No, I replaced the original CD player crystal with an XO module. I had done it previously so I could reclock and buffer the SPDIF output. Whether it makes any difference feeding an I2S signal to a chip that reclocks it anyway, I don't know. It would seem to be redundant, but who knows for sure. It seemed the upgrade to the Tent XO over the generic XO I was originally using also made a difference, but that is a subjective opinion that cannot be substantiated.
The clock on the upsampler board is not just a crystal, it is a self contained XO module. It may be beneficial to replace the Chinese XO on the board with a higher quality one such as a Tent Labs, but I haven't done it yet.
I'm sure the comparison would depend largely on the precision of the SPDIF conversion and transmission. Just using RCAs on the cabling compromises the transmission, it is an incorrect impedance.
Compared to the best SPDIF scheme I could come up with using my Philips player, the I2s scheme was profoundly better sonically.
I sure don't think an SPDIF signal from a puter card could be better in any meaningful way, but whether it is worth the effort, I can't answer that.
Hey thanks guys for the valuable info, much appreciated.
Bill - I found the PS audio thread and I'll try contacting Paul about his implementation. It looks relatively painless as you say. It may be possible to rig up a module using cat5 or other data cable. Paul uses a HDMI interface though.
WDYSUN - That XMOS module does sound like it will do the business doesn't it. I might actually give that a go if I get nowhere with the line driver idea from PS audio, thanks for the links.
Regarding the XO module on the sampler. A friend on PFM has removed the XO can from the sampling board and installed it on a PFM flea module with excellent results. The Flea is a dedicated high quality regulator especially for XO modules. You simply tap the XO signal from the flea to pin 4 of the vacant position on the sampler board. Giving the XO a dedicated regulated power supply is well worth it chaps. And if you can afford the Tentlabs XO - do it, they are simply better.
You can see the flea in action here on Ray De Haan's EzDAC. Boards and advice are available from Ray directly:
Ray's Audio Page
More info here under 'PFM flea':
http://www.acoustica.org.uk/
I should point out that the flea can be configured as a stand alone regulator. It is very good especially for the digital rails, replacing the crappy LM317 regs. You should all think about upgrading the power supply and regulators, massive improvements all round.
Bill - I found the PS audio thread and I'll try contacting Paul about his implementation. It looks relatively painless as you say. It may be possible to rig up a module using cat5 or other data cable. Paul uses a HDMI interface though.
WDYSUN - That XMOS module does sound like it will do the business doesn't it. I might actually give that a go if I get nowhere with the line driver idea from PS audio, thanks for the links.
Regarding the XO module on the sampler. A friend on PFM has removed the XO can from the sampling board and installed it on a PFM flea module with excellent results. The Flea is a dedicated high quality regulator especially for XO modules. You simply tap the XO signal from the flea to pin 4 of the vacant position on the sampler board. Giving the XO a dedicated regulated power supply is well worth it chaps. And if you can afford the Tentlabs XO - do it, they are simply better.
You can see the flea in action here on Ray De Haan's EzDAC. Boards and advice are available from Ray directly:
Ray's Audio Page
More info here under 'PFM flea':
http://www.acoustica.org.uk/
I should point out that the flea can be configured as a stand alone regulator. It is very good especially for the digital rails, replacing the crappy LM317 regs. You should all think about upgrading the power supply and regulators, massive improvements all round.
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yes but from what I understand no Win drivers, no linux drivers! It is natively supported under mac
Pietro
It seems they're available here:
CEntrance -> Universal Driver
If I go this route I shall contact XMOS and confirm the drivers are correct. At the end of the video you linked to it does say win drivers are available, possibly beta though.
mmh! that's very good, keep us updated! Anyway doing a small googling it seems that ALSA guys are working on the Linux drivers as well, see here
usbaudio: Support for USB audio v2.0 devices -- ALSA Devel
Perhaps we should open a new thread on this forums so that we have more than 4 eyes open on it
Best Wishes
Pietro
I must've read through a hundred pages already so I'll just ask.
1.) What does this DAC output with USB input? Is it limited to 16 bit/44khz?
2.) Does it automactically upsample the coax input to 192khz? Is this all the time or can you make provisions to shut it off?
3.) I'm guessing I would have to add switching to accomadate multiple inputs for use seperately, no?
Thanks in advance.
1.) What does this DAC output with USB input? Is it limited to 16 bit/44khz?
2.) Does it automactically upsample the coax input to 192khz? Is this all the time or can you make provisions to shut it off?
3.) I'm guessing I would have to add switching to accomadate multiple inputs for use seperately, no?
Thanks in advance.
The USB input is limited to 48khz.
It upsamples everything to 192khz. If you unplug the upsampler you have to set the mode switches on the dac chip board to match the input signal. It does not auto detect.
The input enable matrix can be wired to a front panel switch very easily.
Email me and I'll send you the manual.
It upsamples everything to 192khz. If you unplug the upsampler you have to set the mode switches on the dac chip board to match the input signal. It does not auto detect.
The input enable matrix can be wired to a front panel switch very easily.
Email me and I'll send you the manual.
Fun
These Big Dac Boards are a very flexible test sled with everything socketed which will allow me to plug in a Twisted Pear Opus when I get some connectors. They are also a lot of fun in that you never know what combination of plug in modules will actually work with each other. Apparently not many people have tried the DIR9001. If you had there would be more raves about the sound quality. It is much better than the CS8416 even through the upsampler and/ or being fed upsampled or direct data from my SRC2496, making the 8416 sound a bit hazy in comparison. There would also be more complaints about the function of the 9001 module. I have two boards and doubles of all of the modules with the exception of never having tried the 4398 yet. One of my DIR9001 modules will only lock to the optical regardless of the input selection jumper settings and the other will only lock to the coax but only if the jumpers are set to optical? I will eventually remove the electronic switch IC under the module to just hard wire them both to coax. One DIR will work with the upsampler and one won't whereas both Big boards will allow the upsampler to work with either 8416. The upsampler is great and offers a more fleshed out, non digital sound except that the CS43122 has a low level whine when the upsampler is used. Anyone listening to 16/44 digital without upsampling it somewhere is missing out.
.
The transformer I/V PCM1798 doesn't whine with the upsampler but I can't get rid a low level buzz. I have tried all of the various ground and loading schemes possible. 40 ohms (plus 20 ohms trans primary) from each leg to ground with the single ended output starred to audio ground under the module, or ground lifted. 80 ohms between the legs (input center tap and resistors ground lifted) which surprisingly still played just the same. No resistors on the legs, loaded only 4-7k at the amps back through the secondary. This tends to be more critical to resistor matching for stereo balance as any deviation between the resistors is multiplied by 64X. This will play only if the input center tap is grounded and seems to sound quite similar although I didn't bother to go back and forth comparing the before trans/ after trans loading schemes yet. I also tried matching the load on both sides with 100R across the primary and 6400R at the amps instead of the usual 20k which interestingly doesn't double the listening level of the I/V. Every possible combination still hums on both boards even with 12v battery power. Maybe I butchered the module board while removing the opamps? I have a couple empty modules to try with PCM1794a later. Listening over the hum, the 43122 sounds better anyway although it still has a slight hiss/ noise floor issue which means I wouldn't want to commit to this set up for an upcoming pc active cross project either. Now that I know the importance of clocks thanks to the DIR9001, I should get my Oettle clock installed with the 4395 in the DCX before I give up on that chip altogether to hear if it is just the receiver that is giving the Big Dac Board most of it's advantage now.
These Big Dac Boards are a very flexible test sled with everything socketed which will allow me to plug in a Twisted Pear Opus when I get some connectors. They are also a lot of fun in that you never know what combination of plug in modules will actually work with each other. Apparently not many people have tried the DIR9001. If you had there would be more raves about the sound quality. It is much better than the CS8416 even through the upsampler and/ or being fed upsampled or direct data from my SRC2496, making the 8416 sound a bit hazy in comparison. There would also be more complaints about the function of the 9001 module. I have two boards and doubles of all of the modules with the exception of never having tried the 4398 yet. One of my DIR9001 modules will only lock to the optical regardless of the input selection jumper settings and the other will only lock to the coax but only if the jumpers are set to optical? I will eventually remove the electronic switch IC under the module to just hard wire them both to coax. One DIR will work with the upsampler and one won't whereas both Big boards will allow the upsampler to work with either 8416. The upsampler is great and offers a more fleshed out, non digital sound except that the CS43122 has a low level whine when the upsampler is used. Anyone listening to 16/44 digital without upsampling it somewhere is missing out.
.
The transformer I/V PCM1798 doesn't whine with the upsampler but I can't get rid a low level buzz. I have tried all of the various ground and loading schemes possible. 40 ohms (plus 20 ohms trans primary) from each leg to ground with the single ended output starred to audio ground under the module, or ground lifted. 80 ohms between the legs (input center tap and resistors ground lifted) which surprisingly still played just the same. No resistors on the legs, loaded only 4-7k at the amps back through the secondary. This tends to be more critical to resistor matching for stereo balance as any deviation between the resistors is multiplied by 64X. This will play only if the input center tap is grounded and seems to sound quite similar although I didn't bother to go back and forth comparing the before trans/ after trans loading schemes yet. I also tried matching the load on both sides with 100R across the primary and 6400R at the amps instead of the usual 20k which interestingly doesn't double the listening level of the I/V. Every possible combination still hums on both boards even with 12v battery power. Maybe I butchered the module board while removing the opamps? I have a couple empty modules to try with PCM1794a later. Listening over the hum, the 43122 sounds better anyway although it still has a slight hiss/ noise floor issue which means I wouldn't want to commit to this set up for an upcoming pc active cross project either. Now that I know the importance of clocks thanks to the DIR9001, I should get my Oettle clock installed with the 4395 in the DCX before I give up on that chip altogether to hear if it is just the receiver that is giving the Big Dac Board most of it's advantage now.
Great post Scott,
Wait til you try it direct without any receiver!
The 4398 is their flagship chip, hows come you haven't tried it yet?
I have yet to experiment with a current out dac, but do you think the 1794 might be having internal problems with the relatively high load impedance? Maybe trying 5 or 10 ohms load could be the solution.
4398
.
The resistor/ transformer I/V on the PCM1798 requires at least that much resistance even though I am using 1:8 transformers in order to play loud enough. The 1794 will need only 1/2 of that and mono mode will be 1/2 again, taking the required resistance all the way down to 10-15R to get somewhere around 0dbu which is all I need and will be right in the sweet spot for load. I had 160R on each leg of the PCM1798 for test at one point. It was very loud but very distorted.
Snow tells me that the 43122 sounds better than the 4398 and I believe her judging from what I am hearing. The only things keeping me from declaring a rave are the slight hiss and the whine when using the upsampler. The 43122 doesn't seem to like something about 192k even though the spec sheet says it can handle it. Is there hardware control on the upsampler to chose different frequencies? Maybe it would like 176K better. As is, it is much better than the CS8420/ AK 4395 in my Behringer.
.
The resistor/ transformer I/V on the PCM1798 requires at least that much resistance even though I am using 1:8 transformers in order to play loud enough. The 1794 will need only 1/2 of that and mono mode will be 1/2 again, taking the required resistance all the way down to 10-15R to get somewhere around 0dbu which is all I need and will be right in the sweet spot for load. I had 160R on each leg of the PCM1798 for test at one point. It was very loud but very distorted.
Hiss and whine, sounds like me when i'm in one of my moods.
I'm still under the impression that the 43122 was a design excercise predating the 4398. They may have had consistancy problems with them because they were using new techniques that have supposedly been perfected now in the 4398. Anyway, I tend to discount vendor's opinions, especially when they are selling something as an upgrade.
I had it in mind that you were using the 1794 for some reason. The 1798 would seem to require a higher trafo ratio than 1/8
I'm still under the impression that the 43122 was a design excercise predating the 4398. They may have had consistancy problems with them because they were using new techniques that have supposedly been perfected now in the 4398. Anyway, I tend to discount vendor's opinions, especially when they are selling something as an upgrade.
I had it in mind that you were using the 1794 for some reason. The 1798 would seem to require a higher trafo ratio than 1/8
I decided to take a risk this evening..
I plugged in the PCM1794 modules coupled to the Lundahls trafos.no smoke...
but it was sound.
Have just been listening a short while with audio from my satelite reciever,
I think it sounds darker than the 4398,but it is still very detailed.
And the sound level is about the same with the 120 Ohms resistor as I/V.
Will listen more closley later,I have to finnish my subamp so I get some bass 2.
I plugged in the PCM1794 modules coupled to the Lundahls trafos.no smoke...
but it was sound.
Have just been listening a short while with audio from my satelite reciever,
I think it sounds darker than the 4398,but it is still very detailed.
And the sound level is about the same with the 120 Ohms resistor as I/V.
Will listen more closley later,I have to finnish my subamp so I get some bass 2.
But why bother? In my opinion CS4397 sounds better than CS4398. And CS43122 is probably essentially the same as CS4397.
And when I tried PCM1798 with passive conversion (150R Riken) and tube gain stage (16x gain) ...
Now I'm absolutely sure there's no return to Cirrus.
gain
Wow! so much gain. 150R per leg? And 16X. That's 18 db more than I am using with my PCM1798. Have you tried smaller resistors? When I had 160R per leg to ground, the sound was horribly distorted. The lower the resistance the better right? Most active I/V circuits aim for a virtual 15R or lower. Did you have tubes following the 4397?
Wow! so much gain. 150R per leg? And 16X. That's 18 db more than I am using with my PCM1798. Have you tried smaller resistors? When I had 160R per leg to ground, the sound was horribly distorted. The lower the resistance the better right? Most active I/V circuits aim for a virtual 15R or lower. Did you have tubes following the 4397?