AIYIMA T20 Tube Pre-amplifier Review

[Schlippwhip68]

…

No offence I swear, but reading through recent posts in this thread, I thought I'd gone back to the subjectivist sites I used to frequent (and annoy in equal measure)

Enjoy your purchase and if using speakers, I'd put your tweaky-attention into optimising the room, speaker position with the possibility of a little eq to optimise the sound best...

No offence taken…’tweaky attention’…lol…I do use Apo EQ etc when using the PC mainly as I find the Aiyima A20 a little bright around 3.15khz - 6khz region and so drop it by 0.2db there. The Horizons are very detailed valves in the T20 with the opa828 and absolutely destroy the stock ECC83 for separation, detail and clarity. They are over twice the price of the stock valve but it’s a night and day difference, very easy to hear why they are the price they are.

Switching out the power supply to the T20 in a couple of days. Judging on the quality of the freebie stock there maybe some improvement ahead but keeping an ‘open ear’ to it anyway or on other words without any preconceived expectation.

I would like to see Aiyima work on there 36v 6a power supply’s. I much prefer these to the 48v version. If they go GaN with the 36v and maybe upgrade internal components to compensate for noise etc. Their 36v has been measured by Kiss Analogue on You Tube and he found it very reliable, constant and relatively quiet and even surpassed Fosi Audio 48v GaN for noise. Still, they could be improved even further.

 

[SMen]

…

No offence taken…’tweaky attention’…lol…I do use Apo EQ etc when using the PC mainly as I find the Aiyima A20 a little bright around 3.15khz - 6khz region and so drop it by 0.2db there. The Horizons are very detailed valves in the T20 with the opa828 and absolutely destroy the stock ECC83 for separation, detail and clarity.

Switching out the power supply to the T20 in a couple of days. Judging on the quality of the freebie stock there maybe some improvement ahead but keeping an ‘open ear’ to it anyway or on other words without any preconceived expectation.

I would like to see Aiyima work on there 36v 6a power supply’s. I much prefer these to the 48v version. If they go GaN with the 36v and maybe upgrade internal components to compensate for noise etc. Their 36v has been measured by Kiss Analogue on You Tube and he found it very reliable, constant and relatively quiet and even surpassed Fosi Audio 48v GaN for noise. Still, they could be improved even further.

I will be interested to know your impressions with the power supply you swap in to the T20 and which one.

 

[JSmith]

I thought I'd gone back to the subjectivist sites I used to frequent (and annoy in equal measure)

Agree... seems to have become more common here again, time to stamp it out.


JSmith

 

[KL....]

Groovy added features indeed and great for a bit of ‘musical chairs’ action switching in and out.

Along similar lines, I know on the A20 (bypass mode) you can switch from XLR to RCA with the same signal and certainly find some difference in cable quality which I found this evening while having Van Damme Tour Grade Classic XLR and Van Damme Plasma 75 ohm RCA. The Plasma was better.

Thank you, for your impressions but you need to be (a little) more objective/scientific. For example (to be precise)....

• Did you have both XLR and RCA outputs connected (output/downstream) to devices when you compared? If yes, then you need to indicate this, why? When the T20 XLR and RCA outputs are both connected to devices, the T20 XLR output will be Loaded down by the XLR device and the RCA LM4564 circuit (ie 2 output/2 input impedances), won't it? As the overview shows, doesn't it?
• In this case, RCA/XLR devices connected, what does the XLR Loading mean, but/well we do not know the circuit, do we, only the overview? The RCA/LM4562 may not be (as) affected by the XLR Load (lets assume so?), and if so, the the RCA output/device will measure/perform higher than the XLR device, won't it? This is what the measurements suggest, don't they?
• What does this mean for the XLR/RCA comparison? The scientific/objective process suggests, to be reasonable and to due to Output Loading effects, that you should disconnect one output while listening to the other output connection, as a minimum approach, doesn't it? By not doing this implys that the Impressions are not valid (subjective and not reasonable) and suggests that it was done this way because it can be, doesn't it?
  • Volume level matching.... we do not know the output V/I/impedance nor input V/I/impedance, do we? This implys that we should volume match, doesn't it? It can be suggested that this is best done at several freq points, such as 80hz/250hz/500hz/1Khz/2Khz/4Khz/8Khz, to be accurate/concise which is reasonable, isn't it?
• 

Lets also discuss the Psvane 12ax7 and Psvane Horizon 12ax7-AT....

• Psvane 12ax7 specs....
  • Heater Voltage 6.3V or 12.6V
  • Heater Current 300mA at 6.3V, 150mA at 12.6V
  • Maximum Anode Voltage 300V
  • Typical Anode Current 1.2mA
  • Maximum Anode Power Dissipation 1W/Triode
  • Amplification Factor mu100
  • Transconductance 1.6mA/V
  • Anode Resistance 62.5kKΩ
  • Input Capacitance 1.6pF
  • Output Capacitance 1.6pF
• Psvane Horizon 12ax7-AT specs....
  • None available and Psvane do not seem to make it easy to find them, other than Impressions. Specs/Measurement are necessary to ensure compatablety and safe utiliseation, aren't they?
  • If you can find them please post them so that we can compare them and discuss them.

 

[antcollinet]

Thank you, for your impressions but you need to be (a little) more objective/scientific. For example (to be precise)....

• Did you have both XLR and RCA outputs connected to devices when you compared? If yes, then you need to indicate this, why? When the T20 XLR and RCA outputs are both connected to devices, the T20 XLR output will be Loaded down by the XLR device and the RCA LM4564 circuit (ie 2 output/2 input impedances), won't it? As the overview shows, doesn't it?
• In this case, RCA/XLR devices connected, what does the XLR Loading mean, but/well we do not know the circuit, do we, only the overview? The RCA/LM4562 may not be (as) affected by the XLR Load (lets assume so?), and if so, the the RCA output/device will measure/perform higher than the XLR device, won't it? This is what the measurements suggest, don't they?
• What does this mean for the XLR/RCA comparison? The scientific/objective process suggests, to be reasonable and to due to Output Loading effects, that you should disconnect one output while listening to the other output connection, as a minimum approach, doesn't it? By not doing this implys that the Impressions are not valid (subjective and not reasonable) and suggests that it was done this way because it can be, doesn't it?
  • Volume level matching.... we do not know the output V/I/impedance nor input V/I/impedance, do we? This implys that we should volume match, doesn't it? It can be suggested that this is best done at several freq points, such as 80hz/250hz/500hz/1Khz/2Khz/4Khz/8Khz, to be accurate/concise which is reasonable, isn't it?
• View attachment 488311

Lets also discuss the Psvane 12ax7 and Psvane Horizon 12ax7-AT....

• Psvane 12ax7 specs....
  • Heater Voltage 6.3V or 12.6V
  • Heater Current 300mA at 6.3V, 150mA at 12.6V
  • Maximum Anode Voltage 300V
  • Typical Anode Current 1.2mA
  • Maximum Anode Power Dissipation 1W/Triode
  • Amplification Factor mu100
  • Transconductance 1.6mA/V
  • Anode Resistance 62.5kKΩ
  • Input Capacitance 1.6pF
  • Output Capacitance 1.6pF
• Psvane Horizon 12ax7-AT specs....
  • None available and Psvane do not seem to make it easy to find them, other than Impressions. Specs/Measurement are necessary to ensure compatablety and safe utiliseation, aren't they?
  • If you can find them please post them so that we can compare them and discuss them.

None of this matters. The listening tests were carried out uncontrolled, and sighted - they will remain pointless and invalid no matter what the test set up is. Further we know the only audible difference that can be gained between balanced and unbalanced connections is noise rejection. Unless the "impression" says

"I heard noise when using RCA, and got rid of it by switching to XLR" then we also know the only possible reason for the listeners perception is bias - nothing to do with the sound-waves reaching their ears.

And even noise is the result of ground loops/bad system set up. Not really a consequence of the cable.


I think we are getting to the point of needing "catchall" threads for cables, and - looking a couple of posts upwards from @Schlippwhip68 and @SMen, power supplies, to take this sort of drivel out of review threads.

 

[esk]

Can this device convert RCA 2Vrms input to balanced XLR 4Vrms output?

 

[antcollinet]

Can this device convert RCA 2Vrms input to balanced XLR 4Vrms output?

A much more interesting question. The documentation doesn't make a clear statement. But looking at the block diagram, I would guess yes. The RCA inputs are converted to balanced internally - then both XLR and converted RCA go into a single selector/volume chip. The output from the chip drives both sets of output buffers in parallel, so unless Ayima has done something stupid, then both outputs will be active - and if the input RCA conversion is done right - at the correct voltage for the output.


However, for a definitive answer - you'll need to ask Ayima support - or an owner who has one. Perhaps @Schlippwhip68 can help here

 

[morillon]

I haven't been following the discussion...
Do we know more about the gain and output impedance?

 

[SMen]

Thank you, for your impressions but you need to be (a little) more objective/scientific. For example (to be precise)....

• Did you have both XLR and RCA outputs connected to devices when you compared? If yes, then you need to indicate this, why? When the T20 XLR and RCA outputs are both connected to devices, the T20 XLR output will be Loaded down by the XLR device and the RCA LM4564 circuit (ie 2 output/2 input impedances), won't it? As the overview shows, doesn't it?
• In this case, RCA/XLR devices connected, what does the XLR Loading mean, but/well we do not know the circuit, do we, only the overview? The RCA/LM4562 may not be (as) affected by the XLR Load (lets assume so?), and if so, the the RCA output/device will measure/perform higher than the XLR device, won't it? This is what the measurements suggest, don't they?
• What does this mean for the XLR/RCA comparison? The scientific/objective process suggests, to be reasonable and to due to Output Loading effects, that you should disconnect one output while listening to the other output connection, as a minimum approach, doesn't it? By not doing this implys that the Impressions are not valid (subjective and not reasonable) and suggests that it was done this way because it can be, doesn't it?
  • Volume level matching.... we do not know the output V/I/impedance nor input V/I/impedance, do we? This implys that we should volume match, doesn't it? It can be suggested that this is best done at several freq points, such as 80hz/250hz/500hz/1Khz/2Khz/4Khz/8Khz, to be accurate/concise which is reasonable, isn't it?

Relating this to my own post about using XLR and RCA simultaneously.
Would you need to disconnect one output and then the other when the receiving unit (in my case a 3e Audio A7) switches between the two?

Equally if the DAC upstream for example switches between RCA and XLR would that make unplugging the cables unnecessary? I am not thinking of A/B testing or such, but getting round the T20's omission of a bypass additional option in their circuit. Can't see why this would be any different to switching sources on a pre-amp.

I suppose another variation would be if the DAC upstream output both RCA and XLR simultaneously and so independently buffers - I was looking into this and on the Schiit analog stages are independently buffered (LME49724 for XLR, OPA1656 for RCA), so connecting both shouldn't compromise performance or cause loading issues?

It is a different use case ... the T20 would only be used in balanced input output mode, but the variations and where someone might get caught out are interesting.

 

[SMen]

A much more interesting question. The documentation doesn't make a clear statement. But looking at the block diagram, I would guess yes. The RCA inputs are converted to balanced internally - then both XLR and converted RCA go into a single selector/volume chip. The output from the chip drives both sets of output buffers in parallel, so unless Ayima has done something stupid, then both outputs will be active - and if the input RCA conversion is done right - at the correct voltage for the output.


However, for a definitive answer - you'll need to ask Ayima support - or an owner who has one. Perhaps @Schlippwhip68 can help here

This I am presuming also addresses a use case for this pre-amp whereby the balanced outputs are used for the main set up, and the RCA's for subwoofers with single ended inputs. This should also handle things like input / output impedance when both single ended and balanced outputs are used at the same time on this T20 unit?

 

[Schlippwhip68]

I will be interested to know your impressions with the power supply you swap in to the T20 and which one.

Apparently according to one user the iFi Power X never made any difference to the overall sound value of the T20. I did ask the person to follow up with some form of descriptive detail, but nothing yet. This answer did not convince me….

….so I have gone and ordered one for my self to see if there is any reduction in perceivable noise, better background etc using it with the T20.

Using the T20/A20 in bypass mode now and will be when the Power X arrives.
I prefer the bypass mode. There is a gain in overall power output from the A20 of approximately 20% and it sounds a bit cleaner.

I would recommend Aiyima make a true power amp version of A20 negating the volume altogether, literally the exact same A20 but without the volume knob and a nice clean flat facia with only the two toggles would be excellent with total volume control from the T20. Maybe even drop the volume dial from the T20 too so we have a ‘flat slab’ with just the digital read out we have already, how cool, and put a small press button identical to the bypass button on the A20 with the red led ring on the rear of the T20 for power on/off. I don’t see a need for the mute function on the T20 already so imo there would be no need to implement it at all except for on the remote control.

I noticed someone concerned about heat of the valves for some reason. I have seen the 12ax7-AT measured at 63 degrees if that helps but mine are not that hot, I would guesstimate around 35-45 degrees at the very most, they are not too hot to touch even after a few hours. I am actually quite surprised as to how cool the T20/A20 run in bypass at 60% volume on the T20 running a signal from the iFi Zen One Signature, Fiio SR11 via balanced 4.4mm and XLR. I am in a warm room and the T20/A20 are very cool in temperature. My A70 gets a lot warmer.

Still dipping my toes boys, sorry I don’t have any further technical information on the valves as present.

 

[SMen]

Apparently according to one user the iFi Power X never made any difference to the overall sound value of the T20. I did ask the person to follow up with some form of descriptive detail, but nothing yet. This answer did not convince me….

….so I have gone and ordered one for my self to see if there is any reduction in perceivable noise, better background etc using it with the T20.

Using the T20/A20 in bypass mode now and will be when the Power X arrives.
I prefer the bypass mode. There is a gain in overall power output from the A20 of approximately 20% and it sounds quite a bit cleaner.

I would recommend Aiyima make a true power amp version of A20 negating the volume altogether, literally the exact same A20 but without the volume knob would be excellent with total control from the T20.

Still dipping my toes boys and sorry I don’t have any further technical information on the valves as present either.

No difference confirmed with the iFi Power X is/would be just as interesting.

 

[esk]

Using the T20/A20 in bypass mode now and will be when the Power X arrives.
I prefer the bypass mode. There is a gain in overall power output from the A20 of approximately 20% and it sounds quite a bit cleaner.

I would recommend Aiyima make a true power amp version of A20 negating the volume altogether, literally the exact same A20 but without the volume knob and a nice clean flat facia would be excellent with total control from the T20.

Is there a difference in sound if you use the T20 in "bypass" at 100 volume and volume control in the A20?

Because I was thinking of putting the T20 in between Wiim Ultra and a power amp and have the volume control of course on Wiim. T20 and power amp in "bypass" or full volume always.

 

[Schlippwhip68]

Is there a difference in sound if you use the T20 in "bypass" at 100 volume and volume control in the A20?

The T20 doesn’t have a bypass mode although some would like to see one implemented to switch from solid state (chip only) to valves and vice versa.

The A20 has bypass for the volume only and using it will allow the T20 to control the volume alone.

Yes there is a slight difference in sound quality. It improves with clarity in bypass mode. We get a cool little red light too when in bypass mode, nice aesthetic I thought.

 

[Schlippwhip68]

No difference confirmed with the iFi Power X is/would be just as interesting.

Agreed.

 

[LSP]

FYI -I had the same problem and I reached out to Aiyama - they sent me a picture of a stereo trigger plug. And it worked. I bought trigger cables and they didn't work. So it's something in the design of the unit, but it does work with the standard stereo plug.

FYI. The triggering of the second device such as an amplifier does not occur until the T20 has gone through its warm-up stage. So for over 20 seconds nothing happens. Then it will turn on the second device.
They made 1,000 of these with the 10th anniversary logo. Those are all sold. Made me wonder if perhaps they would fix this situation with the trigger cable in future models. Who knows?
I am very happy with this preamp. I added opa828 op amps in the XLR stage and upgraded the tubes. It sounds really fabulous. Subjectively. I have no data to support my positive feeling.
It's been fun and I think fun is a big part of music. I would hate to become someone that listens music through their brain instead of through their heart. But that's just me.

 

[JSmith]

I added opa828 op amps in the XLR stage and upgraded the tubes.

It's been fun and I think fun is a big part of music.

I'm glad you enjoyed it... but you could have been listening to music instead.

I would hate to become someone that listens music through their brain instead of through their heart.

What does this mean? Is this some kind of a dig at members here?


JSmith

 

[SMen]

FYI. The triggering of the second device such as an amplifier does not occur until the T20 has gone through its warm-up stage. So for over 20 seconds nothing happens. Then it will turn on the second device.
They made 1,000 of these with the 10th anniversary logo. Those are all sold. Made me wonder if perhaps they would fix this situation with the trigger cable in future models. Who knows?
I am very happy with this preamp. I added opa828 op amps in the XLR stage and upgraded the tubes. It sounds really fabulous. Subjectively. I have no data to support my positive feeling.
It's been fun and I think fun is a big part of music. I would hate to become someone that listens music through their brain instead of through their heart. But that's just me.

Cool ... I have a genuine limited edition! I had no idea it was limited to 1000.

This thread was always going to divide opinion and it's gone too far in both directions - at least the review itself by Amirm is objective, and in no way suggests the T20 measured in such a way you should not listen and enjoy music through it!

 

[SMen]

I'm glad you enjoyed it... but you could have been listening to music instead.

What does this mean? Is this some kind of a dig at members here?


JSmith

There was a user's thread at some point for subjective stuff (I think) which I agree, is where subjective stuff should go, but that seems to have disappeared! That would be the place for tube rolling, op amp rolling, linear (or other) power supplies etc.


There was quite a lot of disparagement going on earlier in the thread with pseudo objective stuff also!

C'est la vie on ASR!

 

[Schlippwhip68]

Looking forward to the Mk2 in everything now.