Zen -> Cen -> Sen, evolution of a minimalistic IV Converter

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#1,681
Nikon1975 said:
Just to doublecheck:

I am building a SEN for the AD1865 Balanced with 1mA current output. I have 4 pairs of 2sk369 already glued on the heatsinks that I wanted to use. Reading once again the article it sound to me that the need to parallel two pairs in the SEN is not only to achieve higher current, but also to lower input impedence. The input impedence of the 2sk170 and 2sk369 looks the same from the datasheet, so do I still need to have a total of four devices for each phase for my application or can I just get away with one pair of 2sk369 ?

Thanks,

Davide
Click to expand...

The 2sk369 is the same as two sk170's in parallell - so one pair of 369 gives same result as two pairs of 170's.
Regardig current. You should look for 2sk369V they are 16-30mA i think. BL grade would give to low current, if you dont handpick the highest rated ones.
 
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#1,685
I have had my dac with buffalo III and SEN running for three years now. I love the sound but I have always had some background hum. The difference from the other people having hum problems in this thread is that in my case it is also present when running balanced interconnects to the pre. When using unbalanced interconnects the hum gets much worse and is louder than the music. I think it is time to finally solve this and hope to get some good advice from you.

I use WaveIO->Ians FIFO->BuffaloIII->SEN. The SEN is battery powered with LC filter. The buffalo is mounted on an aluminum sheet on top of the SEN, the FIFO is also on the aluminum sheet. There are two holes in the sheet through which the wires from the buffalo to the SEN goes.

I have tried to put earthed aluminum foil (only for test) as shields in different parts of the dac but that has not had any effect at all.

The ground is connected to earth through a diode bridge, resistor and capacitor.

I have disconnected everything but the buffalo and the SEN and the hum is still there.

Do you have any clue what might cause the hum? I have tried everything I can think off.
 
#1,686
The first thing to establish is whether the hum is at 50Hz or multiples of.
If yes then it has to do with mains disturbance.
If not then you need to find out where the source of disturbance is.

If it comes from mains then you can try using long wires to connect your DAC to the IV,
so that the IV is far away from any transformers or transformer powered circuits.
Also helps to put the IV in a Faraday's cage (aluminium case) connected to earth
Or try to run everything with batteries.
And connect the battery cases of the IV also to Earth.

Ask NicMac. He has experience with your DAC, I don't.
And I do not comment on someone else's design.


Patrick
 
#1,687
TotoWood I/V konverter

I/V converter for 1mA AD1862/AD1865 D/A...
P1= Offset trimmer (input)
 

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#1,700
Those look pretty convincing compared to a bag of 200 I just opened, which I have had for several years, and have used some others from the same batch, and which conform to the BL bracketing.

What was the drain-source voltage at which you measured Idss?
 
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