A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input) - Page 31 - diyAudio
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Old 7th April 2013, 01:39 PM   #301
IanS1 is offline IanS1  United Kingdom
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Location: UK
Quote:
Originally Posted by AudioH View Post
Sorry for delay, steep learning curve with Eagle PCB software.

I have enclosed design notes including LCD schematic, BOM as requested plus Arduino sketch code.

I don't pretend this is the most elegant solution, but it works.

Best Regards
Thanks for that AudioH, very nice indeed. When I come to put mine into a box I might look into a similar solution.
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Old 12th April 2013, 04:13 PM   #302
Almeg69 is offline Almeg69  United Kingdom
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Progress so far, All soldered up including the three power supplies, I did not want the Dac stack sharing with the SPDIF board.
I have drawn up a case and sent the details off to be machined at our local engineering shop, and primed the Powder coaters to expect some alloy panels appearing through the side door for some Black :-)
There is nothing new done that has not been shown here so I will not bore you with another photo, but I will show how the case comes out.
Then wait for the Transformers to arrive for final wiring, probably another 2 weeks before the big test :-)
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Old 15th April 2013, 02:37 PM   #303
2A3SET is offline 2A3SET  Canada
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Default DSD1794 successful

I have tested NOS with DSD1794 (thanks Doede for the great idea, sounds soooo good!), here is the Arduino i2c code to share, PIN3 (DSD clock) needs to be applied after switching from PCM to DSD, I am using the Amanero board to disable DSD clock with the DSD-enable PIN when it's PCM.

PCM,
Wire.beginTransmission(0x4c); //right channel
Wire.write(B00010010); //start with register 18
Wire.write(B00100000); //DF
Wire.write(B00000001);
Wire.write(B00011000); //same as left channel
Wire.write(B00000001);
Wire.endTransmission();
Wire.beginTransmission(0x4f); //left channel
Wire.write(B00010010);
Wire.write(B00100000);
Wire.write(B00000001);
Wire.write(B00011000);
Wire.write(B00000001);
Wire.endTransmission();

DSD,
Wire.beginTransmission(0x4c); //right channel
Wire.write(B00010010);
Wire.write(B00101000); //enable DF bit as well, otherwise cannot switch back to PCM, using DSD filter-3 to get similar gain as PCM
Wire.write(B00000000);
Wire.write(B00101100);
Wire.write(B00000010);
Wire.endTransmission();
Wire.beginTransmission(0x4f); //left channel
Wire.write(B00010010);
Wire.write(B00101000);
Wire.write(B00000000);
Wire.write(B00101000);
Wire.write(B00000010);

Last edited by 2A3SET; 15th April 2013 at 03:02 PM.
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Old 15th April 2013, 05:43 PM   #304
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Hi 2A3SET,

I don't have this DAC but have built a DSD1794 based DAC as well with the hope to somehow in time be able to program the DAC to play back DSD as well. So when time comes this may be really helpful!

Thanks for sharing :-)

Jesper
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Old 16th April 2013, 06:35 AM   #305
bravi is offline bravi  New Zealand
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Default Performance improvement continues

Further to my earlier posts, an update on changes that provided improvements in sound quality

Common mode Choke- Added one Panasonic 82mh Common mode choke after the raw supply. This improved the quality of sound, especially with regard to bass resolution. Reasons for this could be rfi noise mentioned before.

I/V Resistor- There was a mention by Bas about Rhopoint resistors earlier in the thread. The quality of this was also mentioned by ECDesigns in his thread on TDA1541. Bit the bullet and ordered these from UK. Since 34 ohms was not available, i paralleled two 70 ohms for each position to reach 35 ohms value. The major improvement I noticed over the Dale resistor was a more natural feel to the sound. The slight metallic edge noticeable with Dale was absent and the dynamics, especially on sharp cymbal strikes was closest to a natural feel.
Since I used .01% resistors, another benefit was that the voltage balance between plus and minus outputs was zero volts as measured with my DMM
There be a difference in the microvolt range, but I do not have the equipment to measure. In contrast,with the dales in position I measured around a difference in the mv range (forgot to note the exact value)

The zero value difference encouraged me to try out transformer coupling yesterday. I used an old Opamp labs 10k:10K transformer for this purpose. I was not expecting much, but once again an improvement. But at first, it comes across as a softening of the sound, As you continue to listen, one notices the more natural feel to voices and greater dynamic swings in the music. Unable to account for this. The only possible explanation is that isolation of the grounds probably has a role.

Anyway, one of my most rewarding and exciting DIY journeys.

Cheers!

Ravi
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Old 16th April 2013, 07:53 AM   #306
dddac is offline dddac  Germany
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Thanks Ravi,

this is indeed very valuable feedback and a good motivation to keep trying :-)
what exactly and where did you order the resistors?
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Old 16th April 2013, 10:43 AM   #307
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Having been very lucky and grateful to a fellow DIYAudio member IanS1, who built my DDDAC for me recently, I thought I would share initial listening impressions.

Ian has a very well matched and refined system, with great transparency which is ideal for testing changes. We compared his DDDAC build (4 dac boards and upgraded output caps) to mine (single dac with standard caps). Its clear that the extra boards add a little more refinement, a bit more air, and a sharper focus to the soundstage.

I brought the dac back and put it into my own system and it sounded great - really dynamic. I have made a good number of changes recently in a bid to downsize my set up. So consequently I lack a firm reference to draw upon. Once I've got my ears around what the relative contribution of new active speakers, new preamp, addition of mains reconditioning, and now a newly built dac, all bring - I'll report back!

The new preamp and dac have foxed me to be honest, so with a little swapping out of each I might pin point whats what.

Definitely think the extra dac boards is going to be on the cards - possibly Sowters if they match the input on my preamp.
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Old 16th April 2013, 11:21 AM   #308
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Quote:
So consequently I lack a firm reference to draw upon
This is my problem as well. I'm planning to assemble my RAKK DAC MKII (PCM1794 based as well) soon and compare it side by side with the DDDAC PCM1794 NOS. Ofcourse there will be differences because one is spdif the other usb. But I'll compare them to each other without any output caps.
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Old 16th April 2013, 11:22 AM   #309
bravi is offline bravi  New Zealand
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Default Rhopoint resistors

Hi Doede,

The Rhopoint resistor can be purchased online from the company directly. Their web address is :Temperature Sensors, Pressure Transducer, Dynamic Braking, Load Bank, Motor Control

I used the through hole resistor described as 3ppm/C wirewound econistor 8E16 / 8G16 series.

There are other series which are higher in price for almost similar specification, but I went for the lowest cost option.

Cheers!

Ravi
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Old 16th April 2013, 11:28 AM   #310
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Rhopoint Squaristor GG102A is the one that beat the Texas Components TX2575 Bulk Z-Foil resistor.

RESISTORS Precision (through hole) 3ppm/C wirewound squaristor GR102 / GG102 series
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