Eulipian
Active Member
The tubes keep the hipsters happy, but, more importantly, insure a healthy supply of 12Ax7 tubed for the amateur guitar amp builders of the world. A win-win!
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AIYIMA T20 Tube Pre-amplifier Review
- Thread starter amirm
- Start date
Not balanced signal path I am correct!!
totti1965
Addicted to Fun and Learning
@welwynnick posted the complete list 5 days ago:
You are right. Something like the fantastic Topping A70 Pro would be much more expensive as £118,—
but: 40 dB better SINAD!!!
On the other site: even this is barely audible.
What is your argument against analog volume Control if it is better than 1/4 of a Dezibel Channel matching?
I think, your Aiyima T20 was a good choice.
Could I redirect the question slightly to "how much negative feedback is actually being used on the T20's tubes? I thought anything like this was handled by the op amps?
Thank you - good timing for my request!
For a device to slot in between my DAC and 3eAudio A7 with a remote control I am thoroughly enjoying the T20. I prefer it over the volume being controlled directly by the SMSL Raw DAC I have. Speach broadcasts are more often centered - this is an unexplained side product. Sometimes broadcasts actually require a balance control because of how they are mixed I find - but that is outside the scope of this discussion.
The T20 makes voices sound like a rather more expensive Ladder DAC I tried! All great fun
totti1965
Addicted to Fun and Learning
Aah, this was the reason for you to need perfect channel control. But I really think, this problem of yours is NOT related to the difference between perfect 0 dB deviation and „only“ very good (0.25 dB or so) channel matching.Could I redirect the question slightly to "how much negative feedback is actually being used on the T20's tubes? I thought anything like this was handled by the op amps?
Thank you - good timing for my request!
For a device to slot in between my DAC and 3eAudio A7 with a remote control I am thoroughly enjoying the T20. I prefer it over the volume being controlled directly by the SMSL Raw DAC I have. Speach broadcasts are more often centered - this is an unexplained side product. Sometimes broadcasts actually require a balance control because of how they are mixed I find - but that is outside the scope of this discussion.
The T20 makes voices sound like a rather more expensive Ladder DAC I tried! All great fun
By the way: nice amp! And your love for the Ladder DAC Sound is completely understandable!
Aren‘t we all at least a tiny bit subjectivists??? Have fun!
As a small ps - I would certainly notice a .5db shift in balance when I've tested this - but a whole different discussion.Aah, this was the reason for you to need perfect channel control. But I really think, this problem of yours is NOT related to the difference between perfect 0 dB deviation and „only“ very good (0.25 dB or so) channel matching.
By the way: nice amp! And your love for the Ladder DAC Sound is completely understandable!
Aren‘t we all at least a tiny bit subjectivists??? Have fun!
totti1965
Addicted to Fun and Learning
Same experience in equalization: I think 0.5 dB for me is clearly audible. But at 0.25 dB, maybe we are reaching anybody’s limit. Of course I did not do a scientific test with 20 rounds blindfolded etc. to prove my claim. But find the overall experience much more satisfying, after an our or so listening session, after I had set the roon frequency-correction at 14.000 Hz from minus 1 dB (after a year of listening or so with this correction)
Attachments
Very good hearing at 14k! Once I get up to these realms, it is very much about 'feel' for me. I use a Jico SAS stylus in my technics cartridge / record playing system and this bumps up at 16k but it does not bother me much (if at all).
I also go with extended listening BUT I am very careful with volume matching for the same points / your shared observations here.
A good matching between the 2 triodes working in balanced mode inside each tube will still be critical to achieve H2 cancellation which should dominate in a triode gain stage. I guess that carefully chosen tubes have been mounted to the unit sent to Amirm for the review...
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totti1965
Addicted to Fun and Learning
. Q was 0.71…… So the deviation starts at round about 7.000 Hz. Better let talk about subjective stuff in pm 
I understand the tubes are the the feedback loops of the opamps and I know that feedback loops are essential to how an opamp produces gain, but what exactly are the tubes doing in the feedback looos? What electrical role do they play?
How high in level are the 0.1% harmonics? That’s the key.
Some people forget that simple fun is why many of us are here listening to audio.Could I redirect the question slightly to "how much negative feedback is actually being used on the T20's tubes? I thought anything like this was handled by the op amps?
Thank you - good timing for my request!
For a device to slot in between my DAC and 3eAudio A7 with a remote control I am thoroughly enjoying the T20. I prefer it over the volume being controlled directly by the SMSL Raw DAC I have. Speach broadcasts are more often centered - this is an unexplained side product. Sometimes broadcasts actually require a balance control because of how they are mixed I find - but that is outside the scope of this discussion.
The T20 makes voices sound like a rather more expensive Ladder DAC I tried! All great fun
I have never considered a tube audio device before (and had they included a phono in, I might have bought it [even knowing that it does not spec as well as any other item in my audio chain. Why? because it does spec better than other tube gear AND {from the subjective reports: hard to believe that I am putting that into consideration]}), for a tube anything, it sounds OK. All in fun, just to play with it is what it would be. Of course I could run a phono pre out into a line input on it, but that goes beyond my idea of fun into effort.
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It looks like the 2 triodes in each tube are operated in balanced mode and do provide the gain ( a little less than 40dB?), and due to the high output impedance of such a stage, this stage is followed by a buffer (probably no gain) one implemented for simplicity by opamps and the feedback loop applied to both stages allows reducing gain to a useful value for a line stage and reduces distortion too in a proportional way as it reduces gain.
Btw, because of its high voltage gain and high output impedance, an ECC83 is not considered the best choice for a line stage and other models like ECC82 are prefered for this use. In this case of a mixed tube/opamps design It seems that the high gain feature has been chosen with a view of obtaining more politically correct distortion figures by the use of negative feedback and balanced gain mode, while opamps provide the necessary low impedance output.
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Balance indeed a tricky thing. Also depending on the room setup. It can actually ruin the stereo image.
Really? With such a small difference?
I would think if your stereo image collapses with just 0.5 or 1dB difference, your setup must be highly unstable in that regard in the first place. Come on. Moving your head a few cm to the side has a bigger effect.
Minimalist single ended designs without feedback can easily show huge differences between channels if strict matching of components (tubes, jfets, mosfets ...) is not achieved.
But this Aiyima is by no way minimalist, more like a complex Audio Research (though not all tubes for obvious cost reasons) design than a Sakuma, Audio note, or Nelson Pass, Borbely, etc one...
In fact this Aiyima is a kind of minimalist opamps assisted tube design...
But this Aiyima is by no way minimalist, more like a complex Audio Research (though not all tubes for obvious cost reasons) design than a Sakuma, Audio note, or Nelson Pass, Borbely, etc one...
In fact this Aiyima is a kind of minimalist opamps assisted tube design...
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I found the plots. Published by Bob Stuart, but AFAIK there is another original source.
Edit: this is the source paper. Fig. 3
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First, thanks for this interesting device review.
I have to admit I'm confused about this one.
I mean: what's the use of a hybrid tube/solid state preamp ?
In my opinion, the main interest of tube and transformers is the way they saturate.
Which means: I see them mainly as effect devices.
So why to stand mid way and not to push the idea ?
I'd love to see a preamp like this one, with remote and decent performance... with a "saturation" knob, graduate from "clean" (with matching performance) to "saturated" or "warm" (whatever marketing dictates), with good noise but clear H2 (and H3... or not) increasing with level, reaching up to 3% if pushed to max.
As is, it's a middle ground that just allows to say "look at my tube preamp", while keeping cost low and performances good enough.
But that's me.
I have to admit I'm confused about this one.
I mean: what's the use of a hybrid tube/solid state preamp ?
In my opinion, the main interest of tube and transformers is the way they saturate.
Which means: I see them mainly as effect devices.
So why to stand mid way and not to push the idea ?
I'd love to see a preamp like this one, with remote and decent performance... with a "saturation" knob, graduate from "clean" (with matching performance) to "saturated" or "warm" (whatever marketing dictates), with good noise but clear H2 (and H3... or not) increasing with level, reaching up to 3% if pushed to max.
As is, it's a middle ground that just allows to say "look at my tube preamp", while keeping cost low and performances good enough.
But that's me.
Yes the fun of tubes and transformers based gear is not technical perfection, but rather minimalism. Something that as a diyer I personally found amazing... Full range loudspeakers too...
Btw, It makes sense to mix opamps DSP and tubes if the target is mass production of a low cost piece of gear. An all tubes equivalent of this AIYIMA would probably cost x100 more... I don't even know if AUDIO RESEARCH still exists...
Obviously too, this preamp is trying to make happy both subjectivists and objectivists, which imho IS not a good marketing strategy, as we all know that all people tend to love what others hate... Probably for this reason the votes are reflecting this, and nobody seem to love nor hate too much enough this AIYIMA...
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