Volume uneven from monoblocks with XLR, but not RCA

[Quenya]

I may have bought a faulty set of preamp and monoblocks, though I want to ask if it's a small or big fault. Sorry for a lengthy post.

I bought an Exposure 5010 pre and a pair of Exposure 5010 monoblocks second hand from a seller in Norway while I myself live in Sweden. I have at home noticed an imbalance in volume between the monoblocks and have ruled out bad cables and power source by swapping from right to left one cable and unit at a time and retesting by listening to music (mono recordings). Swapping the monoblocks while keeping everything else the same shifts the imbalance. I have the monoblocks connected to the pre through balanced xlr cables. I have made sure both selectors for balanced/unbalanced are correct on the monoblocks. The problem is independent of the volume pots position on the pre.

After some further troubleshooting, I found that opting for unbalanced rca cables and selecting the unbalanced setting on the monoblocks fixed the volume mismatch. Going back to balanced cables but keeping the monoblocks in the unbalanced setting also resulted in an even volume balance. So the issue seems to be with the balanced setting on one of the monoblocks. Also using unbalanced cables and flipping the switch to balanced creates a volume mismatch.

Does the presumably faulty setting merely add/subtract 6 dB of volume, or is it more complicated than that? Should I just go for unbalanced interconnects and settings, or is this a symtom that indicates that the sound will be degraded even if the L/R-volume is matched by going this way? Can I do balanced signal through XLR but leave the button in the unbalanced setting, since I already bought the cables? Are there any advantages or perhaps disadvantages/risk of damage in doing so?

Thanks for reading.

 

[AnalogSteph]

Clearly the balanced / unbalanced switch must not be doing quite what it says (I would have expected it to be switching between the two inputs). Do you always get some sort of output, regardless of which combination of input type and setting you are using? If so, the switch might just be activating a 6 dB pad, and for some reason that doesn't happen in one of the amps (bad solder joint, bad switch, ...). Try toggling it during playback and observe which of the units actually changes output level.

Since this model only seems to be a few years old, I would also consult the manufacturer regarding how these amps are supposed to behave and a specification for gain in either mode.

 

[Chrispy]

Any problem in just using rca as a result? It wouldn't necessarily be a reduction of 6dB in volume except up front....but need more details

 

[Quenya]

Clearly the balanced / unbalanced switch must not be doing quite what it says (I would have expected it to be switching between the two inputs). Do you always get some sort of output, regardless of which combination of input type and setting you are using? If so, the switch might just be activating a 6 dB pad, and for some reason that doesn't happen in one of the amps (bad solder joint, bad switch, ...). Try toggling it during playback and observe which of the units actually changes output level.

Since this model only seems to be a few years old, I would also consult the manufacturer regarding how these amps are supposed to behave and a specification for gain in either mode.

Okay, so I have gotten confirmation by Exposure that the balance switches have to be correctly set before power on, since there is a software lock out to prevent operation while powered up. The RCA and XLR inputs are not really selected by toggling the balanced/unbalanced switch, but rather the amps gain is optimized if I understand this correctly. It's not uncommon to design this way. I think for instance McIntosh does this too.

I am awaiting answer from Exposure what the intended behavior is from the balanced/unbalanced switch. It seems one monoblock plays louder when started in balanced mode compared to when starting it in unbalanced mode. The other one seems to amplify equally loud no matter what setting is used on startup.

Any problem in just using rca as a result? It wouldn't necessarily be a reduction of 6dB in volume except up front....but need more details

Using RCA instead is what I'm aiming for. The volume is at least equally distributed from the two channels by going this way. I'm trying to figure out how much I'm missing out on by not being able to use the balanced out from the pre and balanced in on the monoblocks. And since I don't really know what is causing this error and what the error does to the amplifier, I'd like to know if the unbalanced setting could also be affected/degraded in any way. What do you mean by "It wouldn't necessarily be a reduction of 6dB in volume except up front"?

 

[Chrispy]

Okay, so I have gotten confirmation by Exposure that the balance switches have to be correctly set before power on, since there is a software lock out to prevent operation while powered up. The RCA and XLR inputs are not really selected by toggling the balanced/unbalanced switch, but rather the amps gain is optimized if I understand this correctly. It's not uncommon to design this way. I think for instance McIntosh does this too.

I am awaiting answer from Exposure what the intended behavior is from the balanced/unbalanced switch. It seems one monoblock plays louder when started in balanced mode compared to when starting it in unbalanced mode. The other one seems to amplify equally loud no matter what setting is used on startup.



Using RCA instead is what I'm aiming for. The volume is at least equally distributed from the two channels by going this way. I'm trying to figure out how much I'm missing out on by not being able to use the balanced out from the pre and balanced in on the monoblocks. And since I don't really know what is causing this error and what the error does to the amplifier, I'd like to know if the unbalanced setting could also be affected/degraded in any way. What do you mean by "It wouldn't necessarily be a reduction of 6dB in volume except up front"?

I look at it more as at what level the signal can extract maximum output from the amp. Hopefully your rca connection provides sufficient voltage. May suffer in noise/distortion but as an audible worry particularly, not so much