"Running in" speakers

[ef37a]

No James, nothing to do with "bathtubs"!

I was in at the very first CTVs (PAL) broadcasts and if you took 50 TV sets off the lorry and just switched them on in the shop (BBC2 only of course!) ALL of them would have purity and convergence errors.
Nothing to do with "reliability" the errors were caused by the TVs swinging through the earth's magnetic field, iron bridges, OH power lines and all other magnetic sources. In fact it would have been statistically virtually impossible to find a set NOT out of whack! Of course once we had the tellies adjusted in the workshop it had to be done all over again at the customer's home and if wifey decided to change the room around..all had to be done again!

Yes, one or two TVs would not work but in truth we could never get enough at any one time to get much of an idea of failure rates (you had to put your name down and a wedge to get a CTV back then!)

By the time the Japanese had entered the UK CTV market purity and convergence problems had pretty much been licked. Philips, Ferguson, Grundig, Sony all worked pretty well straight out of the box and they had now developed 110dgr CRTs and even a 26" TV was a one (strong) man job.

Hugh, we all have "limited knowledge" no need for the dig.

Drew, such failures as you describe would not happen to a new product and since those that occurred over (a long) time were caused by very variable external effects the BT curve does not apply IMHO.
Dave.

[Drew Stephenson]

Drew, such failures as you describe would not happen to a new product and since those that occurred over (a long) time were caused by very variable external effects the BT curve does not apply IMHO.
Dave.

I think we're talking at cross purposes somewhere then Dave because to me they are exactly the kind of thing that applies in the final phase of the bathtub curve.
From wikipedia:
The bathtub curve has 3 regions:
The first region has a decreasing failure rate due to early failures.
The middle region is a constant failure rate due to random failures.
The last region is an increasing failure rate due to wear-out failures.

[Hugh Robjohns]

Hugh, we all have "limited knowledge" no need for the dig.

Not a dig, and you misunderstood my point.

I've had hundreds of speakers here, both to review and for my own use, over the last 30 years or so. That's a lot of experience of listening to brand new speakers, in direct comparison to known references. In comparison, your experience is limited... with all due respect. Thats all I meant.

Under these circumstances, changes of sound character in the early stages of use, if present, are very obvious and can't be attributed to 'getting used to new speakers'.

Perhaps the bathtub analogy was a poor choice and has confused you. I wasn't talking about the Mean Time Between Failure — the usual bathtub association and what you're describing with your legacy TVs.

Instead I was trying to allude to the way material characteristics change and settle down during initial use, then remain stable for a long period, before finally degrading and failing at the end of their working life.

If that initial settling change is substantial or critical to the way the thing works, or it takes a longer time than the factory test, you're likely to notice a 'running in' during initial listening.

If it's insignificant, not critical, or quick, you won't!

And now I'm off to no1 daughter's wedding, so signing off....

[ef37a]

Hugh, we all have "limited knowledge" no need for the dig.

Not a dig, and you misunderstood my point.

I've had hundreds of speakers here, both to review and for my own use, over the last 30 years or so. That's a lot of experience of listening to brand new speakers, in direct comparison to known references. In comparison, your experience is limited... with all due respect. Thats all I meant.

Under these circumstances, changes of sound character in the early stages of use, if present, are very obvious and can't be attributed to 'getting used to new speakers'.

Perhaps the bathtub analogy was a poor choice and has confused you. I wasn't talking about the Mean Time Between Failure — the usual bathtub association and what you're describing with your legacy TVs.

Instead I was trying to allude to the way material characteristics change and settle down during initial use, then remain stable for a long period, before finally degrading and failing at the end of their working life.

If that initial settling change is substantial or critical to the way the thing works, or it takes a longer time than the factory test, you're likely to notice a 'running in' during initial listening.

If it's insignificant, not critical, or quick, you won't!

And now I'm off to no1 daughter's wedding, so signing off....

Please give the bride and groom all my best wishes and commiserations to poor old dad's bank account!

My position stands. There has never been any proper investigation into the subject that I know of and Phil Ward has been sceptical in more than one review (he would be the very man to sort this out!)

But, again, even IF speakers "settle in" after a few hours use I still maintain the factory should do it, at least for the ones north of 2-3k!

Just to be clear? The TVs did not suffer a BT failure. They ALL had the same problem and it was well known.

Dave.

[James Perrett]

Just to be clear? The TVs did not suffer a BT failure. They ALL had the same problem and it was well known.

Maybe we had all the dodgy ones then because I definitely remember a significant number of failures of new and nearly new TVs (in addition to the routine adjustments needed).

[ef37a]

Just to be clear? The TVs did not suffer a BT failure. They ALL had the same problem and it was well known.

Maybe we had all the dodgy ones then because I definitely remember a significant number of failures of new and nearly new TVs (in addition to the routine adjustments needed).

What sort of era were you involved in CTVs James? As I said, I was there at the very start. Huge console models mainly 26" Bush and Pye. These were virtually all valve designs , not the most stable devices for line and field sync and amplitude! But I do not recall a significant number of actual faults. You have to remember that this was 'new technology' at least on the domestic scene and built to sell at a reasonable price (but a 26" CTV still cost as much as a very decent second hand car!).

The rot really set in when the rental market exploded and companies like Thorn (Ferguson) wanted cheap and easily repairable TVs. That prompted the design of the first (I think?) all transistor, 'modular' CTV the idea being that the field tech would start his day with a rake of 'modules'. The fly in that ointment was that it was that the "too bloody clever for its own good" chopper PSU caused 85% of faults and they were a B*****D! to fix in the field. Of the next least reliable module was the line output stage and they were no picnic to fix either!

The upshot was that after the third service call the tech was out of modules and had to go back to base to fix them. Day buggered!

A few years later Grundig came out with a semi-modular design but most of their faults were on the PCB Mother board!

One of the most reliable (and best picture) designs was a hybrid ITT/KB which retained valves for line OP, field OP and sound. Later they went all solid state and they were IIRC pretty reliable.

Dave.

[Arpangel]

I see an opportunity to post a rather "I’ll get my coat" joke, at this point, just to cheer things up.

What do you call a dog that lives on a submarine?

a "sub-woofer"

[James Perrett]

What sort of era were you involved in CTVs James?

I was working at the TV shop from 1978-1980 while I was at college. I was mainly a sales assistant but also fixed simple things like kettles. I did Saturdays and school holidays. PIL tubes had just started coming in as I remember it.

The rot really set in when the rental market exploded and companies like Thorn (Ferguson) wanted cheap and easily repairable TVs. That prompted the design of the first (I think?) all transistor, 'modular' CTV the idea being that the field tech would start his day with a rake of 'modules'. The fly in that ointment was that it was that the "too bloody clever for its own good" chopper PSU caused 85% of faults and they were a B*****D! to fix in the field. Of the next least reliable module was the line output stage and they were no picnic to fix either!

The upshot was that after the third service call the tech was out of modules and had to go back to base to fix them. Day buggered!

Yes, I saw quite a few of those modular sets in the workshop and PSU faults seemed common. The cheapest set we sold was a Thorn and it was quite popular. I don't remember many valves by the time I was there although there were still a few in boxes on the shelf.

[Arpangel]

What sort of era were you involved in CTVs James?

I was working at the TV shop from 1978-1980 while I was at college. I was mainly a sales assistant but also fixed simple things like kettles. I did Saturdays and school holidays. PIL tubes had just started coming in as I remember it.

The rot really set in when the rental market exploded and companies like Thorn (Ferguson) wanted cheap and easily repairable TVs. That prompted the design of the first (I think?) all transistor, 'modular' CTV the idea being that the field tech would start his day with a rake of 'modules'. The fly in that ointment was that it was that the "too bloody clever for its own good" chopper PSU caused 85% of faults and they were a B*****D! to fix in the field. Of the next least reliable module was the line output stage and they were no picnic to fix either!

The upshot was that after the third service call the tech was out of modules and had to go back to base to fix them. Day buggered!

Yes, I saw quite a few of those modular sets in the workshop and PSU faults seemed common. The cheapest set we sold was a Thorn and it was quite popular. I don't remember many valves by the time I was there although there were still a few in boxes on the shelf.

I seem to have wives that were part of the TV repair world, my current "partners" dad was a TV repair man, had his own business, in fact, my studio is in his old workshop, my damp basement!
My first wife’s father was a leading light in Radio Rentals, in the 50’s/60’s
I found loads of old valve TV components down in the basement, left over from her fathers days, all interesting stuff.