AIYIMA T20 Tube Pre-amplifier Review

[SMen]

I understand the hate on this product to a degree, but because it's such a quirky product (like how the Platypus is a quirky animal), I can't help but love it.

I find myself having to refer back regularly to the conclusion in words to his review by Amirm!

I believe I detected respect!

doesn't do the totally "beyond doubt" clean measurements that we've come to know for DACs/amps recently here on ASR).

Any ASR participant who tries one of these will almost certainly be using a DAC upstream, and an amplifier down stream that measure "beyond doubt" so they will be able to judge for themselves simply by plugging it in between the two. But of course (it would appear) they won't be able to hear any difference ... so there is no point. Or it will just be worse - except it measures too well for that - or maybe not.

I think it is great - I wish it had a switchable solid state option. Personally, I am not sure at all about the looks with two valves sticking out of the top. In fact, I was prejudiced against tubes without transformers etc. and it comes with a switch mode power supply oh no...

I'm going to try a linear power supply - just for fun. I remain prejudiced against switch mode power supplies in such devices.

 

[kazsud]

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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As always, questions, comments, recommendations, etc. are welcome.

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Is there a none tube mode?

 

[SnakeLord]

Can anybody explain me the advantages of this type of device over non tube one?

 

[pma]

Nothing.

 

[amirm]

Is there a none tube mode?

No.

 

[JSmith]

Can anybody explain me the advantages of this type of device over non tube one?

It glows a warm glow?

Is there a none tube mode?

Nope.


JSmith

 

[SMen]

Is there a none tube mode?

Unfortunately not. If there was, it would take a lot of the subjectivity out of the debate regarding the use of valves.
And set up perfect conditions for blind testing so long as output volume was matched between the two modes. An opportunity perhaps in a V2.

 

[morillon]

Gain?
Impedance output?
(would have been perhaps more fun with a decent integrated headphone stage ;-) )

 

[SMen]

Gain?
Impedance output?
(would have been perhaps more fun with a decent integrated headphone stage ;-) )

I don't understand this. My understanding is that the impedance output is low because of the use of the op amp after the valve. Gain is provided by the valve. This I thought an interesting design element.

Currently the thread seems to be becoming disjointed / disconnected from the actual review here of the T20!

 

[morillon]

I don't understand this. My understanding is that the impedance output is low because of the use of the op amp after the valve. Gain is provided by the valve. This I thought an interesting design element.

Currently the thread seems to be becoming disjointed / disconnected from the actual review here of the T20!

I'm just asking what are the values and typical characteristics , gain too, of this type of machine... what's surprising?
Normal for a review...no?
These are not trick questions... very useful....

 

[SMen]

I'm just asking what are the values and typical characteristics , gain too, of this type of machine... what's surprising?
Normal for a review...no?

Ah! ok. This is just language. Sorry - These looked like statements - as far as I can tell also, this kind of hybrid pre-amplifier in balanced form, is novel at this market level.

I am pretty sure that both the gain and the output impedance questions have been answered earlier in this thread. I have checked back:

AIYIMA T20 Tube Pre-amplifier Review

I like these glowing bulbs. I made a lot of them myself. But for this type of AMP with an op-amp chip, the bulbs might just be for decoration. I replicated an early McIntosh pre-amp, and I think the sound is really pleasant. Compared to the sharp sound of Class D, it's much milder and sweeter.

www.audiosciencereview.com

OK I can see you were asking for more details on this ... but I had to do the heavy lifting to look back and work that out!

 

[Nzama]

Also I am not sure we could see the total output and gain of this preamp from the review measurements only unity gain

 

[pma]

Guys, this is how the "real tube distortion" should look like. Then we may speculate on "tube sound" .

Edit: please note that this very simple, tube-only circuit (without a band-aid of opamps) has much lower mains frequency residuals, in absolute voltage level, than the reviewed amp in the post #1. This is not a good credit to @AIYIMA designer.

 

[Ropeburn]

Guys, this is how the "real tube distortion" should look like. Then we may speculate on "tube sound" .

View attachment 483727

View attachment 483728

View attachment 483730


Edit: please note that this very simple, tube-only circuit (without a band-aid of opamps) has much lower mains frequency residuals, in absolute voltage level, than the reviewed amp in the post #1. This is not a good credit to @AIYIMA designer.

I like that. Start with that, then overdrive it. Terrific sound!

 

[Nzama]

Guys, this is how the "real tube distortion" should look like. Then we may speculate on "tube sound" .

View attachment 483727

View attachment 483728

View attachment 483730


Edit: please note that this very simple, tube-only circuit (without a band-aid of opamps) has much lower mains frequency residuals, in absolute voltage level, than the reviewed amp in the post #1. This is not a good credit to @AIYIMA designer.

Exactly. Would be interesting to see if this leak can be fixed with one of the famous audiophile linear power supply

 

[Nzama]

No, because the chart only refers to audibility of harmonics when listening to a single test tone. As pointed out above by PMA - completely inaudible with music. Much larger tones in the music will completely mask the harmonic tones.

If you want to find out what levels of distortion you can hear in music, you can try the klippel listening tests. Most people can't even manage to hear -40dB (1%).

With the music in the clips absolutely challenging above -40db!!

 

[SMen]

Exactly. Would be interesting to see if this leak can be fixed with one of the famous audiophile linear power supply

I am not sure if this is audiophile ... or indeed famous ... but in the context of the T20 (which would appear now to be out of context on this thread) this works very well:

https://www.aliexpress.com/item/1005006176001515.html?spm=a2g0o.order_detail.order_detail_item.3.453cf19c3GSu9j&gatewayAdapt=fra2glo

Those who want that warm valve fuzzy sound will prefer the smps that comes with it

 

[Jon L]

I am not sure if this is audiophile ... or indeed famous ... but in the context of the T20 (which would appear now to be out of context on this thread) this works very well:

https://www.aliexpress.com/item/1005006176001515.html?spm=a2g0o.order_detail.order_detail_item.3.453cf19c3GSu9j&gatewayAdapt=fra2glo

Those who want that warm valve fuzzy sound will prefer the smps that comes with it

It's kind of funny, but I tried an HDplex linear power supply and 12V Li battery with T20 and ended up going back to the stock smps It's a heck of a lot smaller and convenient.

 

[SMen]

It's kind of funny, but I tried an HDplex linear power supply and 12V Li battery with T20 and ended up going back to the stock smps It's a heck of a lot smaller and convenient.

Those HDplex look somewhat more upmarket! But also larger. I'll try the smps back again in a while for self detection of anything 'bias' oriented ... but today I just found that I was losing the need to crank up the volume - always a good sign.

 

[pma]

Tubes are magical