this early JBL transformer

[pyonc]

Hi

I need your advice on these two units of JBL SA600 of the 1960s era. I'm a great fan of vintage JBL gear.
Just take a look at the two pics here. The first one show a very early version, and the second a much later model.
At the moment, both have been tested work fine, all functions working.
In particular, the first one has the early-style output transformer, compared with the later metal-mounted one.
I'm curious about this particular transformer of the very early model, common in other vintage brands of the same era.
Could anyone tell me some characteristics about this kind of transformer?
Googling on this, it looks like they're magnetic components.
Also, do you think it needs replacement in the near future, compared with the metal-mounted later model?
What's the main difference between the early and later transformers?
Any feedback and comments are welcome.

[Joseph Smith Jr]

One simply has covers, or bells, the other does not
They are, or can be, functionally identical, meaning the values found at the taps
The windings and subsequent taps determine the transformer's ratings, the bells have nothing to do with it
Leaving off the covers simply saves a few pennies per unit
End bells can conceivavbly offer some degree of shielding if a unit is used in a sensitive area, but the efficacy of such would be circuit and design specific
Many times, transformers with bells are also potted
There may, or may not, be any technical difference between these two SPECIFIC examples, only a service manual or actual measurements could tell me this for sure
But the bottom line is, it is merely a difference in manufacturing execution, not functionality
It is also to some degree a cosmetic and safety practice
The covers have noting to do with the function of a transformer, other than to facilitate potting and theoretically make for a safer and more quiet unit
In the case of these two amps you have presented, the difference is probably because JBL sourced them from different vendors, or, the vendor changed their design
One of them could even be an in the field service replacement, I do not have enough intimate knowledge of these amps to tell you whether or not that is the case, but I doubt that it is
You can see quite clearly that more than a few parts underwent changes either in design or supplier over the life's run of the model
No, you don't need to worry about changing your transformer

Joe

[pyonc]

One simply has covers, or bells, the other does not
They are, or can be, functionally identical, meaning the values found at the taps
The windings and subsequent taps determine the transformer's ratings, the bells have nothing to do with it
Leaving off the covers simply saves a few pennies per unit
End bells can conceivavbly offer some degree of shielding if a unit is used in a sensitive area, but the efficacy of such would be circuit and design specific
Many times, transformers with bells are also potted
There may, or may not, be any technical difference between these two SPECIFIC examples, only a service manual or actual measurements could tell me this for sure
But the bottom line is, it is merely a difference in manufacturing execution, not functionality
It is also to some degree a cosmetic and safety practice
The covers have noting to do with the function of a transformer, other than to facilitate potting and theoretically make for a safer and more quiet unit
In the case of these two amps you have presented, the difference is probably because JBL sourced them from different vendors, or, the vendor changed their design
One of them could even be an in the field service replacement, I do not have enough intimate knowledge of these amps to tell you whether or not that is the case, but I doubt that it is
You can see quite clearly that more than a few parts underwent changes either in design or supplier over the life's run of the model
No, you don't need to worry about changing your transformer

Joe

Got it, Joe! Thanks a lot for your kind and detailed information on this.
My long doubt on this issue has been finally solved!
By the way, are the components of the transformer without end bell magnetic? Just want to double check.

[Joseph Smith Jr]

Got it, Joe! Thanks a lot for your kind and detailed information on this.
My long doubt on this issue has been finally solved!
By the way, are the components of the transformer without end bell magnetic? Just want to double check.

http://www.electronics-tutorials.ws/...er-basics.html

http://www.learnabout-electronics.or...sformers03.php

https://en.wikipedia.org/wiki/Transformer

https://en.wikipedia.org/wiki/Transformer_types

[JeffW]

In particular, the first one has the early-style output transformer, compared with the later metal-mounted one.
I'm curious about this particular transformer of the very early model, common in other vintage brands of the same era.
Could anyone tell me some characteristics about this kind of transformer?

Seeing as how it's a solid state amp, and there's only a single transformer, my guess is that it's the power supply transformer - not an output transformer.

[grumpy]

By the way, are the components of the transformer without end bell magnetic? Just want to double check.

thin interleaved steel plates, regardless of covers or not...

Magnetic? Sure. Magnetized? Probably not.

[pyonc]

http://www.electronics-tutorials.ws/...er-basics.html

http://www.learnabout-electronics.or...sformers03.php

https://en.wikipedia.org/wiki/Transformer

https://en.wikipedia.org/wiki/Transformer_types

I love these websites! Thanks much again.

[pyonc]

Seeing as how it's a solid state amp, and there's only a single transformer, my guess is that it's the power supply transformer - not an output transformer.

You know better than I, and you're right. Thanks for correcting me.

[pyonc]

thin interleaved steel plates, regardless of covers or not...

Magnetic? Sure. Magnetized? Probably not.

Yes, magnetic..... Thanks for your sharp observation, grumpy.