AIYIMA T20 Tube Pre-amplifier Review

[jayapple]

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.

 

[KL....]

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.

Thank you @jayapple, decoration/maybe? The ECC083/LM4562, while they are in the same GFB/Closed loop, they are DC/Coupled/Open Loop (appears so! although the DSP bit is wrong, isn't it?), aren't they? RCA/XLR SINAD/etc results/measurements are very similar, aren't they? The LM4562 provides the ECC083 with buffer/input impedance/V/I compatiblety and low output impedance/drive/compatiblety to the device it is feeding, doesn't it?

Edit: re DSP/NJW1195 chip.... Apologys, above I indicated 'no DSP/wrong' but on refection, perhaps it does, burnt not programable (at least with this implementation). Although the specs do not indicate that it does utilise DSP nor is it Digital NJW1195 - 4-Channel Electronic Volume with Input Selector :=)

 

[pma]

The LM4562 provides the ECC083 with buffer/input impedance and low output impedance/drive/compatiblety to the device it is feeding, doesn't it?

Not only. The tube is inside LM4562 feedback loop which allows to reduce tube distortion significantly. Visually, there is the tube, practically, like if there was not, doing only some degradation of parameters. However, enthusiasts wish to be fooled.

 

[Sokel]

Not only. The tube is inside LM4562 feedback loop which allows to reduce tube distortion significantly. Visually, there is the tube, practically, like if there was not, doing only some degradation of parameters. However, enthusiasts wish to be fooled.

I know nothing about tubes but if I were to guess acts like a resistor in the loop?

 

[KL....]

I know nothing about tubes but if I were to guess acts like a resistor in the loop?

Thank you, the ECC083 will have a reactive output impedance (R) but it is really for Gain (maybe H2 and appearance/look), isn't it? The LM4562 is really a Buffer with Drive/Compatiblety, isn't it? Quite Novel and THD+N/SINAD is acceptable/sufficient, isn't it....

 

[pma]

I know nothing about tubes but if I were to guess acts like a resistor in the loop?

No . Nonlinear resistor would be closer.

 

[AIYIMA]

 

[KL....]

No . Nonlinear resistor would be closer.

Thank you @pma, yes, re Nonlinear Resistor.... the ECC083 haveing a reactive output impedance (Nonlinear/Variable R), would mean the same, in this instance, wouldn't it?

 

[SSS]

After viewing the block diagram I think that the tube can be omitted and replaced by a good op-amp. Reason is that the signal is anyway passing DSP and IC output buffer silicon.
So for me the tube is just for fancy fun. isn't it?

 

[amirm]

It would indeed be nice to have a fully solid state version of this.

 

[Nzama]

I know nothing about tubes but if I were to guess acts like a resistor in the loop?

(Resistor )^(-1)

 

[jayapple]

Thank you @jayapple, decoration/maybe? The ECC083/LM4562, while they are in the same GFB/Closed loop, they are DC/Coupled/Open Loop (appears so! although the DSP bit is wrong, isn't it?), aren't they? RCA/XLR SINAD/etc results/measurements are very similar, aren't they? The LM4562 provides the ECC083 with buffer/input impedance/V/I compatiblety and low output impedance/drive/compatiblety to the device it is feeding, doesn't it?

View attachment 482594

From this perspective, it is indeed clear that power and signals pass through the bulb. But in my opinion, it is mainly the buffer amplifier chip at the back that plays the main role. This is a key reason for its high fidelity.

The distortion of the bulbs I made myself would be quite significant. It's just that many transistors are responsible for stabilizing the voltage to ensure the stable output of the bulb. This type of bulb has no power supply part at all. I think it's just for lighting.

 

[jayapple]

From this perspective, it is indeed clear that power and signals pass through the bulb. But in my opinion, it is mainly the buffer amplifier chip at the back that plays the main role. This is a key reason for its high fidelity.

The distortion of the bulbs I made myself would be quite significant. It's just that many transistors are responsible for stabilizing the voltage to ensure the stable output of the bulb. This type of bulb has no power supply part at all. I think it's just for lighting.

The core of McIntosh lies in its transformers, which no one can replicate. The one I use is the most basic type, so it's very difficult to replicate that specific sound. However, it still sounds great.

For the circuit part, the light bulbs require many transistors to stabilize the voltage, which makes the sound slightly more high-fidelity. Some old-style bulbs without voltage stabilization have extremely large distortion.

 

[AIYIMA]

From this perspective, it is indeed clear that power and signals pass through the bulb. But in my opinion, it is mainly the buffer amplifier chip at the back that plays the main role. This is a key reason for its high fidelity.

The distortion of the bulbs I made myself would be quite significant. It's just that many transistors are responsible for stabilizing the voltage to ensure the stable output of the bulb. This type of bulb has no power supply part at all. I think it's just for lighting.

Hello, thank you very much for your attention!

Our T20 preamplifier circuit includes a transformer design that allows the ECC83 (12AX7) tube to reach a maximum operating voltage of 180V. The tube uses anode amplification and works together with the subsequent op-amp stage to amplify the signal. Therefore, it is not just a decorative light, but an important component that actively participates in the sound amplification.

We hope this explanation helps you better understand the design and sound performance of the T20.

 

[morillon]

Hello, thank you very much for your attention!

Our T20 preamplifier circuit includes a transformer design that allows the ECC83 (12AX7) tube to reach a maximum operating voltage of 180V. The tube uses anode amplification and works together with the subsequent op-amp stage to amplify the signal. Therefore, it is not just a decorative light, but an important component that actively participates in the sound amplification.

We hope this explanation helps you better understand the design and sound performance of the T20.

Its maximum gain?
Its output impedance?
For output gain ...type of curve used.. classic log?
Thank you...
(It seems that there is no carbon potentiometer here (?) ..so no problem with track imbalance depending on the gain ;-) )
honestly...the first data to observe for preamp, even before a sinad at 1khz it seems to me ;-)

 

[totti1965]

Its maximum gain?
Its output impedance?

@welwynnick : Something to add to your legendary table!

 

[KL....]

It seems that there is no carbon potentiometer here (?)

Thank you, no carbon potentiometer, it utilises the NJW1195 chip.

The digitally control volume produces perfect channel matching:

 

[morillon]

Thank you, no carbon potentiometer, it utilises the NJW1195 chip.

It is the precise observation in the case of other solutions of the track potentiometer type which is interesting...there, it was not of much use with these technologies. ;-))

 

[morillon]

@welwynnick : Something to add to your legendary table!

View attachment 482660

having orders of magnitude, knowing the precautions to take depending on the "marriages"...is generally enough for me ;-)

 

[KL....]

It is the precise observation in the case of other solutions of the track potentiometer type which is interesting...there, it was not of much use with these technologies. ;-))

Thank you, Aiyima indicate that the NJW1195 chip utilises DSP....

Re DSP/NJW1195 chip.... Apologys, above/previously I indicated 'no DSP/wrong' but on refection, perhaps it does, burnt not programable (at least with this implementation). Although the specs do not indicate that it does utilise DSP nor is it Digital NJW1195 - 4-Channel Electronic Volume with Input Selector :=)