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Old 10th Jun 2020, 7:00 am   #21
Half a Mullard
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Default Re: RS Audio Transformer

Many thanks for the comments folks. Thanks for the video Kevin, that's very useful. It certainly gives good results from that demonstration. I think Dave did mention that by taping the laminations some bass response would be lost?

I am a bit vague about saturation though. What effect does it have audibly and electrically? Does it cause any damage? All help appreciated!
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Old 10th Jun 2020, 8:29 am   #22
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Default Re: RS Audio Transformer

I would leave it as it is. On a set running only a smallish quiescent current (<40mA) it ought to be far enough outside saturation. By my calculations from the datasheet, it is already going to be a bit light on bass even for a small radio, so rearranging the laminations to create a gap to keep it further away from saturation will not be of great value, while the loss of bass may be noticeable.

Saturation sets the onset of distortion and puts an ultimate limit on the power a transformer can pass.

David
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Old 10th Jun 2020, 10:18 am   #23
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Default Re: RS Audio Transformer

I also recommend that you don't try to re-arrange the laminations in this particular transformer - I have already tried to do this but had to give up... they are not only tightly clamped together but the varnish used is like a strong glue and they simply will not come apart : I tried solvents as well to no avail.
I have modified certain 100V line output transformers which came apart easily but as has already been stated, the inductance reduces and with the majority of these, it is not particularly high to start with.
The earlier version of this transformer that RS used to sell (different part no.) did have stacked 'E' and 'I' laminations with an insulating gap but the current one, as you've noticed, is interleaved.
When this changeover occurred I 'phoned RS technical help line to enquire about these differences but they didn't know what I was talking about...

Andy
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Old 10th Jun 2020, 10:55 am   #24
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Default Re: RS Audio Transformer

Saturation sets the onset of distortion and puts an ultimate limit on the power a transformer can pass.

Like an automatic limiter by the sound of it. So no adverse effect on the radio itself.

So I certainly need to leave it alone which I'm more than happy with.

You've all been really helpful and informative, thank you very much!
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Old 10th Jun 2020, 3:24 pm   #25
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Default Re: RS Audio Transformer

It won't damage the radio, but you might not like the sound.

David
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Old 10th Jun 2020, 4:12 pm   #26
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Default Re: RS Audio Transformer

That was my main concern David, thank you.
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Old 10th Jun 2020, 4:31 pm   #27
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Default Re: RS Audio Transformer

If it's going into a DAC90A then I wouldn't hesitate. Certainly mine, and I'm not blowing my own trumpet here, is one of the nicest sounding AM-only valve radios I have. I have quite a handful of DAC90/90A's but none restored, so I can't compare it to an original transformer.

Maybe I should try and make a better video.
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Old 10th Jun 2020, 5:13 pm   #28
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Default Re: RS Audio Transformer

I think the video was very helpful, it gives a good idea, always difficult to get exact sound with the variables involved. I also have a DAC90a awaiting attention which I know has an O/C transformer. I agree, very interesting to compare.
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Old 10th Jun 2020, 7:40 pm   #29
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Default Re: RS Audio Transformer

I've used the RS output transformer in a Bush BS35. It performed well and I did not notice any change when l managed to mend and replace the original transformer back. This set overall sounds superb when fed audio from a Bluetooth receiver.
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Old 10th Jun 2020, 7:48 pm   #30
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Default Re: RS Audio Transformer

There are places on the internet where this transformer was used as a transformer in a low power push-pull headphone amplifier. I guess having no air gap would be a bonus here, using tags 1 & 4 to feed the Anodes with tag 2 providing the HT.
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