Topping A90 Headphone Amplifier Review

[Nobi_one]

Hello, my 1st post here in ASR. Just wanted to share my Fuse blown issue with A90.
It just happened suddenly 2 days ago and I used up the spare Fuse provided by Topping in the unit.
Now the Fuse provided by Topping states: F500mAL250V and I think it translates to a 0.5A fuse.
However I emailed Topping product support and they told me to use a fuse rating of 1A.
Now, should I follow the Email advise and purchase a 1A fuse replacement? Or stick to the spare one?
Does that mean Topping provided the wrong fuse?

Thanks!

 

[Veri]

Hello, my 1st post here in ASR. Just wanted to share my Fuse blown issue with A90.
It just happened suddenly 2 days ago and I used up the spare Fuse provided by Topping in the unit.
Now the Fuse provided by Topping states: F500mAL250V and I think it translates to a 0.5A fuse.
However I emailed Topping product support and they told me to use a fuse rating of 1A.
Now, should I follow the Email advise and purchase a 1A fuse replacement? Or stick to the spare one?
Does that mean Topping provided the wrong fuse?

Thanks!

First batch was under-fused. Definitely get the 1A one as recommended! Will have much less chance for ever blowing again.

 

[Nobi_one]

First batch was under-fused. Definitely get the 1A one as recommended! Will have much less chance for ever blowing again.

Thank you!!!

 

[Harmonie]

Make sure it's an F1A and not a T1A
Fast vs Temp

 

[Patrick1958]

Make sure it's an F1A and not a T1A
Fast vs Temp

Strange, also had a blown fuse, contacted seller and he told me the opposite, use temp/slow 1A.

 

[Veri]

@JohnYang1997 can you advise about which fuse is recommended by Topping? Thank you,

 

[Patrick1958]

@JohnYang1997 can you advise about which fuse is recommended by Topping? Thank you,

Just checked the mail, exact wording is : Slow is ok but the best is temporised. 1A

 

[Mr:River]

Strange, also had a blown fuse, contacted seller and he told me the opposite, use temp/slow 1A.

Waiting for my A90 to arrive, I don't know which batch it is part of, I bought it at Aoshida Hi Fi, I hope it's from the updated fuse batch.
Buying releases we are all subject to these times.

 

[Harmonie]

Strange, also had a blown fuse, contacted seller and he told me the opposite, use temp/slow 1A.

May be so, but strange:
Original one was F0,5A and from there they advise you, to use double that value and Temp/slow. Means that 0,5 was really either under rated, or it would blow off so frequently that they take a comfortable margin and are confident that you will have no risk to blow more than the fuse (the head amp itself) and advise you 1ampere and slow or temp ....
After all, you are surely under warranty so do it

 

[Nobi_one]

Can anyone advise whether to use a ceramic fuse or just stick to a glass one? Thanks in advance!

 

[Patrick1958]

Can anyone advise whether to use a ceramic fuse or just stick to a glass one? Thanks in advance!

And exact type and value please, conflicting information thus far.

 

[Mr:River]

And exact type and value please, conflicting information thus far.

@Ddd Ah. Ok. Just checked with the datasheet of the power supply module and my colleagues. 0.6A is for single module, so it's safe to use 1A for two modules. Using 0.5A was indeed too low. It is used because it's used on other products and didn't raise any issue while designing. The inrush current can be as high as 40A. The new A90 comes with 1A fuses hence solved the issue. And if I'm understanding correctly(just went back and read again) the unit is currently working fine right? PM me if you experience any issue.

 

[Harmonie]

Can anyone advise whether to use a ceramic fuse or just stick to a glass one? Thanks in advance!

Naa,
You should use the audiophile fuse at 49$99/pce !

 

[LEGCRAMP]

Hmmmm I was looking at potentially getting this amp but seems like there's some quality control issues with them blowing fuses.

 

[Mr:River]

Naa,
You should use the audiophile fuse at 49$99/pce !

@JohnYang1997

Could you inform us correctly the fuse better, people would be more relaxed with this information.
My A90 has not arrived yet, I hope it is from the new batch with the correct fuse.

 

[Nobi_one]

Naa,
You should use the audiophile fuse at 49$99/pce !

Prior to my post here, whilst I was searching for a solution, I came across this: https://www.synergisticresearch.com/fuses/orange-fuse/
$159.99/pce!!
But I think I'll stick to the much more affordable glass or ceramic fuses instead once someone can advise which is better for the A90 =)

 

[Veri]

Hmmmm I was looking at potentially getting this amp but seems like there's some quality control issues with them blowing fuses.

This was only with original underfused units. The ones sold right now all have double amperage rated fuses.

 

[auronthas]

Yesterday when I switched on my A90 to HPA mode, there's no green indicator light , I checked several time, swapped power cable (D90), but I still could not turn on.

When I opened the fuse cartridge, I did not see any sign of fuse blown , but there's spare little fuse (500mA?) , so I made a swap, put the fuse cartridge back, aye, A90 back to work.

Surprise, I did not see or hear any "symptom" or "sound". What's the root cause? Is the fuse rated 500mA ? I barely can see the wording and need clarification. 230V x 0.5A = 115W ?

 

[EdW]

Yesterday when I switched on my A90 to HPA mode, there's no green indicator light , I checked several time, swapped power cable (D90), but I still could not turn on.

When I opened the fuse cartridge, I did not see any sign of fuse blown , but there's spare little fuse (500mA?) , so I made a swap, put the fuse cartridge back, aye, A90 back to work.

Surprise, I did not see or hear any "symptom" or "sound". What's the root cause? Is the fuse rated 500mA ? I barely can see the wording and need clarification. 230V x 0.5A = 115W ?

At turn on there is a huge surge of current as the discharged storage capacitors in the power supply initially present a short circuit to the transformer and rectifiers. This surge current substantially exceeds the continuous rating of the fuse. This over-current resolves over a few cycles of the mains supply and the current through the fuse then falls back to a much lower steady state value - well inside the fuse rating. This phenomenon occurs fairly frequently in power supply design and is sometimes mitigated by the use of ‘slo blo’ fuses which are better able to absorb an initial surge.

 

[auronthas]

This phenomenon occurs fairly frequently in power supply design and is sometimes mitigated by the use of ‘slo blo’ fuses which are better able to absorb an initial surge.

'Slo Bo' ... so it's some kind of 'withstand' the inrush transient current with a time delay. What's your best fuse recommendation and current rating?