V4.1 Kit DAC output levels uneven (Solved)

while running my tests on my new Zynthian, I have noticed that the right and left output levels (balanced, to a Zoom Livetrak L-12) are uneven.
In order to have the same output level on the right and left channle I have to set a difference of about 14-18, depending on volume level.
The measurement is not super accurate as I used the Livetrak leds but it is immefiately noticeable with both channels set at the same volume.
I have tried the usuals, check the cables (TRS balanced) switch them, use a third one, same results …
Is there something I can check/calibrate on the hifiberry side?

Could you record an output using the zynthian audio recorder and upload it here ( a couple of seconds will surfice and probably best to do a wav) ? That will indicate that the zynthian is producing a balanced source.

Sure, here we go:

Same test tone, as recorded on the DAW through the Livetrak, levels at 100% on both channels

The first stereo pair are being produced at Identical level ( well to my eyes anyway)

so the zynth is generating audio at equivalent levels.

I can’t download your second track & it has regular clicking in it when I play it.

IS it ok at your end?

Sorry, the take from the DAW (garageband) had the metronome in, another one sans metronome tick:

Using Audacity Recording meters at differnt mixer settings:

Looks like a constant 5-6db difference between the channels

Well it’s certainly there in the second sample…

I’d put a scope across the zynthian outputs.

Does swapping the cables out of the zynth turn it round? ( I know you’ve said it does, but just humour me:-) )

You say you are coming out balanced, do you have signals on hot & cold ? A jack plug and a wire with two croc clips can held testing this.

Hello Matt,

can you test with the unbalanced line inputs 9/10 or 11/12?
These stereo channels don’t have a gain knob or pad so their input gain is fixed and should be the same for both channels.

You should be able to match both channel 3 and 4 gains with more acuracy if you use pad as recommended for line sources.

Also, in your mixer picture I can only guess your faders 3 and 4 have identic positions…

Greetings and God bless, Marius

@wyleu: sorry, software guy here, no scopes around, only soldering iron and I’m already dangerous enough with that …
Things I have tried:
swapping the cables
using different combination of inputs
Always the same unbalance on the same output channel from the hifiberry (right channel 5db more than the left)

Using the inputs 9/10 (unbalanced, but still the TRSs) I have the same level, albeit much lower than the 3/4 inputs
Padding: I tried as suggested, but with padding enabled the input levels drop to -30/-48 and I have to work on the gains to bring them up to -12db … and the right channel need less gain to get level with the left one

@mj_prod: fader position is not important, the reading is on the source signal after gain and compression and before any eq/effect/input fader

Ok, mistery solved and it shows my lack of understanding of all things electrical …
The two balanced cables, they’re different length …50 cm vs 150cm …
when I use two cables of the same length, levels are the same, as expected … sorry for wasting your time guys :frowning:


You won’t lose 6dB over a metre of cable. It is more likely that one of the cables is faulty or wired differently.


I have to agree with @riban ( yeah right…) the cable length really wont make that much distance. IT’s worth getting a small multimeter (they are pretty cheap) and learn to use it to check this sort of thing, as electrons only go where they can, and if there’s a break or a short ( especially in balanced lines ) these are the sort of effects you get.

You can then move on to the joys of cable reverses and all the fun that involves…

But glad you sorted it.

Which moves me on to matters bureaucratic. Zynthian towers contains many, many rooms where we collect sound samples, and althou’ you have so far produced five seconds of what is probably the most boring sample we have received since my early attempts at Jethro Tull covers, we have nothing in the dungeon marked ‘Matt’ …

So let’s be having a :face_with_monocle: !!

@riban: right tested with another pair of 200cm cables, same type (balanced) and I do not get the signal drop even when mixing them with the 50cm ones.
Oh well, in the bin they go, and sorry for wasting everybody’s time :slight_smile:

Only one of them will be bad …

Take it apart and see if you can see what caused it.

I’ve got my evening cup of rook soup on it being a short …

6dB drop is typically indicative of using an unbalanced cable over a balanced one in fact!


…resists temptation to explain balance, but won’t if provided with a :face_with_monocle: prompto . . .

@wyleu Please indulge the less engineering minded in the crowd :slight_smile:

@Baggypants, given they were supposed to be balanced and that both of them drop 6db I’d guess a cold solder/cable loose on the 2nd ring … time to bring out the tester … but both of them?