I agree with you on this. There are a number of things that don't make sense when you look through the datasheet. Their datasheets are absolute rubbish. Somehow they have made a part more annoying than the ESS in terms of output requirements.
I would also assume it's because of the amount of current. It is not elegant for sure. They are certainly designing for numbers, so it not any surprise to me that this is the approach they took.
I disagree with your thoughts on the subjective qualities of the caps, but let's leave that out here. Using polymer caps || ceramics can be a recipe for anti-resonant peaking in your PDN. Many Al Polymer caps are too low ESR.
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Thanks for the information John. It sounds like you can never completely avoid them. I've always gone with a ceramic solution for parts under 100uF and then supplementing with big aluminum electrolytics but I'm not usually dealing with high end audio and how it might apply to the power rails.
Now I want to create a beefy headphone amp with lots of capacitance and I'm worried about what to pick based on your experience. I don't want to spend a million dollars on polymer capacitors just to get several thousand uF of capacitance (I'm exaggerating of course).
When you say organic, are you referring to Aluminum organic polymer which has lots of capacity per volume or some other type of costly alternative? I'd also like to acknowledge the fact that I enjoy your posts and have read them for quite some time! Do you ever post links to the stuff you make and for what company they exist? I'd love to see what the final products look like.
Michael
I have seen a few organics fail, but they are ones from the 80's. I have seen about 3 failed caps in Studer A820 recorders (out of hundreds). SAL types. The exception, not the rule.
The biggest problem with the new organics is the leakage, which is much higher than other electrolytics.
Alan
The biggest problem with the new organics is the leakage, which is much higher than other electrolytics.
Alan
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Mine is Panasonic ECPU. Hard to use in existing designs as form factors are limited, but for new designs i see no reason to use ceramics. Other than price and a somewhat limited range of values.
You had been searching for data on AK4499 Direct DSD operation level.
If You are still interested, I find the same relationship is valid also here like in the case of 4490.
PCM / DSD direct amplitude relationship is 1,51.
That is, - 3.6dB less in case of DSD direct.
Ciao, George
Some OT removed.Playing a - 82dBFs 12KHz signal in Direct DSD, 256 mode, on the direct output of the 1656 I/V converters I see a raised ~flat noise floor up to 2Mhz. The level is around - 77dBV/sqrtHz, on a 1Mohm probe.
That is 200mV RMS in 2MHz bandwith, which is coincident with what comes from the RfCf corner frequency (2.2MHz).
That is giving on scope a ~1200mVpp white noise trace, some outlier peaks are 1,8Vpp.
It does not change much with signal. Max output is 2.64VRMS, (this is DSD direct). And I'm using 330ohm Rf. (had a bunch to select)
So.. The job of the I/V converter opamps is not exactly a smooth easy task.
Best, George
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Thanks...
It looks like the DAC can be adjusted for gain (not the volume control) such that the output level is the same for DSD (direct) mode as it is for regular mode. See page 67, section 9.8 of the data sheet for this information.
I am wondering a bit about this, because I am playing with a Topping D-90 DAC which according to Topping allows for DSD direct mode, but still outputs the same level in DSD direct mode as it does in regular mode.
It looks like the DAC can be adjusted for gain (not the volume control) such that the output level is the same for DSD (direct) mode as it is for regular mode. See page 67, section 9.8 of the data sheet for this information.
I am wondering a bit about this, because I am playing with a Topping D-90 DAC which according to Topping allows for DSD direct mode, but still outputs the same level in DSD direct mode as it does in regular mode.
Yes, and for this I have made the test with everything fixed. The gain setting is to 'normal', (not low or high), the volume control was set to 0dB all time.
In a moment I can tell what happens to output level if DSD is used, but the set flag is changed from DSD with volume control to DSD direct.
I foresee that it will be like in AK4490:
PCM level = DSD with volume control > DSD in bypass
It can happen that maybe Topping is not handling that bit correctly? Can You still change volume in DSD mode?
In a moment I can tell what happens to output level if DSD is used, but the set flag is changed from DSD with volume control to DSD direct.
I foresee that it will be like in AK4490:
PCM level = DSD with volume control > DSD in bypass
It can happen that maybe Topping is not handling that bit correctly? Can You still change volume in DSD mode?
well...
The D-90 has a mode which disables the volume control for both PCM and DSD input. I sent an e-mail directly to Topping asking if the DSD direct mode was available in the D-90, and if there was any change in the output level with DSD playback. Their response was that when the DAC is in the volume disable mode (nominally "DAC" in the DAC menu settings), the DAC is in DSD direct mode, and they also stated that the output levels remain the same regardless of PCM/DSD input or DAC mode. My testing confirms output levels staying the same.
As I mentioned above, it looks like the chip can be configured (gain control, p.67 of the data sheet) such that the output stays the same for PCM/DSD input and for both output modes. If Topping's response is correct, then they must be setting the gain control such that the output level is the same for PCM/DSD in either mode of operation
The D-90 has a mode which disables the volume control for both PCM and DSD input. I sent an e-mail directly to Topping asking if the DSD direct mode was available in the D-90, and if there was any change in the output level with DSD playback. Their response was that when the DAC is in the volume disable mode (nominally "DAC" in the DAC menu settings), the DAC is in DSD direct mode, and they also stated that the output levels remain the same regardless of PCM/DSD input or DAC mode. My testing confirms output levels staying the same.
As I mentioned above, it looks like the chip can be configured (gain control, p.67 of the data sheet) such that the output stays the same for PCM/DSD input and for both output modes. If Topping's response is correct, then they must be setting the gain control such that the output level is the same for PCM/DSD in either mode of operation
Thanks!
Good to know, sounds like Topping's response is accurate then and one can be assured that in "DAC" mode the D-90 is indeed using the DSD direct mode of the AKM 4490.
Sounds really good, BTW, for a $699.00 Chinese DAC!
Good to know, sounds like Topping's response is accurate then and one can be assured that in "DAC" mode the D-90 is indeed using the DSD direct mode of the AKM 4490.
Sounds really good, BTW, for a $699.00 Chinese DAC!
Listened to a D90 a couple of days ago, also compared it with Benchmark DAC-3. With some good 24/192 source material the D90 definitely was preferred. It produced excellent bass and a very wide sound stage, although midrange vocals were a bit off.
Regarding the above observation it should probably be noted that DAC-3 upsamples everything to 211kHz. It tends to compete better when compared to non-upsampling dacs (such as D90) when playing lower sample rate source material such as CD audio.
The AK4499 eval board here was down for some modding work so no direct comparison with it. However, we (Jam Somasundram and I) agreed the D90 would need some things fixed to sound as good at midrange and higher frequencies as we think the dac chip is capable of (based on our memory of how good we have heard the modded eval board sound). That said, D90 a remarkably good sounding dac for $700, and it is also the first commercial AK4499 dac we have had a chance to audition. Hopefully there will be some other equally good or better AK4499 dacs before too long. In particular, I am curious to see how good a dac someone can come up with using AK4499.
Regarding the above observation it should probably be noted that DAC-3 upsamples everything to 211kHz. It tends to compete better when compared to non-upsampling dacs (such as D90) when playing lower sample rate source material such as CD audio.
The AK4499 eval board here was down for some modding work so no direct comparison with it. However, we (Jam Somasundram and I) agreed the D90 would need some things fixed to sound as good at midrange and higher frequencies as we think the dac chip is capable of (based on our memory of how good we have heard the modded eval board sound). That said, D90 a remarkably good sounding dac for $700, and it is also the first commercial AK4499 dac we have had a chance to audition. Hopefully there will be some other equally good or better AK4499 dacs before too long. In particular, I am curious to see how good a dac someone can come up with using AK4499.
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Thanks George,
your information is very valuable. I always wonder if we need a low pass filter to minimize the out-of-band noise of DAC chip.
Thanks Mark. Very interesting info. An acquaintance of mine had a similar impression. I would be curious to know more about the Gustard implementation with its discrete output.
I guess that any serious sound optimized development outside of China will automatically push such a 4499 Dac into USD 2000 plus territory…?
Hello Mark
Thanks for feedback, how would you describe more precisely "midrange vocals were a bit off" , do you mean that topping is too "soft" in midrange vocal area, missing some dynamic or transparency? and could you also compare with your modded ES9038QM chinese board, do you also have opportunity to hear toppping DX7 pro or Sabaj D5, these two have ES9038pro chip and very good measuring data and should be in price range from 450-600 dollars the best commercial implementation of ES9038Pro , thanks
Hello Blackfear
Briefly, I must defer trying to answer your questions until the D90 comes back around here, and probably until the AK4499 eval board is back up. Both things should occur pretty soon, probably within a couple of days. Hopefully after spending some more time listening and some time comparing the dacs I can give more details.
Unfortunately, the ES9038Q2M dac is no longer is service. Also, I don't have access to any other Topping dacs. However, I can say the the reason I stopped preserving the ES9038Q2M dac project is because AK4499 is so much better (when well implemented).