March Audio HPA1

[Music1969]

Not matter who says this even it's amir. Digital volume control doesn't attenuate noise it's a fact and no room for discussion. 10kohm or less pot will improve a lot in dynamic range at any volume except maximum.

A cool solution is a digitally controlled analogue volume control.

There's been various implementations but in the more affordable price range, the little iFi xDSD uses this method of volume control.

Similar to this that @amirm measured

"Boy, I did not expect this. The volume control feels like a cheap little potentiometer which I predicted would have horrible balance. Not so at all. There is zero deviation until the end, indicating that it is a mono pot that is sampled. That digital value is likely then used to change the volume in the DAC chip. Very nice!"

 

[JohnYang1997]

A cool solution is a digitally controlled analogue volume control.

There's been various implementations but in the more affordable price range, the little iFi xDSD uses this method of volume control.

Similar to this that @amirm measured

"Boy, I did not expect this. The volume control feels like a cheap little potentiometer which I predicted would have horrible balance. Not so at all. There is zero deviation until the end, indicating that it is a mono pot that is sampled. That digital value is likely then used to change the volume in the DAC chip. Very nice!"

View attachment 30208

This looks like a analog controlled digital volume than otherwise. Analog volume needs potentiometer and/or resistors arrays. It's possible to combine digital and analog control to achieve best of both worlds. But shouldn't be the case here.
EDIT: Ehh i seems both are pure digital control to me.

 

[Music1969]

EDIT: Ehh i seems both are pure digital control to me.

Agree regarding DACPort HD - looks to be digital volume control, upon re-reading Amir's comments.

But iFi xDSD is different. From the iFi manual:

 

[Music1969]

It's possible to combine digital and analog control to achieve best of both worlds.

Measured well too:

https://ifi-audio.com/wp-content/uploads/2018/06/xDSD_HiFiNewsReviewOutstaning.low-res.pdf

 

[JohnYang1997]

Agree regarding DACPort HD - looks to be digital volume control, upon re-reading Amir's comments.

But iFi xDSD is different. From the iFi manual:

View attachment 30209



View attachment 30210

Just found out this. So just like any other volume control ic. They introduce distortion and noise themselves. So not a perfect solution. Yulong DA10 also used volume control ic to perform volume control.

 

[Music1969]

They introduce distortion and noise themselves.

No free lunch. Measures well overall though:

https://ifi-audio.com/wp-content/uploads/2018/06/xDSD_HiFiNewsReviewOutstaning.low-res.pdf

 

[JohnYang1997]

Measured well too:

https://ifi-audio.com/wp-content/uploads/2018/06/xDSD_HiFiNewsReviewOutstaning.low-res.pdf

It's just ok. Typical ifi. -100db is 0.001% and high impedance should have really low distortion. 25ohm is somewhat good. 330mw 25ohm 0.003% and 20mw 0.0003%. But not impressive at all.

 

[March Audio]

Not matter who says this even it's amir. Digital volume control doesn't attenuate noise it's a fact and no room for discussion. 10kohm or less pot will improve a lot in dynamic range at any volume except maximum.

You repeat this as much as you like but in real world its a non issue as discussed and demonstrated.

The HPA1 is either 0dB or +6dB gain. Noise is utterly inaudible.

 

[Music1969]

It's just ok. Typical ifi. -100db is 0.001% and high impedance should have really low distortion. 25ohm is somewhat good. 330mw 25ohm 0.003% and 20mw 0.0003%. But not impressive at all.

Yes certainly not state of the art but good measured performance in my opinion. Certainly not broken, as amir would probably say.

 

[JohnYang1997]

You repeat this as much as you like but in real world its a non issue as discussed and demonstrated.

The HPA1 is either 0dB or +6dB gain. Noise is utterly inaudible.

This is the original post. The other thread was after this.
Then noise is not audible for speaker systems but audible in iems. I have dx3pro it has 2uV noise but noise is easily audible. I then connected to my own headphone amp and it's inaudible only when I turned down to 10 o'clock.

 

[March Audio]

I hear nothing with my Westone IEMs

 

[JohnYang1997]

Yes certainly not state of the art but good measured performance in my opinion. Certainly not broken, as amir would probably say.

So in that case it's not actually better than digital volume control. Digital volume control at least reduces distortion and doesn't rise noise. If the dac design is really good it will be much better than volume control ic.

 

[JohnYang1997]

I hear nothing with my Westone IEMs

Which one? w40? w80? I used final audio heaven V. And it's not close the highest sensitivity iems. It's only 112db. There are many 120db+ sensitivity iems.

 

[Music1969]

So in that case it's not actually better than digital volume control. Digital volume control at least reduces distortion and doesn't rise noise.

I can't make that comment.

I don't have enough info to say if the analogue volume control is the weakest link in performance, or if it's the analogue section? Or something else?

 

[trl]

TI's PGA2310/2311 could be a nice try, as long as you're using these as attenuators only.

 

[JohnYang1997]

I can't make that comment.

I don't have enough info to say if the analogue volume control is the weakest link in performance, or if it's the analogue section? Or something else?

I didn't say specifically xdsd, but in general. Surely if the dac design is horrible with lots of noise to attenuate, volume control ic would make sense. But I guarantee it's higher than 1uV and highly possible to higher 2uV, 5uV even. 2uV being noise of normal well designed dac.

 

[Music1969]

I didn't say specifically xdsd, but in general. Surely if the dac design is horrible with lots of noise to attenuate, volume control ic would make sense. But I guarantee it's higher than 1uV and highly possible to higher 2uV, 5uV even. 2uV being noise of normal well designed dac.

Ah yes agreed. I'm only talking about xDSD though. Overall good performance (not broken), even if not state of the art.

 

[March Audio]

Which one? w40? w80? I used final audio heaven V. And it's not close the highest sensitivity iems. It's only 112db. There are many 120db+ sensitivity iems.

According to Amirs measurements the DX3Pro does not have a 2 uV noise level, it only acheives 108dB through the headphone output. That equates to 8uV noise level.

Westone 4R which is around 118dB/mW I beleive.

 

[JohnYang1997]

According to Amirs measurements the DX3Pro does not have a 2 uV noise level, it only acheives 108dB through the headphone output. That equates to 8uV noise level.

Westone 4R which is around 118dB/mW I beleive.

I used the dac out. I think it's specified as 2uV right? Headphone out is noiser than that. Well i have to say there is difference between loud and audible, quiet and completely silent.

 

[March Audio]

I used the dac out. I think it's specified as 2uV right? Headphone out is noiser than that.

105/106dB

Look, I am sure if you try hard enough you can fins some IEMs that are sensitive enough to make some noise audible, but these are the outliers.