xDuoo TA-20 Tube Balanced Headphone Amplifier Review

[pmconsulting]

I don't recommend any tube amplifier. I see no positives in them other than nostalgia.

It's now 2021 and I just stumbled across this forum and this particular post. What a huge timesaver this forum has been for me. This quote from amirm is pure gold! I really appreciate your mathematical accuracy. Truly simplifies decision making. I can be sure that whatever I buy in the way of tube amp will only ever be about horsing around to soften the audio like any other reverb or filtering might give me my jollies. But if I want to hear what the musician wanted it to sound like, stick to the numbers. Thanks amirm!

 

[seamon]

Just want to confirm - If I connect powered speakers to the RCA out, will it go through the tube preamp section?
It should but I want to confirm definitively.

 

[hmscott]

Just want to confirm - If I connect powered speakers to the RCA out, will it go through the tube preamp section?
It should but I want to confirm definitively.

I haven't tried the TA-20 AUX Out / Pre-amp function myself yet, I may get time soon to try it and report back. Perhaps I answered you on head-fi? I replied there now to a similar question. Perhaps my answer there will help until I get a chance to test it:
xDuoo MT-604 Balanced Tube | Headphone Reviews and Discussion - Head-Fi.org

I am assuming the function of an AUX Out would be to provide a variable volume output - not a fixed or untouched "passthrough" output, but again I haven't tested it yet, I can try to get time to do it and report back here (and on Head-Fi.org) later.

 

[seamon]

I haven't tried the TA-20 AUX Out / Pre-amp function myself yet, I may get time soon to try it and report back. Perhaps I answered you on head-fi? I replied there now to a similar question. Perhaps my answer there will help until I get a chance to test it:
xDuoo MT-604 Balanced Tube | Headphone Reviews and Discussion - Head-Fi.org

I am assuming the function of an AUX Out would be to provide a variable volume output - not a fixed or untouched "passthrough" output, but again I haven't tested it yet, I can try to get time to do it and report back here (and on Head-Fi.org) later.

I would appreciate it if you can test this out

 

[hmscott]

I would appreciate it if you can test this out

I've found the TA-20 RCA AUX Out is a fixed output. And, the TA-20 has no switch to change between fixed or variable output.

The TA-20 Volume knob cannot be used to control the output volume level of the AUX Out, so the TA-20 cannot be a Volume Control Pre-amp to a fixed gain Amplifier.

If you have powered speakers with a remote control for volume, that would work great.

More later.

 

[seamon]

I've found the TA-20 RCA AUX Out is a fixed output. And, the TA-20 has no switch to change between fixed or variable output.

The TA-20 Volume knob cannot be used to control the output volume level of the AUX Out, so the TA-20 cannot be a Pre-amp to a fixed gain Amplifier.

If you have powered speakers with a remote control for volume, that would work great.

More later.

Then looks like the tubes won't affect the RCA out

 

[hmscott]

Then looks like the tubes won't affect the RCA out

The TA-20 manual page has a diagram for the back panel with brief details about the AUX Out:

10. AUX analog stereo output port, the sound source is taken directly from AUX1 or AUX2

That is useful if we are inserting the TA-20 headphone amplifier into an existing source chain, so we can pass-through an audio signal.

Another useful feature for a future revision would be to have a Preamplifier Output, switched for fixed output or variable output.

I have emailed [email protected] and asked if the XLR input has the same effective signal passthrough, I'll update when I get a response.

Spoiler: TA-20 Back Panel Diagram from TA-20 Manual

Spoiler: How to find the TA-20 manual page

I had a problem with the TA-20 manual online:

The TA-20 manual download from xduoo.net pops up showing a TA-10 manual page. The TA-20 page didn't show up for me until I used another previewer just now. The TA-20 Manual PDF has the TA-10 page above the TA-20 page:
Product Manual - xDuoo official store
https://drive.google.com/file/d/1D0FWQAQaGAa0LMhbdnIqIa4PJ8hdJF-9/view?usp=sharing

The xduoo.com Chinese TA-20 manual PDF doesn't have the TA-10 manual page in it, and I can see the diagram for the TA-20, but the description for Item #10 is in Chinese:
产品说明书下载 - 深圳市乂度科技有限公司 官方网站 (xduoo.com)
文件分享 (weiyun.com)

I've asked [email protected] to please fix the English TA-20 Manual.pdf download by removing the leading TA-10 manual page.

Update: I received the answer from Xduoo: "AUX OUT直接从XLR输出" - "AUX OUT output directly from XLR". So all 3 inputs are simply passed through without touching the Tube Preamplifier or Solid-State final amplifier of the Xduoo TA-20.

 

[cestmoi]

Is the TA-20 still a good purchase nowadays?

I've been looking for my first 'tube' amp and the TA-20 seems a good option, but I'm not used to tube amps, so my conclusion may be not that accurated...

 

[hmscott]

Is the TA-20 still a good purchase nowadays?

I've been looking for my first 'tube' amp and the TA-20 seems a good option, but I'm not used to tube amps, so my conclusion may be not that accurated...

Sure, why not? Good designed Tube amps, in general, "last" a long time, there are popular Tube amps decades old, and the TA-20 is "only" about 6 years old as a product, so it is still a young design.

Remember though, that the TA-20 is a Tube Hybrid, so it isn't the tubiest of tube amps, but for the price the TA-20 Tube Preamp tube rolling does change the sound to some degree. I'm using Brimar 6060 Yellow "T" 12AT7 tubes, and they sound great, but then again the stock tubes sounded great too, but had a more SS sound.

A "real" tube amp will be more expensive and it is tough to find a good tube amp with the same output power and tolerance of Planar Headphones - like my Hifiman / SendyAudio headphones. That is where the SS amplifier section comes in, and why I bought a Hybrid instead of a 100% tube amp.

The Xduoo product family has a number of other models in it, with newer releases, but no replacement for the TA-20 Balanced Headphone Amplifier only features, so the TA-20 is the current model with its features.

The TA-30 would be the next model "up" in Xduoo's line, with 1W more power but about 2x as expensive and a good portion of the cost is spent on an internal DAC. I already had a DAC, the Topping D90 MQA, so I was set up with the DAC part already. If you are looking for a DAC/AMP combo the TA-30 Balanced DAC/AMP might be a great choice.

I'm hoping Xduoo will release a higher power TA-20, but so far Xduoo doesn't see the need, so the TA-20 might be "it" for a while, as it has been since 2016 when the TA-20 was released.

What do you have now? And, if you do get the TA-20, please come back and let us know.

 

[cestmoi]

@hmscott

I own just a few entry level stuff such as Fiio K5 Pro, E1DA Pdv2, Fiio Q3, and a SMSL sh-8s amp. As you see, they all are SS amps.


My primariry use of the tube amp will be to drive a HD6xx and a HE4xx as well. I was thinking of grabbing a TA-10r, but it is a non-balanced combo and I've just ordered an 'alternative' balanced DAC to pair with the sh-8s. With the TA-20, I could run all balanced...

 

[hmscott]

@hmscott

I own just a few entry level stuff such as Fiio K5 Pro, E1DA Pdv2, Fiio Q3, and a SMSL sh-8s amp. As you see, they all are SS amps.

My primary use of the tube amp will be to drive a HD6xx and a HE4xx as well. I was thinking of grabbing a TA-10r, but it is a non-balanced combo but I've just ordered an 'alternative' balanced DAC to pair with the sh-8s. With the TA-20, I could run all balanced...

Well, that sounds like a great combination to try out. What is the make/model of the Balanced DAC?

The TA-20 balanced output - into a 4-pin to 4mm adapter - sounds great with my HD660s and other Dynamic headphones. My Sennheiser HD598cs's sounded so good on the TA-20 I ordered the HD660s's and they sound great too.

The Sendyaudio Aiva sound great too, and at the time the Hifiman HE6SE V2 and Ananda were on sale and they sound great too!, and I haven't felt the need to buy any new headphone/IEM since then. The TA-20 tube rolling has been enjoyable with all of my headphones.

I still have my Topping A90, rotating it into listening sessions, but I always gravitate back to the TA-20.

You might enjoy the TA-20 as well

 

[cestmoi]

Well, that sounds like a great combination to try out. What is the make/model of the Balanced DAC?

The TA-20 balanced output - into a 4-pin to 4mm adapter - sounds great with my HD660s and other Dynamic headphones. My Sennheiser HD598cs's sounded so good on the TA-20 I ordered the HD660s's and they sound great too.

The Sendyaudio Aiva sound great too, and at the time the Hifiman HE6SE V2 and Ananda were on sale and I haven't felt the need to buy any new headphones since then, and the TA-20 tube rolling has been enjoyable with all of my headphones.

I still have my Topping A90, rotating it into listening sessions I always gravitate back to the TA-20.

You might enjoy the TA-20 as well

I own a HD599se. I hope it may improve with the TA-20 too...

The DAC is a 'LEAF Dac Dual 9038Q2M' (it has a topic here).

 

[SIY]

From tube to tube (within the same type), there will be some variations in noise and microphonics. Most of the rest of the differences will disappear if you evaluate ears-only, assuming that the tubes aren't wildly out of spec.

If this is the typical Chinese design, the topology will be a pseudo-SRPP; pseudo because the loading will almost never be optimized to achieve actual push pull operation. It's really not a great way to do things (distortion is high in exchange for larger swing, not needed here), but for whatever sociological reason, that circuit just seems to have firmly taken hold there, whether for preamps, power amps, headphone amps...

Someone with actual knowledge could drop that distortion by an order of magnitude with a few circuit mods and simplifications. 12AU7/ECC82 is not a particularly linear tube, but you can still get more out of it than they did. Or optimize the circuit for something better but less fashionable.

 

[hmscott]

From tube to tube (within the same type), there will be some variations in noise and microphonics. Most of the rest of the differences will disappear if you evaluate ears-only, assuming that the tubes aren't wildly out of spec.

If this is the typical Chinese design, the topology will be a pseudo-SRPP; pseudo because the loading will almost never be optimized to achieve actual push pull operation. It's really not a great way to do things (distortion is high in exchange for larger swing, not needed here), but for whatever sociological reason, that circuit just seems to have firmly taken hold there, whether for preamps, power amps, headphone amps...

Someone with actual knowledge could drop that distortion by an order of magnitude with a few circuit mods and simplifications. 12AU7/ECC82 is not a particularly linear tube, but you can still get more out of it than they did. Or optimize the circuit for something better but less fashionable.

Why don't you buy a Xduoo TA-20?, and then you can try out your ideas hands-on, as useful modding info would be welcome to other TA-20 owners.

BTW, 12AU7's do sound great, but 12AT7's are the sweet spot with the TA-20, IMHO. After listening to my first pair of 12AT7's the sound was even more solid and enjoyable, and I've been finding great sounding 12AT7 compatible tubes since. The 12AX7's I've tried are a bit too "hot" sounding.

But, all of that is with the TA-20 stock circuits, perhaps you can improve on them? If you do, please keep us posted on your progress

 

[SIY]

Why don't you buy a Xduoo TA-20, and then you can try out your ideas hands-on, as useful modding info would be welcome to other TA-20 owners.

BTW, 12AU7's do sound great, but 12AT7's are the sweet spot with the TA-20, IMHO. After listening to my first pair of 12AT7's the sound was even more solid and enjoyable. 12AX7's are a bit too "hot" sounding, too forced.

But, all of that is with the stock circuits, perhaps you can improve on them? If you do, please keep us posted on your progress

If you want to buy me one (edit: or send me yours), I'd be glad to. If I were in the market for a tube HP amp for myself, I'd design/build from scratch.

A 12AX7 is not suitable for circuits designed for 12AU7. They are VASTLY different tubes. For some reason, people think that if it fits the socket, they can usefully swap it in. People are wrong.

 

[hmscott]

If you want to buy me one (edit: or send me yours), I'd be glad to. If I were in the market for a tube HP amp for myself, I'd design/build from scratch.

A 12AX7 is not suitable for circuits designed for 12AU7. They are VASTLY different tubes. For some reason, people think that if it fits the socket, they can usefully swap it in. People are wrong.

When I asked Xduoo if the TA-20 that comes stock with a pair of 12AU7's will operate correctly with 12AT7 / 12AX7 tubes, and they said they support all 3 tubes in the TA-20 under warranty. I've posted their responses to my questions I've asked them here in this thread before, you must have missed them.

Also, I've met someone recently that is running E80CC's in the TA-30 - and Xduoo said the same thing, that they support it under warranty.

And yes, I've checked the design documents and specifications for ECC81/ECC82/ECC83 12AU7/12AT7/12AX7 and more recently for the E80CC - all put out over many decades by numerous manufacturers and I see the optimal recommended component values, and that they all draw 12V 150mA - the E80CC draws 300mA, but if Xduoo says they can support these tube variations in their Hybrid headphone amplifiers under full warranty, I'm going to enjoy rolling the tubes, and listening to them.

It is clear Xduoo is doing some auto adjustment internally based on the gain of the Pre-amp tubes, so as to not overload the final SS amplifier. The 12AT7 and equivalents - like the Brimar 6060 Yellow "T"'s I am running right now sound more forceful and full, but the 12AX7's are a bit "hot" sounding, no distortion but you can tell the circuit is dealing with the higher gain - some may like it; I don't dislike it, but I prefer the 12AT7's for my listening.

When you design your own amp, you might want to check out the Xduoo designs first, for some tips on how to make it all work together, under warranty...

On second thought, you might as well buy one when they go on Sale during the Holidays, the TA-20 went for as low as $349, perhaps that will happen again this next holiday season.

 

[SIY]

When I asked Xduoo if the TA-20 that comes stock with a pair of 12AU7's will operate correctly with 12AT7 / 12AX7 tubes, and they said they support all 3 tubes in the TA-20 under warranty. I've posted their responses to my questions I've asked them here in this thread before, you must have missed them.

Also, I've met someone recently that is running E80CC's in the TA-30 - and Xduoo said the same thing, that they support it under warranty.

And yes, I've checked the design documents and specifications for ECC81/ECC82/ECC83 12AU7/12AT7/12AX7 and more recently for the E80CC - all put out over many decades by numerous manufacturers and I see the optimal recommended component values, and that they all draw 12V 150mA - the E80CC draws 300mA, but if Xduoo says they can support these tube variations in their Hybrid headphone amplifiers under full warranty, I'm going to enjoy rolling the tubes, and listening to them.

It is clear Xduoo is doing some auto adjustment internally based on the gain of the Pre-amp tubes, so as to not overload the final SS amplifier. The 12AT7 and equivalents - like the Brimar 6060 Yellow "T"'s I am running right now sound more forceful and full, but the 12AX7's are a bit "hot" sounding, no distortion but you can tell the circuit is dealing with the higher gain - some may like it; I don't dislike it, but I prefer the 12AT7's for my listening.

When you design your own amp, your might want to check out the Xduoo designs first, for some tips on how to make it all work together, under warranty...

On second thought, you might as well buy one when they go on Sale during the Holidays, the TA-20 went for as low as $349, perhaps that will happen again this next holiday season.

Those are the heater numbers, not the tube operating points.

A 12AX7 wants to run at 0.5 - 1mA idle, has a mu of 100-ish, and a transconductance of 1500umho under usual conditions. 12AT7 about quadruple the idle current and transconductance along with a lower mu (if memory serves 50-60). 12AU7 runs higher currents, has even a lower mu (20-ish). Biasing is greatly different. You won't break anything, but performance will be highly compromised with the wrong tubes.

With all due modesty and deference, these are not the guys I'd be trying to learn from. My tube designs have significantly better performance.

 

[spede]

Balanced truly outputs 3.4W @50hm?

Got HE6SE coming, wondering if this will be powerfull enough. Owned HE500 with SE cable and if i recall right (been a while) had to crank volume pretty high, even near 80 (95 is max) if i wanted to "headbang" with some EQ.

 

[hmscott]

Balanced truly outputs 3.4W @50hm?
Got HE6SE coming, wondering if this will be powerfull enough. Owned HE500 with SE cable and if i recall right (been a while) had to crank volume pretty high, even near 80 (95 is max) if i wanted to "headbang" with some EQ.

The TA-20 MAX volume indication is 95, and I "rock out" at 80-85 with the HE6SE V2, but normally listen at 60-70, the Ananda about 10 points lower.

The TA-20 @ 2W (32 ohm) with a 12AT7 rather than a 12AU7, depending on the tube, is more dynamic sounding - but the SS section remains at the same output - at least my volume reading doesn't change for the same listening level.
xDuoo TA-20 Balanced Tube Amp-xDuoo Official Store

The TA-30 adds another 1W for 3W total, both are "enough", but not high enough to tax the HE6SE V2, which might be a good thing. I've read posts by owners that popped a Planar element by going "too far" on the volume dial when running from a speaker amp, a couple actually.
xDuoo TA-30 Tube Headphone Amplifier - xDuoo official store

I'm looking at a couple of tube amps and solid-state amps around 7-15w range, but I'm enjoying the TA-20 fine right now.

For $399 I think the TA-20 is a fun option
XDUOO TA-20 Balanced Classical 12Au7 Tube stereo audio headphone AMP — HiFiGo

Spoiler: Images

 

[Cirodx]

I am using the sundara with both 90 topping and loxjie p20 and I don't like it at all, fatiguing sound and forward mid-highs, would this TA20 go well with sundara? has anyone tried?