4493 is slightly different here. It has SCF output which is basically an OP paralleled with a capacitor. The job of the OP is to keep the capacitor at steady voltage. Ideally, you want this OP to devote all current to the capacitor with no leakage to the next output stage,
Yep, looks pretty standard to me. So its not different really - the output comes from an opamp and that opamp doesn't have too great PSRR. Best load it as lightly as possible with the following stage, which is normally a 4 resistor differential-SE stage built around an opamp. The higher the resistor values, the lower the current drawn from the opamp in the DAC.
Yeppers. If close loop can fix any phase shift problem, nobody would bother to publish phase shift chart in OP's datasheet. All OPs can easily reach 10MHz.
OP is also a form of amp. All amps have phase shift and there is just this much you can do with negative feedback.
AKM has its own fab. They can do more tricks on this output stage. It is not like ESS which has to rely on TSMC, etc, generic CMOS power houses. Not sure what AKM has done to 4493's outputs. It just has this unique sound. On the other hand, reference circuits in 4493's datasheet all use fairly low output load resistance.
Do they publish distortion with various loads anywhere?
I saw 4497 has a heavy load drive mode, but the key measurements are made with it off and the rep I emailed couldn’t tell me if there was any price to pay for using it, other than quiescent current.
It used to be that AKM fabbed Crystal Semi's parts, not sure if that's the case now that CS is Cirrus.
Yeah they do this to get the lowest possible noise for the datasheet, which also leads them to choose bipolar opamps. Specs matter in marketing. However I only have 16bit music so just need my DAC a few dB quieter than the dither noise on my recordings. No need to aim for <-120dB.
Structure wise, 4497 is a dual 4495 inside with final switchable output driver.
Heavy load drive mode means driving the output with parallel ops. This will make measurement number bad yet in practice, drive the next stage better.
It's up to the designer to choose.
Crystal parts were made by several fabs. Same for Cirrus Logics.
Someone told me the new CS43198 is very good with sound signature somewhere between ES9038 Pro and AK4497. I am thinking of trying it out.
Most 4497 implementations I saw have low load resistances, same case here for DX3. Bipolar OP has lower input noise hence chosen for measurement.
24bit/48KHz music data, for instance, is more than enough. The DSD512 support gives me the option to do upsampling better with software like HQPlayer instead of relying on the DSP inside 4493. The DSP inside 4493 is fairly good already though.
CS43198 is a nice looking part for sure. I am thinking of making a USB bus powered DAC using it. The datasheet seems to imply that there is no need for even a first order external LPF. They connect the outputs directly to an XLR jack via 100 ohm resistors. Not sure that's what I would do... but it's a first for a high end DAC that I've seen. Seems to just edge out AK4492ECB on specs.
Then can you point out the implied measurable distortion this “delayed” feedback would produce?
Being a 'mobile' chip, would the power supply constraints limit CS43198 in any way ?
I think the proof is in the specs. So, could they make a better part with higher power consumption? Probably. The pseudodifferential outputs might be a compromise to that end.
Just because it’s targeted low power consumption doesn’t change the fact that it’s extremely high performance if the datasheet is correct.
It also has a built in charge pump which I’m sure will make someone on this forum start to twitch.
Due to the outputs, this might be the first recent DAC chip I’d feel like using in mono mode.
Beyond the expected rise in distortion from the coinciding 20 dB per decade OLG rolloff, I mean.
I'm wondering if there is a non-mobile counterpart without the power constraints.
Regarding charge pumps, why are we not seeing it in any DAC design ?
I mean, there are a lot of DACs using 5V USB supply which need a higher voltage for its DAC chips !
I
Several don't need higher/more than just 5V, thinking ES9023 and PCM5102. Probably there are others.
I have read this thread a couple of times but I'm not confident enough of my understanding of the modifications to plonk down a couple of hundred bucks for a DX3 Pro.
I am a builder of audio kits and I am quite good at soldering/desoldering but I can't look at a schematic or a DAC and identify components and their function. Consequently I can't follow most of this thread. However, I might be able to figure out a few of the modifications.
Any chance that one of the participants in the thread could list the most effective modifications to the DX3 Pro.
It would be quite a job, but a picture with the components circled would be more help than you could imagine. I may not understand anything about how a DAC works
but I can desolder and replace a component as well as most.
Any guidance would be appreciated.
I am a builder of audio kits and I am quite good at soldering/desoldering but I can't look at a schematic or a DAC and identify components and their function. Consequently I can't follow most of this thread. However, I might be able to figure out a few of the modifications.
Any chance that one of the participants in the thread could list the most effective modifications to the DX3 Pro.
It would be quite a job, but a picture with the components circled would be more help than you could imagine. I may not understand anything about how a DAC works
but I can desolder and replace a component as well as most.
Any guidance would be appreciated.
What many of us do is to google the numbers printed on all those parts and see what they are and then find out what they do. Then you can have a better idea of the architecture, the power supply will be identified easier that way, as well as everything else.
I will often take a picture of the board, and make notes or point out certain things for reference.
The charge pump is there to make it easier to have a dual rail supply from a single (battery) supply as is typically used in a phone. Other chips do this for the output stage when it is contained within the chip, I suspect that’s the same with the cs chip.
I will often take a picture of the board, and make notes or point out certain things for reference.
The charge pump is there to make it easier to have a dual rail supply from a single (battery) supply as is typically used in a phone. Other chips do this for the output stage when it is contained within the chip, I suspect that’s the same with the cs chip.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.