[STUkh]

They seem like 2 different chips to me, the one I linked and the one you linked.
Are you sure they will use the two-channel ?

You are right. This is 2 different chips.
AK4499EQ - old
AK4499EX - new

AK4499EX always should be implemented with external modulator AK4191EQ.

For some reason they disappointed everyone giving the whole new chip architecture the same name as before.

 

[nioh]

For some reason they disappointed everyone giving the whole new chip architecture the same name as before.

Because it is the same chip. They just separated the modulator part and re-released it after the burned down factory was restored. There aren’t any big differences between the two.

 

[Ben86]

Just got my ROHM module, will post my impressions later today...

 

[Ferdinando1968]

Have you tested the current in eco/charge mode and while charging with the amplifier turned off?

Yes, but I don’t remember now.
This evening I will repeat the measure and let you know.

 

[urid]

And i got mine too... with Rohm and Sparkos!

Burning it in..... first impressions are FANTASTIC.
The USB cable MATTER!!

 

[Ferdinando1968]

Have you tested the current in eco/charge mode and while charging with the amplifier turned off?

Yes, but I don’t remember now.
This evening I will repeat the measure and let you know.

Here I am.

ECO MODE WHILE CHARGING

CHARGING WHILE OFF

Both measured with nominal 12V input.

Obviously the 12V voltage drops when the power supply (5 EUR) has to deliver the charging current, which is at least double the current that is absorbed during operation in NORMAL mode.

 

[quaddac]

Here I am.

ECO MODE WHILE CHARGING


CHARGING WHILE OFF


Both measured with nominal 12V input.

Obviously the 12V voltage drops when the power supply (5 EUR) has to deliver the charging current, which is at least double the current that is absorbed during operation in NORMAL mode.

Thank you very much, is the battery deeply discharged, does the result change significantly in eco/charge mode when listening to loud music?

 

[Ferdinando1968]

Thank you very much, is the battery deeply discharged, does the result change significantly in eco/charge mode when listening to loud music?

Well we should try... but I always try to avoid operating devices powered by lithium batteries in low battery and high absorption conditions.

There are technical reasons for this.

When lithium batteries are close to being completely discharged, they tend to increase their internal resistance, and this leads to greater power dissipation inside them (they heat up).

At the same time, the device's power supply (DC/DC converter) tries to continue to maintain its constant output power, but having the lower input voltage, this translates into a higher input current (absorbed by the batteries), which therefore they are in the worst conditions:

they have to deliver a greater current than when they were charged, they have a greater internal resistance, and therefore heat up more.

To answer your question, making a hypothesis (having never tried), if the device has an excellent internal DC/DC power supply, the sound quality should be affected little, because the power supply tries to keep the output power constant .

Likely, no matter how good the power supply is, it may have difficulty performing its job well, especially during fast musical transients, which translate into transients of power absorption from the power supply.

So, yes, the sound performance could in my opinion be negatively affected.

 

[quaddac]

Well we should try... but I always try to avoid operating devices powered by lithium batteries in low battery and high absorption conditions.

There are technical reasons for this.

When lithium batteries are close to being completely discharged, they tend to increase their internal resistance, and this leads to greater power dissipation inside them (they heat up).

At the same time, the device's power supply (DC/DC converter) tries to continue to maintain its constant output power, but having the lower input voltage, this translates into a higher input current (absorbed by the batteries), which therefore they are in the worst conditions:

they have to deliver a greater current than when they were charged, they have a greater internal resistance, and therefore heat up more.

To answer your question, making a hypothesis (having never tried), if the device has an excellent internal DC/DC power supply, the sound quality should be affected little, because the power supply tries to keep the output power constant .

Likely, no matter how good the power supply is, it may have difficulty performing its job well, especially during fast musical transients, which translate into transients of power absorption from the power supply.

So, yes, the sound performance could in my opinion be negatively affected.

I should be more precise.

 

[quaddac]

Well we should try... but I always try to avoid operating devices powered by lithium batteries in low battery and high absorption conditions.

There are technical reasons for this.

When lithium batteries are close to being completely discharged, they tend to increase their internal resistance, and this leads to greater power dissipation inside them (they heat up).

At the same time, the device's power supply (DC/DC converter) tries to continue to maintain its constant output power, but having the lower input voltage, this translates into a higher input current (absorbed by the batteries), which therefore they are in the worst conditions:

they have to deliver a greater current than when they were charged, they have a greater internal resistance, and therefore heat up more.

To answer your question, making a hypothesis (having never tried), if the device has an excellent internal DC/DC power supply, the sound quality should be affected little, because the power supply tries to keep the output power constant .

Likely, no matter how good the power supply is, it may have difficulty performing its job well, especially during fast musical transients, which translate into transients of power absorption from the power supply.

So, yes, the sound performance could in my opinion be negatively affected.

I don't mean extreme conditions, because we know that the battery should not be completely discharged and, if possible, we should avoid fully charging it. I wonder if the charging current is higher when the battery is charged, say 25 - 30%, even 40%. I think that such a test would be more precise with more demanding headphones and with louder listening at the balanced output. I have a sennheiser hd424, it's 2000Ω. On the unbalanced output, the volume is less than modest (99 turbo), unfortunately I don't have a balanced cable, it would be an interesting test (Sorry, I doubled the posts )

 

[quaddac]

Well we should try...

I managed to carry out simplified measurements myself and our results are very similar. One battery line in eco/charge is 14W, when the device is turned off it is 11W. With an almost full battery, as far as I remember it was 5-7W. Thank you once again.

 

[Ferdinando1968]

I don't mean extreme conditions, because we know that the battery should not be completely discharged and, if possible, we should avoid fully charging it. I wonder if the charging current is higher when the battery is charged, say 25 - 30%, even 40%. I think that such a test would be more precise with more demanding headphones and with louder listening at the balanced output. I have a sennheiser hd424, it's 2000Ω. On the unbalanced output, the volume is less than modest (99 turbo), unfortunately I don't have a balanced cable, it would be an interesting test (Sorry, I doubled the posts )

I hope I have understood your question..

In theory, lithium chargers should charge the battery with constant current (CC) from 0% to approximately 95% of its charge, after which they should change their behavior, switching from CC to CV mode (constant voltage), decreasing the charging current.

But what is written concerns exclusively the charging current of the battery; relatively to the external power supply (the USB one so to speak), the current that it must supply always rises while charging from 0% to approximately 95%, because even if the current that is put into the battery is constant, the voltage on the battery rises, and therefore the power absorbed by the power supply increases.

To this power you must add that consumed by the DAC to power itself and the headphones.

This in theory.

In practice, things can be different if whoever designed the charger inside the DAC wanted to achieve a different goal.

For example, he may have wanted to keep the power absorbed by the USB constant, and consequently the charging current on the battery decreases as the battery charges.

So (and I hope I have understood your question) in theory the current absorbed by the USB should increase with the most charged battery compared to the most discharged battery (except when the battery is almost charged, let's say it is above 90%).

However, things could be different in practice if whoever designed the internal charger of the DAC decided differently.

Again we should try on XDUOO to get the certain answer in our specific case.

 

[quaddac]

I hope I have understood your question..

In theory, lithium chargers should charge the battery with constant current (CC) from 0% to approximately 95% of its charge, after which they should change their behavior, switching from CC to CV mode (constant voltage), decreasing the charging current.

But what is written concerns exclusively the charging current of the battery; relatively to the external power supply (the USB one so to speak), the current that it must supply always rises while charging from 0% to approximately 95%, because even if the current that is put into the battery is constant, the voltage on the battery rises, and therefore the power absorbed by the power supply increases.

To this power you must add that consumed by the DAC to power itself and the headphones.

This in theory.

In practice, things can be different if whoever designed the charger inside the DAC wanted to achieve a different goal.

For example, he may have wanted to keep the power absorbed by the USB constant, and consequently the charging current on the battery decreases as the battery charges.

So (and I hope I have understood your question) in theory the current absorbed by the USB should increase with the most charged battery compared to the most discharged battery (except when the battery is almost charged, let's say it is above 90%).

However, things could be different in practice if whoever designed the internal charger of the DAC decided differently.

Again we should try on XDUOO to get the certain answer in our specific case.

Right now I'm listening and charging for about 90 minutes - it's still at 14W. I may have made a mistake, I'll check again.

 

[Ben86]

Very impressed with this new ROHM dac chip (listened with HD650 and V5i-D). Have tested it for 3 hours straight. For the first 20 minutes of listening I thought that it was nothing special at all, as for first it seemed to me not as polished and refined in details, and not as engaging as the ESS9039SPRO. Only after 1-2 hours of listening I realized how exceptional and extremely natural it sounds with Jazz, Blues, Classic, Opera, Symphonic Metal and so on, just couldn't stop listening how natural and involving vocals and instruments sounded with these genres, especially with highest quality DSD files. It is "must have" dac for these genres. Instruments and vocals sound very "true to life", natural, cozy and comfortable. Perfect for long listening sessions. When listened to Adele album "25", I was mesmerized by her voice and overall atmospheric presentation. It sounded very convincing and natural.

On the other hand I still prefer ESS9039SPRO for genres like metal, rock and some other "aggressive and engaging" genres with "raw emotions expression".

Now really waiting for AKM4499EX dac chip

XD05PRO is becoming "a golden brick" for me

The best portable audio device that I've ever had

 

[quaddac]

Again we should try on XDUOO to get the certain answer in our specific case.

After another 90 minutes (?) - 12W - I wrote it, looked again - 11W. After another 12 minutes - 10W+3min-9W+20MIN - 8W +20min - 7W (it's cooler) +20 min - 5W - almost cold (photo)