[supercurio]

Stupid question: I forgot to run tests @48kHz. You think it would be interesting because it's a fs multiple?

 

[holland]

Quote:

Interesting!
However, I don't understand why the DAC is not setup to use the SPDIF clock as source. Based on the input source clock, it's possible to generate a master clock that would be used for the DAC, set in DSP or I2S slave right ?

I'm not really sure why it is selectable like that.  I guess it's really designed to have a microcontroller front end or be hardcoded a certain way depending on what it is used in.
 
It's really selecting the oversample rate and not the clock.  I guess it is cost and complexity for the DAC to handle it itself.  You do want to be able to disable the oversampling in order to use it with an external DSP, if you so choose.  That much I agree with.  I'm not so sure about the other 2 modes, but it probably comes down to cost and figuring that anyone who actually uses upsampling will do it a specific way.  That's just a guess.  Only Wolfson would know the real answer.

 

[holland]

Quote:

Stupid question: I forgot to run tests @48kHz. You think it would be interesting because it's a fs multiple?

No.  The oversampling selection is for 44.1KHz/48KHz, 88.2KHz/96KHz, or 192KHz.  3 modes.  What you did is fine.

 

[supercurio]

Quote:

  That's just a guess.  Only Wolfson would know the real answer.

 
Actually the guy who designed the WM8741 saw the first graphs and was disapointed of course
I was told the comparison with WM8994 smarphone audio hub was source of some inside jokes ^^

 

 

[Slaughter]

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.

"DAC" and "Headphone" output look the same in measurements.
Low gain is usless, it only attenuate the input signal (so, you only loose in terms of performance or benchmarks)

 

 

[supercurio]

Quote:

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.

 
Sorry I don't have the knowledge to answer this question.
However, I can tell is that you can hear hiss when using sensitive in-ears with the low gain mode.
Cause is that with lower knob gains the SNR is reduced, and if you lose again 10dB SNR using this switch the hiss becomes audible.

 

[Slaughter]

If you don't know, then saying the low gain only attenuates the signal might not be accurate. And according to the Audio-Gd website, low gain is 0dB and high is +12, so low is not attenuating anything as it is 0dB. Have you tried different loads? 300 ohms and 33 ohms should produce different results and might give people a better idea of which phones might pair better with the amp. Thanks for all your testing. It is very interesting,
 
Quote:

Quote:

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.

 
Sorry I don't have the knowledge to answer this question.
However, I can tell is that you can hear hiss when using sensitive in-ears with the low gain mode.
Cause is that with lower knob gains the SNR is reduced, and if you lose again 10dB SNR using this switch the hiss becomes audible.

 

[Elanzer]

This is interesting, I've been playing around with the SoX resampling plugin for FB2K. Wouldn't resampling say, 44.1khz music to 192khz directly cause more problems than just leaving it non-resampled 44.1khz, or resampled 88.2khz/176.4khz? Since it isn't a multiple, wouldn't there be mathematical rounding imperfections?

 

[Kassem]

Quote:

If you don't know, then saying the low gain only attenuates the signal might not be accurate. And according to the Audio-Gd website, low gain is 0dB and high is +12, so low is not attenuating anything as it is 0dB. Have you tried different loads? 300 ohms and 33 ohms should produce different results and might give people a better idea of which phones might pair better with the amp. Thanks for all your testing. It is very interesting,

 
 
Thats what I'm talking about...
 

 

[supercurio]

Quote:

If you don't know, then saying the low gain only attenuates the signal might not be accurate. And according to the Audio-Gd website, low gain is 0dB and high is +12, so low is not attenuating anything as it is 0dB. Have you tried different loads? 300 ohms and 33 ohms should produce different results and might give people a better idea of which phones might pair better with the amp. Thanks for all your testing. It is very interesting,
 
Quote:

Quote:

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.

 
Sorry I don't have the knowledge to answer this question.
However, I can tell is that you can hear hiss when using sensitive in-ears with the low gain mode.
Cause is that with lower knob gains the SNR is reduced, and if you lose again 10dB SNR using this switch the hiss becomes audible.

 

 
I agree, it's what's written on the website, this is why I was surprised that both listening and measurement show the opposite.
 
High: 0dB
Low: -12dB on signal, no effect on noise/hiss

If there was another difference in the signal than its level, I was unable to pick it.
 
I tried with 300 Ohms (HD 650), 55 Ohms (PL50), 64 Ohms (RE0), and line-in.
 
PS: sorry it seems every time I talkl about this product or answer questions I'm trashing it. That's not my goal.
I'm just a demanding listener equiped by trained ears and some analysis tools ^^

 

[holland]

Quote:

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.
 


 

It shouldn't be, but I'll trace the circuit when I get mine in March or so.  The high/low gain should be current amplification in ACSS....that is ACSS is a transconductance amplifier, using a voltage out DAC as the voltage controlled current amplifier.  gm = dI(output) / dV(input).  The gain switch should be changing the gm of the ACSS stage.  The diamond buffer is the output stage, the volume control is the output of the ACSS which helps to performs I/V conversion based on the potentiometer's position.  The converted voltage then feeds into the diamond buffer.
 
At least, that's how the topology should work.  It would be insane to have low gain go through the diamond buffer and high gain go through something else, IMO.  That's unnecessary complexity.

 

[treaves]

So, has anyone actually e-mail KingWa and ask for additional information?  Or are we still just speculating?

 

[Slaughter]

I admit I am not knowledgable enough to know, but according to the website, it states that low impedance phones use the diamond output stage. So is it possible that it is sensing the load and rerouting the output? I believe that is how the new Schiit Lyr is going to operate. Or is the website just saying that the diamond output stage is always there, but especially to help low impedance phones which need more current?
 
"For low impedance, we applied a diamond output stage which is quite less colored than most conventional circuits."
 
Quote:

Quote:

Uh, doesn't low gain use a diamond output vs ACSS on high? These are two different circuits within the unit.
 


 

It shouldn't be, but I'll trace the circuit when I get mine in March or so.  The high/low gain should be current amplification in ACSS....that is ACSS is a transconductance amplifier, using a voltage out DAC as the voltage controlled current amplifier.  gm = dI(output) / dV(input).  The gain switch should be changing the gm of the ACSS stage.  The diamond buffer is the output stage, the volume control is the output of the ACSS which helps to performs I/V conversion based on the potentiometer's position.  The converted voltage then feeds into the diamond buffer.
 
At least, that's how the topology should work.  It would be insane to have low gain go through the diamond buffer and high gain go through something else, IMO.  That's unnecessary complexity.

 

[cdanguyen08]

Chinese New Year just started today soo i doubt you'll get a response soon.

Kung Hei Fat Choi!

Chúc Mừng Năm Mớ!

 

[BuFFys]

Quote:

I admit I am not knowledgable enough to know, but according to the website, it states that low impedance phones use the diamond output stage. So is it possible that it is sensing the load and rerouting the output? I believe that is how the new Schiit Lyr is going to operate. Or is the website just saying that the diamond output stage is always there, but especially to help low impedance phones which need more current?
 
"For low impedance, we applied a diamond output stage which is quite less colored than most conventional circuits."

 
Well when I look on the NFB-12 and Fun page, an I’m only get confused :
 
About Diamond output i find:
NFB-12: The output buffers are Non-feedback. For low impedance, we applied a diamond output stage which is quite less colored than most conventional circuits.
 
Fun: The FUN applied the diamond  output stage. It is a very neutral sound output stage just increase the power output without any coloration,
 
 
About gain and ACSS
NFB-12: As you can see, ACSS circuits have no gain, as it is a completely different circuit.
 
Fun: The FUN has special DAC output sockets, owners can connect to the DAC output sockets, but I advise owners to try to connect to the Preamp output sockets, turn the volume to proper position (at high gain, volume placed around 10:00 to 14:00) which is proper output level. Doing this benefits from the ACSS gain circuits , and can improve the sound quality.