Topping A90 supposedly lacks ESD protection?

[solderdude]

With the caveat that I haven't studied electricity, so these may be newb questions:

• If there was a large electrical differential between myself and an A90, and I put on headphones attached to the A90 via a cable, and the headphones+cable don't have adequately high resistance, could that damage the A90?

ESD voltages can be as high as 30kV. AFAIK Topping tests up to 10kV. After the L30 debacle I believe they now test at 30kV.
Protocols prescribe all inputs, outputs and parts that can be touched (volume control, buttons, switches, displays, cabinet) must be tested with air and direct discharges.
Voltages above 30kV are not really possible/likely in practice.
10kV is easily reached on the body by walking across a carpet in low humidity.

So whether or not the A90 can be damaged ... I can't really say.

• Is it possible that the headphones could develop a electrical differential if detached from the A90, and upon connecting it, that could also damage the A90?

When you have developped ESD and you hold the plug of the headphone while plugging it in this could potentially damage something when high enough (in voltage and or duration)

You will know when you produce 'sparks' when touching grounded things in the house.
What happens is that the ESD voltage on your body finds a path to ground via the amp (which is grounded usually) and components inside the amp must be able to withstand currents flowing from the inputs or outputs through these parts to ground.

This can be XLR inputs and outputs as well as TRS and Pentaconn and RCA.

Unplugging... no

 

[solderdude]

Clarity!

Its a common misconception to think that XLR plugs give more clarity to the sound.

 

[kenshone]

Its a common misconception to think that XLR plugs give more clarity to the sound.

My understanding is that it is a balanced architecture which gives improved clarity + power, and that balanced plugs are necessary but insufficient for an end-to-end balanced system.

 

[Holmz]

Topping initially had a problem with static discharge with their L30 headphone amplifier. If a product is CE marked, it is supposed to meet certain EMC (electromagnetic compatibility) requirements. Please see this post for the specific test requirements.

Sequential damage

Audio Technica w5000. Ouch! My condolences

www.audiosciencereview.com

The European CE or the Chinese C E marking?

 

[solderdude]

My understanding is that it is a balanced architecture which gives improved clarity + power, and that balanced plugs are necessary but insufficient for an end-to-end balanced system.

More power yes, better clarity no. The sound will be exactly the same. Balanced is more immune to unwanted signals (external) induced in cables and for ground loops. That is the main reason for using balanced cables. Not sound quality.
Balanced connections are sufficient for all systems, regardless if it is end to end.
That said, for the majority of (domestic) systems RCA is already more than sufficient.

 

[RHO]

More power yes, clarity no.

Well, you could say that noise is reduced so clarity is improved. Also when you can remove a ground loop with a balanced connection that you have when using SE, clarity is also improved.
But I get what you mean. And I wouldn't recommend a balanced connection for improved clarity reasons. Compared to a clean SE connection there is no improvement in clarity.

 

[solderdude]

The European CE or the Chinese C E marking?

CE marking is self certification needed to be able to sell that product on the E.U. market.
The manufacturer, when someone sues a complaint, must produce evidence that tests applicable to that product have been performed.
For most domestic applications ESD testing up to +/- 1kV is usually enough.

 

[solderdude]

Well, you could say that noise is reduced so clarity is improved. Also when you can remove a ground loop with a balanced connection that you have when using SE, clarity is also improved.
But I get what you mean. And I wouldn't recommend a balanced connection for improved clarity reasons. Compared to a clean SE connection there is no improvement in clarity.

Clarity is in the 2-5kHz range. Perhaps with clarity you mean signal fidelity ?
A good SE connection is not noisier or poorer than balanced. Poor SE connections are more common than poor balanced ones though.
In some cases measurable and even audible improvements (hum, weird unwanted noises) can easily be solved or prevented with balanced connections.

 

[RHO]

Clarity is in the 2-5kHz range.

I took it the "audiophile way". Not the technical, well informed way. Like "it sounds cleaner", "there is more detail", ... mostly imagined things.

A good SE connection is not noisier or poorer than balanced. Poor SE connections are more common than poor balanced ones though.
In some cases measurable and even audible improvements (hum, weird unwanted noises) can easily be solved or prevented with balanced connections.

Yes, a good SE connection should not have any audible noise or even more noise than a balanced connection. But, as you say, they are not always implemented as clean as they could be.

 

[JayGilb]

A properly designed male xlr connector will have any ground pins slightly longer than the signal pins to make sure a ground connection is established first to discharge any static buildup. It's rare to see this implemented, but is good practice.

I can't believe I'm adding to a thread that started from a single, unverified quote in Headphones.com

 

[solderdude]

A properly designed male xlr connector will have any ground pins slightly longer than the signal pins to make sure a ground connection is established first to discharge any static buildup. It's rare to see this implemented, but is good practice.

I can't believe I'm adding to a thread that started from a single, unverified quote in Headphones.com

Unfortunately in the case of the 4-pin headphone XLR connection the 1 pin (which makes contact first) is +L.
It is quite easy (and cheap) to protect an output for ESD though.
As the OP devices are TPA6120A which have limited ESD protection (but are used with lower than usual output resistors ?) one would assume, using good PCB/wire routing, the output should be safe.

 

[OWC]

More power yes, better clarity no. The sound will be exactly the same. Balanced is more immune to unwanted signals (external) induced in cables and for ground loops. That is the main reason for using balanced cables. Not sound quality.
Balanced connections are sufficient for all systems, regardless if it is end to end.
That said, for the majority of (domestic) systems RCA is already more than sufficient.

I agree that the word "clarity" is a rather strange choice.

But a reduction of common mode noise is always a win in my book.
Although it depends how long the cables are we are using of course.
They do suffer a lot less from ground-loops as well and ground-lifts can easily implemented.
Still beats me why it's not standard these days for the cost of a couple of resistors, or in the more high-end cases one extra IC.

 

[solderdude]

The RCA connector is simply the most common one. A horrible plug (signal before ground) yet it seems there to stay.
At least the DIN plug is completely phased out now (except for MIDI).
For the same reason I thing the Pentaconn connector will never be as widely adopted as most people already have a 6.3mm (or 3.5mm) TRS plug on their headphones.
Balanced requires extra parts (opamps, line drivers, input circuits), bigger and more expensive connectors and board space and thus bigger enclosures.
Requires double the amount of cables as well.

In the professional world we still see the TRS and XLR also used side by side. One would think all of that could have been XLR by now.

 

[OWC]

bigger and more expensive connectors and board space and thus bigger enclosures.
Requires double the amount of cables as well.

Not really, there is something called mini-XLR, but a balanced signal would also work totally fine with a stereo (mini)jack connector.
It requires more cores, not more physical cables, since it's very easily possible to have more cores in just one cable.

The very vast majority of input stages already contains something like a opamp buffer circuit.
Even a simple differential-to-single ended circuit will perform much better.
Which will cost 2 more resistors compared to the single-ended version of it.
If you want to do it more properly, it will be a bit more.

The driver side is a bit of a different story, that's true.
Although every DAC (I mean the IC, not the whole device) these days is differential out anyway, which they mix to a single-ended output.

 

[restorer-john]

Maybe if people simply plugged in their system before powering it up, it wouldn't matter one iota which signal connector made contact first..

The totally silly arguments about hot before cold are irrelevant in that case. Mountain out of a molehill much.

 

[solderdude]

Mini XLR is common on small mics and some headphones, but only on the mic and headphone side and not on the amp/console side.
One would be introducing yet another connector for audio connections.
Just like the balanced RCA connector this is bound not to catch on with the public and thus also not for manufacturers.
The mini jack is very common as well but not the most reliable one. RCA and (mini)XLR are far better connections.

Most audio gear, when it uses XLR, will be using the regular sized ones which simply requires more space and is more expensive.

Maybe if people simply plugged in their system before powering it up, it wouldn't matter one iota which signal connector made contact first..

The totally silly arguments about hot before cold are irrelevant in that case. Mountain out of a molehill much.

Very true and is certainly best practice (a forgotten art ?) but mini jack and RCA plugs remain the most problematic connectors in audio, regardless if you feel everyone must plug in before using gear.
Good quality RCA connectors do exist though.

 

[RHO]

Good quality RCA connectors do exist though.

Like these: https://www.neutrik.com/en/product/nf2c-b-2 ?
I think these only make sense when you disconnect and reconnect frequently.

 

[solderdude]

Like these: https://www.neutrik.com/en/product/nf2c-b-2 ?
I think these only make sense when you disconnect and reconnect frequently.

Those are indeed only needed when hot swapping RCA plugs.
I meant there are plenty of good quality 'normal' RCA plugs, not all of them are crap.

 

[wacomme]

If you don't get static electricity zaps in your home when touching metal doorknobs, metal water taps or anything where it can discharge then there is low chance of damage due to ESD. A90 has earthed metal enclosure so it has advantage in that aspect over amps that use power bricks or two prong power connectors. The ESD charge can dissipate through earth connection in your home wiring. Earthed enclosure is probably most robust anti ESD measure there is. It's one of the reasons I preferred to get A30pro.

So how is the A30Pro different than the A90. What's the difference in the two enclosures?

 

[usern]

So how is the A30Pro different than the A90. What's the difference in the two enclosures?

They both have internal PSU with 3 pin power connector so most likely A90 enclosure is earthed too so no difference in that aspect.