diy audio transformer winding

[Bernhard]

To further simplify and purify my DAC setup, I wound my first TVC.
It will convert from balanced to SE and provide 25 taps on secondary for volume control and give very low output impedance directly from the parallel DAC chips and the low impedance passive filter.
First impression is very good.

Primary has 2 x 500 windings and I did what I have seen on Siemens transformers.

Instead of 500 windings they used stranded wire composed of 10 single enameled wires and made 50 windings only. The ends are connected outside such that all windings are in series, as if it was a single wire with 500 turns.

Any advantage from that trick (?) ?

[Bernhard]

Measured frequency response flat 0,1 dB from 10 Hz to 20 kHz with 10 k load.

25 taps, 2 dB steps plus one each 3, 4, 5 dB steps on the lower end.

6 dB gain, 1000 primary to 1995 secondary, wound on old Siemens core, 0,1mm sheets with MU shield.

[kevinkr]

Hi Bernhard,
Pretty impressive, sounds like rather a lot of work actually. I have some old telefunken transformers and maybe at some point I will follow in your foot-steps.

Can you post more detail about how you wound yours - maybe post a few pix of the transformers themselves if not inconvenient and you're not too shy...

Results sound very encouraging. These days all of my sources - even the tube ones will drive a 10K load without problems.. hmmm....

[Bernhard]

Where to by amorphous cores ?

Originally posted by kevinkr
These days all of my sources - even the tube ones will drive a 10K load without problems.. hmmm....

Like any other transformer it needs a defined load to linearize the frequency response, without load it is + 0,6 dB @ 20 kHz.

[Bernhard]

Originally posted by kevinkr

Can you post more detail about how you wound yours - maybe post a few pix of the transformers themselves if not inconvenient and you're not too shy...

Just finished my second TVC, here a picture of unfinished chaos...

[Bernhard]

[kevinkr]

Hi Bernhard,
Looks really good, you are a lot more patient than me..

[analog_sa]

Originally posted by kevinkr
These days all of my sources - even the tube ones will drive a 10K load without problems.. hmmm....

I suspect that the primary inductance is quite low. Maybe tubes won't be so happy driving it.


Bernhard

Would you mind describing the winding geometry? Have you got any data on the cores?

[Bernhard]

Originally posted by analog_sa



I suspect that the primary inductance is quite low. Maybe tubes won't be so happy driving it.


Bernhard

Would you mind describing the winding geometry? Have you got any data on the cores?

My L-meter told me 27H primary inductance with secondary open.
It has 1000 windings.

I have no data for the core but the metal sheets are very thin and fine polished.

No special geometry, see first posting.
I will not use the center tap so no requirement for true balanced geometry.
Maybe next time...

[analog_sa]

Hi again Bernhard

Just to make sure i got it: Litz primary and a single section multitap secondary, right?

The whole thing seems absolutely tiny. Ultracool.