AIYIMA T20 Tube Pre-amplifier Review

[Noske]

i do not get the point of such devices. Distortion is too low to hear any "tube sound" anyway. So why would anyone buy it instead of solid state preamp which would be cheaper and have excellent performance. It's just because of tube aesthetics? or is it marketed for ppl who are looking for tube sound and do not realize it is not there

Is H2 at 90 and H3 at 80 inaudible? I thought the threshold was about 110 or thereabouts.

Reviews elsewhere, however subjective, suggest that there are definite tube characteristics to this amp. If not, then I agree, what's the point.

 

[pma]

The only thing I wonder about is the overtone spectrum. 3rd harmonic being the loudest is suspicious and points towards it really being solid state "with tube support", instead of the tubes doing the actual work. And turns out, that exactly is the case. Odd.

This is how quite a good result from tubes (no SS support, local FB only) looks like:



Please note absence of high order harmonics. It is a SRPP, thus H3 as well.

 

[Panelhead]

Cannot force myself to go back to any preamp. Got way too many in attic already.
But if a preamp was needed this would be high on the list. I had started using a buffer or unity gain line stage a long time ago. Did not need another gain stage in signal path.
It is amazing, less than 200.00. Hope they sell a million of them.

 

[pma]

Is H2 at 90 and H3 at 80 inaudible? I thought the threshold was about 110 or thereabouts.

It is absolutely inaudible. There is a rumour only here at ASR that it must be -110dB or more. You may find dozens of research publications on H2 and H3 audibility.

 

[Juhazi]

Tube sound (=distortion) is best deliverd by a weak tube amplifier, then H2 nicely rises to even tens of % at music signal peaks. Preamps most often don't relly add audible distortion (or do any other audible signal modification.

By the way I have a tube preamp in my mancave stereo signal chain... https://www.stereophile.com/content...e-tube-preamplifier-seven-monoblock-amplifier

 

[Noske]

It is absolutely inaudible. There is a rumour only here at ASR that it must be -110dB or more. You may find dozens of research publications on H2 and H3 audibility.

Thanks. I should have known that.

That reminds me of the SMSL sound colour feature on some DACs. They are at most -60dB, as per a chart provided here by @JSmith last year. At that level 2nd and 3rd harmonics are noticeable, but not significantly only just (from subjective personal experience).

 

[Billy Budapest]

What role are the tubes playing in the circuit according to the diagrams released by Aiyima?

 

[pma]

As far as I remember, the SRPP tube circuit is not the most convenient solution.
Maybe cathode follower is better.

Gain?

 

[Dzhaughn]

Impressive fidelity for the technology, I hope they make a gramophone soon!

The digital display on the tube app is jarring. I think a split-flat display would be super cool, but I'd settle for a 7-segment red leds.

 

[pma]

REVIEW. Aiyima T20 Fully Balanced Tube Preamp, AKA Why do I do this to myself?

Due to some favorable impressions on the 'net, I bought the just-released Aiyima T20 Fully Balanced Tube Preamp. Attractions included the low price considering fully balanced input/output, tubes being used for actual gain not just buffer, remote control, and socketed opamps for rolling. With...

www.head-fi.org

And from AIYIMA web:

Tubes are driven from DSP and buffered by LME4562. Then you can do almost anything.

Please note that the tube is inside the opamp feedback loop!!

 

[Panelhead]

The mains frequency component could maybe be reduced by addressing the heaters. Heater hum is always there, even with dc heater circuits. Assume the heaters are pulling 500 - 600 ma dc.

 

[DSJR]

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?

Probably already answered, but I've seen a lot of 'valve' products over the years when third order seems higher than second order distortion.

 

[JeremyFife]

Thanks for the review, one to puzzle over slightly.
A tube pre-amp that performs quite well; clean enough, low enough distortion, nice and flat ... so it won't sound like tubes. So what's the point?

Taking it as it is, decent pre-amp. Not for me.

 

[pma]

A tube pre-amp that performs quite well; clean enough, low enough distortion, nice and flat ... so it won't sound like tubes. So what's the point?

The tube is inside opamp feedback loop. That is the whole trick. Just trick.

 

[raindance]

It isn't a tube preamp. It is a hybrid preamp.

 

[mmuetst]

The mains frequency component could maybe be reduced by addressing the heaters. Heater hum is always there, even with dc heater circuits. Assume the heaters are pulling 500 - 600 ma dc.

I see only a 12 volt DC input to the amp. But the 60Hz can be controlled beter when using a beter powersuply.

 

[Pulkass]

It sounds very good in my system.

 

[Herbert Shooler]

The 2nd harmonic needs to be dominant,listened to a Feliks Envy amp which has such a distortion spectrum and the 2nd is very dominant, also the Envys noise level was 10uv which is great, so its possible to have very good measurements (bar SINAD of course) but have the desired distortion harmonic, best of both worlds,this amp is certainly a big step in that direction.

 

[BR52]

Naked tubes.... ? Temperature wise, breakable, 160V, electric safety? Are we sure this will fulfil any safety regulations? I know it looks great but anyhow, with children in the house it can be dangerous. I can imagine CE or UL won't be happy.
Furthermore, I voted poor for my safety concerns.

 

[Nzama]

I see only a 12 volt DC input to the amp. But the 60Hz can be controlled beter when using a beter powersuply.

Agreed!