Weird(?) issue with Qudelix 5K and Meze Empyrean

[JustAnAudioLover]

Hi there!

I've recently got the chance to purchase a second-hand Meze Empyrean (first gen) for a fraction of its original price, and I've been enjoying it ever since.

But I had one major problem, which was that sub-bass was pretty much absent on most tracks. I ended up thinking it was normal, given I'm used to the sound of my Sony WH-1000XM3 which are very bass-y headphones.

For context, my setup simply consists of an Android phone streaming from Youtube Music in high quality (so OPUS 256 kbps I believe?) to the Qudelix 5K using LDAC, and the Empyrean is plugged into that using a 6.35 to 3.5 mm adapter.

Now, I had a weird experience just right now, and I'm sure there's a totally logical explanation to that but I'm not sure of the reason. Basically, when I listened to the headphones for the first time I ended up going all the way up in terms of volume, almost to 100% of the Qudelix' capacity. So I switched the gain to "HIGH" and went with it. But not matter how much EQ I did, I never got the right amount of sub-bass.

This evening I was playing a little with the EQ again, and some other settings of the amp. And just for fun I switched the gain to "NORMAL" again. To my surprise, the volume very much didn't change at all. It even seemed a tad louder. But also, the sound seems definitely better now. I though at first that it could be some nocebo effect, but after listening to the headphones for longer there's definitely more sub-bass now that what I got in HIGH gain even when I used EQ with a very high sub-bass boost.

I don't get why the volume isn't higher in high mode and why the sound is better now. My only guess would be the following, tell me if I'm right or wrong:

The Qudelix has a limited amount of power. Going into high gain 'artificially' increases the volume, which means it can reach higher volume on the same scale. But to do that, it will obviously require more power at higher levels. Going to high volumes with the Empyrean with the Qudelix in HIGH gain could have ended up using too much current compared to what the amplifier is capable of providing, effectively making it clip, hence the lack of sub-bass (which are the part that go away first as they're the most power-consuming part of the frequency spectrum).

This explanation seems to make sense (to me at least), but given the Empyrean is rated for 32 Ohms and a 100 dB sensitivity, I don't get how HIGH gain could require too much power from the Qudelix. Also, I noticed the dBSPL conversion in the app doesn't make sense - at pretty low volume (to my ears) it tells me I'm at 90+ dB, and at full volume I would be at about 115 dB (using the sensitivity and resistance of the headphones I input in the app). This seems extremely weird as 115 dB would be an ear-bleeding volume, and 90 dB is still extremely loud but the sound was pretty low in volume to my ears.

Could someone explain what happened to me?

Many thanks

 

[staticV3]

This evening I was playing a little with the EQ again, and some other settings of the amp. And just for fun I switched the gain to "NORMAL" again. To my surprise, the volume very much didn't change at all. It even seemed a tad louder.

The Qudelix is programmed so that switching gain alone does not change the volume. With the gain switch the volume control is automatically adjusted to counteract the gain.

Switching to High gain for example just unlocks more volume control. Basically it's Low gain->Increase volume to 100%->Switch to High gain->Now you can increase volume to 150% or whatever.

Though whatever difference in sound quality or subbass amount you heard between Low and High gain is most likely not real. Just your mind playing tricks on you.

The Qudelix has a limited amount of power. Going into high gain 'artificially' increases the volume, which means it can reach higher volume on the same scale. But to do that, it will obviously require more power at higher levels. Going to high volumes with the Empyrean with the Qudelix in HIGH gain could have ended up using too much current compared to what the amplifier is capable of providing, effectively making it clip, hence the lack of sub-bass (which are the part that go away first as they're the most power-consuming part of the frequency spectrum).

Clipping is a nasty, very obvious sound. It's not just a subtle drop in subbass.

Also, I noticed the dBSPL conversion in the app doesn't make sense - at pretty low volume (to my ears) it tells me I'm at 90+ dB, and at full volume I would be at about 115 dB (using the sensitivity and resistance of the headphones I input in the app). This seems extremely weird as 115 dB would be an ear-bleeding volume, and 90 dB is still extremely loud but the sound was pretty low in volume to my ears.

The dBSPL calibration assumes 0dBFS input signal. Input signals lower than that will throw off the numbers.

 

[JustAnAudioLover]

Thanks for your explanations

I re-did some sighted A/B testing, and it seems like there is a small difference in volume, with NORMAL gain being a bit louder than HIGH gain. I have no idea why, as the displayed power in mW and dBSPL volume are the exact same in both mode, but there seems to be a difference. When quickly switching and putting a higher volume on HIGH gain than on NORMAL I feel like there's more bass on HIGH now, probably because there's actually more bass thanks to the higher volume.

Would that make sense?

 

[staticV3]

When quickly switching and putting a higher volume on HIGH gain than on NORMAL I feel like there's more bass on HIGH now, probably because there's actually more bass thanks to the higher volume.

higher volume doesn't increase actual bass response, it just boosts the perceived bass response due to equal loudness contours.

 

[JustAnAudioLover]

higher volume doesn't increase actual bass response, it just boosts the perceived bass response due to equal loudness contours.

Yeah I meant that more volume = more of every single frequency, including bass.
But there's also what you mentioned, yes