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Hardware Teardown of xDuoo TA-01 DAC and Headphone Amplifier

amirm

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#1
This is a follow up to my review of xDuoo TA-01 DAC and headphone amplifier. The TA-01 is powered by an external switchmode power supply:

xDuoo TA-01 DAC Power Supply.jpg


Nearly a dozen screws hold the unit together. Once open, you are greeted with this:

xDuoo TA-01 Main PC Board.jpg


Cleverly, it uses some kind of off-the-shelf DAC module vertically mounted. No shielding is provided though so noise leakage could occur between it, and the rest of the unit.

Overall "feel" of the PC Board is that of cheap chinese stuff you buy from ebay. Nothing to put your finger on per-se, but it is just typical of the kind.

Architecture is rather simple with either the analog input or the output of the USB DAC driving the tube pre-amp stage. That in turn powers a set of transistors on yet another daughterboard. This allows the output impedance to be much lower than if you used the tube as is.

What was puzzling was the transformer on the input and a pair of diodes. May be some kind of filter but a bit odd.

The tube in the unit I received was the Russian Genalex. Don't know if that is stock or an upgrade:

xDuoo TA-01 Genalex Tube.jpg


Capacitor brands seem to be mixed from no name to treasured Rubycon:

xDuoo TA-01 Rubycon Capacitor.jpg


Something doesn't smell right though. Notice the jagged writing on the capacitor on the left, compared to the picture in Rubycon catalog. Can't say it is counterfeit but it might be.

On the positive side, a number of capacitors were rated at 105 degree C which is a plus over the cheaper 85 degree parts. Then again if the caps are fake, this designation doesn't mean much.

Zooming in the DAC we see:

xDuoo TA-01 DAC board.jpg


An Xmos controller handles USB functions and then drives a pair of stereo CS4398 DACs. I am assuming they are combined to get better signal to noise ratio.

xDuoo TA-01 Xmos USB Controller.jpg


Here is the view from rear of the main board:

xDuoo TA-01 DAC Rear PCB.jpg


We see a couple parts whose ID is scratched off. Boo! :D

Like the spring at the bottom and two ground traces on each side. The ones on the side though sit on anodized aluminum rails of the chassis so likely don't do much (where the spring lands is nicely sanded off for good contact).

Conclusions
Overall look and feel of the xDuoo TA-01 DAC guts is rather cheap. Outside of suspicious capacitors though, nothing jumps out that is unsafe or horribly made. In other words, you are getting what you paid for but no more. This is in contrast to feel of the control and overall industrial design of the unit which is a step above bargain price products.
 
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#2
What is the purpose of them scratching off part numbers?

Hiding origins? 2nd-hand parts? Design permissions?

Regardless, this would instantly make me not trust a company if I found the same thing.
 

amirm

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#3
The main reason is to stop others from copying their design. This being China, everyone copies stuff so they are trying to make it a bit harder.
 

Rod

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#4
It comes with a cheap Chinese made tube. The Genalex was added for its more neutral tone. The Mullard Remake and Electro-Harmonix tube in this dac/amp did not make it sound better with there more tube like sound to me. So I was trying to hide the sound signature of the tube as much as I could. I agree with Armin, the tube wasn't needed. I felt I didn't overpay or underpay, I got what I was expecting in this price range.
This will become travel gear since its 12 volt. Good enough for the occasional use.
Thanks Amirm
 
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Rod

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#6
"What was puzzling was the transformer on the input and a pair of diodes. May be some kind of filter but a bit odd."
Could it be this? I dont know circuit design much at all, just a hunch.
Screenshot (4)_LI.jpg
 

Jimster480

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#8
Surprised to see dual DAC at this price point? It also has the wrong specs according to this screenshot.... it says WM8740*2 but its CS4398?
I understand that Crystal bought Wolfson, but it doesn't make the 2 chips the same.
 

watchnerd

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#10
The tube in the unit I received was the Russian Genalex. Don't know if that is stock or an upgrade:

View attachment 12483
Is that tube really doing much?

Given the tiny size of the transformer, the lack of any rectifier / followers, and no apparent boost converter, I can't see how there is enough voltage going to the tube (which looks to be a 6DJ8?) for it to be doing any meaningful amplification.
 

Rod

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#11
I dont think its there for gain. I could tell a difference between the 3 tubes I tubes used to test it, so it is having an effect on the sound sig. The gold lion 12au7(low gain tube) was the smoothest, most neutral so I used it. Does it have the tube sound of a descent tube amp? No.
 
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Rod

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#12
Depended on the song to. Male deep gravely voice? Yes I could hear the tube.
High pitched female voice or instrumental? Hard to tell.
 

watchnerd

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#13
I dont think its there for gain. I could tell a difference between the 3 tubes I tubes used to test it, so it is having an effect on the sound sig. The gold lion 12au7(low gain tube) was the smoothest, most neutral so I used it. Does it have the tube sound of a descent tube amp? No.
Depended on the song to. Male deep gravely voice? Yes I could hear the tube.
High pitched female voice or instrumental? Hard to tell.
Oh, so the tube must just be an output buffer....in which case tube rolling will only have a mild effect compared to a more purely tube amp.
 

Rod

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#14
Yes, I can see also why the gold lion was the more expensive tube than the other ones I tried. Maybe transparent is the correct descriptive word instead of neutral. Sorry its hard for me to describe what I hear.
 

watchnerd

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#15
Yes, I can see also why the gold lion was the more expensive tube than the other ones I tried. Maybe transparent is the correct descriptive word instead of neutral. Sorry its hard for me to describe what I hear.
I get it...sound is always hard to describe, and tube differences are frustrating to describe since so much of the signature is in differences in harmonic distortion components as opposed to fundamental tones.

BTW, if you're looking for a less-tube-sounding tube, I would suggest the Sovtek 12AX7 LPS. No idea if it will work here, but since you said you had a 12AU7 in there before, it might...
 
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#16
I think there was a bunch of complaining about this on Massdrop if I recall correctly.
I have one of these and having issue finding the xmos driver, xDuoo sent me one but it wouldn't work.

Otherwise I think it sounds great with lots of power, I got a NOS IEC Mullard ($30) and it leveled up on quality times 5 (clarity, sound stage, imaging, smoothness etc.). xDuoo said the reason they switched chips was the Cirrus chip had newer features. Just wish the driver wasn't an issue for me. I had got a workaround but it was only 16-bit so probably the incorrect xmos driver.

I liked it so much I ended up buying an open box TA-10 so should have that next week.

Russian Genalex is probabaly better than the stock Chinese one I got, they make the Gold Lion tubes everyone raves about.
 
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Rod

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#17
I have one of these and having issue finding the xmos driver, xDuoo sent me one but it wouldn't work.

Otherwise I think it sounds great with lots of power, I got a NOS IEC Mullard ($30) and it leveled up on quality times 5 (clarity, sound stage, imaging, smoothness etc.). xDuoo said the reason they switched chips was the Cirrus chip had newer features. Just wish the driver wasn't an issue for me. I had got a workaround but it was only 16-bit so probably the incorrect xmos driver.

I liked it so much I ended up buying an open box TA-10 so should have that next week.

Russian Genalex is probabaly better than the stock Chinese one I got, they make the Gold Lion tubes everyone raves about.
xmos driver that works with windows----https://mega.nz/#F!hCBkVBDA!BgS6cuIjKbD0seDxDGKBNQ
You will need version 3.0
The xduoo I had is the one reviewed here.
 
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#20
I have to admit I really enjoy using it with my modified m1060c's and the Mullard tube made a difference even though it's not a pure tube amp. I had a somewhat decent solid state DAC and preferred this over it even though it's cheaper.
 
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