xDuoo TA-20 Tube Balanced Headphone Amplifier Review

[hmscott]

Your description matches closely the Philips 5814A sound. I'm reluctant to recommend them at this price though ($49.19). I bought them in 2019 for $28.

In Europe, on eBay, I could get a pair for $67-$98... . Anyway, I'm looking around. Thx!

A little searching on the US eBay site and I found a pair for $29.95

Condition: New. Order total: $32.80. Phillips ECG 5814A Preamp Vacuum Tube Pair - FREE Shipping. You should get this by Jan 28.

eBay listing photo, and in person they look as crisp and clean as in the photo

Phillips ECG 5814A Preamp Vacuum Tube Pair - FREE Shipping | eBay

"Phillips ECG 5814A Preamp Vacuum Tube Pair
Bought as a spares but never used
Guaranteed not DOA
FREE First Class domestic shipping"

I've asked the seller if there are any more available, I'll update when I hear back.

Update: that pair of Phillips ECG 5814A were the only pair he had.

Update: @Noodles - Yup, these have something special, even after a few hours, there is a forceful well defined mid fat sound with vocals that insists on my attention. No kidding these sound great. I'll update in a bit of time longer, perhaps I'll put together some kind of comparison with whatever tubes I have decided to keep long term. I may not have that yet, but I might. These arrived today a full 4 days early, via USPS, nice.

 

[BubbaJay]

I bought a pair of nos military stock GE 12AU7 tubes from Upscale Audio that will be here today and they are said to be some of the best pre-amp tubes you can get for under $100. There are 3 types of different quality they have and I got the mid-set that was $100 for 2 and I'm hoping they're as good as they say but I'll report back how they sound compared to my other 2 pair I have.

 

[Veri]

All this talk reminds me why I should stay away from tube amps lol. What a major money sink.

 

[BubbaJay]

I've only been using the nos GE tubes on my TA-20 for like 30mins and I can say without a doubt they're the best sounding ones I have. The TA-20 has such an airy open sound now with really good clarity as well, and the bass sounds very impactful but not so much so that it overwhelms the rest of the frequencies. I've only used my Z1R so far but it sounds wonderful but I'll post more in depth impressions after I've used it longer and with other headphones.

 

[hmscott]

I bought a pair of nos military stock GE 12AU7 tubes from Upscale Audio that will be here today and they are said to be some of the best pre-amp tubes you can get for under $100. There are 3 types of different quality they have and I got the mid-set that was $100 for 2 and I'm hoping they're as good as they say but I'll report back how they sound compared to my other 2 pair I have.

I've only been using the nos GE tubes on my TA-20 for like 30mins and I can say without a doubt they're the best sounding ones I have. The TA-20 has such an airy open sound now with really good clarity as well, and the bass sounds very impactful but not so much so that it overwhelms the rest of the frequencies. I've only used my Z1R so far but it sounds wonderful but I'll post more in depth impressions after I've used it longer and with other headphones.

Are these the GE NOS you bought in "Platinum" quality?
GE Military Stock 12AU7 / 6189W – Upscale Audio

(17155) GE 12AU7/6189W Vacuum Tube Review w/ Upscale Audio's Kevin Deal - YouTube

Have you tried an IEM on your TA-20 + GE NOS yet?

My RCA Cleartop NOS tubes sounded great on all of my full sized headphones, but as soon as I connected the KZ ZAX I heard a "wall of HISS" that isn't there on current production tubes like the JJ Electronic ECC82 / ECC802s, PSVANE ECC802s, and the TA-20 included Shuguang ECC82's.

I am still enamored with NOS tubes, so I would like to find an affordable pair of 6189 12AU7's as you found with the GE's from upscaleaudio.com IDK if it's something particular to NOS construction or age, but I'd like to figure it out before I buy more NOS tubes.

Here is a nice short write up on the 6189W tubes from audiotubes.com:
"6189 / E82CC: This can be both a military spec tube and a premium industrial tube. Often, the military versions will be marked 12AU7WA in addition to having 6189 etched in the glass. The older vintage of these tubes are usually blackplate with the extra "triple mica" spacer at the top. GE made this in their 5-star line for broadcast. The RCA military 6189 is gold lettered 12AU7WA, has blackplates, and extra support rods. These are excellent step up tubes in the 12AU7 family, when you can find them! Look for super rare triple mica versions from Mazda, Siemens, and Mullard, some with silver plates. Among the best 12AU7 tubes ever made."
http://www.audiotubes.com/12au7.htm

That page also lists his inventory (in/out of stock) and mentions the GE 6189w for a great price, out of stock right now:

"12AU7WA/6189 GE Military/Commercial Grade New Old Stock White Box and original box. Rugged build, long life tube, getting hard to find. Some manufactured for Sperry-Rand aviation in military boxes. $20.00, out of Stock"

NOS - GE Military Stock 12AU7 / 6189W – Upscale Audio
NOS - Brimar CV4003 / 12AU7 – Upscale Audio
New - Gold Lion ECC82 / B749 / 12AU7 – Upscale Audio
New - Genalex - Gold Lion B749 / ECC82 / 12AU7 Preamp Vacuum Tube | TubeDepot.com

Which one should I try next?

PS: Found a note and some discussion about the fire that closed the Shuguang tube factory:
Shuguang Tube Factory Fire- bad news Discussion in 'Audio Hardware' started by allied333, Dec 22, 2019.
Shuguang had a fire next to their tube manufacturing plant. Local city of Changsha will not allow rebuilding nor continued manufacturing of tubes either. If city will not change their mind, Shuguang will move their plant and that will stop tube production for perhaps 18 months. You may want to buy Shuguang tubes now before stock runs out.
Valve Tube Supplies in 2020 Updated 9th May 2020 – Valve Tube Guitar Amps

 

[Noodles]

I'm giving away my TA-20 to a friend that needs an amp. If i get another tube one it will be something simple like these:
https://www.xduoo.net/product/mt-601/
https://www.xduoo.net/product/mt-602/

@hmscott For the NOS tubes ... All that i've tried have the wall of hiss (Miniwatts, GE's, RCA's, Sylvania). It's probably just the unicorn ones that dont have the higher noise floor.

 

[hmscott]

I'm giving away my TA-20 to a friend that needs an amp. If i get another tube one it will be something simple like these:
https://www.xduoo.net/product/mt-601/
https://www.xduoo.net/product/mt-602/

@hmscott For the NOS tubes ... All that i've tried have the wall of hiss (Miniwatts, GE's, RCA's, Sylvania). It's probably just the unicorn ones that dont have the higher noise floor.

It's difficult to tell from our small sample, but of course, it's going to seem that way if all of our tubes are showing IEM's that noise seemingly consistently.

I'm going to work with a couple of suppliers that are amenable to testing with sensitive IEM's to see if they can pick IEM quiet NOS tubes. I'll let you know how that testing goes.

Maybe Upscale Audio already does what we need?

(17155) GE 12AU7/6189W Vacuum Tube Review w/ Upscale Audio's Kevin Deal - YouTube

Fortunately, my most recent NOS tubes: Phillips ECG 5814A have far less HISS than the NOS RCA Cleartop Baldwin's, and I still need to do more testing over a couple of weeks, but it is encouraging

Please let us know what you think of those new Xduoo Hybrid Tube headphone amps if you get them, they are nice and affordable enough as a first headphone AMP.

Hopefully, someone will send both of them to @amirm for testing. They are inexpensive at $89/$99:

Spoiler: Xduoo MT-601, MT-602

 

[icsi85]

On the Left, the Chinese stock tubes, and on the right are Jan Sylvania USA 6189 (green).
About sound changes, I can't say now anything, need some time with it.

Spoiler: Stock tubes vs Jan Sylvania USA 6189 (Green)

 

[hmscott]

On the Left, the Chinese stock tubes, and on the right are Jan Sylvania USA 6189 (green).
About sound changes, I can't say now anything, need some time with it.

Spoiler: Stock tubes vs Jan Sylvania USA 6189 (Green)

View attachment 108290

There is always some variation in the glass envelope and alignment of the internals, I see the Jan Sylvania USA 6189 have oblique imperfections too, but not as amusing as that China tube glass envelope.

The China tubes that came with my Xduoo TA-20 were very clean/normal looking, nothing out of the ordinary worth posting.

The Jan Sylvania USA 6189 is another brand/model I am also looking at, there are so many! I'm very interested in how they sound to you, and if you find they have HISS on IEM's.

Each make/model of tube has it's own sound variations, which gives the TA-20 more fun in listening variations.

I am getting close to the point of hanging on with my particular cache of tubes, keeping a pair in longer and longer. I hope more owners that have a TA-20 keep posting their tube listening results. I think I'll probably take a break at some point soon, sit back and watch others go through the wide variations of tubes available, and dip back in to try various pairs myself as time goes on.

I'm not sure if I prefer the NOS Phillips ECG 5814A over my previous pairs or not, maybe I need more listening time on them. I wouldn't call them shouty, they are definitely vocal forward, but not in a displeasing way. Oddly enough it's the vocal dominant - podcasting/youtube review audio where they are odd to me. I don't want to simply give up on them.

Update: I am listening to the JJ Electronic ECC82's Short Plates - the JJ Electronic ECC802s Long Plates are really something, I'm definitely stocking up on those.

So far the JJ Electronic ECC82 Short Plates are more pleasing in tone than the NOS Phillips ECG 5814A, more balanced across instrumental and vocal tracks, and if the ECC82 Short Plates are like the ECC802s Long Plates more run time will make them sweeter sounding.

There isn't a huge price difference between the JJ ECC802s and ECC82 as a pair after paying the upcharges for gain matching, high gain, noise/microphonics, triode balance culling if selected at tubedepot.com

 

[hmscott]

xDuoo XA-10 Balanced DAC - xDuoo official store
xDuoo XA-10 Balanced DAC & Headphone AMP Dual AK4493 — HiFiGo

Spoiler: Marketing images

More info:
https://www.xduoo.net/product/xa-10/

 

[oldsysop]

So far the JJ Electronic ECC82 Short Plates are more pleasing in tone than the NOS Phillips ECG 5814A, more balanced across instrumental and vocal tracks, and if the ECC82 Short Plates are like the ECC802s Long Plates more run time will make them sweeter sounding.

 

[hmscott]

There is always some variation in the glass envelope and alignment of the internals, I see the Jan Sylvania USA 6189 have oblique imperfections too, but not as amusing as that China tube glass envelope.

The China tubes that came with my Xduoo TA-20 were very clean/normal looking, nothing out of the ordinary worth posting.

The Jan Sylvania USA 6189 is another brand/model I am also looking at, there are so many! I'm very interested in how they sound to you, and if you find they have HISS on IEM's.

Each make/model of tube has it's own sound variations, which gives the TA-20 more fun in listening variations.

I am getting close to the point of hanging on with my particular cache of tubes, keeping a pair in longer and longer. I hope more owners that have a TA-20 keep posting their tube listening results. I think I'll probably take a break at some point soon, sit back and watch others go through the wide variations of tubes available, and dip back in to try various pairs myself as time goes on.

I'm not sure if I prefer the NOS Phillips ECG 5814A over my previous pairs or not, maybe I need more listening time on them. I wouldn't call them shouty, they are definitely vocal forward, but not in a displeasing way. Oddly enough it's the vocal dominant - podcasting/youtube review audio where they are odd to me. I don't want to simply give up on them.

Update: I am listening to the JJ Electronic ECC82's Short Plates - the JJ Electronic ECC802s Long Plates are really something, I'm definitely stocking up on those.

So far the JJ Electronic ECC82 Short Plates are more pleasing in tone than the NOS Phillips ECG 5814A, more balanced across instrumental and vocal tracks, and if the ECC82 Short Plates are like the ECC802s Long Plates more run time will make them sweeter sounding.

There isn't a huge price difference between the JJ ECC802s and ECC82 as a pair after paying the upcharges for gain matching, high gain, noise/microphonics, triode balance culling if selected at tubedepot.com

When I finally had to remove the NOS Phillips ECG 5814A - they were not pleasant to listen to for long periods of time - I have pretty sensitive ears - and when even simple voice material was grating on me during a long listening session it hit me all at once that I needed to swap out those tubes.

When I'd had it with the NOS Phillips ECG 5814A, I swapped in the JJ Short Plate ECC82's, and after they warmed up gradually my ears relaxed. It was no problem continuing with my listening session after swapping out the NOS Phillips ECG 5814A's.

Try the JJ Long Plate ECC802s Gold Pin and JJ Short Plate ECC82 Gold Pin tubes, you might like them.

 

[oldsysop]

I have pretty sensitive ears

Okay. No more questions.

 

[hmscott]

Guys/Gals, I've found my next round of tubes to test: a NOS pair, and 2 more recent production pairs:

Matched Pair Tung-Sol JTL Military 12AU7/ECC82 BLACK Glass tubes 1950's
Matched Pair (2) Tung-Sol 6189/ECC82/12AU7W tubes
Matched Pair (2) Genalex ECC82/12AU7/B749 tubes Gold Pins

I was looking for the Genalex and found all three after striking up a conversation with the store owner.

Even better, I ran into sales on the top 3 headphones I have been looking at for a long time, so I've got a pair of HD660s, Hifiman HE6SE V2's, and Hifiman Ananda's on the way.

Hopefully driven balanced from the A90 / TA-20 those will all be happy, or I'll need to find a nice tube AMP to go with the Hifiman HE Adapter - AMP speaker output to XLR adapter. Then there is the Emotiva A-100 + full output straps mod, which is known to tame hard to drive headphones.

It is going to be a busy week next week

 

[bgtip]

Guys/Gals, I've found my next round of tubes to test: a NOS pair, and 2 more recent production pairs:

Matched Pair Tung-Sol JTL Military 12AU7/ECC82 BLACK Glass tubes 1950's
Matched Pair (2) Tung-Sol 6189/ECC82/12AU7W tubes
Matched Pair (2) Genalex ECC82/12AU7/B749 tubes Gold Pins

I was looking for the Genalex and found all three after striking up a conversation with the store owner.

Even better, I ran into sales on the top 3 headphones I have been looking at for a long time, so I've got a pair of HD660s, Hifiman HE6SE V2's, and Hifiman Ananda's on the way.

Hopefully driven balanced from the A90 / TA-20 those will all be happy, or I'll need to find a nice tube AMP to go with the Hifiman HE Adapter - AMP speaker output to XLR adapter. Then there is the Emotiva A-100 + full output straps mod, which is known to tame hard to drive headphones.

It is going to be a busy week next week

I think that it would be helpful if everyone of us writes a short sound description of the tubes he owns. Thus we can compile a guide similar to the one I posted above.
I used to own HD660s, they respond nicely to tubes, especially soundstage.

 

[hmscott]

I think that it would be helpful if everyone of us writes a short sound description of the tubes he owns. Thus we can compile a guide similar to the one I posted above.
I used to own HD660s, they respond nicely to tubes, especially soundstage.

That's a great idea about us all helping to build up a TA-20 tube guide and in the long term that is where I hoped we were going by posting our listening tests for new tubes we try.

I do think I need to put a long time into listening to each tube pair that gives me a chance to run through the headphones / IEM's to get a good cross-section of experience with the differences each reflects with each tube pair. And, it gives me time to enjoy the music.

We aren't professionals, so we can take our time listening and comparing.

In a microcosm, Zeos recently went through in one short video what we have been posting here with our TA-20's, with the Feliks Elise - another of the headphone amps on my list before I decided on the easier driving Tube/SS TA-20. Zeos rushed himself way too fast and almost burned up the Feliks Elise by plugging in the wrong tubes - a misorder by his patron that sent it in for review. There is a pinned comment by the patron explaining he ordered the wrong rectifier tubes to have sent to Zeos.

It is worth a watch for entertainment purposes, and to see what can go wrong when we aren't paying attention. But his observations on the few headphones he had time to comment on camera are similar to what I hear, differences in the effects of the Tube / SS sound through various headphones / IEM's. That's also why I like the TA-20, only 1 tube - 12AU7 - model.

I think his video also shows how the Hybrid Tube / SS amp design like the TA-20 can ameliorate the impedance driving difference experienced with tube only headphone AMPs. Of course, each amp is its own animal, so some are easier than others on headphone collections with a wide range of impedances. I have seen some tube amps that have impedance jumpers or transformer taps, or better - external impedance switches - like a gain switch - to match headphones/speakers to that amp.

Thank you for the comments on the HD660s, and yet I'm still wondering if I should have gotten the HD600 or HD650 - the discount was highest on the HD660s, but I was looking for an HD650 - of course the HD600 is also a good choice to connect up to a tube amp. Many (all?) of the Sennheisers respond well driven by tubes, the HD598cs for me started me in search of the HD650. And, Zeos comments on the HD280Pro as being great listening on the Feliks Elise - at a much more affordable price, and how his beloved HD600's shine the best on tubes.

Fortunately, with the TA-20 we don't need to worry about the impedance issues with tube only, the TA-20 supports 16ohm-600ohm headphones. I'll have to try the impedance dongles with my lower impedance IEM's.

What other headphones would you recommend that respond well to the TA-20? What do you like to listen with?

 

[hmscott]

A quick update on the TA-20 power output. I bought a HIfiman HE6SE V2 - Adorama Special and those are infamous for needing lots of power.

Hifiman developed the Hifiman HE-Adapter to convert AMP speaker outputs to a headphone 4-pin XLR to get enough power to drive the HE6 / HE6SE. The Emotiva A-100 AMP with jumper mod for full speaker power out the headphone jack is popular with HE6SE V1 owners + HE-Adapter.

The TA-20 does a great job driving the HE6SE V2 for my tastes. Most music listening is around 75 out of 95 on the volume dial, rocking out at 80-85, leaving some margin. And, so far after hours of listening the TA-20 hasn't overheated or shown its protection light.

Hopefully Xduoo will upgrade the TA-20 with a version to the same 3w SE/4w Balanced output power as the new XA-10...or the 4w of the TA-30.

For now, I'm very happy with the TA-20 driving the Hifiman HE6SE V2

 

[cursive]

This thread has been a great read, thanks for all the contributions so far. I just ordered a TA-20, so I'm excited to try out my first tube amp.

Quick question for all of those that are 'tube rolling', is it even worth trying and using the stock tubes, or should I look at upgrades immediately? I'm looking for a nice tube sound, I already have nice accurate amps, so looking for the tub experience really.

I've read through some of the purchases, but I'm looking for something that's on the cheaper side, but something that sounds tube like, or gives that nice tube distortion. I'm always on a budget, so if there's tubes you guys have tried that you like the best, please let me know.

 

[hmscott]

This thread has been a great read, thanks for all the contributions so far. I just ordered a TA-20, so I'm excited to try out my first tube amp.

Quick question for all of those that are 'tube rolling', is it even worth trying and using the stock tubes, or should I look at upgrades immediately? I'm looking for a nice tube sound, I already have nice accurate amps, so looking for the tub experience really.

I've read through some of the purchases, but I'm looking for something that's on the cheaper side, but something that sounds tube like, or gives that nice tube distortion. I'm always on a budget, so if there are tubes you guys have tried that you like the best, please let me know.

Yes! The Shugaung "China 12AU7" stock tubes are sweet, quiet, no IEM hiss, and sound great.

The stock tubes sound to me like the JJ Electonic ECC822 12AU7 newly manufactured tubes, with the JJ's sounding a bit better - but the JJ ECC82's I bought are the Gold Pin version while the stock tubes are corrodable steel pins. Initially not a big (any?) difference, but over time tubes with Gold Pins won't corrode as badly and will cause fewer intermittency issues - you can always pull the tubes and scrub the pins. It also helps if the socket contacts are gold plated, but the TA-20's aren't.

The JJ Electronic ECC802 ECC82's I got from TubeDepot, but they are available from many places. I picked TubeDepot as they can be asked to cull the tubes for noise, gain, and provide triode internal matching and gain pair matching, if you select all the services it overall doubles the price but I would recommend at least do the pair gain matching for the TA-20. For a single Triode 12AU7 model then the Triode internal matching would be my suggested option.
https://tubedepot.com/t/brands/jj-electronic-tesla

As far as budget, you could spread out the tube rolling over more time than we've used for the spinning of new tubes - use the stock tubes for as long as you like - which realistically could be a long long time, continue to read up on the other tubes, reviews, suppliers, etc - and when you are so inspired pick up a pair or two. I recommend 2-3 pair at a time only because it is disappointing when one of the pair doesn't work out and you are left waiting another week or two to find, pay for, and get shipped another suitable tube pair, at least I'm happy I had 2 other pair when the new PSVANE 12AU7-S Art Series Gain Matched Pair had 1 soft tube.

Also, when you get fed up with rolling, take a break and enjoy the music, if it gets frustrating or disappointing - as all things electronic can - keeping it fun and special by maintaining patience is foremost - live long and be happy with patience.

BTW, the Hifiman Ananda really sounds great on the TA-20, and uses a much lower volume setting than the HE6SE V2 - 60-65 rocking out vs 80-85, and not only sounds as good as the HE6SE V2 it sounds better in a different way - which is great as I was concerned the HE6SE V2 was going to ruin me for other headphones, seriously. But, the Ananda kicks it with Bass and really widens up the sound stage and adds a surrounding sound that other headphones don't have at all.

Xduoo has come out with less expensive hybrid headphone amps, and new models of their DAC/AMP hybrid's, so there is an even wider range of headphones amps to try with tubes.

Not all tube / hybrid amps use the 12AU7, so be sure to check up on the tube types the amp you like uses before buying, and if you are interested in tube rolling check into the availability of stock and variance is available for that tube and its equivalents.
Have fun

 

[bgtip]

This thread has been a great read, thanks for all the contributions so far. I just ordered a TA-20, so I'm excited to try out my first tube amp.

Quick question for all of those that are 'tube rolling', is it even worth trying and using the stock tubes, or should I look at upgrades immediately? I'm looking for a nice tube sound, I already have nice accurate amps, so looking for the tub experience really.

I've read through some of the purchases, but I'm looking for something that's on the cheaper side, but something that sounds tube like, or gives that nice tube distortion. I'm always on a budget, so if there's tubes you guys have tried that you like the best, please let me know.

Stock tubes are not bad, but eventually you'll want to try something different. Tube rolling is one of the points of having a tube amp. Initially I didn't plan to buy any other tubes. Now I have 5 different pair of tubes and I'm waiting for other two pairs to arrive. Also I try to give each pair at least 48 hours of burn in.