No, I didn't listen to the DAC. 
It was an initial test to investigate if it could be used for some upcoming projects.
And yes, I also looked at it from a test equipment point of view.
In many respects it looked interesting, but I don't like the noise floor at high frequencies when sampling at 192 kHz. Above around 45 kHz it increases gradually and hits a level of more than 30 dB above the flat noise floor (of the audio band) when reaching 90 kHz.
For audio playback I wouldn't expect this to be an issue, but for an audio analyzer, it is not ideal. Although it can be seen on some audio analyzers!
It was an initial test to investigate if it could be used for some upcoming projects.And yes, I also looked at it from a test equipment point of view.
In many respects it looked interesting, but I don't like the noise floor at high frequencies when sampling at 192 kHz. Above around 45 kHz it increases gradually and hits a level of more than 30 dB above the flat noise floor (of the audio band) when reaching 90 kHz.
For audio playback I wouldn't expect this to be an issue, but for an audio analyzer, it is not ideal. Although it can be seen on some audio analyzers!
No, I didn't listen to the DAC.
And yes, I also looked at it from a test equipment point of view.
In many respects it looked interesting, but I don't like the noise floor at high frequencies when sampling at 192 kHz. Above around 45 kHz it increases gradually and hits a level of more than 30 dB above the flat noise floor (of the audio band) when reaching 90 kHz.
For audio playback I wouldn't expect this to be an issue, but for an audio analyzer, it is not ideal. Although it can be seen on some audio analyzers!
Understood. WRT rising noise floor at higher frequencies, which DAC did you find had the flattest HF noise floor, given a level post DAC LPF 'playing field'?
Many of the AKM DAC's like AK4490 and AK4497. I use the AK4490 in the RTX6001 audio analyzer. The post DAC filter is essentially flat to 100 kHz and so is the noise floor. There is some noise at high frequencies, but at much lower levels. It looks like some kind of mirrored signals, rather than a rise in out-of-band quantization noise.
I used the evaluation board.
So the load on each output pin from the DAC was 200pF//600 ohm with a series resistor to the XLR of 100 ohm.
I tried to move the jumpers for the output load to use 10k instead of 600 ohm. I didn't document the results, but as far as I remember, there was virtually no difference in performance.
Measured with a passive 1 kHz notch filter I measured a distortion of -133.49 dB at 0 dBFS (48 kHz sample rate).
With a direct input to the RTX6001 (without the notch filter) the distortion increased to -132.9 dB. The balanced output level measured was around 11 dBV.
So the load on each output pin from the DAC was 200pF//600 ohm with a series resistor to the XLR of 100 ohm.
I tried to move the jumpers for the output load to use 10k instead of 600 ohm. I didn't document the results, but as far as I remember, there was virtually no difference in performance.
Measured with a passive 1 kHz notch filter I measured a distortion of -133.49 dB at 0 dBFS (48 kHz sample rate).
With a direct input to the RTX6001 (without the notch filter) the distortion increased to -132.9 dB. The balanced output level measured was around 11 dBV.
Hi,
I finished the mod level 1 (all the parts arround the OPA including the OPA) !
I did some quick AB test with the second dx3pro and 2 koss porta pro headphones.
I find the improvements impressive !
I will have to make some tests in my HiFi set up that is using the topping D50.
I used a hot air gun, some solder paste to do all the job.
I just get 2 resistor to re heat with some flux because I probably put too many solder paste.
Thanks for sharing the mod !
I finished the mod level 1 (all the parts arround the OPA including the OPA) !
I did some quick AB test with the second dx3pro and 2 koss porta pro headphones.
I find the improvements impressive !
I will have to make some tests in my HiFi set up that is using the topping D50.
I used a hot air gun, some solder paste to do all the job.
I just get 2 resistor to re heat with some flux because I probably put too many solder paste.
Thanks for sharing the mod !
Attachments
Pics too.To observe; i kept with orginal values execept input power i choose 220uF and the original 1612 opamp (i like it, compared it few yrs ago with amny others and 1611 and 1612 came out on top) if i would do more it would be a discrete opamp from ex Burson.
Also damped some part that was ringing with bitumen incl chassis. I use it only as a dac with USB.
Space is very limited and i had the caps already so well it worked but a bit tight, Anyway my DAC works flawless after modd.
After modd sound is very dynamic, fast and has good resolution. Bass is better (more and deeper but same time tighter) overall one thing that comes to mind is that it sounds very "airy" and transparent now. I'm very happy. With LPS i wonder how much i have to pay for something better...
Attachments
Last edited:
Isn't there a way to make a cleaner mod on these lower priced Toppings?
I came here to DIYAudio looking for somebody that did perform mods on the D50, which is the one I would like to modify, and found this DX3 mods.
Unfortunately the first thing I don't like about the DX3 is that all supply seems to be DC-DC, which is just something I would like to get away from for a D50 mod.
Even if I must confess I haven't yet read all the thread pages, the abundance of shielded inductors all over the board is not too promising.
The D50 has one good thing for it, power wise, which is that the DAC's regulation, from the input 5v to 3.3v, is all linear. If you use a linear regulated external supply, you should have a good linear power on the DACs.
Problem is the D50 uses DC-DC for its analog stage regulation, boosting 5v to +/-8v, which could be better too.
As the DAC have balanced outputs, and I would not like to touch the D50 SMD parts, my idea had been to solder the balanced wires, and assemble analog stage and linear regulated supply on the outside.
It's obvious that I should start a new topic for such a project, but maybe somebody has had a go at modding the D50 too. That's why I sort of hijacked this thread.
Also there might be comments or tips I could get here.
I came here to DIYAudio looking for somebody that did perform mods on the D50, which is the one I would like to modify, and found this DX3 mods.
Unfortunately the first thing I don't like about the DX3 is that all supply seems to be DC-DC, which is just something I would like to get away from for a D50 mod.
Even if I must confess I haven't yet read all the thread pages, the abundance of shielded inductors all over the board is not too promising.
The D50 has one good thing for it, power wise, which is that the DAC's regulation, from the input 5v to 3.3v, is all linear. If you use a linear regulated external supply, you should have a good linear power on the DACs.
Problem is the D50 uses DC-DC for its analog stage regulation, boosting 5v to +/-8v, which could be better too.
As the DAC have balanced outputs, and I would not like to touch the D50 SMD parts, my idea had been to solder the balanced wires, and assemble analog stage and linear regulated supply on the outside.
It's obvious that I should start a new topic for such a project, but maybe somebody has had a go at modding the D50 too. That's why I sort of hijacked this thread.
Also there might be comments or tips I could get here.
This is a documented issue with even the stock units. I have owned one for little over a year and mine is one of the faulty first batch, though I have only experienced it once myself when the listening session went on for four hours.
The second run from Topping used different headphone output circuit, replaced the tantalum coupling caps with Nichicon Muse, and all the relays were changed to soft-mutes. They pinpointed the issue as originating the opamp used for the first stage of the older headphone circuit, which is surprising as mine was never connected to headphones.
It performed much worse than the original. There should be a review up somewhere on Amir's site.
I have not done any mods to mine, but like Sangram said above, it's a known issue with the older units (I bought mine shortly after the DX3 Pro was released).
I used to leave mine running as a DAC (not using the headphone amp) continuously, and roughly every two weeks, it would go into standby mode. Usually it happened in the middle of the night or some other time when I wasn't listening, but every now and then it would happen while listening. Annoying, but just had to push a button to turn it back on. (It's since been moved to the basement, where it isn't playing continuously.)
IIRC, the headphone amp portion is arguably worse, but the DAC portion is the same (or maybe even better?). So if you use it as a standalone DAC, then I think either version is no worse. Again, that's from memory, so double-check Amir's site before reaching for the credit card!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.