SMSL VMV A2 Review (Stereo Amplifier & DAC)

[Roland68]

Does anyone have a picture of the inside (with the whole Printed Circuit Board) of the SMSL VMV2?

Or has anyone found pictures of the whole circuit board of the VMV A2?

 

[Spaxton]

We are clearing the 16 bit audio hurdle at just 5 watts which is my target which sadly many amps fail to achieve.

The second puzzle was the frequency response. Here I am driving the amplifier using Coax at 192 kHz sampling so we should have flat response to half of that but we don't:

View attachment 138311

Indeed, you can set the sample rate to anything you want, change to USB, etc. and you always get what seems to be 44.1 kHz sampling! SMSL advertises the "high-res" capability heavily in this amp but while the DAC is likely capable of delivering that, the amplifier happily shuts any extra spectrum above audible band.

Dear amirm,

First of all, thank You very much for Your detailed review. I am an old user of SMSL products, I own SMSL A8 and DP3. Since I had some problem with A8 (it had a bad design that every A8 had a hissing sound when the silence is on the input), I searched for the reviews and I found this.
However, I would like to point You to something which You probably missed here regarding the sampling rate and hearing specter.

A 20 kHz sine wave in 16 bit 44.1 kHz sampling rate is actually not a sine wave and it is pretty much distorted because this sampling rate resolution is not enough to pack 20 kHz sine wave in it. The amplifier actually cuts of everything out of the hearing specter and that has no connection with frequency response You described here. Increasing sampling rate will have a huge affection on the audio even if the amplifier cuts of everything above 20 kHz (nobody will hear it anyway).

To explain You what I mean, I generated 6 different files in Sound Forge software with different sampling rates but same frequency (all of them 20 kHz).

Please check the photo

The last one is actually 768 kHz but I wrote it wrong. (try to zoom the photo)

You will see that 20 kHz sine wave starts to look like a sine wave actually when we increase the sampling rate. This proves that 16 bit 44.1 kHz sampling rate is far away from real 20 Hz to 20 kHz sine wave range.

Beside this, can You tell did the A2 amplifier produce any kind of sound when the silence is on the input (even if You put Your ear on the speakers) ?

Best Regards.

 

[Toku]

Your calculation result is correct. However, after this, it passes through a low-pass filter and is shaped into a sine wave.

Theoretically no noise is generated when there is no input, but in reality it generates a small amount of noise. But it's at an inaudible level.

 

[PeterOo]

Dear amirm,



A 20 kHz sine wave in 16 bit 44.1 kHz sampling rate is actually not a sine wave and it is pretty much distorted because this sampling rate resolution is not enough to pack 20 kHz sine wave in it.

View attachment 313953

I think nothing explains this common misconception better than this classic from xiph.

44.1kHz sampling rate is plenty to capture a 20kHz sinus wave.

 

[Spaxton]

Your calculation result is correct. However, after this, it passes through a low-pass filter and is shaped into a sine wave.

Theoretically no noise is generated when there is no input, but in reality it generates a small amount of noise. But it's at an inaudible level.

Hello.

The photo I showed isn't related to class D amplifiers (which are actually analog amplifiers. Calling it digital is just marketing. The amplification is analog). The photo shows how does a 20 kHz sine look like when I generate it in the sounfourge at different sampling rates.

I think nothing explains this common misconception better than this classic from xiph.

44.1kHz sampling rate is plenty to capture a 20kHz sinus wave.

Thanks for the link. I didn't know any concept he mentioned but only generated sine wave at 16 bit 44.1 kHz in soundforge. Indeed, I didn't measure it with real instruments but I may do that as well.

 

[Spaxton]

I think nothing explains this common misconception better than this classic from xiph.

44.1kHz sampling rate is plenty to capture a 20kHz sinus wave.

Here is one more example made with software audio editor Audacity which will make it more clear. It is similar to looking at 800x600 display resolution and 4K or higher. Listening high res files will for sure be noticable even if the amp does not play outside of 20Hz to 20 kHz. That was my point anyway.
Check the photo. All tracks are 20kHz sine. Sampling rates and bit depth can be seen on the left side.

 

[NTK]

Here is one more example made with software audio editor Audacity which will make it more clear. It is similar to looking at 800x600 display resolution and 4K or higher. Listening high res files will for sure be noticable even if the amp does not play outside of 20Hz to 20 kHz. That was my point anyway.
Check the photo. All tracks are 20kHz sine. Sampling rates and bit depth can be seen on the left side.

View attachment 314424

You have been a member since 2019 and still don't know the sampling theorem? Below is from Wikipedia.

 

[Spaxton]

You have been a member since 2019 and still don't know the sampling theorem? Below is from Wikipedia.
View attachment 314426

It is great that You know it.

 

[PeterOo]

Here is one more example made with software audio editor Audacity which will make it more clear. It is similar to looking at 800x600 display resolution and 4K or higher. Listening high res files will for sure be noticable even if the amp does not play outside of 20Hz to 20 kHz. That was my point anyway.
Check the photo. All tracks are 20kHz sine. Sampling rates and bit depth can be seen on the left side.

View attachment 314424

The only thing your picture shows is that for your eye it is easier to reconstruct the sine wave if you have more samples.
that says nothing about the analog signal you get when you apply digital to analog conversion to these samples followed by proper low-pass filtering. The 20 kHz sinus will be perfectly reconstructed for all sampling frequencies .

You did not seems to have watched (or understood) the video.

 

[Spaxton]

The only thing your picture shows is that for your eye it is easier to reconstruct the sine wave if you have more samples.
that says nothing about the analog signal you get when you apply digital to analog conversion to these samples followed by proper low-pass filtering. The 20 kHz sinus will be perfectly reconstructed for all sampling frequencies .

You did not seems to have watched (or understood) the video.

Thanks for Your reply.

I did watch the video. The guy showed analog signal being digitized and back to analog again. He used two oscilloscopes (and obsolete emagic converter ) to show that the analog 1 kHz sine wave signal wasn't distorted as well as all up to 20 kHz. I didn't use the concept he mentioned about connecting dots, I just looked at what should be the visual representation of the analog signal (the photos I shared).
Anyway, if we are talking about sampling, shouldn't one dot be a sample? If so, it must benefit something to have more samples than less samples as otherwise all these high res, DSD, etc things make no sense...
When listening music, the difference between CD and DSD (or SACD) is noticeable if You have something where playing high res would have sense.

Now I can back to my point... listening high res files can have difference even if the amplifier operates only within the hearing specter.

 

[PeterOo]

[…] it must benefit something to have more samples than less samples as otherwise all these high res, DSD, etc things make no sense...

I think you are on to something!

Now I can back to my point... listening high res files can have difference even if the amplifier operates only within the hearing specter.

if you check your empty mailbox every minute for a whole day, instead of once per day after the mailmen made his round, is it more empty?
Perhaps provide some evidence to support that hypothesis.

 

[Spaxton]

I think you are on to something!

If You want to say that I've discovered that high res makes no difference, You are wrong. Sorry. I listened to so much music on so many systems, compared a lot of them and yes, it makes difference. I simply discovered new things in some songs after listening in DSD.

if you check your empty mailbox every minute for a whole day, instead of once per day after the mailmen made his round, is it more empty?
Perhaps provide some evidence to support that hypothesis.

Hahahahahaha. A great one but not applicable to our topic. However, let me answer... It's not more empty but You will know more precisely that it is empty.

 

[PeterOo]

If You want to say that I've discovered that high res makes no difference, You are wrong. Sorry. I listened to so much music on so many systems, compared a lot of them and yes, it makes difference. I simply discovered new things in some songs after listening in DSD.


Hahahahahaha. A great one but not applicable to our topic. However, let me answer... It's not more empty but You will know more precisely that it is empty.

the question then becomes how you did you perform your comparison of DSD to 16bit @44.1kHz. DSD files often use different masters as used for CD releases. If you did the conversion to 16 bit yourself, how did you do it and did you check the levels your DAC outputs etc.
If there are advantages to high res has been discussed here at length in various threads(like this one started by amir), but is a bit off topic for the VMV A2 thread I think.

 

[Spaxton]

the question then becomes how you did you perform your comparison of DSD to 16bit @44.1kHz. DSD files often use different masters as used for CD releases. If you did the conversion to 16 bit yourself, how did you do it and did you check the levels your DAC outputs etc.
If there are advantages to high res has been discussed here at length in various threads(like this one started by amir), but is a bit off topic for the VMV A2 thread I think.

Hi,

Thanks for the reply.

The files they played were played in CD quality first and then in DSD. No conversion was done by myself as this was done on a hifi presentation. Back then they had a devialet and mcintosh amps (both were used sequentially but what I am talking is related to devialet), B&W speakers, tbh, I don't remember other equipment. I guess You want to point me to psychoacoustics (a fraction of a theory) because people can hear the difference even if it does not exist if their mind expect the difference. If this was the case back then on a hifi show, I would be suspicious myself but no, this was not the case. They asked us which one sounds better.
By the way, You are right. I think SMSL A2 is much out of this league and I will quit discussion about it because it can be endless. I want A2 for my office to pair with dynaudio speakers.

 

[PeterOo]

If you are thinking about buying the A2, did you look at the Sabaj A30a?
appears to be the same Axign based design from (more or less) the same company just at half the price!
On the down side, the A30a is not half as nice looking as the A2 imho.

 

[Spaxton]

If you are thinking about buying the A2, did you look at the Sabaj A30a?
appears to be the same Axign based design from (more or less) the same company just at half the price!
On the down side, the A30a is not half as nice looking as the A2 imho.

The words about it are useful, so thanks for mentioning.
I did look at it a few times but what actually pushes me to A2 is the EQ in SMSL and the design as well. I mentioned before that I own SMSL A8 (one of their first VMV) but A8 produces some high tone hissing sound at around 14 - 15 kHz accompanied with white noise which is constantly present no matter which input is selected. Basically, this is not easy to hear (with some speakers You need to put Your ear near to the speaker) and most of my friends said that they don't hear it but I do and I don't like it. Currently it drives some vintage bookshelfs from Magnat. Knowing this about A8 I needed to check if someone has experienced something similar with A2 and here I am.

What are Your thoughts about Sabaj A30a? If we exclude the design disadvantage, is there anything else? I noticed it has no fan but how about other things? A2 has the great result with SINR and THD.

 

[PeterOo]

I am a big fan of the Axign controllers. I love the elegant concept of getting near hypex/purify performance for a fraction of the cost and in a small package. They claim to be almost impervious to hum and noise. I have a Harman Kardon Citation Amp with Axign myself.

The A30a does have a fan but I do not read too many complaints about it. It did get some updates in the beginning like HP filtering on the main speakers if you use the Sub-output. But there are still some bugs and it looks like Sabaj has stopped updating this amp. Too bad. Not sure if the A2 has the same features and if it is being updated still. Not many owners reporting online.

 

[Spaxton]

Thanks for the info. I don't understand why they leave "holes" like they did not learn anything from previous problems. I don't use subwoofers so i wouldn't use sub output but if on the speakers isn't absolute silence (even if I put my ear on the speaker) once I stop playback or press mute, that is a big deal breaker for me.
So, basically it makes sense somewhere that it activates HP if You use a sub out but yet this should be left up to user to choose wether to activate HP on main speakers or not.
Maybe I should wait for A3 since I waited so much after receiving A8. I didn't even use it for a while (almost 3 years not used ) since I was very disappointed.

 

[muchkaev]

The other day I became the owner of vmv a2. I was confused by some things.
1) The equalizer has many more profiles than the 8 listed in the device description. Maybe a new version? But there are no new versions on the official website
2) The pitch of changing the timbre of high and low frequencies changes by two divisions, not one at a time. Maybe someone has encountered this?
3) The serial number is listed on the product, but I did not find the same serial number on the box

 

[Roland68]

The other day I became the owner of vmv a2. I was confused by some things.
1) The equalizer has many more profiles than the 8 listed in the device description. Maybe a new version? But there are no new versions on the official website
2) The pitch of changing the timbre of high and low frequencies changes by two divisions, not one at a time. Maybe someone has encountered this?
3) The serial number is listed on the product, but I did not find the same serial number on the box

According to the manual, the VMV A2 has 16 EQ profiles, just like the A30a.
The serial number issue is not unusual, I've had it several times.