input transformer - mumetal casing etc.
 

Dear All, investingating the possibility of building a pmillet universal PP amplifier

Push-pull KT88 class A amp with "universal" driver PCB

I researched one of the most expensive components (on the PCB that is)...the input transformer.

either a sowter or lundhal will do according to pete millet. Here is the link to the sowter product

3575

To reduce cost and shipping problems I would have liked to have all the transformer parts made and shipped through edcor electronics. I have contacted them in relation to the sowter part (to have it "cloned") and the reply is the following:

1. They don't use mumetal cans or electrostatic shielding
2. "What we can do is the 1:1 ratio PC and PCW series transformers (on our website) and could put a external copper shield on the transformer for an additional cost"

I am no engineer and would like to ask some input to some of the guys on the forum. Can such a solution work? Waht would be a good choice among the EDCOR products to emulate the charaacteristics of the sowter part?

Thanks
Alex

one of the solutions might be this:

EDCOR Electronics Corporation. PCW10K/10K

or

EDCOR Electronics Corporation. WSM10K/10K

comments?

Thanks again
Alex

If I understand you correctly, then the input transformer should have a screen. preferably of magnetic material. such as permalloy, nickel-containing alloys. sometimes requires a dual screen. copper in this case is not suitable.

The sowter seems to have one, I guess the edcor should have one as well...

what would be the effect from using copper instead of a megnetic material?

[QUOTE=Alexontherocks;2826761
what would be the effect from using copper instead of a megnetic material?[/QUOTE]

No screening from low frequency stray fields.

you need to protect the transformer coil from external parasitic interference with magnetic origin. such as power transformer. Copper does not have this property

Is there anyway to obtain sheets of magnetic material and have them formed to create a screen?

In conclusion you all foresee problems with using the EDCOR alternative, correct?

I have plenty of tools and machines (a friend has a CNC/metalwork shop) so forming, bending and such would not be a problem...

Go Cinemag. Prices are very reasonable and the quality is as good/better than Sowter. The input transformer I've been using seems identical in performance to the Jensen JT11P1 at half the price.

cinemag's site seems to be down...

Audio Transformers By Cinemag Inc.

Came right up for me.