Mhdt Labs Pagoda Review (R2R Tube DAC)

[audio2design]

There is a chance it is a supplemental tab for grounding. I feel I need to give them the benefit of the doubt,

However, these are the voltage jumper to select where the mains connects to the transformer, and those appear to be ground traces around it. Posted a few of their products. Scary.

On this particular one (Pagoda), it is not evident there is a PCB to case connection. Look at the PCB at the screw closest the AC Connector.

 

[solderdude]

Actually the ground was connected at least in this earlier revision ?
The socket has an extra lug that is not connected but on the PCB side there are 3 solder pins.

Below the Pagoda PCB with the transformer removed.
It seems to be a revised PCB though but the same mains socket.
In Amir's picture the ground plane does not come near the mains socket any more so it looks like the safety ground is not connected.
They should have used the socket without the safety ground pin in such case. There are no double insulated signs on the rear though and we cannot see the bottom side of the PCB (where the other mains wire seems to run) so can't say for sure.
Only an owner (or @amirm when he still has it) can confirm.

 

[antcollinet]

There is a chance it is a supplemental tab for grounding. I feel I need to give them the benefit of the doubt,
...

Good shout. A quick search for images suggests many PCB mount connectors have a supplemental tab - eg:

However, still begs the question about clearance to the ground plane being insufficient.

 

[oscar_dziki]

You need 1000$ interconnects to appreciate this tube buffer magic. I bet you haven't used those for testing Amir, did you?

 

[tomtoo]

I'd hazard a guess and claim that >= 90% of listeners won't be able to tell a difference vs a SOTA DAC with music, at least when considering distortion alone. Don't believe?

Try @pkane's Distort with similar settings :
View attachment 169004
The curvature of the voltage transfer can already be seen and yet it is not at all easy to identify this 1.5% distortion @ 0dBFS, in a blind listening test (ABX).

Same goes for the filterless NOS thing, once you really start to do proper (== single variable) comparisions you'll find that the ultrasonic images are inaudible.

Yes i believe, but why then buy a shiit dac for 1000$++, when i can buy a 100$ dac, that works better?
Its like saying you can buy perfect h2o for 1$, why not buy h2o with cowpiss in it for 1000$? You wont taste the difference?

 

[antcollinet]

Yes i believe, but why then buy a shiit dac for 1000$++, when i can buy a 100$ dac, that works better?
Its like saying you can buy perfect h2o for 1$, why not buy h2o with cowpiss in it for 1000$? You wont taste the difference?

Pretty certain I would

 

[ElNino]

Why is THD+N vs Freq measured to 20kHz with 90kHz BW here, but for example the Topping PA5 is measured to 15kHz with 45kHz BW:

Where the PA5 seemingly has the highest bump in THD+N under the same conditions:

View attachment 169134

Not an accusation of malfeasance, but spontaneously it seems like we're stretching the measurements in one case to show something, while not doing it in the other case.

This gets the award for the weirdest post I've ever seen on this forum. You're comparing a DAC that reaches 50% THD (!?!) at 20kHz to a power amp that reaches less than 0.02% THD at 20kHz? And somehow saying the latter has "the highest bump" in distortion? LOL. And then trying to draw some conclusion from all of that about Amir's selection of measurement bandwidth?

 

[radix]

On the bright side, I bet one can ABX identify it with high confidence.

 

[mhardy6647]

You need 1000$ interconnects to appreciate this tube buffer magic. I bet you haven't used those for testing Amir, did you?

Yup. Just the thing for a $99 tube "buffer" -- which is, in fact, not a proper buffer at all... but rather a distortion (effects) box.


Speaking of misues of tubes -- one of my personal favorites, FWIW.
At least it is cheap.

FX Audio 6j1 tube preamp - a $31 wonder

I've been spellbound by the tiny FX for several weeks now. If you follow the TPA3116 thread you know I'm not the only one who has fallen for this pint sized beauty. There's so much buzz in the other thread after pairing it with the class d Volt+D I thought it deserved a thread of it's own. The...

audiokarma.org

203 pages of fun.

 

[Lupin]

On the bright side, I bet one can ABX identify it with high confidence.

I bet the majority here can't.

 

[Trell]

I bet the majority here can't.

Do you mean the ability to setup a proper ABX with all needed equipment and knowledge? I think so too, and that includes me as well, and you I guess.

 

[voodooless]

Do you mean the ability to setup a proper ABX with all needed equipment and knowledge? I think so too, and that includes me as well, and you I guess.

I’m pretty sure he meant doing the actual test regardless of it’s complexity

 

[Trell]

I’m pretty sure he meant doing the actual test regardless of it’s complexity

Sometimes I enjoy pulling legs.

 

[Mnyb]

I bet the majority here can't.

Or the designers of this train wreck or thier customers

That’s what’s bewildering with this kind of cargo cult engineers. They optimise be ear what they can’t hear , due to bias of using sighted testing

But I would think this would be audible with some kind of music for some listeners , but I can’t prove that .

The other end of the spectrum is these DAC’s at the -115dB or better part of the charts , where it is said on this forum ? That they would be transparent on all all music for all people all the time . If they also have flat frequency response i’m Inclined to believe that . Seems reasonable.

Why do I think the pagoda will be audible ? It’s close to cassette tape in performance. Casset was alaways audible even with the best decks one could buy ? Or i’m I wrong does it performs a tad better than cassette ?
That and noise if product is noisy everyone can hear that . I think low noise is more important than extraordinary low levels of THD.

For testing purposes one must stop attribute any value to sighted uncontrolled listening tests . An infinite amounts of anecdotes is still not prof of anything, it’s just recollections of how someone experienced the product. Nothing more nothing less.

In fairness it’s no longer rocket science or cost much to achieve perfectly transparent performance for a DAC preaamp or headphone amp so we should expect that and point out products that deviate.

 

[KSTR]

I think ABX'ing this DAC against one of the top-tier DACs would be successful just alone from the difference in background noise. Once that is factored out -- by mixing the idle noise signal into the output of the reference DAC -- I would guess ABX'ing the distortion performance is going to be quite a bit harder. ;-)

 

[solderdude]

What could be fun is that for instance when controversial equipment like this is reviewed that @amirm makes a 2 downloadable files available where a reference piece of music is recorded (using reference quality ADC) of the DUT (DAC Under Test ) and via a reference DAC.

I understand Amir has better things to do though but it could be interesting.

 

[thulle]

This gets the award for the weirdest post I've ever seen on this forum. You're comparing a DAC that reaches 50% THD (!?!) at 20kHz to a power amp that reaches less than 0.02% THD at 20kHz? And somehow saying the latter has "the highest bump" in distortion? LOL. And then trying to draw some conclusion from all of that about Amir's selection of measurement bandwidth?

If I misinterpreted it that way I'd also think it was among the weirder posts, but that's not what I'm saying. "The highest bump" isn't a comparison between the devices, but a comparison of where the difference occurs in the graph on the same device when we change the measurement bandwidth. It doesn't matter for my point if the Pagoda (or the PA5 for that matter) was -500dB distortion+N or +50dB distortion+N, it's about what measurement bandwidth we use and why.

 

[dc655321]

If I misinterpreted it that way I'd also think it was among the weirder posts, but that's not what I'm saying. "The highest bump" isn't a comparison between the devices, but a comparison of where the difference occurs in the graph on the same device when we change the measurement bandwidth. It doesn't matter for my point if the Pagoda (or the PA5 for that matter) was -500dB distortion+N or +50dB distortion+N, it's about what measurement bandwidth we use and why.

To be fair, I've read your post several times and your complaint is not clear to me either.
Is it just that the bandwidth is different?

FWIW I quickly checked a few reviews here - the bw for thd+n measurements was 90kHz for dacs and 45kHz for amps.
Amir seems relatively consistent, so...?

 

[Rottmannash]

Here, we have a perfect example of wasting your throwing good money out for bad

Pray tell, what is a "vampire BNC"? I need one, whatever it is.

 

[thulle]

To be fair, I've read your post several times and your complaint is not clear to me either.
Is it just that the bandwidth is different?

FWIW I quickly checked a few reviews here - the bw for thd+n measurements was 90kHz for dacs and 45kHz for amps.
Amir seems relatively consistent, so...?

Yeah. That's the same note as the earlier reply I got in this thread:

Mhdt Labs Pagoda Review (R2R Tube DAC)

What the artist / recording engineer intended? Sounds like we need "Artist / Recording Engineer" approved gear....that is gear that can actually provide the experience that was intended. Otherwise who knows what they intended something to sound like...do you? Oh excuse me while I finish...

www.audiosciencereview.com

But no answer on the clarification: Why do we care about high frequency distortion that could intermodulate down into the hearable range in one case and not the other?