Topping A50S issue: shuts down on high volume???

[unconfortablynumb]

So, I noticed a problem with my Topping A50S: when using a 4,4mm-to-3,5mm adapter in the balanced jack, my A50S shuts down with a loud crackling sound at high volume when playing songs dominant in the treble range.

I am using it with a FiiO k3 DAC and Beyerdymic DT1990 Pro headphones.

Has anyone experienced this or is my unit defective?

 

[NA Blur]

Sounds like the amp's protection circuit may be kicking in or there may be two wires super close together which essentially short at high powers. Time to take a look inside perhaps.

Do you set your DAC and player volume to 90% and use the amp volume control? May help you turn down the power and avoid the power limiter.

 

[unconfortablynumb]

Sounds like the amp's protection circuit may be kicking in or there may be two wires super close together which essentially short at high powers. Time to take a look inside perhaps.

Do you set your DAC and player volume to 90% and use the amp volume control? May help you turn down the power and avoid the power limiter.

I usually have the DAC at about 70%, I would say. It only happens when I listen to songs that are heavy on the treble. Do you think it could be the DAC's fault? I'd rather not open the amp up as I wouldn't know what to look for.

 

[MrWalkman]

How does this adapter works?

A balanced port has something like L+ L-, and R+ R-, so no common ground.

The L- and R- shouldn't be connected together to create the common ground for a 3.5 port which has L+ R+ and ground.

 

[unconfortablynumb]

How does this adapter works?

A balanced port has something like L+ L-, and R+ R-, so no common ground.

The L- and R- shouldn't be connected together to create the common ground for a 3.5 port which has L+ R+ and ground.

Here's a picture of it. You think it's at fault?

 

[MrWalkman]

Here's a picture of it. You think it's at fault?

It might as well be, if your amp doesn't use the ground pin of the 4.4 port (which could then be used for the common grounf of the 3.5 port) and if the ground for the 3.5 adapter is made from combining the L and R negatives.

Can't say for sure, of course, but it's something to think about.

Do you have some 4.4 headphones to use directly and to see if your amp behaves the same?

 

[unconfortablynumb]

It might as well be, if your amp doesn't use the ground pin of the 4.4 port (which could then be used for the common grounf of the 3.5 port) and if the ground for the 3.5 adapter is made from combining the L and R negatives.

Can't say for sure, of course, but it's something to think about.

Do you have some 4.4 headphones to use directly and to see if your amp behaves the same?

Hey! I think you may be right! I have Phillips Fidelio X3 that are natively balanced. They don't have a 4,4mm jack, but I have a 2,5mm-4,4mm adapter that fits the jack in the amp. They also have a single-ended cable that terminates into a 3,5mm male (which can be used with the 3,5-4,4mm adapter) I tested both cables with both adapters, and I had the same problem on these phones as I did with my single-ended DT1990's. But it worked flawlessly with the 2,5mm-4,4mm adapter even at deafening listening levels.

So, it's probably the adapter then... but I still kind of want an adapter that will convert 3,5mm to 4,4mm without triggering the protection circuit or whatever is happening. Is this impossible or is it just a crappy adapter ?

 

[MrWalkman]

So the 4.4 balanced output has L+, L-, R+, R-, and also a ground, which sometimes it's not actually connected to the board internally.

If it would be connected, you should be able to use an adaptor which uses the L+, R+, and the ground of the 4.4 output.

These adapters are not so common from what I've seen some time ago. If you can't find one like this, you could try tinkering with the existing adapter or make one yourself or something.

Also, as the amp acts like this when using your existing 4.4 to 3.5 adapter, I think it would be wisest to stop using it, as you may damage something.

 

[MrWalkman]

Now if the ground pin on the 4.4 port is not connected on the Topping A50S board (like it's not connected on the Sony WM1 players, for example), you could also try something like this - using the ground of your AMP's 3.5 port:

It's basically an Y cable, with one 4.4 male and a 3.5 male that both go into the amp, and a 3.5 female where you can plug your 3.5 headphones.

The thing is that for both the "Proposed adapter" above and this adapter in the image in this post, the volume won't be as high as when just plugging headphones with a balanced cable directly into the balanced port, but it should work safely.

It would be something like this, more precisely:

I used something like this on my Sony WM1A player, and it works fine. Whenever there is something plugged in the 4.4 port, the 3.5 port is not active, so both ports are not outputting sound or something. It's just using the ground pin of the 3.5 port.