Benefits of the new AKM 4499EXEQ?

[Nkam]

Besides that it has the ΔΣ modulator on a different chip, does anyone else know of the benefits or ‘ increased technology ‘ of this chip? 
 

anything special about it?
 

https://www.akm.com/us/en/products/audio/audio-dac/ak4499exeq/

 

 

thank you in advance.  

[Miska]

It is not much different in terms of converter compared to AK4499EQ. But it just splits out the digital filter + modulator to a separate chip and leaves D/A converters on a single chip. This helps reducing the noise induced by the DSP, because there's no longer DSP processor on the same piece of silicon. This also allowed them to put slightly beefier DSP on the AK4191EQ filter/modulator chip.

 

Nice thing about it is that you can now just take the D/A converter part and leave out the digital filter and modulator chip to make a pure DSD DAC easily.

 

[bogi]

8 hours ago, Miska said:

Nice thing about it is that you can now just take the D/A converter part and leave out the digital filter and modulator chip to make a pure DSD DAC easily.

Since no DSD input appears in AK4499EX chip a converter from 1bit  to 5-7 binary weighted bits would be necessary. That converter output fs would need to adapt to supported fs of AK4499EX data inputs, which is lower than DSD1024 and DSD512 rates. So some digital processing would be needed yet before data enters the DAC chip (I did not tell that it would be lossy).

If advantage of split solution is to lower influence of DSP section (interpolator and modulator) noise, interesting question is if this DSP section of AK2299EQ (and AK4191EQ) generates noise also in direct DSD path case (when it is unused).

The question is how much of benefit the split solution brings for people who always send DSD bitstream into DAC.

[Miska]

31 minutes ago, bogi said:

Since no DSD input appears in AK4499EX chip a converter from 1bit  to 5-7 binary weighted bits would be necessary. That converter output fs would need to adapt to supported fs of AK4499EX data inputs, which is lower than DSD1024 and DSD512 rates. So some digital processing would be needed yet before data enters the DAC chip (I did not tell that it would be lossy).

 

Sure, but it is just simple logic rearranging bits, no DSP necessary.

 

31 minutes ago, bogi said:

If advantage of split solution is to lower influence of DSP section (interpolator and modulator) noise, interesting question is if this DSP section of AK2299EQ (and AK4191EQ) generates noise also in direct DSD path case (when it is unused).

 

Likely there is no big difference in that respect, since I don't think there's much power management on such a small chip to power down unused sections. Slightly less switching noise, but at least it is not obvious from the measurement results.

 

31 minutes ago, bogi said:

The question is how much of benefit the split solution brings for people who always send DSD bitstream into DAC.

 

I think you can get some idea if you compare dynamic range specs of AK4499EQ and AK4499EX. Although we don't know how many elements EQ has. It may be that EQ is just those 5 bits worth (32) while EX has 7 bits worth (128). That would explain 6 dB worth of difference.

 

[bogi]

2 minutes ago, Miska said:

Sure, but it is just simple logic rearranging bits, no DSP necessary.

2 minutes ago, Miska said:

Likely there is no big difference in that respect, since I don't think there's much power management on such a small chip to power down unused sections.

Thanks. When that simple logic produces less noise, then of course benefit is here.

[Miska]

Just now, bogi said:

Thanks. When that simple logic produces less noise, then of course benefit is here.

 

I mean enough data arrangement could be easily done in USB interface firmware. Which is already shuffling the data from 32-bit words packed into USB transfer units.

 

[bogi]

Other point is I'm not sure if there would be enough customers for DSD only DAC since usual music consumers don't understand benefits of such a thing. But it could be interesting for DIY and open source hardware world.

[Miska]

41 minutes ago, bogi said:

Other point is I'm not sure if there would be enough customers for DSD only DAC since usual music consumers don't understand benefits of such a thing. But it could be interesting for DIY and open source hardware world.

 

Yeah, I would be happy to make such device. And it would be easier project than the DSC1. Right now I don't have time for it though. I'm fully occupied with the software.

 

[OE333]

44 minutes ago, Miska said:

 

Yeah, I would be happy to make such device.

 

 

Last year when I retired I had the idea to make a DSD-only DAC as a DIY project but I found that currently it seems impossible to get hold of the required chips.

I know that my former employer (T+A) currently pays horrific prices to get some rare STM32H743 (about 10 times the price before the chip crisis)...

[Nkam]

With the ΔΣ on a separate chip, wouldn’t that give the flexibility to bypass the ΔΣ portion completely and use HQplayer in PCM at any upsample rate exclusively? 
 

and also offer the direct DSD path with is available on the chip to use HQplayer exclusively as well?

 

 

[Nkam]

I don’t understand why more manufacturers haven’t embraced this chipset quicker from the added flexibility.  
 

 

[Andrey Boldakov]

10 hours ago, OE333 said:

Last year when I retired I had the idea to make a DSD-only DAC as a DIY project but I found that currently it seems impossible to get hold of the required chips

Looks strange as DSD-only DAC do not require al chip. I'm using a DSD-only boutique DSC2 dac on extreme quality components, and it has no chip at all. 

[Miska]

7 hours ago, Nkam said:

With the ΔΣ on a separate chip, wouldn’t that give the flexibility to bypass the ΔΣ portion completely and use HQplayer in PCM at any upsample rate exclusively?

 

It is not a PCM converter chip, it is SDM converter chip. You cannot send PCM there. So you will need to have the delta-sigma modulator somewhere.

 

But you could certainly leave the digital filter + delta-sigma modulator chip out and replace it with HQPlayer.

 

[Miska]

2 hours ago, Andrey Boldakov said:

Looks strange as DSD-only DAC do not require al chip. I'm using a DSD-only boutique DSC2 dac on extreme quality components, and it has no chip at all. 

 

The DACs @OE333 has been designing are just like that, discrete DSD converters. Such as the T+A DAC 200.

 

[Nkam]

On 3/17/2023 at 12:51 AM, Miska said:

 

It is not a PCM converter chip, it is SDM converter chip. You cannot send PCM there. So you will need to have the delta-sigma modulator somewhere.

 

But you could certainly leave the digital filter + delta-sigma modulator chip out and replace it with HQPlayer.

 

Pardon my ignorance.   Yeah that’s what I meant.  
 

would that make it better than the current design of older AKM chips where you have to upsample to the highest integers to bypass the filters?   

[bogi]

20 minutes ago, Nkam said:

would that make it better than the current design of older AKM chips where you have to upsample to the highest integers to bypass the filters?   

'you have to upsample to the highest integers' with both older chip and the newer one 'to bypass the filters'.
I think the difference was already explained here https://audiophilestyle.com/forums/topic/67778-benefits-of-the-new-akm-4499exeq/?do=findComment&comment=1235386

 

[OE333]

On 3/17/2023 at 6:44 AM, Andrey Boldakov said:

Looks strange as DSD-only DAC do not require al chip. I'm using a DSD-only boutique DSC2 dac on extreme quality components, and it has no chip at all. 

 

How do you receive and decode USB signals without a chip ????

[Nkam]

On 3/17/2023 at 12:51 AM, Miska said:

 

It is not a PCM converter chip, it is SDM converter chip. You cannot send PCM there. So you will need to have the delta-sigma modulator somewhere.

 

But you could certainly leave the digital filter + delta-sigma modulator chip out and replace it with HQPlayer.

 

 

could you do that through a bypass option in the Chip itself and use HQplayer as software?

 

for example could an option be used on the AK4499 chip that completely bypasses the AK4191EQ? So you could use only HQplayer?

 

thanks 

[Miska]

9 minutes ago, Nkam said:

could you do that through a bypass option in the Chip itself and use HQplayer as software?

 

for example could an option be used on the AK4499 chip that completely bypasses the AK4191EQ? So you could use only HQplayer?

 

Yes, you could build a DAC with AK4499EX, without the AK4191 at all.