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Output transformers for DACs

Hello everyone who looking for Sound!
:wave:

After years of expirience the output transformers for current and voltage output DACs have been developed. Transformers tested with following DACs: ES90x8S/K2M/PRO/Q2M, AK4x9x, PCM56/58/63, PCM1702/04, AD1862/65, PCM1792, PCM1794A, TDA1541/43, DSC dac and others. Speaking in general, transformers can be suited for any current or voltage DAC both in SE or PP modes.

These transformers are made on high permeable cores, have the low DC resistance at desirable inductive impedance to achieve the best frequency response of the DAC. Transformers provides significant sound quality improvement compared to other output versions. Your music will begin to live a new life, it will sparkle with a naturalness without plastic nervousness :)

25GHrhC



D60 trafos.
Transformers I/V stage for iancanada DM9038Q2MPi DAC
1675168366489.png 1675168857503.png 1675168905879.png

Transformers I/V (V/I) stage Twisted Pear Audio Buffalo-IIISE PRO DAC
PXL_20230209_032233778.jpg PXL_20230209_033610984.jpg
1675168944940.png 1675169033581.png 1675169590255.png


D46 trafos:
1675169440982.png 1675169176721.png
1675169095665.png 1675169130661.png 1675169746929.png

The simplest way to connect my transformers to your circuit without soldering directly to pins (sometime DIYers wants to try different types in quick manner for example) is to use receptacles from Mill-Max:

1-st way is using receptacles with the soldered to them wires. PN is ED90595-ND
receptacles.jpg

2-nd way is using through-hole type of receptacles for PCB (PN is ED10169-ND):
PCB_receptacle.jpg


Here are some impressions from iancanada IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...

And here is the page from Andrea Ciuffoli: DSC Output transformers test

Dimensions D46 type: OD=46mm, H=24mm
Dimensions D60 type: OD=62mm, H=30mm

Frequency Responce of transformer with ES9038q2m at 1.4VRMS (~8kOhm in secondary loaded on 100pF cable): 20Hz=-0.3dB, 20kHz=-0.2dB (rel.1kHz):
ES9038_4Vpp_1m_cable.png

Same, but with 470pF in parallel with secondary:
ES9038_4Vpp_1m_cable+470pF.png

The possible output level and the LF losses are depends on the output current of the DAC (and I/V resistance).

Here is an example of connection:
common_circuit.JPG


The prices for pair of transfomers are (single primary coil, single secondary coil):
D46(mm) size = 241 USD
D60(mm) size = 446 USD

Worldwide shipping (small package service) cost and half of PP fee are included. Usually takes 2-3 weeks for delivery.


Various assembled boards with pair of my transformers are available from:
$272 for D46(mm) size
$497 for D60(mm) size

Here you can find all the contact info: https://ivxformres.com

Lead time depends on existing orders. Thanks.

The relevant current documentation for my transformers available here: Output transformers for DACs
 

Attachments

  • D46H23.stp
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  • D60H30.stp
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Excellent,
I have tested a lot with this Transformers. You did nice work. They are really optimized for current output dacs. I have not used any cap at output because at test is used 1.5 long cable with capacity of around 100pf or even more. Adding cap reduced 20khz response in my configuration. After a lot of testing we also added B1 and Tube buffer. I had a feeling that in some configurations dac couldn*t handeled load. Similar is seen in Audio note dacs.
For me this transformers are better than opamp stage. Highly recommendet.
At es9038q2m you can save a lot of time with testing opamp stages if you use this transformers.
It is pitty that this design is not intend for voltage out dacs, as far i know both constructors can*t do it because of large input impedance. Ak449x can handle till 1kohm...can*t be done something?
Congratulation this is not easy job what both of you did.
 
Very nice work you did there. Congratulations!
Thank you!

Well done and well presented BR & Ivan
Thanks guys.

Such a low step-up ratio will certainly exceed the voltage compliance range of many dac chips. Do you find this to be the lesser evil compared to the compromises associated with higher ratio transformers?

In my understanding step-up transformers are for current output DACs mostly. I think, that the main problem of many other step-up transformers on market is that they have simultaneously too low inductance (LF losses) and too high DC impedance of primary coil (undesirable voltage presence attached to the output during "signal generation") , that make bad impact on the output of the curent type DAC.

In case of Voltage Type DAC like AK4490 it is better to use 1:1 with high primary inductance and DCR. But I do not recommend use such 1:1 with its 450 Ohm DCR with PCM63 for example, because to the output will be attached (as I said earlier) undesirable voltage presence that will degrade the whole SQ.

Regarding step-up vs step-down transformers. It is always better to use step-down transformer to store the load capability (current) of the source and FR. But in case of the curent type DAC it is hard to get simultaneously the high enough signal and flat FR from 20 to 20k. If 0.5 V (p-p) instead of 2 V is enough for the next device input, then to save output current of the DAC is better to use 1:1 instead of 1:4. But my practice say that is is better to get as high signal as possible straight from the DAC, instead of make futher amplification of lowlevel signal, because you are limited on the "bottom" by PSU noises and no amplification will returns the beaten\lost signal.
So my opinion is for Current DACs is better to use step-up transformers, for Voltage DACs - step-down transformers (1:1).
 
Hi bisesik,


Your transformers look good.
I tested a Jensen JT-11-DM with a DAC AK4490 and it works really well.
If your transformers work as well then it's wonderful because the price is more interesting!
I'm going into active tri-amplification and I'll be interested in getting you a pair.
What is the delivery time and price for France?

Is it possible to have a picture of the inside of the box?


nounouchet
 
What is the delivery time and price for France?
nounouchet

Last time delivery to Germany was 2 weeks (registered air), but Christmas is coming soon, may be will longer. $10

Is it possible to have a picture of the inside of the box?
nounouchet
Transformer is made on this nanocrystalline core
IMG_20181205_000833.jpg

after winding the transformer, it is filling with epoxy inside the screen
 
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Still, very dubious these will work well with pure current output dacs. Whether the loading resistor is applied to the primary or secondary the effective load seen at the dac output is way too high for any reasonable voltage compliance. With voltage output dacs, these seem perfect but unless SE>BAL or BAL>SE conversion is required i cannot quite see the purpose of a transformer. Is it to act as a low pass?

Not arguing at all with the excellence of the transformers, just the application.