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Review and Measurements of SMSL AD18 DAC & Amp

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amirm

amirm

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Maybe you didn't study the circuit diagram of the amplifier.
No, it is not part of my job description. :(
In my opinion, it is a bad headphone amplifier and DAC, because it uses
MAX97220A and TAS1020B&VT1620A and they are low-quality and sound bad.
I am asking if this is a "digital amplifier" why it would create a digital bitstream from USB as well as its S/PDIF input. If it has a DAC then it is not a digital amplifier. Which is it?
 

bluesky

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No, it is not part of my job description. :(

I am asking if this is a "digital amplifier" why it would create a digital bitstream from USB as well as its S/PDIF input. If it has a DAC then it is not a digital amplifier. Which is it?
My understanding is that AD18 is a digital amplifier but it need to support multiple inputs to compete with other digital amlifier such as Topping mx3 and FX-Audio D802C in this price range. If possible, please measure this amplifier in this way to clarify the truth of "full digital amplifier". An amplifier, low cost, good sound quality is an impossible mission.Thanks a lot!:)
 
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daftcombo

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For me it wasn't clear, but I just had the confirmation that the analog input of the AD18 had an ADC just afterwards, before amplification.
 

daftcombo

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Which means, if I read well, that Amir tested ADC + DAC for:

frequency response graph
ultrasonics graph
SNR graph

The performance might be better with USB in, without that ADC step.
 

vert

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Thank you Amir for a greatly anticipated review. The results bring no validation to the views laid down in the following articles by a French audiophile (possibly an engineer) about a different FDA amp, the FX-Audio 802C. Here's somebody who's had access to all kinds of first-class gear, saying this thing basically represents an end-game giant killer. Those articles were what sparked my interest in such amps in the first place, even though I ended up taking a different route (separate DAC + AVR). They're well worth a read. The author hasn't posted anything else on his blog about FDAs in the four years or so since the original articles. In the comments under one of the articles, a reader asked him about the AD18, and he said he could make no recommendations other than for the 802C. Another reader commented some 802C units had different components and didn't work as well. So whether FDAs are the future of high fidelity or not shall remain a mystery for the time being.

https://audiolalies.blogspot.com/2015/03/derriere-le-micro-exactement.html
https://audiolalies.blogspot.com/2015/05/retour-sur-le-fx-audio-d802.html
https://audiolalies.blogspot.com/2015/08/volume-44.html
 

daftcombo

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Hi,

I confirm a channel mismatch.

On this graph, my left speaker is fed by the left channel (bottom) then by the right channel (top, with yellow glowing).

Around 1dB difference, getting worse after 10 kHz.

I can hear it on electronic music where all is supposed to be centered.

EDIT: I made a mistake in my measurements (one curve had windowing, the other didn't) & just deleted the post I've quoted above.

Actually, THERE IS NO CHANNEL MISMATCH WITH MY UNIT.


I guess I really wanted to find a mismatch... especially because I heard one. My bedroom isn't symetrical and the speakers I use are DIY so the difference could probably come from the room + speakers but no from the amp.

So to state it again: when I plug the same speaker with the L channel then with the R channel of the SMSL (through optical in), I have a very good match...

I will do the same with the right speaker to confirm.
 

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daftcombo

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Here I feed my right speaker (D) with :
a) a left channel sweep in the left channel of the amp
b) a right channel sweep in the right channel of the amp
NO MISMATCH. :) (Or at least < 0.1 dB everywhere, except on a resonnance peak where I see almost 0.2 - that could be a measurement error. Nothing special after 5 kHz anyway.)
(Phase is almost identical too, just a few degrees difference around 30Hz.)

Chain is:
PC (Foobar2000) [USB out] --> USB cable --> Topping D10 [USB in, optical out] --> 10 meters optical cable --> SMSL AD18 [optical in, speaker out] --> speaker cables -->
DIY speakers



Don't forget that @amirm didn't do that test. He noticed a mismatch when feeding the SMSL via AUX INPUT, not optical.

So either I was lucky with my unit, or optical and AUX have a different behaviour. I cannot test AUX for the moment.
 

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bluesky

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Here I feed my right speaker (D) with :
a) a left channel sweep in the left channel of the amp
b) a right channel sweep in the right channel of the amp
NO MISMATCH. :) (Or at least < 0.1 dB everywhere, except on a resonnance peak where I see almost 0.2 - that could be a measurement error. Nothing special after 5 kHz anyway.)
(Phase is almost identical too, just a few degrees difference around 30Hz.)

Chain is:
PC (Foobar2000) [USB out] --> USB cable --> Topping D10 [USB in, optical out] --> 10 meters optical cable --> SMSL AD18 [optical in, speaker out] --> speaker cables -->
DIY speakers



Don't forget that @amirm didn't do that test. He noticed a mismatch when feeding the SMSL via AUX INPUT, not optical.

So either I was lucky with my unit, or optical and AUX have a different behaviour. I cannot test AUX for the moment.
I also hope amirm do this test!
 

daftcombo

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I also hope amirm do this test!

I am happy that my unit doesn't have this mismatch issue on the optical in. Now the only remaining problem would be distortion. I cannot hear distortion as I speak, but in a comparison with another amp it could be something noticeable, I don't know.
 

daftcombo

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I think there is balance control in AD18 and if so, you can compensate there.
I didn't find the balance control. I think there isn't any.
But once again, some units (like mine) might be ok via optical.
 

daftcombo

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It would be very useful to know which version Amir tested.

Mine is V3.1.
There are at least a V1 and a V2.2 around.
 

Paulmac

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Hum... How do you amplify a multichannel system, then?
I have given up on dolby surround in any variant. The dialogue gets lost. I use the passive Hafler system to run a third rear speaker. I enjoy the AD18 - I think its fine, and it produces clear dialogue. I have to say to anyone reading this if you are tempted to try the Hafler type passive rear speaker set up, google it first. Its very simple but not all amps tolerate it. When I tried it on my Ad18 I half expected it to blow up, but it didnt. Ive been running like that for 7 months without issue. I have never heard dolby system that produced clear dialgoue. Ive heard plenty. And even in movie theatres, for me, its a waste of time going. I have a friend with an expensive home theatre system and its case of putting up the sub titles if one wants to know the dialogue. Dolby in any variant sucks badly. but that's just my opinion. Human hearing alters dramatically with aging. What sounds great for a teenager is very different to what sounds good to an old croak like me. For sure, its a waste of time me buying tickets to go out and watch a movie these days - I cant understand a word said. I wait till I can watch the movie at home via the Fetch box. Im quite happy with what I have. The problem with dolby is not dynamic range, there is something else going on. At home I dont need to turn the bass down so its not purely that. If I owned a movie theatre I'd cater for the old croaks like me via bluetooth streaming of the soundtrack in good old stereo. Bring your own head phones. And that was a partial solution for me at home too but with what I have now I dont need to. Im mainly talking action movies, but it can afflict any soundtrack. Don't get me wrong, the testing of AD18 done here is excellent and very useful. The amp has its place and it certainly isnt the gift from god some reviews (I have read some of those French ones also) claim. Its a good little amp in a non critical situation. I'm not disappointed with mine.
 
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Paulmac

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I've been reading the patent application for the Icepower class D amplifier here: https://patents.google.com/patent/US6297692B1/en and from what little of it I understand, well, the Nielsen type class D, now known as ICEPower, are significantly improved over prior class D designs. Which means, reading the application, high levels of distortion are to be expected in those prior designs. Seeing as I have the AD18, and seeing as if I spaghetti for a month straight I can afford to buy an ICEPower ASX125x2 module next pay, well, I'm going to get the AX125x2 going and compare it to the AD18, selling the loser. I read that the input characteristics of the icepower module will be tricky, but I do have a couple of preamps and a Behringer miniFEX 800 which should be suitable to feed the icepower module. If I dont blow myself up in the process of wiring up the icepower module, I'll report what my perceptions are here.
 

Paulmac

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Excuse me again for popping in again. I have been thinking and listening to the AD18. And actually, after considering getting an ICEPower ASX125x2 module and playing with that, I reconsidered. Ive just watched another action movie and enjoyed it, almost every word being clearly reproduced. And I'm now thinking dang it, I like the sound of the system I've got. It eats soundbars for breakfast and I have no complaints. It's a great little amp and Im glad I bought it. Being an eccentric I hooked up a Behringer Minifex 800 to the AD18 and set Independence Day Resurgence to "Cathedral" through the FEX800. It was very interesting, as if I was part of the universe. Most convincing. Way better than Dolby.
(TRS to rca adapters were all I needed). I guess, if this is ok, I want to share this: https://www.wsj.com/articles/cant-hear-in-noisy-places-its-a-real-medical-condition-1474909624
Can’t Hear in Noisy Places? It’s a Real Medical Condition
New studies of causes and treatments for deterioration in your brain’s ability to decode words in loud situations, also known as hidden hearing loss.

Many people have trouble understanding conversations in noisy situations. Scientists are beginning to understand why.
The problem is sometimes called “hidden hearing loss”: Standard hearing tests don’t measure it, and sufferers are often told their hearing is normal. But the distress they feel struggling to discern what others are saying in crowded restaurants and business meetings is real.
Now there’s growing evidence that the causes of problems processing speech amid noise are different than the causes of problems hearing sound. Scientists believe exposure to loud noises can erode the brain’s ability to listen selectively and decode words, without causing traditional hearing damage. Difficulty understanding speech amid noise can set in long before traditional hearing loss.
“This is something we’ve recognized for a long time—and this research tells us why it’s happening,” says Anne Oyler, associate director for audiology at the American Speech-Language-Hearing Association. “Audiologists will have to start actively looking for this disorder.” end quote. I propose that this is my problem, and that my difficulty living with dolby surround sound is caused by the same condition that causes me to loose the words of a conversation I am listening to in pubs and cafes. In any case, I can live with the Ad18 and can follow the dialogue of movies with my set up. Whereas I'd run like hell from a surround sound receiver playing an action movie. The ears and brain are the last link in the chain of sound reproduction. People need to buy equipment which suites them. "Hifi for Oldies" might not be much of a brand name, but its a real need.
 
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Paulmac

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The cheapest icepower based amplifier I could find in fully built form was a pioneer car amp. (https://www.pioneerelectronics.com/...r+Amplifiers+Bring+About+the+Next+''ICE''+Age ) and this one is the cheapest one: https://www.pioneerelectronics.com/PUSA/Car/Amplifiers/GM+Digital+Series/GM-D1004 GM-D1004. All the GM-D series contain icepower car modules. The D1004 is small. It cost me $129 new on Ebay Australia. I have a regulated 13.8 volt 12 amp power supply. I wired it up using it in stereo mode using the standard wiring (not bridged, with the rms power being therefore 45 watts a channel. Listening to Aurora (
etc) the sound stage was wider, far more forward with a greatly improved clarity. The bass was a little recessed. I then consulted the Pioneer online manual as the paper manual omitted bridge mode wiring instructions, which I recalled the online manual contained. Rewired into stereo bridge mode (90 watts rms per channel for two channels only) the bass became stronger. The power supply remained cold over two listening of thrashing the pioneer. Switching back to the SMSL AD18, the sound was still the pleasant sound I am used to from it, but clearly the D1004 was superior. Oddly, for the first two minutes or so of listening to the AD18, both I and the friend listening with me were aware, for the first time, of an echo which just seemed to be present. We both soon stopped noticing it. It was very slight and a bit weird. For the listening test of the Pioneer I was using the headphone socket output to the feed the Pioneer. I have read people not considering the headphone output to be the best, but even so, the Pioneer romped all over the AD18. I still like the AD18 - its a very good little amp. My el cheapo icepower comparison leads me to think that investing in an ASX series icepower amp module would be a worthwhile thing to do. Meanwhile, the Pioneer might go in my car or I might sell it on ebay. It was just an experiment that won't, in the end, cost much. Im still happy with the AD18. You get what you pay for.
 

Paulmac

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Correction to my post above. I rechecked the Pioneer web pages that describe their car amps that are Class D and which use IcePower chips. I have found that some pages are now down. It is now quite confusing. I removed the Pioneer GM-D1004 from its case to look at the chips. None of them are labelled IcePower. I now believe I either mis read the Pioneer pages 3 weeks ago - The page at the time described the GM-D series amps as having Icepower technology. I cannot confirm this as of today. In any event the GM-D1004 is a very nice sound amp. It appears I am in error in thinking it possessed IcePower chips.
 

daftcombo

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After I let it on for 12 hours (forgot to turn it off), the unit was a bit hot and the knob was and is still acting strangely. I couldn't turn it off with a long press, I had to use the remote.

Now, the knob allows me to turn the unit on (short press) and control the volume, but I can't change options anymore. I have to use the remote everytime, including for turning it off.
 

dorirod

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Hello, new to the forums, thank you for all the great reviews!

I am currently using the AD18 to power KEF Q100 speakers for my tv room. I am wondering if it would be worth it to add a Topping DX3 Pro to use as the DAC and also HP amp, and then just feed its RCA output to the AD18 to drive the speakers until I find a more decent speaker amp.

Do you think I would get much benefit in fidelity from this? I occasionally use the HP out of the AD18 with a long cable, and I hear a buzz that's annoying, but I rarely use it so it would mainly be to get better performance out of the speakers for music listening.

Thanks,
Dori
 

daftcombo

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Hello, new to the forums, thank you for all the great reviews!

I am currently using the AD18 to power KEF Q100 speakers for my tv room. I am wondering if it would be worth it to add a Topping DX3 Pro to use as the DAC and also HP amp, and then just feed its RCA output to the AD18 to drive the speakers until I find a more decent speaker amp.

Do you think I would get much benefit in fidelity from this? I occasionally use the HP out of the AD18 with a long cable, and I hear a buzz that's annoying, but I rarely use it so it would mainly be to get better performance out of the speakers for music listening.

Thanks,
Dori
Hi and welcome.

No for adding a DAC because the amp section is the limiting factor of the AD18.
 
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