SMSL VMV A1 Pro Stereo/Mono Amplifier Review

[ICIETDIYEUR]

Hi Danyboun

How stupid can I be to think like that, just like the engineers who created these components 'for nothing': everyone knows that...

It's obvious that we shouldn't use OPAMPs like the TI OPA1612A, nor dedicated audio components like TOPPING, for example: how stupid they are

(NB: this is a class A amp, not class D)

The OPA1612A OPAMPs are used for their excellent technical characteristics.These are bipolar OPAMPs and consume 7.2mA for both channels.

For portable or USB-powered devices, it's best to use the OPA1692 (bipolar) OPAMPs, with excellent technical characteristics too, which consume only 1.3mA for both channels !

Staying in the realm of portability, the best choice for FET-type OPAMPs is the OPA1652 OPAMP, with excellent characteristics again and only 4mA for both channels (almost half the consumption of an OPA1612A), and without the inherent problems of a high or 'unbalanced' load at its inputs.

And finally a excerpt from a post from an ADI engineer:

"...Most ceramic capacitors are biased, the capacitive rating can decrease by as much as 50%! The higher grade (X7R) types suffer less from this, but you should be aware that a 1 uF might be acting like a 0.68uF in the circuit. We have also found that ceramic capacitors suffer from microphonic effects: the audio passing through the part will actually physically resonate and cause distortion! I would only use ceramic capacitors in the audio path where performance is not an issue,..."

 

[RogerSmith]

Maybe better to focus on DACs and headphone amps, SMSL?

 

[ICIETDIYEUR]

Hello Roger Smith

I think testing is a 'necessary step' to improve and draw the necessary conclusions, but it shouldn't be to the detriment of customers with excessively high prices...

I take for example Alexander Lin from O-NOORUS who preferred to delay the release of his D3 PRO model rather than offer a device with certain defects that could have been avoided although it must still have some like every device on the market:

the perfect device does not exist because it depends on the expectations of each person but also on their (financial) means

 

[JeremyFife]

Thanks for the review, interesting to see GaN equipment coming through now.

Performance isn't great though: load dependant, loss of power at lower frequencies and that set-up problem.
We see better for the money, and for much less.

 

[beefkabob]

SMSL has good, bad, and ugly. I own one of the ugly, which I bought years ago. Don't buy anything of theirs without measurements.

 

[xanalog]

SMSL has good, bad, and ugly. I own one of the ugly, which I bought years ago. Don't buy anything of theirs without measurements.

You are luckier than I!
I own a bad and an ugly SMSL, of 2024 vintage. Yet, both have great measurements.
One boots-up to tell me to disconnect USB, and the other is ditzy about its ARC input.

 

[beefkabob]

You are luckier than I!
I own a bad and an ugly SMSL, of 2024 vintage. Yet, both have great measurements.
One boots-up to tell me to disconnect USB, and the other is ditzy about its ARC input.

Look upon these measurements, ye mighty, and despair: https://www.audiosciencereview.com/...q5-pro-dac-and-stereo-amplifier-review.10719/

 

[beefkabob]

Also, they stopped making drivers for it, and I think it does need drivers.

 

[bmwr75]

Sad that the VMV brand label has been put on this device.

 

[amirm]

VMV line seems to follow the traits of high-end audio, emphasizing mostly component selection, design, etc. as opposed to performance. Ordinary SMSL products usually perform better in objective measurements where the focus is that, than what goes in marketing material.

 

[phoenixdogfan]

Nice looking design, but it's overpriced, underpowered, and hardly goundbreaking when it comes to the measureables. Personally I don't know why anyone would choose this over the Fosi V3, so not terrible is a fair grade.

Thanks for the fine review, Amir.

 

[ICIETDIYEUR]

People hi

I've already said that FOSI should remake a V3 model in MKII version

All it would take is adding the PFFB circuit, using a digital volume control (NJW1195), and adding two XLR inputs (truly balanced) in addition to the RCA inputs (single-ended), allowing input selection with a simple manual switch (4 contacts/2 positions) on the back of the unit.

Ideally, it would be offered with a 51V/12A PSU (with Gan transistors, LOL).

NB: TI used a MEANWELL HEP600-48 power supply for its datasheet tables but it is rather expensive

This could be offered at an attractive price (they know how to do it very well), and the unit thus 'designed' would offer top-of-the-line features and a SINAD.

I can send them schematics if needed...

This amplifier could very well be accompanied by an SMSL D6s DAC because for this SMSL really masters its products, especially this 'reduced price' model which is nevertheless excellent

 

[Ropeburn]

Thank you for the review. GaNFET may see it's day, but not today.

It'll see its day when its properties are actually utilised in designs, for example for higher switching frequencies. So far, they haven't been really, except marginal power saving, and looks like it'll stay a fancy marketing term for the time being.

 

[daniboun]

Hi Danyboun

How stupid can I be to think like that, just like the engineers who created these components 'for nothing': everyone knows that...

It's obvious that we shouldn't use OPAMPs like the TI OPA1612A, nor dedicated audio components like TOPPING, for example: how stupid they are

(NB: this is a class A amp, not class D)

The OPA1612A OPAMPs are used for their excellent technical characteristics.These are bipolar OPAMPs and consume 7.2mA for both channels.

For portable or USB-powered devices, it's best to use the OPA1692 (bipolar) OPAMPs, with excellent technical characteristics too, which consume only 1.3mA for both channels !

Staying in the realm of portability, the best choice for FET-type OPAMPs is the OPA1652 OPAMP, with excellent characteristics again and only 4mA for both channels (almost half the consumption of an OPA1612A), and without the inherent problems of a high or 'unbalanced' load at its inputs.

And finally a excerpt from a post from an ADI engineer:

"...Most ceramic capacitors are biased, the capacitive rating can decrease by as much as 50%! The higher grade (X7R) types suffer less from this, but you should be aware that a 1 uF might be acting like a 0.68uF in the circuit. We have also found that ceramic capacitors suffer from microphonic effects: the audio passing through the part will actually physically resonate and cause distortion! I would only use ceramic capacitors in the audio path where performance is not an issue,..."

Please read :
About Rolling op amps and capacitors update
We have enough perspective on the subject. ASR can prevent us from falling into confirmation bias.

Capacitor upgrade in crossover - Is it audible?

As the topics "capacitor upgrade" and therefore "capacitor sound" is very controversial, the test method and its results are explained in detail. This cannot be dealt with in one minute. Sorry for this and I hope your attention span is still sufficient to read through a long text - whereby the...

audiosciencereview.com

Does Op-amp Rolling Work?

When I post my last video on review of Douk A5 amplifier, I mentioned that rolling (changing) op-amp ICs in there is fruitless. I got have a dozen comments under that video in youtube asking why so I thought I experiment again with the A5. Note that I have done the same testing with both DACs...

audiosciencereview.com

 

[Endibol]

This is a review and detailed measurements of the SMSL VMV A1 Pro GaNFET Class D stereo amplifier (bridgeable into mono). It was sent to me by their distributor, Aoshida audio, and costs US $495.
View attachment 454660
I like the inclusion of volume control and display (there is also a metal remote). Back panel shows the inclusion of power supply which is very nice:

View attachment 454661
I wish trigger input was available. Bridge mode requires changing modes in the menu. When I did that, the amplifier would not produce any output and some red LEDs would be blinking through the back terminals. I tried a few things and eventually gave up. Also, and maybe related, the positive speaker terminal for the right channel was loose.

In use, the amplifier ran very cool, much cooler than its competitors. It mildly got warm to touch. Maybe this is one of the benefits of GaNFET transistor technology.

SMSL VMV A1Pro Amplifier Stereo Measurements
As usual, we start with our dashboard of 1 kHz into 4 ohm load:

View attachment 454662
Distortion and noise are low enough to land the A1Pro in the top of our "competent" category:
View attachment 454663
View attachment 454664

Noise performance is very good:
View attachment 454665
Company frequency response measurements show slight sensitivity to load. I measured more but still less than some other amps without post filter feedback:
View attachment 454666

IMD distortion is within the expected range:
View attachment 454667
View attachment 454668

Crosstalk is not bad either although I expect better numbers in lower frequencies:
View attachment 454669

At 4 ohm, distortion sets in a bit early but noise performance is very good:
View attachment 454670
We do fall short of company specs for power:
View attachment 454672

I was surprised to see a sharp drop in power at 40 Hz:
View attachment 454673
View attachment 454677

This is reflected just the same at 20 Hz in our frequency power sweeps:
View attachment 454674

Amplifier is stable on power up:
View attachment 454675

And may only have a power off pop:
View attachment 454676

Conclusions
Performance of the A1Pro is above average in a number of categories but for the price, it should be that way across the board and it is not. To wit, it should not have load dependency, nor the sharp power drop at lower frequencies. As with a number of GaNFET designs I have tested, the marketing value of the technology seems to be higher than reality. Here, the only benefit seems to be lower power consumption. Otherwise, even IC amplifiers outperform the A1Pro. Those products are messier to use though by having large external power supplies.

I was close to recommending the SMSL VMV A1 Pro but at end, I could not. Company should strive to do better to match the excellence of the rest of their product line.

------------
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/

@amirm Thanks Amir for again another nice review. Question: Would it be a good idea to add to the % of max power to the 40 Hz power graph? That's probably a more interesting metric since all these amplifiers listed have different max power ratings.

 

[daniboun]

VMV line seems to follow the traits of high-end audio, emphasizing mostly component selection, design, etc. as opposed to performance. Ordinary SMSL products usually perform better in objective measurements where the focus is that, than what goes in marketing material.

The funny thing about the VMV line is that the more you advance over time, the less good the performance is) in fact only the VMV A1 and A2 have the hi res audio label.

 

[ICIETDIYEUR]

@Daniboum

I don't need to reread what was tested and measured by Amirm (and others): EVERYTHING written and observed is accurate

However, there was a certain Ken Ishiwata whose life was rather 'prolific', improving, for example, CD players of his time with other components selected by himself, including OPAMPS and capacitors ('KI signature' devices).

Do you think he possessed less skill than Amirm ?

Perhaps he was measuring 'certain things' that we don't measure because the devices he modified clearly had better SQ.

The problem is that we're talking about subjectivity when we talk about SQ, since there's no way to quantify it, even though the measurements currently being taken undoubtedly contribute to it...

... I'm well aware that 'psychoacoustic phenomena' exist, but I find it regrettable to systematically fall back on this explanation when we can't explain a 'phenomenon' experienced by a certain 'majority' of people (at least a small number), especially when they know absolutely nothing about the technology of the devices.

Are they all 'affected' by psychological problems, so to speak ? I don't think so.
I have a question for you:

why does TI label OPAMS with the 'AUDIO' designation when some of their other models have better technical characteristics in measurements ?

(e.g: OPA1656 Burr-Brown™ Audio Operational Amplifier vs OPA2156 Ultra-Low Noise, Wide-Bandwidth, Precision Operational Amplifier)

Perhaps they are also 'affected' by 'psychoacoustic' issues ?

 

[JSmith]

Are they all 'affected' by psychological problems, so to speak ?

No... it's just inherent biases present in all human beings. This is why we use controls when making such comparisons.

Best we stick to discussion of the amp that was tested, being a review thread.


JSmith

 

[ICIETDIYEUR]

Hello JSmith

You're quite right

Returning to the device in question, it's clear that Daniboun didn't understand my comment about the device's operating class, which is Class A and not Class D.

This operating mode is different from Class D, and therefore Amirm's comments regarding 'OPAMP rolling' do not apply to this Class A device, the SMSL VMV A1 Pro...

 

[Roland68]

Hello JSmith

You're quite right

Returning to the device in question, it's clear that Daniboun didn't understand my comment about the device's operating class, which is Class A and not Class D.

This operating mode is different from Class D, and therefore Amirm's comments regarding 'OPAMP rolling' do not apply to this Class A device, the SMSL VMV A1 Pro...

Unfortunately, you're not quite right.
This is about the new VMV A1 Pro which is based on Infineon's MERUS Class D technology, and not the old VMV A1 with Class A technology.