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

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#402
Hi there, I am new on DIYaudio.

I am also building the new DDDAc1794, with eight decks. Stil now two to go, and I have to look for the LM7805. Maybe next week I can finish my project. A lot of 24/192 music to play...!
Regards,
Altjo
 
#403
bravi said:
Hi Supersurfer,

Do you by any chance have spare transformers in your bin to try an experiment? If you have some with a similar voltage to the one you have powering the shunt regs, try paralleling to them so that you have at least 2 or 3 times the VA and see if you hear any difference.

The suggestion is made since a choke input supply designed for critical current flow should not have any difference just by increasing the current rating of the power transformer ( By the way I was running it at only 35% capacity, well below the possible utilisation for a choke loaded supply). But it seems that even though the sec voltage is the same and the rectified voltages are the same, the improvement in sound quality is quite obvious.

Cheers!
Click to expand...

Hi Bravi,

I have used a toriodal 300va transformer, with a variac to adjust to the right voltage, just before my transformers arrieved. And, yes there is a difference.
I also have the experience that there is a big difference in sound using other rectifier tubes (in my amps and another dac with tube outputs) or furutech power supply shuko connectors for that matter.

So it is all a matter of combining the right items to create the sound balance you want.
The sound balance of your dac should fit the balance of your complete set, I often need to change some component somewhere else in my setup: when I upgrade a component like the dac, I end up changing the tube settings of my amp to correct the balance.🙄

Regards,
 
#404
another one who has just bought the kit, looking forward to it arriving. unlike most of you guys i don't know much about the technical stuff but i can solder and have enjoyed making phono stages, headphone amps, power supplies and some speakers.

have any of you experimented with the capacitors?
 
#409
Hi Ian,

That looks very good! For best performance you need to remove the 47uf capacitors downstream of the regulators: c18, c32 and c27 (left channel example).

If you keep these , the shunt regulators will feed the capacitors and that will slow down (dampen) the regulation.

I am very curious on your findings how this compaires to the standard 4 board set; please keep us posted!

Regards,
 
#416
#418
iV Resistors

Hi All, I was intrigued to read the post re the I/V resistor a short while ago. Being a mechanical engineer I thought a resistor was a resistor within the bounds of value and wattage . Apparently not !

So after some web research there are apparently
1) different material and mechanical compositions that make up the resistor
2) different manufacturers of the differing compositions.

Opinions abound as to which is the 'better'.

So I have some quotes for the Rhopoint 8g16D and GG102D types at roughly £5 and £9 each respectively.

Alternatively HiFi Collective offer many brands from pence to £15 plus each!

Shinkoh Tantalum- 0.5W, 1W & 2W simply the best.
Audio Note`s Tantalum- 0.5W, 1W & 2Ws.
Amtrans Carbon film- 0.75W & 2Ws.
Kiwame- 2W and 5W, superb carbon films.
Allen Bradley- 0.125W to 2W, NOS carbon composites.
Holco- original H4 0.5W & H2 1W metal films.
Mills- Mills 12W non-inductive wirewounds.
MResist Supreme- 20W non-inductive wirewounds.
TAKMAN carbon & metals -0.25W, 0.5W & 1W.
Duelund- CAST & standard silver resistors.
Arcol- New 0.5W carbon composites.
Charcroft- 0.4W Z-bulk foils

So to help me pin down the choice before spending money can a recommendation be made on 1) the resistor type and 2) more difficult, any particular manufacturer.

Many Thanks
Howard
 
#419
I would dare to suggest thin film resistor 5w apparently the best but comes expensive 10 usd each,or Holco 0.5-1w .about carbon film i know that the noise is double respect to the metal film same watt --- so 0.5w metal film Equals to 1w carbon in terms of noise -NO CARBON COMPOSITE ,they have some undesired capacitance
??? one question ho would you use them In parallel to I+, I- ..or in reference to GND
I+ gnd, I- gnd
 
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