AIYIMA T20 Tube Pre-amplifier Review

[antcollinet]

Hopefully you’re not that serious with the comment but anything is possible. People try to get inexpensive things which are good to begin with, to sound better. Sometimes that’s not measure better but sound better. This is a hobby and this is about listening to music so there are worse things that people could be doing. Some inexpensive products actually are very, very good. It’s surprising sometimes how good they could be for so little money.

Which takes me back to my question.

Why do random trial and error - hence non engineered - changes to a product always result in better sound. I've never once seen someone say "I changed it and it sounded worse"

 

[RandomEar]

Which takes me back to my question.

Why do random trial and error - hence non engineered - changes to a product always result in better sound. I've never once seen someone say "I changed it and it sounded worse"

Have to disagree on that point. I have definitely seen people who did sighted testing, were unhappy with the changes and reversed them.

That being said: I would still say that by far most of the reports are positive, which is not very plausible. Randomly switching components without any deeper understanding of a circuit and getting "clear improvements" in what feels like 90% of those self-reported cases is, to put it mildly, statistically unlikely.

 

[rebbiputzmaker]

Which takes me back to my question.

Why do random trial and error - hence non engineered - changes to a product always result in better sound. I've never once seen someone say "I changed it and it sounded worse"

Well, some may think is random or just arbitrary changes, but not all the time. In fact, a lot of this comes from experience, although I know they’ll be major disagreement here. For argument say the capacitors. Dielectric material and construction does make a difference. So IMO that’s not a random change. Now the opamps, I realize that people say that doesn’t make a difference here which is fine, and sometimes the differences are minuscule or maybe even placebo. But they do have different characteristics, and something simple to do. The manufacturers are putting the sockets in just for that reason. People like to have something to play with. It is still a hobby.

 

[antcollinet]

So IMO that’s not a random change.

It is random because if you don't know and understand the circuit - then you can't know what those differences will do to its performance.

Take op amp rolling - you can pick the best specified op amp. you can find and stick it in the circuit. But if the circuit has not been designed with the necessary features to make *that* op amp stable - you will more than likely degrade performance.

Same with a capacitor - if it has different characteristics from the one selected by the design engineer - you know - the guy who acutually deisgned the circuit and knows intimately how it functions - you are quite likely to make it perform worse. Even if you believe it to be a "better" capacitor. To take advantage of "better" specifications - you normally need to design the whole circuit around those specs. At best - it will make no difference. Rarely you might get lucky - but note the use of the word "rareley"

 

[SMen]

Which takes me back to my question.

Why do random trial and error - hence non engineered - changes to a product always result in better sound. I've never once seen someone say "I changed it and it sounded worse"

I am not sure that it is a one way street (always better). Certainly I have found worse results when experimenting ... I'm pretty sure I have reported such on ASR too.

Or indeed no difference - people often report no difference with the simplest of testing (not blind or such). I'm in favor of people having a cost effective way of establishing differences or lack of differences for themselves... and indeed listening. There is a hobby side to all this. I've recently "downgraded" my dac ... happily.

There are multiple arguments, and zero'ing in on argument 'A' does not win 'B'. "Do not experiment because the designer is always right" or "anything you might hear is not something you hear ... it is just bias" ... these shut down the hobby side. "Be aware of bias when you compare equipment because our brains bring bias" is a very good message, but "you can't hear this or that or the other because it is all bias in your head" is not (imo).

Speakers run into budget limits rapidly when it comes to cabinet resonance so we pay more for the engineering that tackles this hopefully in more expensive speakers ... but this is a valve pre-amplifier thread. I couldn't blind test speakers easily but I sure can hear boomy cabinets. It's all a question of degree, and I've found most of the recent posts here pretty balanced (forgive the pun).

 

[SMen]

Have to disagree on that point. I have definitely seen people who did sighted testing, were unhappy with the changes and reversed them.

That being said: I would still say that by far most of the reports are positive, which is not very plausible. Randomly switching components without any deeper understanding of a circuit and getting "clear improvements" in what feels like 90% of those self-reported cases is, to put it mildly, statistically unlikely.

Yes. Related to this and regardless of blind testing, switching back to previous state and listening again is often very revealing (of bias going from A to B, and then back to A again ... I have not needed blind testing to realize that A to B quite often equals B back to A)! You are describing "wishful thinking" bias, or something like that

 

[Winemaker]

I've hooked up the T20 — I haven't had a chance to try it with music yet, only in the evening with the TV. I kind of get the feeling that the Purifi is now delivering its full power better and much sooner than it did when I was using the Eversolo as a preamp. I've noticed a more pronounced bass presence, and the vocals too feel deeper and less cold than before — fuller and more complete, as if that coldness was somehow taking something away from the sound, like it was holding it back instead of letting it open up and fill the room. Could just be my imagination, though!


I've now put the Eversolo in pass-through mode and I'm using the T20 to drive the Purifi's volume.


The one thing that's not working is the trigger connection — I've connected the T20's trigger output to the Purifi (which does have a trigger input) so I can turn both of them on at the same time with the remote, but nothing happens. It's as if the Purifi isn't receiving any power-on/off signal at all, even after waiting out the 19-second countdown before you hear the relay click.


I've reached out to Microsim — let's see if they can sort it out or at least figure out what the problem is.

 

[JRowland]

I've hooked up the T20 — I haven't had a chance to try it with music yet, only in the evening with the TV. I kind of get the feeling that the Purifi is now delivering its full power better and much sooner than it did when I was using the Eversolo as a preamp. I've noticed a more pronounced bass presence, and the vocals too feel deeper and less cold than before — fuller and more complete, as if that coldness was somehow taking something away from the sound, like it was holding it back instead of letting it open up and fill the room. Could just be my imagination, though!


I've now put the Eversolo in pass-through mode and I'm using the T20 to drive the Purifi's volume.


The one thing that's not working is the trigger connection — I've connected the T20's trigger output to the Purifi (which does have a trigger input) so I can turn both of them on at the same time with the remote, but nothing happens. It's as if the Purifi isn't receiving any power-on/off signal at all, even after waiting out the 19-second countdown before you hear the relay click.


I've reached out to Microsim — let's see if they can sort it out or at least figure out what the problem is.

Are you using a stereo cable?

AIYIMA T20 Tube Pre-amplifier Review

Thank you, @SSS, perhaps you could show us the circuit diagram that you have in mind that utilises the 12AX7 in the FB Loop with the opamp (as the T20 overview shows) and measurements? This is an excellent circuit (SRPP), as provided by @pma (thank you :=)), isn't it, which utilises the 12AU7...

www.audiosciencereview.com

 

[Winemaker]

Are you using a stereo cable?

AIYIMA T20 Tube Pre-amplifier Review

Thank you, @SSS, perhaps you could show us the circuit diagram that you have in mind that utilises the 12AX7 in the FB Loop with the opamp (as the T20 overview shows) and measurements? This is an excellent circuit (SRPP), as provided by @pma (thank you :=)), isn't it, which utilises the 12AU7...

www.audiosciencereview.com

Yes, a little long and not very large in section, like the headphone cable.

 

[JasonC331]

Yes, a little long and not very large in section, like the headphone cable.

I am almost positive Trigger cables have to be mono

 

[Winemaker]

You need to use a 3.5mm stereo cable.

It does not work with the stereo cable;
I bought a 3.5mm mono cable, which should arrive, but it doesn't work with the stereo one.

 

[antcollinet]

Dear @AIYIMA

How on earth am I supposed to read a user manual that looks like this when I open the PDF - it is next to useless. What is preventing you from creating a PDF manual with 1 page per page like everyone else does?

I'm not going to buy one - but if I was thinking of it - this would likely stop me.

 

[SMen]

I've hooked up the T20 — I haven't had a chance to try it with music yet, only in the evening with the TV. I kind of get the feeling that the Purifi is now delivering its full power better and much sooner than it did when I was using the Eversolo as a preamp. I've noticed a more pronounced bass presence, and the vocals too feel deeper and less cold than before — fuller and more complete, as if that coldness was somehow taking something away from the sound, like it was holding it back instead of letting it open up and fill the room. Could just be my imagination, though!


I've now put the Eversolo in pass-through mode and I'm using the T20 to drive the Purifi's volume.


The one thing that's not working is the trigger connection — I've connected the T20's trigger output to the Purifi (which does have a trigger input) so I can turn both of them on at the same time with the remote, but nothing happens. It's as if the Purifi isn't receiving any power-on/off signal at all, even after waiting out the 19-second countdown before you hear the relay click.


I've reached out to Microsim — let's see if they can sort it out or at least figure out what the problem is.

Yes subjectively I hear fuller body with broadcast voices, but thankfully not 'warmth'.

 

[antcollinet]

Yes subjectively I hear fuller body with broadcast voices, but thankfully not 'warmth'.

Have you compared with levels matched?

 

[SMen]

Have you compared with levels matched?

Yes, and indeed at multiple levels, and at consistently "preferred" volume for listening to broadcasts over a number of months.

 

[Winemaker]

I finally got around to testing the system yesterday after adding the T20.

The whole setup sounds deeper now—more complex and full-bodied. But, compared to when I was using the Eversolo as a preamp, I feel like I’ve lost some clarity and that 'clinical' edge. It sounds a bit more 'congested' now; the instruments aren't as sharp and the imaging feels a little blurred. On the flip side, the bass is definitely deeper and richer in harmonics.

Maybe it’s just me, I don't know. I’ve lost that cold, sterile feel and gained these harmonics that (I think) just weren't there before. Overall, it’s a much more pleasant listening experience than it used to be.

Just to be clear: this is all just my personal take—no measurements or hard data to back it up.

 

[edzoba]

Actually I'm in a trouble When using 2x OracleII-02 in XLR (U2 and U3 OPA position) and 1x Oranged DD in RCA output position (U17) the sound was great (using RCA-RCA cable to power amp). Than I figured out to "bypass" RCA pos. opa with an XLR-to RCA cable. A high background noise appeared on 0 level of preamp. Then I put back a 49720 to RCA pos. (I sold Oracles), and RCA/RCA cable to power amp: the sound became pianfully dull. I don't know whether the cable wiring or what caused that noise

 

[SMen]

I finally got around to testing the system yesterday after adding the T20.

The whole setup sounds deeper now—more complex and full-bodied. But, compared to when I was using the Eversolo as a preamp, I feel like I’ve lost some clarity and that 'clinical' edge. It sounds a bit more 'congested' now; the instruments aren't as sharp and the imaging feels a little blurred. On the flip side, the bass is definitely deeper and richer in harmonics.

Maybe it’s just me, I don't know. I’ve lost that cold, sterile feel and gained these harmonics that (I think) just weren't there before. Overall, it’s a much more pleasant listening experience than it used to be.

Just to be clear: this is all just my personal take—no measurements or hard data to back it up.

I am curious as to whether this was with the stock tube that came with the amp?

 

[Winemaker]

I am curious as to whether this was with the stock tube that came with the amp?

It happened with the original valve that came stock — I'm not replacing it now because I'm waiting for the usual 40-50 hours of break-in.

 

[Winemaker]

I am curious as to whether this was with the stock tube that came with the amp?

I had some time to sit down and listen yesterday afternoon.


A bit of everything — Rob Wasserman's Duet with Cheryl Bentyne, with the T20, Cheryl's voice gained more body, more breadth, as if it filled the room more. Then I moved on to Stavros Lantsias (Diary of Dreams) — the piano also seems to have picked up more harmonics (I know it could just be a placebo effect) — and Karajan's Also Sprach Zarathustra came across as much deeper and richer.


Sure, the Eversolo's DSP correction played a part, but the sound itself has a different texture — less sharp and clinical than before (when I was using the Eversolo as a preamp), but more engaging, even at higher volumes.


Another thing I noticed is that with the T20, the Purifi seems to have doubled in power. Before it felt a bit soft and sluggish, but now the 1ET400A feels like it has endless headroom — I get just past the halfway point on the volume and I can't go any further, partly because the R3s might not survive it.


I think once it's past the 50-hour burn-in mark, things can only get better. Down the line we'll see what a tube swap does, and after that, the op-amp rolling.