Issue with balanced output on P20, ideas on what to test?

[MrC]

I am running an SMSL SU-8 balanced output into the Loxjie P20 (the unbalanced from the SU-8 goes into an Atom).

I have converted a pair of Beyerdynamic Custom Studio to balanced by replacing the 3.5mm TRS with a 3.5mm TRRS wired:

Tip: L+
R1: R+
R2: L-
Sc: R-

I have also made two adapters, the first is to convert the TRRS (at amp end) into a 1/4" TRS for Single ended use, this is wired:

TRS ------ TRRS
Tip ------ Tip (L+)
Ring------ R1 (R+)
Screen --- R2 + Screen (L- and R-)

The second adapter is to convert the TRRS to a 4 pin XLR for use with the Loxjie P20 balanced output. This is wired:

XLR4 ------ TRRS
Pin1 ------ Tip (L+)
Pin2 ------ R2 (L-)
Pin3 ------ R1 (R+)
Pin4 ------ Sc (R-)

I have tested all of these connections and the all are correct with no shorts.

When connected to a single ended output (using the TRS to TRRS adapter) they work fine on both the Atom and the SE output of the Loxjie. However, when connecting the headphones to the balanced output of the Loxjie P20, I get a very weird sound that sounds like a combination of out of phase and slow motion, as if everything is happening a lot slower.

I have also tested the output of the Loxjie to make sure there are no shorts between cores on the outputs, but that seems to be fine also.

My question is, even though I have already tested connections multiple times, if something was indeed out of phase, wouldn't this also affect the headphones when running in SE mode? I mean, if a + and - was crossed somewhere in my connections, then it would be crossed when using SE also.

Is it possible that the wiring of the Loxjie balanced output is different to that stated in the manual?

Any suggestions on what to test would be greatly appreciated!!

Thanks in advance.

 

[MrC]

As an update after some more fault finding...

I, again, tested for continuity and resistance each of the connection points I have made. Each of them tests fine with no issues.

I put the headphones back to unbalanced, and maybe it is just my mind playing tricks (I don't have any way to measure headphones) but they seemed to be clearer than when running the balanced cable and adapter to SE.

I took another pair of headphones (a cheaper Sony set) that has a cable on each cup and sums up at the connector. I chopped off the connector and replaced it with an XLR4 (wired the same as above), these work fine with the balanced output.

So, my only guesses are either the male to female TRRS cables (I tried 3 different ones) or the actual TRRS 3.5mm cables themselves which were a cheap set I bought.

Or maybe the Beyer CS don't like balanced...

I will order some better connectors and continue the search for the issue.

 

[rrg]

I bought a cheap 3.5mm surface mount solder and it had the same effect you said with sound just not correct on a headphone jack conversion.
Replaced it with a more expensive Philmore 3.5mm solder type connector jack and everything worked perfect on those headphones.

I'm also waiting for the Loxjie P20 and ordered the 3.5mm TRRS 4 pole female for my DT1770 on the headphone. I will remove the 3 pin mini-XLR. I don't like the shoulder touch when I use them.
So I will also be doing what you did with a few adapters to go to 3.5mm 3 pole.

Stay tune, everything is ordered and I'm waiting.

 

[MrC]

I bought 4 pole Tiny XLR's in the end as I know their quality is decent (and are much easier to solder than the 3.5mm TRRS), I just haven't had time to fit them yet.

 

[Gyroscopics]

My current setup is similar to yours (MrC) but I don't experience the issues you mentioned.

My SMSL SU-8 simultaneously feeds 1) JDS Labs Atom via RCA and 2) red Loxjie P20 via XLR. I use a pair of Monoprice XLR male to XLR female cables between the Loxjie and SMSL. I don't use TRRS as my Focal Elex already came with a 4 pin balanced XLR cable. I bought an aftermarket 4 pin balanced XLR cable for my Senn HD6xx and that cable works perfectly on my system.

The HD6xx sound improved a lot with the balanced input from Loxjie P20 that I don't use the HD6xx with the Atom anymore. The Elex became punchier with the Loxjie and still relatively good with the Atom. The headphone I don't use with the Loxjie is the M1060 because the combo emphasizes the already strong bass from the planar magnetic. The M1060 is better with the Atom. BTW, I use aftermarket GE tubes on the P20.

 

[MrC]

My current setup is similar to yours (MrC) but I don't experience the issues you mentioned.

My SMSL SU-8 simultaneously feeds 1) JDS Labs Atom via RCA and 2) red Loxjie P20 via XLR. I use a pair of Monoprice XLR male to XLR female cables between the Loxjie and SMSL. I don't use TRRS as my Focal Elex already came with a 4 pin balanced XLR cable. I bought an aftermarket 4 pin balanced XLR cable for my Senn HD6xx and that cable works perfectly on my system.

The HD6xx sound improved a lot with the balanced input from Loxjie P20 that I don't use the HD6xx with the Atom anymore. The Elex became punchier with the Loxjie and still relatively good with the Atom. The headphone I don't use with the Loxjie is the M1060 because the combo emphasizes the already strong bass from the planar magnetic. The M1060 is better with the Atom. BTW, I use aftermarket GE tubes on the P20.

The issue was with the 3.5mm TRRS connectors, while they tested ok, the sound output was not good. Swapped to Tiny XLRs and the issue doesn't exist.