[Hooster]

Just got my unit, still testing.

My first serious question:

IF it's really a totally A class amplifier, then why does it get hotter in high gain mode than in low gain mode?

It doesn't make sense for me.

What evidence do you have to support this? It does not make any sense to me either. Are you confusing gain and bias? What has class A got to do with high and low gain?

 

[labeelen]

Just got my unit, still testing.

My first serious question:

IF it's really a totally A class amplifier, then why does it get hotter in high gain mode than in low gain mode?

It doesn't make sense for me.

It doesn’t when you select 100mA current. I just tested it at a room temperature of 21 degrees my S17 remains at 56 degrees both at high or low gain.

However when I select 50mA the temperature increases from 43 degrees to 46 degrees when I switch from Low to High gain.

So, in my case (with an HE6se v2 balanced at volume 44) it is full class a at 100mA and switches to class ab at 50mA.

 

[DeckHiFi]

It doesn’t when you select 100mA current. I just tested it at a room temperature of 21 degrees my S17 remains at 56 degrees both at high or low gain.

However when I select 50mA the temperature increases from 43 degrees to 46 degrees when I switch from Low to High gain.

So, in my case (with an HE6se v2 balanced at volume 44) it is full class a at 100mA and switches to class ab at 50mA.

Nice find. Well that probably helps settle that question. So the jist is - the two potential issues with this amp don’t seem like much of an issue if using this as a standard headphone amp. Perhaps as a pre-amp could be some issues if you need a certain problematic volume area? Is that a good jist of this product so far? Oh yea and it seems like everyone agrees the sounds it produces are awesome.

 

[Hooster]

Nice find. Well that probably helps settle that question. So the jist is - the two potential issues with this amp don’t seem like much of an issue if using this as a standard headphone amp. Perhaps as a pre-amp could be some issues if you need a certain problematic volume area? Is that a good jist of this product so far? Oh yea and it seems like everyone agrees the sounds it produces are awesome.

I use it as a pre amp with no issues whatsoever. The only "issue" I can imagine is if you use it with a source that has a fixed high output and you can't attenuate it enough for your taste. In that case you could always resort to something like this: https://www.enjoythemusic.com/magazine/equipment/0803/rothwell.htm

 

[Ichos]

Quick reminder:
100mA bias=Class A working mode
50mA bias=Class AB working mode

 

[quawn0418]

Quick reminder:
100mA bias=Class A working mode
50mA bias=Class AB working mode

Are you sure? I’ve yet to read or hear this from an official

 

[Ichos]

Are you sure? I’ve yet to read or hear this from an official

"Hi Petros,

50mA: bias current for Class AB
100mA: Class A"

Official email correspondence.

 

[labeelen]

"Hi Petros,

50mA: high bias current for Class AB
100mA: Class A"

Official email correspondence.

Ichos, I’m not sure if we are consistent in the terminology we use (Gain vs Bias/quiescent current vs Volume)

I understood it as follows:
1. We can switch between 50mA or 100mA of quiescent current (a.k.a. Bias)
2. The higher the Bias the more headroom you have to remain in class A (at higher Volumes)
3. Apparently with a bias of 100mA the S17 will always remain in 100% class A (independent of the chosen Volume or Gain setting)
4. To my knowledge with a Bias of 50mA it will depend on the chosen Volume/Gain combination weither you remain in class A (low volume) or class AB (high volume). I could imagine that a High Gain/Low Volume setting could still be within the class A boundaries even with 50mA Bias (but I’m not sure, if I have some time tomorrow I’ll try it out)

 

[Ichos]

Ichos, I’m not sure if we are consistent in the terminology we use (Gain vs Bias/quiescent current vs Volume)

I understood it as follows:
1. We can switch between 50mA or 100mA of quiescent current (a.k.a. Bias)
2. The higher the Bias the more headroom you have to remain in class A (at higher Volumes)
3. Apparently with a bias of 100mA the S17 will always remain in 100% class A (independent of the chosen Volume or Gain setting)
4. To my knowledge with a Bias of 50mA it will depend on the chosen Volume/Gain combination weither you remain in class A (low volume) or class AB (high volume). I could imagine that a High Gain/Low Volume setting could still be within the class A boundaries even with 50mA Bias (but I’m not sure, if I have some time tomorrow I’ll try it out)

Unfortunately I am not the designer of the amplifier. What the company representative told me when I asked is that when you select the 50mA bias current then the amplifier is constantly working in Class AB.
When you select the 100mA bias then the amplifier is constantly working in pure Class A.

 

[labeelen]

Unfortunately I am not the designer of the amplifier. What the company representative told me when I asked is that when you select the 50mA bias current then the amplifier is constantly working in Class AB.
When you select the 100mA bias then the amplifier is constantly working in pure Class A.

I think we all agree, my confusion was the use of the word ‘High Bias’ in your previous statement:

“50mA: high bias current for Class AB”

… you probably meant ‘High Gain’ as 50mA is ‘Low Bias’

Your remark about 50mA (low Bias) always being class AB makes sense as indeed you can actually hear the difference with 100mA (high Bias) class A.

 

[Ichos]

I think we all agree, my confusion was the use of the word ‘High Bias’ in your previous statement:

“50mA: high bias current for Class AB”

… you probably meant ‘High Gain’ as 50mA is ‘Low Bias’

Your remark about 50mA (low Bias) always being class AB makes sense as indeed you can actually hear the difference with 100mA (high Bias) class A.

You are right. I have made a typo, the word "high". I am going to edit it so people don't get confused.

 

[quawn0418]

You are right. I have made a typo, the word "high". I am going to edit it so people don't get confused.

Hey ichos, did you notice any volume control issues? I didn’t notice at first, but I’m on my second unit already, first unit took 3-4 steps to notice an increase in volume, and the unit i have now increases in volume with every 2 steps, it’s easiest to notice with white or pink noise playing. I’m a lot more content with this new unit and had it demonstrated the same volume control as the first unit I’d just write it off, but with it behaving better than the first unit i now kind of have hopes of running into a perfect unit. Amazon makes returns easy especially when things like this are at play.

 

[Ichos]

Hey ichos, did you notice any volume control issues? I didn’t notice at first, but I’m on my second unit already, first unit took 3-4 steps to notice an increase in volume, and the unit i have now increases in volume with every 2 steps, it’s easiest to notice with white or pink noise playing. I’m a lot more content with this new unit and had it demonstrated the same volume control as the first unit I’d just write it off, but with it behaving better than the first unit i now kind of have hopes of running into a perfect unit. Amazon makes returns easy especially when things like this are at play.

From what I know there are some units that demonstrate this kind of behavior when adjusting the volume. Sudden rise from 0 to 1 and then normal behavior and then again a sudden jump from 50 to 51 if I remember well. The review sample has normal behavior.

 

[Giangi]

In case of discharge...how could I change the Aune remote battery???

 

[MiguelP]

I am waiting the delivery of a unit bought in Aliexpress two weeks ago. After asking many times about the delay of the order (it hasn't been shipped yet), the store gave me the information that the factory was checking all units before delivery. Hope that all goes well and I get a fully working unit! Fingers crossed...