Using a DC power supply in place of a AC transformer

[DF96]

So you think that the quality of the transformer does not have any impact on the sound of this unit ?

Given sufficient quality, yes.

In general you can have two parts with the same value, for instance two resistor. Same ohm, same wattage.
One costs 50 times the other.
There must be a reason if not the expensive one would not have market

In audio, as in other fashion industries, the increased cost creates its own market. People will naively believe that if it costs much more then it must be much better. In a fashion market you don't even need to tell lies to sell an expensive product, the price alone can be sufficient.

The key here is better isolation from the mains noise i think

A filter will do that for you.

 

[claudiomas]

AC required for +B and -B,
if you replace AC to DC +B power supply , then no more -B.
find schematics and you can put a better regulated and filtered symmetric power supply, you should also mount a 3 poles jack on the DAC.
one other good solution its to use a better AC/AC transformer and main 50/60Hz HI-pot filter

 

[ginetto61]

Given sufficient quality, yes.
In audio, as in other fashion industries, the increased cost creates its own market. People will naively believe that if it costs much more then it must be much better.
In a fashion market you don't even need to tell lies to sell an expensive product, the price alone can be sufficient.
A filter will do that for you.

Thanks a lot for the valuable advice
I think i will try a filter before the stock transformer
I tried to open the unit without success.
I read that in the old days they provided the schematics with every unit
A schematic would be useful i think
Good old days
Today to find a service manual of new equipment is almost impossible
Thanks again and kind regards
gino

 

[ginetto61]

AC required for +B and -B,
if you replace AC to DC +B power supply , then no more -B.
find schematics and you can put a better regulated and filtered symmetric power supply, you should also mount a 3 poles jack on the DAC.
one other good solution its to use a better AC/AC transformer and main 50/60Hz HI-pot filter

I would be willing to buy the schematic but i do not know where to look
I think that this dac has some potential
The sound is clean, detailed, extended
I saw some measurements and they were pretty good

Cambridge Audio Azur DacMagic D/A converter Measurements | Stereophile.com
Thanks and kind regards,
gino

 

[Twobeers]

To answer this question simply NO. A 12vac transformer is a 12vac transformer. The transformer gives you isolation from the mains & allows your DAC device float to whatever your plugging into the XLR connectors on pin 1 which is the electronic ground. The power supply is built into the DAC unit. That is why it is using 12vac input. If everyone looks closely at the picture you will see the squigly line beside 12V, that specifies that the power input is 12vac.

 

[still4given]

It would be interesting to see if the DAC is actually using all of the output of the stock AC transformer. If it is not, there is probably nothing to be gained from using a bigger supply.

 

[ginetto61]

To answer this question simply NO. A 12vac transformer is a 12vac transformer.
The transformer gives you isolation from the mains & allows your DAC device float to whatever your plugging into the XLR connectors on pin 1 which is the electronic ground. The power supply is built into the DAC unit.
That is why it is using 12vac input. If everyone looks closely at the picture you will see the squigly line beside 12V, that specifies that the power input is 12vac.

Thanks a lot for your advice
I would like to tell a little experiment we did with a friend
We had a DIY line preamp on a board to test
First we tried a toroidal transformer of apparent good quality (Talema i think)
Every time the lights in the room were switched on a noticeable noise came from the speakers
Then we replaced the toroidal with a EI transformer
Well this noise was very much reduced. Almost gone.
So we concluded that the EI transformer was providing a better isolation from noises from the mains
A very trivial test but telling.
As i read that digital is particularly sensitive to noise from the mains my feeling is that a good quality EI transformer would be beneficial
I do no know which kind is the original by the way, as it is sealed.
Thanks again and kind regards,
gino

 

[AndrewT]

Switching the light experiment proves your RF attenuation is not adequate.

I do not reach the conclusion that the EI is better than the Toroid, just that it is different.

 

[ginetto61]

Switching the light experiment proves your RF attenuation is not adequate.
I do not reach the conclusion that the EI is better than the Toroid, just that it is different.

Hello and thanks.
Sorry but does this mean not that the EI has a better RF attenuation than the toroid ?
I guess that a RF filter maybe is the optimal solution, but still ...
Besides can you confirm me that RF noise in the mains is bad especially with digital circuits as i believe ?
I think that analogue is more robust. Much more robust to this kind of noise.
Thanks a lot and regards,
gino

 

[DF96]

You are looking for simple answers to complex questions.

 

[ginetto61]

I think i will try, for a start, a mains filter like the one i see in this high quality dac

An externally hosted image should be here but it was not working when we last tested it.

If they have put it this should mean is beneficial
I cannot see the part number anyway
Regards,
gino

 

[bumbum35]

ginetto61, do you you connected to your DAC, voltage 12VDC? Is nothing happened? Is the voltage 12VDC not damage anything in the DAC?

 

[ginetto61]

ginetto61, do you you connected to your DAC, voltage 12VDC? Is nothing happened?
Is the voltage 12VDC not damage anything in the DAC?

Hi i have put the dac away. This evening i will test it again.
But i do not think so ... maybe feeding AC to a DC input could be worse ?
Speaking of the dac i think it is a decent one.
A better PS and maybe output stages could elevate its performance, but also in its stock form is ok. Maybe not very 3D in soundstage ?
Kind regards, gino

 

[msdin]

Hello !
please excuse me for a maybe silly question
I have a dac using an external transformer with out of 12VAC

I have a very good power supply with 12VDC out
Can i try it without problem ?
I think so but i am not so sure
Thanks a lot indeed
Kind regards,
gino

You will need to use a 12V AC supply, it will not work with a DC supply because it has a voltage double to generate a +/- 12-15 volt supply.

 

[ginetto61]

You will need to use a 12V AC supply, it will not work with a DC supply because it has a voltage double to generate a +/- 12-15 volt supply.

Hi and thanks for the helpful reply.
I would like to try a better transformer but i do not know which is the best option.
For digital equipment i think that EI type could be a good solution like the one attached. What do you think ?
Thanks again, gino