SMSL PA-X Stereo Amplifier Review

[Lsi]

I'm still waiting for mine from amazon usa .waiting patiently

 

[olds1959special]

This is a review and detailed measurements of the SMSL PA-X GaN based Class D stereo amplifier. It was sent to me by Shenzhen Audio and costs US $699.
View attachment 446326
The PA-X is gorgeously designed. It would look even better with the display on, had I not damaged the unit in testing (see below). A volume control IC is used allowing use of remote control:
View attachment 446327
I wish SMSL would include trigger functionality. The unit weighs a "ton" for its size, oozing feeling of quality.

If you are not familiar with my amplifier measurements, please watch this tutorial:

SMSL PA-X Amplifier Measurements
With balanced amplifiers, I start with that input:
View attachment 446329
Usually that produces better performance but not in this case as RCA does better:
View attachment 446330
Likely some kind of conversion is performed from balanced to unbalanced (due to volume control IC?), degrading performance. Either way, the PA-X scores well when it comes to noise and distortion:View attachment 446331
View attachment 446332
At the bottom is one of the first GaN based designed I tested. So not bad at all.

We can see the better noise figure for RCA input with our SNR tests:
View attachment 446333
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Frequency response shows some load dependency. It is manageable but at the cost of 4 ohm roll off:
View attachment 446335

Crosstalk performance is a bit disappointing in the way it gets worse with lower frequencies. Usually it is the other way around as we see from our references:
View attachment 446336

Multitone performance is good:
View attachment 446337
Due to increasing distortion at higher frequencies, 19+20 kHz intermodulation distortion test shows worse performance (typical):
View attachment 446338

PA-X more or less meets is power specs:
View attachment 446339
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There is a curious menu option to set the load to 4 or 8 ohm. It has no impact on the testing above, but does boost the power for 8 ohm:

View attachment 446342

At this point, I ran my FTC like power sweep where the amplifier is repeatedly pushed into clipping in order to generate the max power possible at 1%THD. The sweep starts from right and goes to the left:
View attachment 446343

Measurements stopped around 40 Hz. I looked at the amp and it had shut down. This is typical as many amps will complain and turn off. Alas, the PA-X would no longer power on. I waited a while until it cooled off and it still doesn't power on. I will test it again tomorrow but I suspect it is permanently damaged.

As I have said countless times, such stress times can damage amplifiers for no good reason. No one is going to push an amplifier into clipping for such extended amount of time as I did above. And at any rate, there is little industry awareness that such tests need to be passed. So to some extend, I feel responsible for damaging the unit.

Amplifier is stable on power up:
View attachment 446344

Conclusions
Other than the frequency response droop, the PA-X performs well and looks gorgeous while doing it. With the data we have, if it had not been damaged, I would have likely recommended it. As is, I am sitting here with a sense of regret.

My appreciation to Shenzhenaudio.com for sending the amplifier in for testing.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

My PA200 died too. I was trying to drive large speakers. Maybe it overworked the amp.

 

[Lsi]

Hi all
Need help ,I get the amp today
Connected to kef ls50 meta and smsl ultra dac via XLR cable and bluesond 2i as source .the amp sound is amazing .
The problem is when I put the volume more then 40 the left side stop working for 3 second all the time ,
I try to put the the amp on 4-ohm ant it's working without problem
Should I return the item ?
Thanks shay

 

[OdiusEX]

This Orchard Audio GaN amp costs You almost 4.450USD delivered to Your home.
That is almost 20 times the amount You would pay for a set of Fosi Audio V3 Mono amps.
I don't think, they are in the same boat, but one may be challenged by the comparison...

¡Híjole! ¡Órale!​

​

​

 

[pma]

Frequency response shows some load dependency. It is manageable but at the cost of 4 ohm roll off:

The biggest problem is the 2.5 dB difference at 20 kHz, into purely resistive load, between 4 ohm and 8 ohm load. It indicates to several ohm output impedance at 20 kHz and still very high output impedance at 10 kHz. This may become audible with some speakers, depending on their complex impedance vs. frequency characteristics, because the dB difference will be shifted towards lower frequencies (output LC filter creates a frequency dependent divider with speaker complex impedance).

 

[Lsi]

Hi all
Need help ,I get the amp today
Connected to kef ls50 meta and smsl ultra dac via XLR cable and bluesond 2i as source .the amp sound is amazing .
The problem is when I put the volume more then 40 the left side stop working for 3 second all the time ,
I try to put the the amp on 4-ohm ant it's working without problem
Should I return the item ?
Thanks shay

This is the answer I get from the dealer.
"Hello, The thrust may be too high. It is recommended to turn on the preampli- fier to full and lower the PAX appropriately."
Is that logical ?
When I put the amp 4 ohm impedance it's working properly

 

[Lsi]

What do you guys advise me to do? return the amplifier or stay with the 4 ohm configuration? Will such a configuration reduce the quality of the amplification with the KEF LS 50 speakers?

 

[abrcdbra]

As a professional electronics designer, I understand that the 8 or 4 ohm settings change the level at which the amplifier's built-in speaker overvoltage protection will trip.
That is, for 8 Ohms, the voltage level when the protection is triggered is higher, and for 4 Ohms, the trigger level is lower.
I believe that the choice of this setting should be based on this.


I don't understand why Topping can't explain this to its customers. Probably a translation problem, like mine.)))

 

[Lsi]

They had an answer that was nothing short of amazing, they wanted me to send the amplifier to China for testing.

 

[abrcdbra]

Hey guys!
I can't understand the Chinese manual for the PA-X...

In the general description there is a mode called "Stereo pure amplifier pass-through mode, use with a pre-amp, the sound is more direct and pure".

But how to enable this "Stereo pure amplifier pass-through mode" is not explained anywhere...

Please help me understand this Chinese manual. )
How is this stereo pass-through mode enabled in the SMSL PA-X?

 

[staticV3]

Hey guys!
I can't understand the Chinese manual for the PA-X...
Please help me understand this Chinese manual.

Try scrolling down the PDF

SMSLs manuals always contain a Chinese and an English version.

 

[abrcdbra]

Did you see a solution to this issue in the English part of this Chinese manual??? Me - no.

Please copy the answer to my question for me in that case.

 

[jmc06]

The B200 is in a completely different league.
That's the difference between SMSL and Topping.
While SMSL mostly uses standard designs from component manufacturers, adapts them, and optimizes them based on measured values, Topping draws on its own developments in many areas and further optimizes them.

The SMSL amplifiers PA200, PA-X, and VMV A1 Pro are presumably all based on the EVAL_AUDAMP24 reference design/evaluation board from Infineon.
Based on the current measured values, I would always prefer my decades-old NAD 2200 and, of course, the A30a to the SMSL amplifiers PA200, PA-X, and VMV A1 Pro.

The question is also whether there is a significant sonic difference compared to the significantly cheaper SMSL A300, which delivers a measured 400 watts at 4 ohms and 220 watts at 8 ohms (1% THD) in BTL mode. Two SMSL A300s with 2 x 400 watts can be purchased for under €400.

I come from China. Regarding toppings and smsl, we have a greater preference for smsl. The indicators for toppings are better, but smsl generally receives better feedback in terms of sound quality. In the early days, smsl was also very focused on static indicators, which aligns well with the tone of this forum. This forum is primarily focused on indicators, but it later shifted, now emphasizing dynamic sound quality, and it is very popular in China.

 

[KL....]

I come from China. Regarding toppings and smsl, we have a greater preference for smsl. The indicators for toppings are better, but smsl generally receives better feedback in terms of sound quality. In the early days, smsl was also very focused on static indicators, which aligns well with the tone of this forum. This forum is primarily focused on indicators, but it later shifted, now emphasizing dynamic sound quality, and it is very popular in China.

Thank you,@jmc06, music is nonLinear and Playback/Amplifycation are (hopefully) Linear/Transparent (and hopefully, if possable, Real/Right), reasonable? For recording engineers/studios, the Contrast in/of the recorded music is (usually) the priority with much effort, isn't it, reasonable? If the Contrast in/of the recorded music is Real/Right then this is what we would like to hear when played back (without addition), wouldn't we, reasonable?

Re now emphasizing dynamic sound quality.... do you mind clarifying what this means for you and SMSL, especially with reference to SMSLs Playback/Amplifycation products?.... thank you :=)

 

[Roland68]

I come from China. Regarding toppings and smsl, we have a greater preference for smsl. The indicators for toppings are better, but smsl generally receives better feedback in terms of sound quality. In the early days, smsl was also very focused on static indicators, which aligns well with the tone of this forum. This forum is primarily focused on indicators, but it later shifted, now emphasizing dynamic sound quality, and it is very popular in China.

We often conduct blind tests as part of a project.
In direct comparisons, none of the SMSL Infineon GaN amplifiers (PA200, PA-X, VMV A1 Pro, PA400) have been able to compete with amplifiers like the Sabaj A30a, Topping PA5, B100, Purifi, etc. and convince us.
We focus most on the reproduction of the instruments as we know them.
Among other things, we also noticed the load-dependent behavior with different speakers, which is not the case with any of the other amplifiers.

Especially when it comes to amplifiers, GaN is currently nothing more than a marketing gimmick.
Especially with constantly changing loads, the advantages of GaN, which are undeniable under continuous, permanent load, collapse. As a result, the actual advantage of better energy efficiency is only 0.5-1%, but usually less. It may even be that other Class D designs are more efficient, but I haven't seen any measurements of this yet.
In any case, other leading amplifier manufacturers have decided against using GaN technology in their power amplifiers after extensive testing.

Marketing also suggests that these are special GaN amplifier developments.
In fact, this is the standard Infineon MERUS Class-D controller technology, which can be equipped with either extremely low RDS(on) power MOSFETs or GaN transistors. Since Infineon itself only acquired GaN technology two years ago and the current Merus controllers existed before then, everyone can draw their own conclusions about "specially developed GaN amplifiers."
It should be no secret by now that the SMSL GaN amplifiers (as is unfortunately often the case with SMSL) are based on the manufacturer's evaluation boards.

By the way, a true and comparable comparison of conventional Class D technology based on Merus controllers with power MOSFETs with extremely low RDS(on) and alternatively GaN transistors would be no problem at all, since they are the same controller. For this, SMSL would only have to equip one device with the power MOSFETs.
As a manufacturer, I would have done exactly that first to demonstrate the significant differences, but for that to happen, the significant differences would have to exist.

The much cheaper A300 demonstrates that even conventional Merus technology without GaN is very energy-efficient. Two bridged A300s deliver over 2 x 400 watts into 4 ohms and 2 x 200 watts into 8 ohms, as measured by Amir.

 

[Evo42]

I come from China. Regarding toppings and smsl, we have a greater preference for smsl. The indicators for toppings are better, but smsl generally receives better feedback in terms of sound quality. In the early days, smsl was also very focused on static indicators, which aligns well with the tone of this forum. This forum is primarily focused on indicators, but it later shifted, now emphasizing dynamic sound quality, and it is very popular in China.

Thank you for your insight I feel often in the West there is so much focus on Chinese companies efforts to replicate rather than efforts to innovate and pursuits for excellence.

 

[Roland68]

Dor what it is worth I have heard

Thank you for your insight I feel often in the West there is so much focus on Chinese companies efforts to replicate rather than efforts to innovate and pursuits for excellence.

Unfortunately, this is often due to a lack of knowledge.
At Topping, the innovation and pursuit of excellence are clearly evident in many of their devices.
At SMSL, unfortunately, a large proportion of their devices are based on evaluation boards and standard application developments from chip manufacturers, naturally with significant optimization of the measured values.

 

[Evo42]

I thought the b200 and other topping amps have had a number of issues despite its performance.

 

[jmc06]

We often conduct blind tests as part of a project.
In direct comparisons, none of the SMSL Infineon GaN amplifiers (PA200, PA-X, VMV A1 Pro, PA400) have been able to compete with amplifiers like the Sabaj A30a, Topping PA5, B100, Purifi, etc. and convince us.
We focus most on the reproduction of the instruments as we know them.
Among other things, we also noticed the load-dependent behavior with different speakers, which is not the case with any of the other amplifiers.

Especially when it comes to amplifiers, GaN is currently nothing more than a marketing gimmick.
Especially with constantly changing loads, the advantages of GaN, which are undeniable under continuous, permanent load, collapse. As a result, the actual advantage of better energy efficiency is only 0.5-1%, but usually less. It may even be that other Class D designs are more efficient, but I haven't seen any measurements of this yet.
In any case, other leading amplifier manufacturers have decided against using GaN technology in their power amplifiers after extensive testing.

Marketing also suggests that these are special GaN amplifier developments.
In fact, this is the standard Infineon MERUS Class-D controller technology, which can be equipped with either extremely low RDS(on) power MOSFETs or GaN transistors. Since Infineon itself only acquired GaN technology two years ago and the current Merus controllers existed before then, everyone can draw their own conclusions about "specially developed GaN amplifiers."
It should be no secret by now that the SMSL GaN amplifiers (as is unfortunately often the case with SMSL) are based on the manufacturer's evaluation boards.

By the way, a true and comparable comparison of conventional Class D technology based on Merus controllers with power MOSFETs with extremely low RDS(on) and alternatively GaN transistors would be no problem at all, since they are the same controller. For this, SMSL would only have to equip one device with the power MOSFETs.
As a manufacturer, I would have done exactly that first to demonstrate the significant differences, but for that to happen, the significant differences would have to exist.

The much cheaper A300 demonstrates that even conventional Merus technology without GaN is very energy-efficient. Two bridged A300s deliver over 2 x 400 watts into 4 ohms and 2 x 200 watts into 8 ohms, as measured by Amir.

sabaj is smsl

 

[Roland68]

sabaj is smsl

Sabaj is not SMSL, but it belongs to the same group/consortium.
Interestingly, Sabaj often has its own designs and also incorporates improvements, especially when devices are released later than SMSL's.
They also take better care to fix problems with the firmware, and some bugs haven't even appeared in the Sabaj firmware.