The KillerDAC Audio forum

General HIFI => Amplification (Pre/Power) => Topic started by: tuyen on August 09, 2011, 04:30:37 PM

Title: line transformers
Post by: tuyen on August 09, 2011, 04:30:37 PM
Which ones have you tried?  What's your thoughts/experiences on using line transformers as compared to other forms of output stages (opamps, tubes, etc.) ?

Lundahl? Jensen? UTC? Moncor? Sowter?   

500ohm? 600ohm?   Current production? Vintage?

Looking at a pair of vintage UTC A-20 on eBay. Have been recommended these to try the voltage output of various signal outputs (balanced input to unbalanced single ended output).
http://www.ebay.com.au/itm/UTC-A-20-Vintage-Iron-Transformer-1-1-Neve-Studio-/220825523563?pt=Vintage_Electronics_R2&hash=item336a3a156b (http://www.ebay.com.au/itm/UTC-A-20-Vintage-Iron-Transformer-1-1-Neve-Studio-/220825523563?pt=Vintage_Electronics_R2&hash=item336a3a156b)
(http://i.ebayimg.com/00/$(KGrHqEOKn!E43OeNv!ZBOPQGLOVeQ~~0_12.JPG)
Title: Re: line transformers
Post by: tuyen on August 09, 2011, 05:15:03 PM
(http://img684.imageshack.us/img684/3543/dac3.jpg)

(http://i48.tinypic.com/2i23q8p.jpg)

(http://t1.gstatic.com/images?q=tbn:ANd9GcR6A7mQJt4LhEv2ixkQ_QScVdKQPo9GJELjMbFEy0-Qo3aF7Akr)

(http://i88.servimg.com/u/f88/13/98/99/48/dac-fi11.jpg)

(http://img523.imageshack.us/img523/9187/p8250008.jpg)

(http://www.diyaudio.com/forums/attachments/digital-line-level/142943d1254849514-experience-diy-dac-img_1762.jpg)

(http://getinthewoodchipper.com/?p=302#)

Some dacs using UTC A-20 line output transformers :)
Title: Re: line transformers
Post by: tuyen on August 09, 2011, 05:22:50 PM
(http://www.triodeguy.com/images/audio%20images/Sowter_DAC.jpg)

(http://cdn.head-fi.org/7/74/1000x500px-LL-744fd1d1_DSC_0003.JPG)

(http://www.kandkaudio.com/images/passive_output.jpg)
Title: Re: line transformers
Post by: ozcal on August 09, 2011, 07:28:07 PM
I have the dac pictured ,Gigawork big dac but just using OPA627
There is a long thread on Diy-audio regarding it's use with various trafos. Will see if I can find the link.
Title: Re: line transformers
Post by: kajak12 on August 09, 2011, 07:45:16 PM
Which ones have you tried?  What's your thoughts/experiences on using line transformers as compared to other forms of output stages (opamps, tubes, etc.) ?

Lundahl? Jensen? UTC? Moncor? Sowter?   

500ohm? 600ohm?   Current production? Vintage?

Looking at a pair of vintage UTC A-20 on eBay. Have been recommended these to try the voltage output of various signal outputs (balanced input to unbalanced single ended output).
http://www.ebay.com.au/itm/UTC-A-20-Vintage-Iron-Transformer-1-1-Neve-Studio-/220825523563?pt=Vintage_Electronics_R2&hash=item336a3a156b (http://www.ebay.com.au/itm/UTC-A-20-Vintage-Iron-Transformer-1-1-Neve-Studio-/220825523563?pt=Vintage_Electronics_R2&hash=item336a3a156b)
(http://i.ebayimg.com/00/$(KGrHqEOKn!E43OeNv!ZBOPQGLOVeQ~~0_12.JPG)
Oh tuyen your a mad man but you must explore go go tuyen
Title: Re: line transformers
Post by: tuyen on August 24, 2011, 12:58:22 AM
Have pair of custom made output transformers by Bud Purvine's O'netics 600ohm:600ohm.   Was recommended it over the vintage UTC A-20 which apparently are still great, but apparently smoothen the sound out a bit in comparison, hence losing some definition/microdetail.

(http://img251.imageshack.us/img251/1561/img0011r0.jpg)

Will fit them into the jkeny/WM8741 OPUS DAC  combo. Which hopefully should help give some life and energy to the presentation!

So, anyone have any experience with direct output tranformer based DACs?  :)
Title: Re: line transformers
Post by: data on September 12, 2011, 08:33:04 PM
Do you have Bud's transformers yet?

Is that DAC chip a voltage out type?

I used Cinemag Quadfilar's 80% Nickle. Very transparent and dynamic.
(http://i8.photobucket.com/albums/a19/df69/CMOQ-2Hsmall.jpg)
Title: Re: line transformers
Post by: tuyen on September 13, 2011, 03:58:58 PM
Yup, they are running on the Opus DAC (WM8741) at the moment.

The DAC chip is voltage output type. So the transformers are connected directly after the voltage outputs of the DAC (no resistors/caps) straight to the rca outputs.     Indeeed very transparent/dynamic :)

My first experience of line output transformers!

Title: Re: line transformers
Post by: data on September 13, 2011, 07:04:56 PM
Very nice mate  8)

I reduced the resistor on my primaries to 100R, but now you have me thinking about removing them all together  :o