Q&A about TSURANAGI

Q1. Which mini-mini cable should I use to make a balanced connection between a player and TSURANAGI?

A1. Please refer to the table at the bottom of this page.

When using the 4.4mm or 2.5mm balanced terminal on a Walkman as a line out, a split cable must be used for GND connection.

If not connected properly, GND will be uncoupled, causing malfunctions, noise generation, and poor sound quality.

Click for the product page of our mini mini cables here。



Q2. Why do the player and TSURANAGI need to be connected to the GND?

A2. There are several causes of the problem, but the result is that TSURANAGI malfunctions or degrades sound quality.

GND is the reference voltage for the circuit. Battery-operated players and amplifiers have an independent reference.

Therefore, if the GND is not shared, from the amplifier side, the misalignment between the GNDs plus the signal is input, and the misalignment is received as DC offset or noise.

This discrepancy can be eliminated to some extent by TSURANAGI's common-mode noise elimination because the balanced signal transmitted in the opposite phase is in-phase, but it can easily exceed the input range of the common-mode signal, resulting in excessive input and noise.

Another effect is that TSURANAGI's common-mode noise rejection cannot operate perfectly if the center point (voltage) of the common-mode noise operation is floating due to DC offset.

The reason why the common-mode signal input range is easily exceeded is due to TSURANAGI's high common-mode input impedance (1.25MΩ).

The reason why the common-mode input impedance is set so high is to allow for some degree of mismatch discrepancy between the HOT and COLD side impedances in operation in the correct state with the GND connected, and to suppress the common-mode noise rejection ratio reduction.

If GND is connected, this is not a problem because the player is connected with low impedance. However, if GND is not connected, the player becomes very sensitive to common-mode noise and picks up noise easily.

This may cause excessive input and malfunction.

As an experiment, we intentionally connected the player and TSURANAGI without GND connection, and when we touched the player's chassis with our hand, we confirmed about 3.5V common-mode noise with an oscilloscope when we looked at the voltage at the signal terminals with respect to the GND of TSURANAGI.

In the case of TSURANAGI, an excess input is quite possible because it is out of the operating range for common-mode noise of approximately 6.6 V or higher.

Since malfunctions during this phenomenon cause a DC offset to the output of TSURNAGI, a DC offset protection circuit ensures that TSURANAGI shuts down safely.

- Common-mode input impedance
- Amplifier common-mode input range
- Amount of noise jumping into the amplifier

It should be noted that there is no generality in the above figures because the degree of the problem depends on above.

*To make the noise waveform easier to understand, the waveform when the player is not playing is used as an example.

For Walkman, GND1 is not connected to the 4.4mm terminal and will be unconnected even if a GND-connected 4.4mm to 4.4mm cable is used, so a branch cable is required.



Q3. I hear noise. Is this a malfunction?

A3. it depends on the case.
There are players on the market that shut down their output after a certain amount of time without playback.

In this case, the situation is the same as when the mini-mini cable is not connected, and the high input impedance of TSURANAGI may cause it to pick up electromagnetic noise.

In this case, it is not a malfunction.

This phenomenon is characterized by the fact that when the TSURANAGI volume is turned down, the noise also decreases.

When playback starts, the player returns from shutdown and drives TSURANAGI so it does not pick up noise.
The reason why the above problem is difficult to occur with portable amplifiers from other companies is probably because their input impedance is not as high as TSURANAGI's.

This is because TSURANAGI uses a high input impedance to prioritize sound quality and minimize distortion of the player's output.

In addition, earphones with low impedance (less than 16 ohms) and high sensitivity may pick up white noise, which may be bothersome.
We recommend listening to the product with your earphones before purchasing.



Q4. Can I use it while charging at my desk, etc.?

A4. Yes.

The function reduces the charging current to the same level as the current consumption of the amplifier circuit only when the battery is less than about 60% and the power is on, allowing use without worrying about battery life while charging.

No noise can be heard while charging, as interference has been thoroughly minimized in the board design.
Therefore, there is no sound quality impact..

However, 24h power ON is not recommended because it increases the charge cycle.
This is only a feature to free you from playback time restrictions.



Q5. TSURANAGI's maximum input is 1.5Vrms. How should I set it?

A5. In most cases, the player side is recommended to be set to the lowest gain setting since the volume is sufficient.

The maximum input listed in the manual refers to the voltage at the maximum volume.

This case shows the condition where the output voltage does not exceed the limit at an input of 1.8Vrms.

By simple calculation, if the volume is squeezed so that the output voltage is halved, the input can be up to 3Vrms.

However, the narrower the volume, the less the input range.

With the volume turned down sufficiently and under conditions that do not hit the output limit, TSURANAGI allows up to 6Vrms for balanced input and 5Vrms for unbalanced input.

We use Astell&Kern's KANN ALPHA as our test equipment.

The balanced output voltage settings are 1.4Vrms/2Vrms/2.5Vrms/4Vrms, but I had to be careful with Astell&Kern.

The actual voltage output is twice as high as this figure, so it should be viewed as 2.8Vrms/4Vrms/5Vrms/8Vrms.

Other balanced line-out outputs were 3Vrms output on FiiO's M11 Plus and 4.1Vrms on Hiby's RS8 at maximum volume and balanced line-out output.

In conclusion, most players on the market can be connected to TSURANAGI for playback.



Q6: Can I replace the battery?

A6: Yes. The case and battery must be replaced together, but this is possible with a refresh plan.

Refresh Plan is here。


Q7. The input/output terminal pins move, is this a problem?

No problem.

The terminals are mounted on a small board separate from the main board and connected to the main board by a cable.

Therefore, the terminals may move, but the force is not applied to prevent solder cracking due to stress.