Balanced output FIIO KA15 (distorted signal, wrong channel separation)

[genius8086]

Hi everyone, I’m struggling to get the audio from the 4.4 mm balanced output of the FIIO KA15 to sound right on my Presonus Eris E4.5 monitors.

1) Buzzing noise on PC. The biggest issue (which does not occur when using an Android smartphone) is a buzzing noise during playback. It happens at specific points in the audio and always in the same places. I suspect it’s related to the overall output level, which becomes distorted when the KA15’s output gain is set higher than ~44 (out of 60). While this might not seem like a big deal, the whole point of using the balanced output was to achieve a louder signal without increasing the volume on the Eris E4.5 speakers (which adds a bit of white noise when turned up). With the unbalanced 3.5 mm output, I can set the KA15 to maximum volume and get a louder, cleaner signal, making the balanced output pointless in this case.

2) Poor channel separation. When using the 4.4 mm balanced output, stereo channel separation is incorrect. I can always hear (quiet, but still audible) a trace of the opposite channel when I carefully listen to the left or the right speaker. I connected headphones to Eris E4.5 and used the proper content, there is no doubt that the audio is separated wrong. This becomes more noticeable as the KA15’s output gain exceeds ~44 (marked as 44A on the device's LCD screen), so I believe this issue is related to the first one. The difference is that on PC, with a high enough output level, you hear the buzzing noise, whereas on Android this noise does not occur.

Wiring details: the balanced output of the FIIO KA15 appears to follow this pinout (starting from the tip of the 4.4 mm jack): L+, L–, R+, R–, ground. The Eris E4.5 has “plus,” “minus,” and “ground” (starting from the tip) for each balanced TRS input, with left and right channels separated. I’m using the following cable: 4.4 mm to 2 × 3.5 mm balanced (https://www.amazon.de/dp/B0FBF7HBVQ?ref=ppx_yo2ov_dt_b_fed_asin_title). I ordered several of this type and checked the contacts with a multimeter, they are compatible and mostly identical. Then I use 3.5 mm to 6.25 mm adapters to connect to the speakers.

For the easy listening test I used the bass sound after the intro in Queen’s song "Breakthrough" (0:35), and both issues are clearly reproducible. You can definitely hear a trace of the opposite channel, which should not be there, and a buzzing noise. Playback was tested with foobar2000 v2.24.5 on Windows 10 (KA15 in ASIO mode), the issue occurs regardless of format (MP3, Audio CD, FLAC, DSD). It’s not even about the media player, the channel separation issue happens with Spotify player on Android.

If I connect only the left or right TRS cable separately, none of these issues occur. There is no distortion even at maximum KA15 output level, and obviously no channel bleed when only one channel is connected. My guess is that the shared ground may be causing the problem, or perhaps these cables are designed for headphones and not intended for use with studio monitors (even entry-level ones).

Some setup details:
FIIO KA15 firmware v1.1.2 (latest)
ASIO driver 5.74.3
NON-OS filter, EQ off, DAC class H, DRE disabled
Eris E4.5 works perfectly with unbalanced connections

Thank you in advance for your help, I’m hoping for some professional advice from this forum.

 

[Curupira]

Try setting the digital volume to lower than 100%/0 dBFS, as some devices clip under those circumstances. Also try using other USB ports, adapters and cables. Finally, try reinstalling its drivers (since the problem doesn't happen on Android).

Regarding the channel imbalance and crosstalk, I'm at a loss. If problem persists with the solutions above, I'd return it.

EDIT: Following your ground conjecture, I've yet to see a 4.4mm pentaconn out that actually uses the ground pin, and just doesn't leave it floating. Maybe your cable is causing the trouble? Try using an unbalanced connection (the Eris have RCA) from the 3.5mm out to see if the crosstalk persists. If it doesn't and you get a reasonable volume, I would restrain from using bal out for your monitors, as it would be causing the exact problem it is tailored to avoid.

 

[CedarX]

I would check and re-check the cable (with the 6.35mm adapters installed) with a multimeter: is the wiring what you expect? What about the resistance between each of the individual paths, is it ~0 Ohm, or infinite, nothing else?

If you have a multimeter with this capability: check capacitances between individual paths… This is a headphones cable with a 4.4mm connector that looks a little longer (and bigger?) than usual. I have a similar cable (Shure…) with an unusually long connector that incorporates RC filters for—I assume—EMI/noise filtration. Fine on a HP, but talk about a way to mess high-impedance interconnections…

 

[Vincent Kars]

A balanced out of a headphone amp means 2x single ended. So L+/L- and R+/R- going to the specific cups.
It is a bit unclear to me why the cable as mentioned ends in a TRS.

It is a bit rare to use a Pentaconn for balanced connections at line level. It is TRRRS and for each channel you need 3 wires (hot, cold, ground).
However, you can solve this by using L+/L- and R+/R- and use the shield as a common ground.
iFi as a 4.4. balanced out on some of their DAC's and they do make a adapter cable https://ifi-audio.com/products/4-4mm-to-xlr-cable
So it must be possible to do balanced with a common ground.

 

[genius8086]

A balanced out of a headphone amp means 2x single ended. So L+/L- and R+/R- going to the specific cups.
It is a bit unclear to me why the cable as mentioned ends in a TRS.

It is a bit rare to use a Pentaconn for balanced connections at line level. It is TRRRS and for each channel you need 3 wires (hot, cold, ground).
However, you can solve this by using L+/L- and R+/R- and use the shield as a common ground.
iFi as a 4.4. balanced out on some of their DAC's and they do make a adapter cable https://ifi-audio.com/products/4-4mm-to-xlr-cable
So it must be possible to do balanced with a common ground.

Thank you for your reply. The cable is ended with a pair of TRS, not a single TRS. This kind of cable (https://de.aliexpress.com/item/1005007187650043.html) is manufactured by FIIO and should be compatible with FIIO DACs (it's not easy to get it in Europe, though), but the basic idea is the same: TRRRS to double TRS with the shared ground. Sleeve is a ground, shared for left and right channels. For this cable (https://ifi-audio.com/products/4-4mm-to-xlr-cable) the idea is similar, though the PIN 1 in XLR is the ground (and the ground is connected to the same sleeve in Pentaconn). Could you please give some details, how exactly my setup can be improved with introducing XLR, are these connectors more robust? Maybe I didn't understand something. I definitely need to buy a pair of XLR to TRS adapters then.

 

[genius8086]

Try setting the digital volume to lower than 100%/0 dBFS, as some devices clip under those circumstances. Also try using other USB ports, adapters and cables. Finally, try reinstalling its drivers (since the problem doesn't happen on Android).

Regarding the channel imbalance and crosstalk, I'm at a loss. If problem persists with the solutions above, I'd return it.

EDIT: Following your ground conjecture, I've yet to see a 4.4mm pentaconn out that actually uses the ground pin, and just doesn't leave it floating. Maybe your cable is causing the trouble? Try using an unbalanced connection (the Eris have RCA) from the 3.5mm out to see if the crosstalk persists. If it doesn't and you get a reasonable volume, I would restrain from using bal out for your monitors, as it would be causing the exact problem it is tailored to avoid.

There are no issues when I use an unbalanced connection: the channel separation is correct and the DAC output volume can be properly set to maximum without adding buzzing noise. Well, if nothing helps, I have to keep using the unbalanced wiring.

I would check and re-check the cable (with the 6.35mm adapters installed) with a multimeter: is the wiring what you expect? What about the resistance between each of the individual paths, is it ~0 Ohm, or infinite, nothing else?

If you have a multimeter with this capability: check capacitances between individual paths… This is a headphones cable with a 4.4mm connector that looks a little longer (and bigger?) than usual. I have a similar cable (Shure…) with an unusually long connector that incorporates RC filters for—I assume—EMI/noise filtration. Fine on a HP, but talk about a way to mess high-impedance interconnections…

Yes, that's a good idea to check not only the connection, but the resistance of every individual path. I'll do that.

 

[Vincent Kars]

how exactly my setup can be improved with introducing XLR, are these connectors more robust?

XLR is very robust but does that solve your problem? Basically 3 pin XLR or 3 pin TRS are identical as they do allow for 3 wires.

It might be a wiring problem say https://de.aliexpress.com/item/1005007187650043.html has an issue e.g. it is not L+-Ground and R+-Ground but you can check that including checking if e.g. L+ and R+ are on the same 3.5 TRS out. Check all possible combinations.
Might be a connecting problem like Pentaconn did not fit properly in the Fiio, 3.5 to 6.4 did not fit properly, etc.

 

[roladyzator]

I'm not getting such issues with my setup:

PC (USB) -> KA15 -> 4.4mm to 2x male XLR adapter -> 2x female XLR to TRS (separate cable per channel) -> Presonus Sub8 BT subwoofer (pass-through) -> 2x TRS cable -> Kali IN-8V2

There is some noise only when music is not playing, it seems like part of the output is shut-off and connection is no longer balanced.
I'm using a 20kHz tone at -100 dBFS to fool KA15 and the output is silent again.

No issues when using max volume and gain on KA15 and using a lower volume in Windows, and I didn't notice any channel bleed that you described.

This is the cable I'm using:

https://pl.aliexpress.com/item/1005006398401430.html

It has one issue - the jack is a bit recessed in the metal enclosure of the cable.

I need to unscrew the enclosure a bit (just a little un-twisting it), and then the jack can fit entirely into the KA15.

 

[nagster]

Hi everyone, I’m struggling to get the audio from the 4.4 mm balanced output of the FIIO KA15 to sound right on my Presonus Eris E4.5 monitors...

Use a DMM to measure the resistance of the sleeve lines of the FIIO KA15's 3.5mm jack and 4.4mm jack.
In my experience, the sleeve of the 4.4mm jack is almost always left unconnected. Similarly, the sleeve of the 3.5mm jack is 100% connected to the device's ground.
When a ground connection is required with the 4.4mm connection, I use the 3.5mm jack. However, this doesn't work with all devices. Connecting both may mute one of them.

If the 4.4mm jack is connected to headphones or IEMs, it's fine if the sleeve is floating, but if it's connected to a device connected to the mains, unexpected problems may occur.

The reason there's no problem with a smartphone may be because the only device connected to the mains power is the speaker.
If you can connect the KA15 while charging your smartphone from the mains power, try that.
Also, if your Windows machine is a laptop, try unplugging the charger. This may provide some clues.

The strange cable in the linked image has wires taken from the sleeve of a 3.5mm plug and soldered to the sleeve of a 4.4mm plug.

Instead of connecting RCA preamp output to XLR pwrd speakers, could I use balanced 4.4 mm headphone jack to XLR?

Class A equipment that is designed for commercial use is allowed to produce more radio frequency emissions than Class B equipment designated for residential use. Your microwave won't cause your TV to flicker. But commercial microwaves in the office cafeteria might cause the same effect for...

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[jkim]

The problem is very SIMPLE. You are using a wrong cable.

The FiiO cable you are using is for headphone connection. Headphones do NOT need an electrical ground node when connected to a device's balanced output jack. The FiiO cable must not connect the ground node since otherwise it may kill the device.

Use a proper cable for your purpose.

 

[nagster]

I’m using the following cable: 4.4 mm to 2 × 3.5 mm balanced (https://www.amazon.de/dp/B0FBF7HBVQ?ref=ppx_yo2ov_dt_b_fed_asin_title). I ordered several of this type and checked the contacts with a multimeter, they are compatible and mostly identical. Then I use 3.5 mm to 6.25 mm adapters to connect to the speakers.

I checked the link. It's very likely that the sleeves on that cable are not connected together.
First, use a DMM to check continuity on all terminals on the cable.