A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

[juancho]

That 100ma does not seem right IME. I have separate analogue and digital supplies in my DAC and the analogue alone for four boards runs at around 700ma, digital a lot less. I'd guess 200ma per DAC board

 

[mbrennwa]

Doede, can you provide some insight?

What is the current consumption of the Tent DAC boards? How many DAC boards can I run off the standard DDDAC PSU? Is the PDF doc on the DDDAC website correct?

 

[MagicBus]

I'm building a DDDAC "clone". I use 12V linear pre-regulators to feed the Tent labs but with a 10 ohm resistor in series to drop it at 11V, a compromise between 12V that might be too much and 10V that might be OK but made me thinking of it all the time. The voltage across the 10 ohm resistor is 950mV so 95mA per tent labs' regulator and since there are two, 190mA per board. The digital section is no more than 50mA per chip depended on the sampling rate, so less than 100mA per board. I would say a total of 280mA max per board.

 

[mbrennwa]

Hmm, thinking about PSU options... I know it sounds like blasphemy, but what about a simple off-the-shelf switching PSU? Those units are cheap, would be very easy to implement, and they are will easily provide enough current for as many DAC boards one can dream of. They usually provide surprisingly clean DC, and the sequence of regulators on the DDDAC boards might deal with the rest.

What do you guys think?

 

[G600]

Borderline blasphemy fur sure, but as it's DIY, you should try!
By the way, regulating after a regulator is not a good idea.
Personally, I would properly heatsink Doede's PSU with a big transformer.
Or even better, draw a low-impedence filtered PSU (transformer followed by CRC or CLC) and let local regulators do their magic.

 

[gentlevoice]

@mbrennwa:

but what about a simple off-the-shelf switching PSU?

Now not having listened to any SMPS'es this is purely a subjective comment ... Depending on what regulators are used many "normal" regulators have quite low high frequency PSRR - meaning that potentially the HF noise from a SMPS may pass through subsequent regulators. Also, typically LF and HF are the frequency areas that are difficult to filter effectively - thus, using a SMPS may cause more HF feed through and also in general more regulator-induced self-noise ... if one may say so ...

Anyway, these were the thoughts that just came up.

Cheers,

Jesper

 

[Almeg69]

Alright. More DAC boards = more current = more heat dissipaton from the TIP.

What is a realistic limit for the number of DAC boards (given the TIP is fine)?

I am running 16 Pre Tent Dac boards with the power supply shown earlier. I used the TIP142 transistor bolted to the heatsink.

I used an Ohmite 63.5 mm heatsink for the rectifier.

For my next project, I want to run 16 Tent boards. I had another PCB made with large traces as I want to be able to run 4A continuous and keep the temperatures as low as possible, 50ºC max.

 

[juancho]

I'm building a DDDAC "clone". I use 12V linear pre-regulators to feed the Tent labs but with a 10 ohm resistor in series to drop it at 11V, a compromise between 12V that might be too much and 10V that might be OK but made me thinking of it all the time. The voltage across the 10 ohm resistor is 950mV so 95mA per tent labs' regulator and since there are two, 190mA per board. The digital section is no more than 50mA per chip depended on the sampling rate, so less than 100mA per board. I would say a total of 280mA max per board.

That is right in line with my guestimate

 

[trung224]

Doede, I'm looking at your DDDAC document, but have a problem regardings Rload (Riv) in your DAC.

From your document, the XLR output of your DAC with Sowter transformer will have 4.8Vrms = 13.5Vp-p, the voltage in the primary of xformer is 13.5Vp-p/2 = 6.75Vp-p because of the ratio 1:2 of xformer. So the voltage swing of each pin in primary winding of xformer will be 6.75Vp-p/2 = 3.375Vp-p.

With one PCM1794 chip in mono mode, each pin of primary winding will get a current sum from 2 output pin of PCM1794 with 7.8mAp-p each. So the Rload will be 3.375Vp-p/(2*7.8mAp-p) = 216 Ohm. So the Rload with several decks is (216 Ohm/ number of decks), and different from your estimated value (216 Ohm/ number of decks).

That is what I calculate, but I could be wrong. Could you offer some insight about it.

 

[dddac]

Doede, I'm looking at your DDDAC document, but have a problem regardings Rload (Riv) in your DAC.

From your document, the XLR output of your DAC with Sowter transformer will have 4.8Vrms = 13.5Vp-p, the voltage in the primary of xformer is 13.5Vp-p/2 = 6.75Vp-p because of the ratio 1:2 of xformer. So the voltage swing of each pin in primary winding of xformer will be 6.75Vp-p/2 = 3.375Vp-p.

With one PCM1794 chip in mono mode, each pin of primary winding will get a current sum from 2 output pin of PCM1794 with 7.8mAp-p each. So the Rload will be 3.375Vp-p/(2*7.8mAp-p) = 216 Ohm. So the Rload with several decks is (216 Ohm/ number of decks), and different from your estimated value (216 Ohm/ number of decks).

That is what I calculate, but I could be wrong. Could you offer some insight about it.

Your assumption of the output current is wrong - through pin 20 I bias a higher output - The output per Dac half is ~ 1,2 V eff in 133 Ohm (so 3,36 pk-pk now through the Sowter 1:2 and using POS and NEG, you get 13,44

 

[dddac]

Doede, can you provide some insight?

What is the current consumption of the Tent DAC boards? How many DAC boards can I run off the standard DDDAC PSU? Is the PDF doc on the DDDAC website correct?

The new Tent Boards take ~ 230-250 mA. So with the 1A standard psu version you can do 4 boards

if you beef this up with bigger transformer, and some more cooling, you can easily do 2 A and 8 boards for example

 

[trung224]

Thanks Doede. I forgot to notice that you change the standard 10k Ohm in Iref pin to 6k Ohm. It makes sense now.

 

[Brumjam]

Nice Alex. The first a noticed after installing 3045 was that the bass sounded more tight with good definition. For me,and in my setup, the 3045 is worth every penny.

Just now I’m struggle to decide if I shall order the fifo II kit from Ian. I am so happy with the sound as it is, but you know how it is....maybe it’s possible to squeeze more out of our beloved dddac than we already have done ?

If I order from Ian, I will go all in with fifo II, isolator board and dual clock board with som high quality clocks. Anyone who have tried or heard Ian’s fifo with dddac? I use waveio,and have discovered how different my two waveio boards sound. My old waveio have NDK sd clocks and my new waveio have the sda clocks from NDK.

To my surprice I like the old sd clocks better than the new sda. The new sda clocks have more punch and dynamic, but loose when it comes down to the most important for me, and that is flow and coherence. The new sda clocks sound more mecanical or unnatural.

What i discovered regarding the new and old clocks got me curious and I started searching for info why this was the case. The answer is simple. In a batch of, lets say 1000, only 100 or so will measure very good with small tolerances between them, and the rest is bob bob..

I remember reading in the waveio tread that there was a guy who had two waveio card with the new sda clocks from NDK, and the sound was night and day between them. I think he ended up sending one back to Lucien.

If I order the fifo from Ian it seems like it is a must to get new clocks which measure as good as possible and is matched against each other. Probably not easy since not many sellers have the right(and very expensive) equipment to do this.

I prefer Allo’s Kali reclocker board to Ian’s FIFO board, although admittedly I haven’t tried the latest version. On the Kali board I upgraded the clocks to NDA SDA and I was amazed at the improvement. The LT3045 regulator was the icing on the cake. This is the best sound I’ve heard from my DDDAC.

 

[dddac]

Thanks Doede. I forgot to notice that you change the standard 10k Ohm in Iref pin to 6k Ohm. It makes sense now.

I tried at the time to squeeze the maximum Output voltage (signal rms) out of the DAC with passive I/V conversion

hence did things, the datasheet was not showing

 

[Hifoli]

Hi guys, I’m new here and on my way building my own DDDAC, if someone could just quickly tell me if my assumptions are right so I can order before reading the rest of this monster of a thread

I have a nice 12V 1A psu so I’ll go with 4boards
Hifiberry or allo DigiOne via i2s for best SQ (the modded Kali Version sounds intriguing too ^^)
Sowter trannies (if still available and not to pricey in comparison to the the Cinemags) for best SQ?
Casing will I print myself (photo and stp following when this works out, will need some shielding perhaps...let’s see)

So thank you guys for all this testing and putting up this thread, I’ll continue reading now

Greetings Oli

 

[dddac]

Hi guys, I’m new here and on my way building my own DDDAC, if someone could just quickly tell me if my assumptions are right so I can order before reading the rest of this monster of a thread

I have a nice 12V 1A psu so I’ll go with 4boards
Hifiberry or allo DigiOne via i2s for best SQ (the modded Kali Version sounds intriguing too ^^)
Sowter trannies (if still available and not to pricey in comparison to the the Cinemags) for best SQ?
Casing will I print myself (photo and stp following when this works out, will need some shielding perhaps...let’s see)

So thank you guys for all this testing and putting up this thread, I’ll continue reading now

Greetings Oli

thanks for your interest in the DDDAC seems you are picking a very nice set up - Sowters are not "cheap" - you can send me an email for current price - Still people spend similar amounts on Capacitors, Interlinks and Power cables

 

[trung224]

I tried at the time to squeeze the maximum Output voltage (signal rms) out of the DAC with passive I/V conversion

hence did things, the datasheet was not showing

Very impressive and innovative way, Doede. I would like to ask one more question, when you change the Iref with 6k resistor, does the output impedance of Iout pin drop?

 

[67339]

I have a nice 12V 1A psu so I’ll go with 4boards
Hifiberry or allo DigiOne via i2s for best SQ (the modded Kali Version sounds intriguing too ^^)
Sowter trannies (if still available and not to pricey in comparison to the the Cinemags) for best SQ?
Hello,
It seems that a choke input power supply is the way to go. The advantage of the choke input is that the transformer can be smaller. Personally i like the Triad split bobbin transformers. The biggest one available is 48VA. They are less than 20 euro so you will have some money left to get yourself a nice choke.
Of course if you have a supply available you could start from there and update later!!
I am using the Sowters too but i didnt try anything else. It will be an investment but they will last for ages!
Doede did develop the transformer together with Sowter i dont think anything better is available.
Currently i am using the aurender BUT i wanna switch tyo the Hifi berry and dump the Aurender.
greetings, Eduard

 

[smooth dancer]

Hi guys, I’m new here and on my way building my own DDDAC, if someone could just quickly tell me if my assumptions are right so I can order before reading the rest of this monster of a thread

I have a nice 12V 1A psu so I’ll go with 4boards
Hifiberry or allo DigiOne via i2s for best SQ (the modded Kali Version sounds intriguing too ^^)
Sowter trannies (if still available and not to pricey in comparison to the the Cinemags) for best SQ?
Casing will I print myself (photo and stp following when this works out, will need some shielding perhaps...let’s see)

So thank you guys for all this testing and putting up this thread, I’ll continue reading now :

Greetings Oli

Hifoli@
I have a Kali in order and want to know more about this modded version.

 

[kartick]

Hifoli@
I have a Kali in order and want to know more about this modded version.

I am also using a standard off the shelf Kali board sandwiched between waveio and dddac. I’d also like to know how to mod the kali board with this better clock? Or is Kali now sold by deafult with the updated clock?