Lowering cost of audio output transformer

[pilovis]

Originally Posted by jean-paul

Thread title:

Lowering cost of SE audio output transformer

Suggested thread title:

Making good SE output transformers at lower cost

Reason: price should not be the only driving factor. Quality is prevalent in audio DIYing since the device will be more expensive than ready built devices anyway.

I pay these custom transformers only 15 Euro each (40VA), it worth a try

[pilovis]

Originally Posted by leadbelly

I actually still don't understand what you are you doing. Are you just ordering a special version of a standard model transformer from a manufacturer, i.e. you instructed them to build you one of their standard power transformer models except to create a gap using paper? Or do you have a transformer in hand that you took down to the laminations without destroying the bobbins and are reassembling it with a gap?

yes, I am ordering a special version of a standard model transformer from a manufacturer and instructed them to build one of their standard power transformer models except to create a gap using paper and wound them according to the winding sequence described above.

[Cassiel]

And they charge you only 15 euros for a custom job? Wow, that's cheap. What's the price of their power transformer? It can't be cheaper. Something doesn't add up here.

[pilovis]

Originally Posted by Cassiel

And they charge you only 15 euros for a custom job? Wow, that's cheap. What's the price of their power transformer? It can't be cheaper. Something doesn't add up here.

They sell a standard 40 VA transformer for 15 Euro plus VAT, for the same price the built me the prototypes.

I also asked them to built me a custom line trasformer (winding shielded) of 150 VA: pri. 220V / sec. 125-0-125 0.5 A, 6.3V 3A, 19V 1 A, I paid it 40 Euro plus VAT.

Their website: http://www.pattrasformatori.com

[ilimzn]

Hopefully you are aware that a gapped core suitable for a 40VA transformer will be able to pass only a fraction of that power at audio frequencies... and if it's wound for voltage transformation derived from a mains transformer calculation, they will also have way too low inductance of the primary to even work at mains frequency, let alone lower. This ill improve with lowering the gap width but then maximum DC current will fall too...