AIYIMA T20 Tube Pre-amplifier Review

[Pulkass]

This is a review and detailed measurements of the AIYIMA stereo tube based balanced preamplifier. It was sent to me by the company and costs US $180.
View attachment 482049
This is an unexpected and attractive design! I love the large and stylish volume control which can be managed using the supplied remote control. The volume function is a bit overloaded with it being power button, the input selector, and mute but is manageable. The back really surprised me:
View attachment 482050
Did not expect XLR balanced input and out let alone trigger support! The included external supply is pretty small and nicely sports a ton of safety logos which inspire confidence.

I must say, my bias is that such a products are horror shows when it comes to measurements. Company shows measurements that are too good to be true for the class. Let's see if we can verify them.

AIYIMA T20 Preamp Measurements
I started with the XLR in/out and set the input to 4 volts, and adjusted the volume to get the same voltage out:
View attachment 482051

I expected a SINAD of 40 to 60 dB but here, we are at 81 dB! Yes, we have more distortion than a solid state design but if one wants that, it would not be a tube product. Using RCA produces similar performance:
View attachment 482052

In the interest of time, I focused on balanced I/O from here on starting with SNR measurement:
View attachment 482053
Wow, this is quite good! I don't think I have tested a tube product with such low noise.

Frequency response is also very good for class:
View attachment 482054

As is crosstalk:
View attachment 482055

IMD test shows higher noise than state of the art transistor pre-amp but again, for this class it is quite good:
View attachment 482056

I expected some increase in distortion at low frequencies but it is less than what I thought we would see:
View attachment 482057

The digitally control volume produces perfect channel matching:
View attachment 482058

Conclusions
Amazing what happens when a company is focused on proper engineering building a tube product. No unnecessary noise and distortion are thrown in there as is the standard for this class of product. Modernization is in play with balanced input/output, remote control, digital volume control/display and trigger automation support. Really, can't ask AIYIMA to do more. They show that using tubes in an amplifier doesn't need to bring with it embarrassment in objective performance.

I am going to recommend the AIYIMA T20 preamplifier. Kudos for the company showing that such a product can be done well, outclassing many solid state products!
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Hallo, being very 'obsessed', with hi fi--- so to say A*nal, (!!!!) I bought a linear power supply, can I power this pre amp at 12.5 volts ???

 

[donjoe0]

I don't understand the distortion spectrum. Shouldn't "benign" K2 be the most dominant distortion when it comes to the "benefits" of tube sound?

What I'm getting from discussions I've been reading recently is it's not all the same if the distortion products are in phase or inverted vs. the signal. High but inverted H3 could add to the "tubiness" instead of subtracting.

 

[Ropeburn]

What I'm getting from discussions I've been reading recently is it's not all the same if the distortion products are in phase or inverted vs. the signal. High but inverted H3 could add to the "tubiness" instead of subtracting.

Waaaait. So you're telling me, a weirdly designed tube stage can effectively remove precious harmonics in music by cancelling them out?

Edit: What you read there is incomplete, or at least your conclusion.

In reality, a tube stage can be (and often is) designed in a way it suppresses 3rd order distortion completely, so that only 2nd order remains. That is technically done by phase invert something feedback something inside the circuit. Someone more knowledgeable please fill in the technical details here.

The 3rd order distortion of the tube circuit itself is cancelled. That's actually the sign of a good design and exactly what you want for "tube sound": a hint of even (="pleasant, rich") distortion, no uneven (="unpleasant, harsh") distortion, and generally clean and neutral otherwise.

You cannot remove signal harmonics this way to make it sound "more tubey". You can only add distortion. What matters is what kind of distortion is added.

 

[SMen]

Hallo, being very 'obsessed', with hi fi--- so to say A*nal, (!!!!) I bought a linear power supply, can I power this pre amp at 12.5 volts ???

If it is the BRZ in your photo it is reviewed here with measurements. Are you sure it is 12.5? Looks like 12.1!

Post edit, unless there is a trimmer in there and you are thinking of upping it? Not sure why you would want to do that. I think you should drive everyone mad with your impression vs the supplied unit!

 

[mhardy6647]

Thus thead is killin' me!

 

[Schlippwhip68]

I don't know to be honest, but at the price (similar to the Teradak) it might be worth a punt. Someone in the comments following your link seems to have measured it:

"The load behaviour is disappointing. At a load of 0.4a, it is still 12v. At 1a, it is still 11.7v, and at a load of 2a, it is 11.3v. The noise behaviour is also significantly worse than with the original studer. The noise is 25uv from 10-100hz and drops to 1uv from 300hz." But who knows - comments on ali express are not exactly measured opinion on ASR!

Teradak seem to do pretty much one thing, which is power supplies - so I gave theirs a go.

Personally I found that when switching units to compare with what I consider to be a high quality balanced ladder control, or indeed just the digital volume on the SMSL Raw DAC I currently use, that the T20 lost the 'warmth' that people seem to want but that I don't seek with valves, after putting in Tung-Sol valves and the Teradak.

I however keep a slightly enhanced depth and width perspective, solid sound stage, and body to strings and voices ... subjective listening opinion alert...!

I'm going to set up parallel inputs using RCA and XLR - with RCA going through the passive balanced ladder control. It is not in any way a scientific control test, simply a way to listen and hopefully enjoy and identify differences over time, with the closest I can get to switching being between RCA and XLR on the source DAC unit and my 3e audio A7.

The Douk Audio U2 Pro (2025) made a much bigger difference. Big improvement.

 

[SMen]

The Douk Audio U2 Pro (2025) made a much bigger difference. Big improvement.

I fear that for me digital audio interfaces are right up there with cables and op amps where it comes to 'big improvement(s)'!

If I may make a serious point though, the Aiyima T20 is a far more interesting product in use than I expected ... and at least the review upon which this thread is based does it justice, as does your enthusiasm for it.

 

[Pulkass]

If it is the BRZ in your photo it is reviewed here with measurements. Are you sure it is 12.5? Looks like 12.1!

Post edit, unless there is a trimmer in there and you are thinking of upping it? Not sure why you would want to do that. I think you should drive everyone mad with your impression vs the supplied unit!

I just wanted some overdrive. Yes there is a trimmer. I can put it at 12.5

 

[SMen]

I just wanted some overdrive. Yes there is a trimmer. I can put it at 12.5

My understanding is that the T20's tube stage runs at a fixed internal high voltage - and that Aiyima boost this up from the 12v input ... its op-amp buffer handles output drive - and this is more about impedance in the latter's case (lowering it to drive the power amp and longer cable run capability).

If anything it is more about having sufficient amps surely ? ... switch back to the supplied smps maybe? My experience with a different power supply was the opposite of yours ... no sense of needing to boost anything - the opposite in fact. Makes me wonder about the Brz. I found myself chasing the volume up with the supplied smps.

 

[Pulkass]

My understanding is that the T20's tube stage runs at a fixed internal high voltage - and that Aiyima boost this up from the 12v input ... its op-amp buffer handles output drive - and this is more about impedance in the latter's case (lowering it to drive the power amp and longer cable run capability).

If anything it is more about having sufficient amps surely ? ... switch back to the supplied smps maybe? My experience with a different power supply was the opposite of yours ... no sense of needing to boost anything - the opposite in fact. Makes me wonder about the Brz. I found myself chasing the volume up with the supplied smps.

I m content with this linear power supply, I m not changing the voltage. Just like the digital display. It s supposed to be filtering some noise.....

 

[gwing]

Waaaait. So you're telling me, a weirdly designed tube stage can effectively remove precious harmonics in music by cancelling them out?

Edit: What you read there is incomplete, or at least your conclusion.

In reality, a tube stage can be (and often is) designed in a way it suppresses 3rd order distortion completely, so that only 2nd order remains. That is technically done by phase invert something feedback something inside the circuit. Someone more knowledgeable please fill in the technical details here.

The 3rd order distortion of the tube circuit itself is cancelled. That's actually the sign of a good design and exactly what you want for "tube sound": a hint of even (="pleasant, rich") distortion, no uneven (="unpleasant, harsh") distortion, and generally clean and neutral otherwise.

You cannot remove signal harmonics this way to make it sound "more tubey". You can only add distortion. What matters is what kind of distortion is added.

Perhaps there is a bit of an understanding mixup here? If there isn't and I'm wrong I'd love to see the tube circuit design which completely suppresses 3rd order distortion.

Cancelling *even* order distortion of tube circuits is indeed common and for example the common class B push-pull circuit will eliminate these completely. Cancelling odd order distortions by design is AFAIK impossible but you can minimise these by operating within the linear response region of your valve so class A triode based low power designs would be a suggested starting point. Also bear in mind that 3rd order distortion isn't that important as the ear is pretty tolerant to this, higher level 5th,7th and 9th order distortions are the ones you need to keep low.

 

[mhardy6647]

Perhaps there is a bit of an understanding mixup here? If there isn't and I'm wrong I'd love to see the tube circuit design which completely suppresses 3rd order distortion.

Cancelling *even* order distortion of tube circuits is indeed common and for example the common class B push-pull circuit will eliminate these completely. Cancelling odd order distortions by design is AFAIK impossible but you can minimise these by operating within the linear response region of your valve so class A triode based low power designs would be a suggested starting point. Also bear in mind that 3rd order distortion isn't that important as the ear is pretty tolerant to this, higher level 5th,7th and 9th order distortions are the ones you need to keep low.

You are correct.
Single Ended FTW.

 

[Pulkass]

Perhaps there is a bit of an understanding mixup here? If there isn't and I'm wrong I'd love to see the tube circuit design which completely suppresses 3rd order distortion.

Cancelling *even* order distortion of tube circuits is indeed common and for example the common class B push-pull circuit will eliminate these completely. Cancelling odd order distortions by design is AFAIK impossible but you can minimise these by operating within the linear response region of your valve so class A triode based low power designs would be a suggested starting point. Also bear in mind that 3rd order distortion isn't that important as the ear is pretty tolerant to this, higher level 5th,7th and 9th order distortions are the ones you need to keep low.

So you think this T20 pre amp is badly designed.

 

[gwing]

So you think this T20 pre amp is badly designed.

No.

 

[Ykar]

I'm quite confused about the trigger sockets on that unit :

• Back plate seems to say both sockets are "output"
• Manual says Ouput for both
• Audiophonics states "One trigger is dedicated to turning on the DAC, while the other turns on the amplifier. This protects the tubes and allows them to warm up before processing the audio signal."

but :

• that guy seems to say he triggers T20 on from Wiim's trigger out : head-fi

"Overall, the T20 is super easy to integrate into any system, and I used it both with WiiM Ultra triggering it to wake up and connected to the A20 triggering that amplifier in turn to wake up when it needed to play music"

• the below diagram (unconfirmed source) shows trigger output AND trigger input

Anyone knows if T20 can be triggered from external source, or not ?

 

[morejazzplease]

If you look at a photo of the T20, you can see that it has two 12v trigger ports. The decals on the case has a label of "out" in-between the two ports, seemingly labeling them both as "outs". Aiyima's marketing materials only refer to the T20's trigger output functionality. They never mention or infer a trigger input.

I read that quote from Head-fi differently than you do. To me, the user is saying that they used the T20's trigger outputs to trigger the WiiM and the A20 amplifier. This makes sense given that the T20 has two trigger outputs. The subject in that sentence is the T20 so, when they say they "used it" with both the WiiM and the A20, I believe they are saying they used the T20's trigger ports to turn on the WiiM and A20. This would track with the port's labels (DAC trigger = WiiM and Amp trigger = A20). However, I do think that is a poorly structured sentence!

I am not sure why Aiyima labels one as a "DAC" trigger and the other as an "Amp" trigger. We are so used to seeing one input and one output on preamps (Like the Fosi ZP3). Perhaps the signals are sent out at different times? Typically, you want to turn on sources and pre-amps before turning on power amps. Perhaps the "amp" trigger out port has a delay that waits to send the trigger signal until after the T20 goes through its warm up cycle? I don't know, my T20 is set to be delivered today and I can play around with it and see what I find!

 

[Ykar]

I read that quote from Head-fi differently than you do. To me, the user is saying that they used the T20's trigger outputs to trigger the WiiM and the A20 amplifier. This makes sense given that the T20 has two trigger outputs. The subject in that sentence is the T20 so, when they say they "used it" with both the WiiM and the A20, I believe they are saying they used the T20's trigger ports to turn on the WiiM and A20. This would track with the port's labels (DAC trigger = WiiM and Amp trigger = A20). However, I do think that is a poorly structured sentence!

The thing is Wiim Ultra has no trigger in port, only trigger out !

 

[morejazzplease]

The thing is Wiim Ultra has no trigger in port, only trigger out !

Oh yeah...lol forgot about that detail! However, I just had my T20 delivered and my hunch was correct and it clears up what the Head-fi user was saying.

The upper trigger port labeled "DAC" does seem to be a trigger input! The "amp" trigger port (lower) sends a trigger out signal, but only after the 20 second warm up timer is completed. That is actually a nice detail as its desirable to only turn on your power amps after the preamp is on and stable. I'd wager this 20 second delay is why other users have thought their trigger was not working! The manual makes no mention of this delay and I can totally understand someone turning the T20 on and then assuming it wasnt working when the trigger out appeared to do nothing (as the T20 was still warming up).

The labels on the case could be clarified and these features (in and out triggers, delay on the trigger out) should be in the manual...However, the schematic you posted above seems correct! The upper port is an input and the lower one is a (delayed) output.

 

[Ykar]

The upper trigger port labeled "DAC" does seem to be a trigger input!

Did you actually achieve to start the T20 from that socket ?

 

[Mikig]

Got it!
Arrived, already assembled and in use. Both with tube and SS amps.
With balanced Fosi and RCA inputs with other amps.
What can I say: it works really well. A little gem
Thanks Amirm for the review!!