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Output transformers for DACs

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#422
kasbor said:
Hi!
Why is the DCR so high for such a core and 80H inductance?
Click to expand...
Hi!
Depends on what transformer with do you trying to compare.

kasbor said:
May be 800H or 45 Ohm? Thanks.
Click to expand...
No, it was the correct data for that period of time: 450Ohm/80H @ 1kHz.
Such transformers was made for AK449x, where within its datasheet the Note regarding minimum resistance for output was given. Later, I decided not to adhere to these recommendations, since the transformer is connected without ground.
I want to attract your attention that usually for transformers on market the inductances are given at 50-100Hz as at higher frequency inductance can be few times less.
 
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#424
Do you guys know of any sensible priced dacs using AK4499 or Sabre 9038Pro which would easily accomodate Ivan's transformers? Many dacs has really small enclosure which makes it a bit fiddly to mount...

My Roksan CDP had several issues, long story short we didnt get the transformers working properly, so next up is trying a dac.
If anybody is interrested in my transformers just pm me.
 
#428
Good day!
Dear friends, I hope that all current orders will be sent in early or mid-July. This weekend, for the first time, in several months, flights began to fly from my country abroad. The ability to send parcels by land exists now, but I find this method too long while, so I think it is better wait for air traffick. Thank you for understanding!
 
#429
UPDATE

Right now there are two ways to ship out transformers/boards from my country (due to pandemic restrictions):

a) by land transport via regular national post - (slow delivery through Lithuania) for this list of countries:
Austria
Belarus
Belgium
Bulgaria
China
Croatia
Czech Republic
Denmark
Estonia
Finland
France
Germany
Great Britain
Greece
Hungary
Ireland
Italy
Latvia
Liechtenstein
Lithuania
Luxembourg
Netherlands
Norway
Poland
Portugal
Russia
Romania
Slovakia
Slovenia
Spain
Sweden
Switzerland
Ukraine
Uzbekistan

b) by FedEx service. Approximate cost for FedEx delivery from 65 to 100$ depending on the country.

There is no FedEx office in my town, that is why shipment through FedEx is possible for me once a week.
Thanks.
 
#430
I have updated a little the design of bottom part in my transformers:

Pin 13 is replaced to internal m3 nut. M3 screw can be used for secure placement on the PCB. Plastic screw can be used if galvanical connection of the shileding is not needed. The safe maximum M3 screw length inside the transformer can be 6 mm.
All the pins are longer now for ~4mm and a bit thicker (was 1.96mm, 2.03mm now). Pin allocation remains the same.

pim_sec.jpg
2pim_2sec.jpg
Transformer_Drawing.jpg

zip-file: CAD, drawing and gerber files (PCB was made in Sprint LAyout 6, Circuit in Splan7)
View attachment 25062020.ZIP


Another update. I have made another universal printed circuit board. Thanks too a banch of jumpers it is possible to use different number of primary and secondary coils, and various circuit connection are available: paralleled, in serial, diff\balanced, SE.

DSC_mill_max_0520_m3_2-4 coils.jpg
view.jpg
view_bot.jpg
top DSC_mill_max_0520_m3_2-4 coils and transformer_photo.jpg
bot DSC_mill_max_0520_m3_2-4 coils and transformer_photo.jpg
 

Attachments

#431
Update.
Another step-up version of transformer have been developed.
Turns ratio: 1:6+6+6 (1:6 or 1:12 or 1:18)
Frequency response (source 40 ohm, 10 K ohm load, 1:18):
-3dB points: 2Hz & 115kHz
-1dB points: 3Hz & 75kHz

Application: impedance matching for moving coil phono cartridges
Price: $205 for pair
 
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#436
angcl said:
Hi bisesik,

I need a output trans for my Twisted Pear Audio ,Buffalo-IIIse Pro ES9038,

what is the price now ? what is the shipping cost to Singapore ?

thanks
With regards
Angcl
Click to expand...

Hi Angcl,
Price for finished i/v board (like showned here Output transformers for DACs )
is $240.

Regarding shipping to Singapore. As I posted previously unfortunatelly there is still no airmail-service within my national post company and many directions are closed due to flights absence. That is why the one only possible way to send it to you right now is via courier-post like FedEx\DHL\UPS. Prices are quite high unfortunatelly ~$100. I am still in the process of finding another more accessible shipment way...
 
#437
bisesik said:
Hi Angcl,
Price for finished i/v board (like showned here Output transformers for DACs )
is $240.

Regarding shipping to Singapore. As I posted previously unfortunatelly there is still no airmail-service within my national post company and many directions are closed due to flights absence. That is why the one only possible way to send it to you right now is via courier-post like FedEx\DHL\UPS. Prices are quite high unfortunatelly ~$100. I am still in the process of finding another more accessible shipment way...
Click to expand...

I thinks I just want the trans, no need the PCB to save cost , this is for twisted Twisted Pear Audio ,Buffalo-IIIse .
 
#438
bisesik said:
I have updated a little the design of bottom part in my transformers:

Pin 13 is replaced to internal m3 nut. M3 screw can be used for secure placement on the PCB. Plastic screw can be used if galvanical connection of the shileding is not needed. The safe maximum M3 screw length inside the transformer can be 6 mm.
All the pins are longer now for ~4mm and a bit thicker (was 1.96mm, 2.03mm now). Pin allocation remains the same.
...
zip-file: CAD, drawing and gerber files (PCB was made in Sprint LAyout 6, Circuit in Splan7)
...

Another update. I have made another universal printed circuit board. Thanks too a banch of jumpers it is possible to use different number of primary and secondary coils, and various circuit connection are available: paralleled, in serial, diff\balanced, SE.

...
Click to expand...

Nice upgrade, bisesik!
Very useful pdf schematics.
The female pins accepting are the same as before or they are differente?
 
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