That does ring a bell. I still recommend testing with CRC and getting it right before ordering your chokes. And once you you measure exact current you may need to go higher with your input volts and drop more through a higher resistance choke to get exactly the right output. Not as complex as it seems.....
I will check it tonight 😉
I can measure Digital + Analogue current thanks to R1 and Analogue on R2, with this, I will know 🙂
But, how do you detemrine the value of your chokes ? Actually, I asked to my choke's builder to make me 2 x 2H (supporting 1A each), without checking resistance and then, I adapted my main transformer for having 10V after my LCLC PS. Mayble I'm wrong.
An other important think is the "constante de temps", I have calculate that for 10ms charging time for the caps, their values has to be about 4700uF but I'm not sure if it is good ?
I can measure Digital + Analogue current thanks to R1 and Analogue on R2, with this, I will know 🙂
But, how do you detemrine the value of your chokes ? Actually, I asked to my choke's builder to make me 2 x 2H (supporting 1A each), without checking resistance and then, I adapted my main transformer for having 10V after my LCLC PS. Mayble I'm wrong.
An other important think is the "constante de temps", I have calculate that for 10ms charging time for the caps, their values has to be about 4700uF but I'm not sure if it is good ?
I need an advice here.
I have 4-board DAC, balanced out - positive and negative straight to output terminals after Rload resistors. I need to add a SE connection for my SE tube pre-amp.
Can you advise a structure of balanced and unbalanced outputs, please. Maybe a switch here?
BTW, I have got 2 x Sowter Type 3603 transformers at hand. Maybe they can be used in the balanced or unbalanced output.
Br, zz
I have 4-board DAC, balanced out - positive and negative straight to output terminals after Rload resistors. I need to add a SE connection for my SE tube pre-amp.
Can you advise a structure of balanced and unbalanced outputs, please. Maybe a switch here?
BTW, I have got 2 x Sowter Type 3603 transformers at hand. Maybe they can be used in the balanced or unbalanced output.
Br, zz
I determined the value of my chokes by calculating the value of the resistance required to drop the input volts to the required level then picked a suitable Hammond choke from their catalogue. If you can vary the input voltage of your transformer you can get the same result. I did not calculate the charge time and 5,600f sound great for me.
I second that.
I want balanced and unbalanced, AND different load for various preamps with impedance that suit the Cinemag...
Hello,
2 Henry will be BIG. I mean really BIG.
Like i did write before if you connect the Lundahl with one coil in plus and one coil in the - that will give the best result. They call it common mode. BUT with common mode bot cables coming from the rectifier will enter where there is a dot.
This link will give some explanation.
J&K Audio Design: 2 coil choke
A choke directly after the recitfier will give a much bigger voltage drop than a resistor with the same serie resistance. But it filters much better.
Greetings, Eduard
My 2 henry's chokes are actually supplying my DDDAC. I thought that more you have inductance, better is the filter.
I have tried Lundahl common mode on my tubes amps but my ears prefers serial mode.
I have tried Lundahl common mode on my tubes amps but my ears prefers serial mode.
Hello,
Using the 2H for choke input will give a big voltage drop so you will need another transformer.
In general a bigger choke will give a better filter. With bigger chokes you can use smaller caps.
I have 3 things that use choke input:
My tube line amplifier. Changed from choke input to '' common mode '' choke input according to Lundahl.
My dac tube part also common mode for high voltage and lower voltages one of them choke input and the other voltage CLC.
But you should connect them the way Lundahl tells you in the pdf files.
Anyway in my set up the common mode for the first choke sounded better.
Greetings, Eduard
Using the 2H for choke input will give a big voltage drop so you will need another transformer.
In general a bigger choke will give a better filter. With bigger chokes you can use smaller caps.
I have 3 things that use choke input:
My tube line amplifier. Changed from choke input to '' common mode '' choke input according to Lundahl.
My dac tube part also common mode for high voltage and lower voltages one of them choke input and the other voltage CLC.
But you should connect them the way Lundahl tells you in the pdf files.
Anyway in my set up the common mode for the first choke sounded better.
Greetings, Eduard
Eduard, would you mind sharing the circuit diagram and cap values so we can see the choke PSU design please?
Hi All,
I've now tried the RPI with Rune Audio and used thru USB to the DDDac. SQ is improved quite dramatically over my Mac Mini already and improves again with a decent psu for the RPI. I've also tried the RPI with a IQAudio dad which uses i2s. Two questions:
1. Is the i2s output Dac specific r will the IQaudio software i2s output work on the DDDac?
2. Which pins does the i2s come out of on the RPI header?
Thanks for any help
David
I've now tried the RPI with Rune Audio and used thru USB to the DDDac. SQ is improved quite dramatically over my Mac Mini already and improves again with a decent psu for the RPI. I've also tried the RPI with a IQAudio dad which uses i2s. Two questions:
1. Is the i2s output Dac specific r will the IQaudio software i2s output work on the DDDac?
2. Which pins does the i2s come out of on the RPI header?
Thanks for any help
David
Ciao David,
I have no idea about the IQaudio but here is the link for the RPI header pin-out that is deeply discussed some months ago. (http://www.diyaudio.com/forums/digi...pcm1794-waveio-usb-input-148.html#post3882762)
Regards,
Enrico
Thanks Enrico. D W James very helpfully tells me the IQAudio software will give me the necessary i2s output so I'm all set for the next phase of this fascinating journey!
RCA ground should go to XLR ground.... in case you have XLR connected to something and RCA connected to something, and those "somethings" connected together... somehow... even through the mains cable & earth assuming both chases are grounded...
the straight answer without reading the above, would be to connect RCA ground to XLR ground, and pick the RCA hot signal from either XLR 2 or XLR 3.
there's always alternative to wire the RCA as per standard way of connecting it... via a capacitor straight from the DAC output -> either + or - in particular if you want to avoid the transformer. In this case you would have two "isolated" outputs.... kind-of...
Nick
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XLR and pin 1 problem.... 🙄 Start reading at page 23. Or when you have a lot of time, just read all of this great document 🙂
Just mentioning source:
This work is based in part on a 1994 AES paper
Original work from Bill Whitlock
Just mentioning source:
This work is based in part on a 1994 AES paper
Original work from Bill Whitlock
Hi Doede,
Just finished your DAC. Immense potential. I modified many great-sounding high end DAC's, but your direct simplistic approach sounds fantastic. I'd say it's almost like listening to whatever the USB signals carry with them, coming straight out of a PC.
Great job.
The power supply PCB's look very good - in particular how you routed grounds / negatives.... nice.
Nick
Thanks, Doede, for the document.
I'm familiar with Bill's work from Jensen site, there is a lot of interesting stuff there. But it is always good to refresh your mind about this grounding issue.
I guess I'll just disconnect transformer centertap from pin1 (pin1 is grounded at chassi) and for a single-end output I will take + from the motherboard to HOT via a capacitor and Rload to a RCA groundpoint.