PCM 1798 is excellent, 1794 is the cherry on sundae but there is a price ! reread carefully my previous post.PCM 1798 is for everybody, not the same for 74, lot of care to get the cherry
Yeah, it would be nice to hear comparisons w/ other DAC kits around. I am perplexed by the Quanghao craze: a million posts, but hardly any feedback on the sound.
I had the Gigawork/UTC (later Altec) going for a while, and then tried out the rainbow hui AD1865 kit on ebay that is also based on Ciuffoli design. Did some of the lampizator mods and found the sound more natural, organic but without loss of detail vs. the Gigawork/transformer dac. Not necessarily better, just more preferable to me. Kind of like SACD vs. Vinyl.
Pierre
Finally in the pursuit of the best for $ I bought a used Monarchy M24 and I don't regret it. It is in another league compared to the chinese dac with transformers.
The M24 has a pair of PCM63K which is still reknowned to be one of the best dac chip ever made.
I tried the PCM1798 and hated it. I think that the CS4398 with Jensen transformers gave me better results.
The M24 is now the one I will have to compare other dacs.
I'm somewhat happy to be the crazy guy who first talked in this topic and tried about using transformers with this dac. My 'disease' reached many peoples.
This is still a honest dac but with all I tried with the chinese dac, I think I perhaps reached the end of tryings.
PCM63 sold
Funny. I sold my Enlightened Audio Designs PCM1000 featuring PCM63 chips when I got my Assemblage Dac2.7 with PCM1704 chips and it sounded much better. I sold my highly modified Dac2.7 when I got my direct out modified DEQ2496 with AK4395 chips and it sounded much better than the 1704. I now have the Big Dac Board with DIR9001/ CS43122 running direct out and it sounds a bit better than the AK4395. I would put the direct out Big Dac Board 3 big steps beyond the PCM63.
Funny. I sold my Enlightened Audio Designs PCM1000 featuring PCM63 chips when I got my Assemblage Dac2.7 with PCM1704 chips and it sounded much better. I sold my highly modified Dac2.7 when I got my direct out modified DEQ2496 with AK4395 chips and it sounded much better than the 1704. I now have the Big Dac Board with DIR9001/ CS43122 running direct out and it sounds a bit better than the AK4395. I would put the direct out Big Dac Board 3 big steps beyond the PCM63.
Don't judge the dac chip alone to give you an idea of the sound. i once heard the Enlighted Audio and hated it. I remember it had miserable op amps for analog output stage.
The M24 has a great analog output stage. The I/V for the PCM63K is made with a resistor followed by passive LC filter and a tube for output stage. This is a good receipe for good sound.
The M24 has a great analog output stage. The I/V for the PCM63K is made with a resistor followed by passive LC filter and a tube for output stage. This is a good receipe for good sound.
PCM 1798 is excellent, 1794 is the cherry on sundae but there is a price ! reread carefully my previous post.PCM 1798 is for everybody, not the same for 74, lot of care to get the cherry
Does it necessary the 1794 need to be couple with 4:1 traffos? What about 1:1 like we used initially (A-20). Will it works????
And the for the little 1798, will it work in the same situation???
I tried the PCM1798 with UTC HA108 (big brother of the A20, 600 to 600 ohms.
The + and - of one channel were connected at both ends of the primary with center tap to the ground. The secondary was loaded at near 1.2K to reflect a load of 220 ohms-0-220 ohms at the primary
Sound level is ok but a little bit low
As the PCM1794 has more current output, it could be better.
By how low you can describe? My guess lower than cs4397/8 with A-20 is it?
Secondly if transformer couple works with current type output DAC then do we really need I/V to convert it to a V output?
yes, you need to convert to voltage somewhere. the transformer will convert a certain amount of the current to voltage, as will the pot and/or other resistance in the next stage but its certainly not the ideal way to go about it. much better to convert I/V at or before the TX primaries. also best to try to get rid of DC before the TX or it may saturate (though some designs will tolerate DC)
Yes, it is lower than the CS4398. I would perhaps guess at half the sound level of the CS4398. You need a preamp otherwise the signal is too weak.
Upsampling
Dear forumers
I use the upsampler board in place as suggested in the picture. However I wonder which kind of upsampling I get. Does the board upsample at the maximum frequency (192KHz) ? Does the upsampling board pass data to the DAC chip through the I2S port?
Anyway it seems to me that the with upsampler into the chain the Gigaworks sound much better. I also tried to remove the upsampler and compare with the file upsampled by the computer using SoX VHQ with mimimum phase (which is considered the best upsampler), it seems that the upsampler board does a better job. Did somebody do some experiment like that?
Best Wishes
Pietro
Dear forumers
I use the upsampler board in place as suggested in the picture. However I wonder which kind of upsampling I get. Does the board upsample at the maximum frequency (192KHz) ? Does the upsampling board pass data to the DAC chip through the I2S port?
Anyway it seems to me that the with upsampler into the chain the Gigaworks sound much better. I also tried to remove the upsampler and compare with the file upsampled by the computer using SoX VHQ with mimimum phase (which is considered the best upsampler), it seems that the upsampler board does a better job. Did somebody do some experiment like that?
Best Wishes
Pietro
Attachments
Greetings, I also have the Gigawork DAC and found a way to pick off the Fs frequency that the DAC samples at. Pin 28 of the CS8416 has the Fs there. Use a scope in the 10X mode of the probe or use a 15K ohm resistor from pin 28 to a DMM that does frequency. Ground is pin 22. My El Cheapo Radioshaft 22-812 DMM meter displays the frequency no problem.
I bought a cheap{20 dollar} frequency counter board and LCD display from a guy on Ebay and use it to display the Fs frequency. Very cool.
You also have to set the M3 and M2 switches on the DAC board to the "one" position and the DAC automatically follows any frequency from 44Khz. to 176.4 Khz. that is the max my PS3 will upsample to.
I bought a cheap{20 dollar} frequency counter board and LCD display from a guy on Ebay and use it to display the Fs frequency. Very cool.
You also have to set the M3 and M2 switches on the DAC board to the "one" position and the DAC automatically follows any frequency from 44Khz. to 176.4 Khz. that is the max my PS3 will upsample to.
I don't get this. If you set M2 and M3 on 1 it should upsample the digital stream.
what's PS3?
I am not sure I got your replay. I think I was asking a different question. My question is about the upsampling frequency.
When the upsampler board is installed, does the gigaworks always upsample at the same frequency? Which one? The quartz on the upsampler board has a frequency which is a multiple of 48KHz so I guess that either it upsamples to 96KHz or to 192Khz. I wonder whether the upsampling frequency is fixed or it rather depends on the input signal.
Cheers
Pietro