying quantities of valves from Eastern Europe in sealed boxes, but, although not ECC83's, I have found them to be the real deal.
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Old 16th Feb 2019, 1:29 pm   #40
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Default Re: "Audio" Valves

I have a new tray of wire ended ex mil ECC8*, they may even have a CV number. I can’t remember which version as I haven’t seen them for 20 odd years. At the time of finding them I heard that they were intended for the electronics in missiles or some such application.

Anybody know anything about them.

Jim
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