input transformer - mumetal casing etc.

[Alexontherocks]

now it works....must have been my wireless connection.

is there any model which could be considered a direct equivalent of the sowter part?

[male42]

I have made myself such transformers. and recommend a dual screen .. need to check in practice

[Alexontherocks]

Cinemag replide and stated that the CMLI-15/15B would be a good choice to replace the sowter part.

http://www.cinemag.biz/line_input/CMLI-15-15B.pdf

is the dual shielding necessary from a practical point of view?

[SY]

It can't hurt! I've gotten such excellent noise rejection performance from the Cinemags (and Jensens) that I just go with it and try not to question their wisdom.

[kevinkr]

Dual shielding is quite important if the transformer is a conventional EI core type which has poor rejection of external magnetic fields. Toroids and C-cores tend to need less shielding as they seem to contain their own magnetic fields more effectively and in so doing are also generally less susceptible to external fields.

I use transformer coupling extensively in my system, and use shielded transformers everywhere except in the driver stage and OPT. The IT is an unshielded Lundahl C-core which given the high signal levels is not a problem. I do go to some trouble to keep power transformers far away from these transformers if possible.

[trobbins]

This paper from 1938 includes a good level of practical measurements to guide those wanting to diy. I may be wrong, but I think the casing metal sheet used for some old floppy disk drives was made from a better magnetic shielding type of steel - it was certainly quite maleable for bending in to shapes.

http://dalmura.com.au/projects/Magne...uly%201938.pdf

[Wavebourn]

I once bought on eBay SMD - mount transformers made for DSL modems. They are tiny, but have 12 Henry windings, both input and output. Stacking such transformers I am getting different ratios. Then found good cases for them: bought a lot of motors made for cassette recorders.

[ruffrecords]

Originally Posted by Alexontherocks

one of the solutions might be this:

EDCOR Electronics Corporation. PCW10K/10K

or

EDCOR Electronics Corporation. WSM10K/10K

comments?

Thanks again
Alex

The trouble with Edcor is they are relatively low inductance transformers - that's why they are cheap. The two mentioned have primary inductances of 8H and 11H respectively. At 20Hz these look like about 1K ohms rather than 10K so unless you can be sure your driving source impedance is a lot less than 1K at 20Hz you will certainly have poor low frequency amplitude and phase response as well as distortion.

Cheers

Ian

[DF96]

Originally Posted by Alexontherocks

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

I understand that mu-metal loses much of its permeability when machined or bent, so it needs to be processed again after forming.

[Gluca]

I have been running 15/15B since ages ... I own 2 pairs. Good stuff.