Experience with this DIY DAC ?

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#2,144
Skorpio said:
I have an idea for doing this without a scope...using a vario transformer and a voltmeter...

Connect a load to secondary and the voltmeter and the vario to primary. Turn op voltage on vario until the secondary no longer follows (saturation). You can check by moving voltmeter also...

Will that work?

Question: What will a magnitized core sound like? And why do the degauss from both primary and secondary? Is is the same core and ac??
Click to expand...


Any comments to this??
 
#2,146
crazyfrog said:
Hi guys,

... It needs a little "clean-up" before wiring the trafos so I removed the two opamps under the board and all the parts in the signal path: resistors and Vima caps. After I put one 100R linked to the ground at each output and finally wired the outputs to the 50 Ohms taps of transformers.

Worth the try.


Pierre G.
Click to expand...
Hello Pierre,
Would you happen to have some decent before/after pics of this "bypass operation"?
Thanks
 
#2,151
teibet said:
Hi Raiatea,
I connected an headphone to the RCA jacks with an adapter.
It works but the output level is low, it apparently needs a preamplifier.
Click to expand...

Thank you for the answer.

I'm wondering if it would be ok to connect a balanced headphone directly to the CS4398 output, via a transformer 1:2.
I don't know yet what the impedance issues would be (HD600 at 300ohms).
Also how would I control the volume ?

Thanks
 
#2,152
I have an idea for doing this without a scope...using a vario transformer and a voltmeter...

Connect a load to secondary and the voltmeter and the vario to primary. Turn op voltage on vario until the secondary no longer follows (saturation). You can check by moving voltmeter also...

Will that work?

Question: What will a magnitized core sound like? And why do the degauss from both primary and secondary? Is is the same core and ac??
Click to expand...

When I understand your procedure correctly, I should work. But be carefully, not to overload/overheat your trannie (I would also control the AC voltage on the input side to be sure).

Personally I prefer for safety a power amplifier as source. The scope can be replaced by the voltmeter safely.

Important is the very slow reducing of the voltage to zero after you reach saturation.

How a magnetized core will sound like?

Simply more distorted.

Why doing it from both sides?

Because you want to bring the magnetic particles in a chaotic order. Doing the procedure several times and from both sides eases this.

Franz
 
Last edited:
#2,153
#2,154
Franz Gysi said:
When I understand your procedure correctly, I should work. But be carefully, not to overload/overheat your trannie (I would also control the AC voltage on the input side to be sure).

Personally I prefer for safety a power amplifier as source. The scope can be replaced by the voltmeter safely.

Important is the very slow reducing of the voltage to zero after you reach saturation.

How a magnetized core will sound like?

Simply more distorted.

Why doing it from both sides?

Because you want to bring the magnetic particles in a chaotic order. Doing the procedure several times and from both sides eases this.

Franz
Click to expand...

Thank you for your reply 🙂

My transformers are no-name, with 150Ohm DC on both primary and secondary side and 1:1 ratio. At what voltage level would you expect the saturation to take place? I will use 50Hz, and I load the primary with 47K, but I think it might be better to use a lower load for this proces? Perhaps 270R?
 
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