Experience with this DIY DAC ?

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#581
Re: Power Tranny

hoverdonkey said:


I have tried my new 50VA EI power transformer. It seems to make the sound less smooth, with harsher mids and less bass, than the toroidal that came with the DAC. Even when it is warmed up 😉

I did notice that it is giving 10.6V a.c., not the rated 9V, so could this be causing a problem? My mains electricity reads correctly at 240V. I would be grateful if someone could have a quick look at my connections (image attached).

Thanks
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Let your dac on with this transformer for at least one day and give me some news.

Another trick: polarize your AC powercord plug correctly

How to do that ?

- Turn on your dac without interconnects to the system and without the third ground pin connected to the 120 or 220 V (Use a cheater plug if the dac is grounded to the third ground pin

- Take an Ac voltmeter and connect a probe to the wall ground outlet pin, Connect the other probe to a ground of the dac (outer pins of RCA outputs are ok. Not digital RCA plug)

- Read the voltage you get on the AC voltmeter and reverse the power cord in the wall outlet
(with cheater plug) Read again the voltage with the reversed plug in the outlet .

- The position of the powercord in the outlet that gives less AC voltage is the right way to connect the power cord of the dac.

Make that to all your gear in the system and you'll be amazed.
 
#582
Re: Power Tranny

hoverdonkey said:


I did notice that it is giving 10.6V a.c., not the rated 9V, so could this be causing a problem? My mains electricity reads correctly at 240V. I would be grateful if someone could have a quick look at my connections (image attached).

Thanks
Click to expand...

Higher voltage than 9V could be normal because the transformer has not a big load. To lower your voltage, place your right wire to 110V instead of 130V.

This is probably a great transformer. It seems to have the same frame as Partridge, Audio note , Sowter transformers.
 
#588
To do the diode trick to drop voltage you either have to tap into the PS after the diode bridge on the board with one on each leg, or use two diodes in parallel with opposing polarities on each transformer leg. Otherwise you will be turning the PS into a half wave rectifier circuit.
As Franz said though, if the regulators aren't getting hot there is no problem.

If you reverse your power cord you are putting the power switch and fuse on the neutral wire, and that is just dead wrong. Swap the transformer leads if you want to experiment.

Best, Bill
 
#589
Is it a bad transformer, or does it just need more load (maybe resistor in series)? Its specification allows 8% tolerance, but 10.6V is +18%.
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What is this transformer specified for?

50VA?

O.K, then load the transformer with about 4 to 5 A (total secondary load) and measure again.

I bet, it will be within 8% tolerance.

Conclusion: not a bad transformer.

But really dont worry: I used this DAC some hours with a 12V transformator, giving 14.4V.

And the regulators got hot, about 60 degrees. But still no problem.

For longtime operation of course too much. You can go up to 12VAC without problem.

Franz
 
#590
Bill Fuss said:
To do the diode trick to drop voltage you either have to tap into the PS after the diode bridge on the board with one on each leg, or use two diodes in parallel with opposing polarities on each transformer leg. Otherwise you will be turning the PS into a half wave rectifier circuit.
Best, Bill
Click to expand...

HI Bill.
First I must say, I don't know this power supply since I don't own this dac.
I was not suggesting to add the diodes in series with the transformer windings, but in the dc path. In this case you have dc in, dc out less 1.4V.
But it may not be feasible or pratical if you have to cut pcb traces. In such a case, I agree it is better to add a back to back pair of diodes before entering the bridge.
On my Buffalo dac the supplies, including regulators are outside the dac and IVY boards.
 
#595
The Jensen values are a good place to start, post #349. A scope would let you see what's going on but it's not a necessity.
Two 250 ohm Rs and .002 cap on primary, 1K with .001 cap on secondary. Anything close will give you a good starting point.

Best, Bill
 
#596
legarem said:



You're right. Sorry, I wrote that before taking coffee in this rainy morning.

The transformer I use has 10.5 vac and I never had any problems. The heatsink regulatore doesn't get too hot.
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Rainy or sunny, whatever, I don't function properly before taking morning coffee 😉

I ordered some 600/600 transformers with center taps for further experiments. I'm going to try to attach it to TDA1547 DAC to provide I/V conversion and desimetrization.
 
#597
hoverdonkey said:
From your reactions, I guess that 10.6V is too much.

Is it a bad transformer, or does it just need more load (maybe resistor in series)? Its specification allows 8% tolerance, but 10.6V is +18%.

Thanks
Click to expand...

I have looked at the photos of the DAC. It is fully regulated.
I would not touch anything since the regulators will take care of the extra voltage.
I am not worried about the additionnal dissipation either because it has been reported here that heat is not excessive.
 
#598
Bill Fuss said:
Jean-Charles, It' a little off topic but how are you getting along with the Buffalo? I was considering it til I saw the price, kinda steep for a DIY project.

Best, Bill
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Hi Bill,
I will be happy to report to you here or privately.
It is now all assembled and tested, but I did not listen to it yet.
I wanted a case for it and add a few upgrades before I start compairing with my present set up.
The price is up a little because they have introduced a new chip.
My Buffalo is based on the ESS9008, but now, they are the first to use the ESS9018. This is a 32 bit baby.
Also the IVY is built in on the DAC board. I have a separate IVY board with my older version. This could be an advantage since I can test any other output set up with the Buffalo, including transformers.
Russ White is presentely designing a new tweaker's board containing only the DAC, where the IVY will be excluded.
This leaves us the freedom to add an external IVY, or a Conterpoint, transformers or anything we can dream of.
I will come back to you soon.
 
#599
Originall posted by Mcgyver:
According to my observations if the solid state amp has low input impedance, the sound of our DAC with trafos alone sometimes becomes "dead". So I'm soldering Version with cathode followers after trafos. There is a picture of my test setup built into CD player. There is mini SMD version of our DAC:M
Mcgyver in the end how did your test's go with Solid state amp, did you find the sound better with Transformer, or tube or even opamp.
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#600
Re: work in progress

McGyver said:


According to my observations if the solid state amp has low input impedance, the sound of our DAC with trafos alone sometimes becomes "dead". So I'm soldering Version with cathode followers after trafos. There is a picture of my test setup built into CD player. There is mini SMD version of our DAC:
Click to expand...


Mcgyver in the end how did your test's go with Solid state amp, did you find the sound better with Transformer, or tube or even opamp.
I'm still deciding if this is the fix for me.:confused
I apologize for the same 2 reply's but I'm having problems with the quote options
 
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