Strange polarity issue with new amplifier (Topping PA5 II Plus)

[nck045]

Just got my new Topping PA5 II Plus amplifier today and got it hooked up right away once I got home. Played my favorite tracks but the sound was strange - hollowed midrange and almost no bass, so I thought it must be a polarity issue. So I swapped the wires of one speaker and the sound was back to normal.

I have used several amplifiers with my current setup (always same source, DAC, cables and speakers) and never had this out of phase problem before, so does this mean the Topping amp has inverted polarity? Should I be concerned? Thanks

 

[somebodyelse]

I haven't seen other complaints about this so it probably isn't usually a problem. From the internal pic in the main thread the terminals are connected to the main board by short manually soldered wires. Most likely one side of yours got soldered the wrong way round and it slipped through whatever tests they do before shipping. If that's what happened it shouldn't change functionality beyond the 'fix' you have already done with the speaker cables. If you got it from someone with good customer service you could swap it for another one to avoid future confusion.

 

[nck045]

I haven't seen other complaints about this so it probably isn't usually a problem. From the internal pic in the main thread the terminals are connected to the main board by short manually soldered wires. Most likely one side of yours got soldered the wrong way round and it slipped through whatever tests they do before shipping. If that's what happened it shouldn't change functionality beyond the 'fix' you have already done with the speaker cables. If you got it from someone with good customer service you could swap it for another one to avoid future confusion.

Thanks! you are 100% spot on. I peeked through the case opening with my phone flash light, and first thing I saw is the L+ on the main board being incorrectly wired into the L- banana plug terminal. I am still in the warranty window so hopefully they will swap me a new one.

edit: added a photo

 

[mhardy6647]

uff da!

 

[restorer-john]

And that was from a batch of 1000 made that week by the new recruit at the Topping factory, Ho Li Sheet, who also wires all the mains IEC sockets... Eeeek!

 

[wwenze]

I have one China amplifier with one channel red and black connector wired opposite. So yes, it does happen.

It's not the end of the world but now the connector color sequence is weird at red-black-red-black.

 

[Sokel]

I have one China amplifier with one channel red and black connector wired opposite. So yes, it does happen.

It's not the end of the world but now the connector color sequence is weird at red-black-red-black.

My OCD just exploded only by the thought of it

 

[Angsty]

Chinese-made does not necessarily mean poor quality control; my iPhone was made in China. But just like anywhere, a crappy product can be produced when QC gets cut.

 

[MRC01]

After seeing a problem like that, one can't help but wonder what other problems he's not seeing.

 

[MAB]

And that was from a batch of 1000 made that week by the new recruit at the Topping factory...

I do wonder if they produce this error in batches. Lots of people never going to figure out they have a polarity issue, sorry to say...

Chinese-made does not necessarily mean poor quality control; my iPhone was made in China. But just like anywhere, a crappy product can be produced when QC gets cut.

Yeah.
Here is a Pamona that got the red and black thumbscrews reversed. It had been rattling around my bench for years. I doubted everything I had done after I discovered this.

So everybody can get the wires crossed. Would be nice to not see these basic manufacturing flaws though.

 

[restorer-john]

Here is a Pamona that got the red and black thumbscrews reversed. It had been rattling around my bench for years. I doubted everything I had done after I discovered this.

Eeek! That's funny- but not. Made me look in my adaptor drawers to check...

 

[restorer-john]

@MAB

Random Aliexpress listing:

400 sold. LOL.

And this one: https://www.aliexpress.com/item/100...sea!AU!3522927307!&curPageLogUid=Se5CcpvFE8KV

 

[solderdude]

who also wires all the mains IEC sockets... Eeeek!

Fortunately this amp has DC input so worst case would be a blown up amplifier (reverse voltage)

Clearly Topping needs better quality control and also check for phase or train their solderboys better...

 

[MAB]

@MAB

Random Aliexpress listing:

View attachment 318232

400 sold. LOL.

And this one: https://www.aliexpress.com/item/1005005916092952.html?spm=a2g0o.productlist.main.35.3ebbAIIyAIIyVe&algo_pvid=adc14f1c-ef14-4dd2-8216-0b6655c7d143&algo_exp_id=adc14f1c-ef14-4dd2-8216-0b6655c7d143-17&pdp_npi=4@dis!AUD!3.24!2.26!!!2.05!!@2103237316970877340642291e16bc!12000034836607625!sea!AU!3522927307!&curPageLogUid=Se5CcpvFE8KV

Oh my. Perhaps this explains why the OP's amp passed QC.

 

[restorer-john]

Clearly Topping needs better quality control and also check for phase or train their solderboys better...

Maybe use black and red wire instead of offcuts of speaker cable and train them - black to black to '-', red to red to '+'. LOL.

 

[solderdude]

We'd better hope Topping is reading your suggestions ..

 

[Sokel]

I'm not for old stuff but it was somehow reassuring opening a device and seeing the familiar checklist sticker signed inside it.
5-10 critical things,check,sign and you're done,can't think of an easier way to offer a good service to your clients.

 

[NoMoFoNo]

I read in another thread that a Topping rep who frequented these forums visits less often after the PA-5 debacle. True?

 

[restorer-john]

I read in another thread that a Topping rep who frequented these forums visits less often after the PA-5 debacle. True?

No great loss.

Topping just lurches awkwardly from one fiasco to another- like a drunk person staggers down a dark alley late at night, crashing into dumpsters, parked cars and trash, before tripping and falling face first into an open drain and passing out. Funny to watch if it wasn't so pathetic.

 

[somebodyelse]

I read in another thread that a Topping rep who frequented these forums visits less often after the PA-5 debacle. True?

Yes, but I wouldn't read too much into it. He had gaps between periods of relatively frequent posting before that too, and kept posting through the L30 issues.