Qudelix-5K Bluetooth DAC & Headphone Amp

[Atanasi]

Here are a couple of measurements of 5K compared to BTR5. They are measured using a balanced connection to MOTU M4, using the maximum volume on the DAC and adjusting the input gain to a reasonable level. DACs are feeded though USB, and the pin 1 of MOTU M4 is tied to the USB ground.
The first measurement uses the high gain of 5K. This results in a SINAD of 87, a bit better than Amir's measurement, which used unbalanced. The noise level of 5K fluctuated a lot: for a moment it could be an order of magnitude higher, and a bit later significantly lower. So I had to enable averaging to get a consistent result.

The graph switched to low gain, which improves the numbers a bit: SINAD 93.

Finally, this measures BTR5. Its noise level was significantly more consistent compared to 5K. Its SINAD was 97.

So, it seems that as a DAC, BTR5 is a bit better.

 

[DanTheMan]

For just a straight DAC, my OCD forces me to use my Hidizs S8 and then amplifying it with the JDSLabs Atom. For normal listening levels, these differences are small to say the least. I do however believe that I hear more detail in the S8. I wonder if I could pass a proper test to demonstrate it though. Half the recordings I listen to have a higher noise floor than any of these devices do.

 

[jhaider]

I’d probably get the original with the balanced plug In your situation.

FWIW there are eBay sellers offering the Drop HD580/600/650 cable for $20-25. There’s a definite headroom improvement running Qudelix bridged over standard. I’m not going to sell my HeadRoom Desktop Amps as a result but they get loud enough for compressed recordings. Note these cables are stupid short for normal desktop amp use (4’) but fine for a tiny little battery powered amp like Qudelix.

Generally these types of cables seem like the type of thing to buy on eBay. I also bought the cheapest 2.5mm TRRS one available for my HD800. It was “WyWires” brand and cheaper/faster than the Alibaba ones I saw. It’s not as good as the stock cable - wrap is cheap petrochemical techflex instead of something more luxurious - and the branding is obnoxious so I had to order white heat shrink to cover it. But it works fine.

 

[bobbooo]

The first measurement uses the high gain of 5K. This results in a SINAD of 87, a bit better than Amir's measurement, which used unbalanced.

Actually that's the same SINAD result as here once the test was re-done with the correct sample rate settings (no idea why the original erroneous results are still up on the first page).

The graph switched to low gain, which improves the numbers a bit: SINAD 93.
View attachment 123358
Finally, this measures BTR5. Its noise level was significantly more consistent compared to 5K. Its SINAD was 97.
View attachment 123359
So, it seems that as a DAC, BTR5 is a bit better.

4dB higher SINAD above an already transparent 93dB will provide no audible benefit whatsoever. The Qudelix 5K's PEQ most certainly will however.

 

[CRKebschull]

Well, nothing to add as for the use and enjoyment of the 5K, which I bought in October 2020.

I also got a TRRS cable for my HD58X from drop.com which (as jhaider descriped) is a bit too short for desktop use, and actually a bit too long for portable use with the 5K, but I just loop the cable with a zip tie and it's fine.

What I do have to add to this discussion is that the Qudelix 5K stopped working yesterday; it doesn't turn on anymore after it was charged - meaning, the lifetime of my unit was not quite a full 6 months before it died.

I bought the unit from the Polish Qudelix distributor audioheaven.eu which I have contacted about a waranty replacment. I have to send it back to them at my cost (from Germany its 10 EU) and then we'll see how long it takes for them to send me a (hopefully new) unit and how long that one ends up working.

 

[CRKebschull]

I should add that I use the 5K via Bluetooth from a Google Pixel 3A Android phone and also from desktop Windows 10 via USB BT5 dongle.

The Pixel 3A will do LDAC, however it is very hard to get it to connect more than 660kbps.

There are no (that I know of) desktop BT LDAC USB transmitters (there are ones that have a DAC and amp built in and will serve to let you hook up analog devices, but I just want a BT5 Transmitter, right? The 5K is the DAC and amp...) so I use a dongle that does aptX-HD, which also works fine with the 5K, and subjectively sounds just as great.

 

[Reinhold]

Qudelix 5K Bluetooth Measurements
Let's start with the most common Bluetooth codec, Apt-x:

This is one crappy codec seeing how it can't handle such a simple signal (sinewave) without substantially raising the noise floor. And creating that step in frequencies above 8 kHz or so.

Hi amirm,

thank you very much for the measurements. I wonder how the "apple" codecs (SBC and AAC) compared to APTX-X and LDAC.
Maybe you could make some measurements next time you will review a new BT dongle?

 

[CRKebschull]

Hi amirm,

thank you very much for the measurements. I wonder how the "apple" codecs (SBC and AAC) compared to APTX-X and LDAC.
Maybe you could make some measurements next time you will review a new BT dongle?

aptX-HD is, on paper, much better than aptX. The Quedelix 5K does it all, which is cool.

As I mentioned in my post regarding the defective 5K, LDAC 990 is also a very nice idea, on paper.

However using my phone (Pixel 3A, Android 11 - although BT codec support is ofcourse a combination of HW radio and OS support), which supports both aptX-HD and LDAC, I find that in order to get a stable LDAC connection at distances that make BT useful in the first place, say 3 or 4 meters from the phone with no obstructions (any closer and I can use a wired connection) I cannot get better than LDAC 660.

So, for me, in reality, the question would be, what is better: aptX-HD or LDAC >660<?
And here I can only say that subjectively I can't hear a difference with my HD58X with SE or balanced connections, nor with my ATH-MSR7 nor with my PSB M4U-2 between aptx-HD and LDAC 660.

 

[faheem]

I should add that I use the 5K via Bluetooth from a Google Pixel 3A Android phone and also from desktop Windows 10 via USB BT5 dongle.

The Pixel 3A will do LDAC, however it is very hard to get it to connect more than 660kbps.

There are no (that I know of) desktop BT LDAC USB transmitters (there are ones that have a DAC and amp built in and will serve to let you hook up analog devices, but I just want a BT5 Transmitter, right? The 5K is the DAC and amp...) so I use a dongle that does aptX-HD, which also works fine with the 5K, and subjectively sounds just as great.

There is the Fiio BTA30 transmitter. There is also a Topping BC3 which is a reciever but also has analog ( 2v ) and optical line out. A brilliant little device that doesn't get enough attention.

 

[mSpot]

There is the Fiio BTA30 transmitter.

The BTA30 can transmit LDAC for optical input, but not for USB input. I saw on Head-Fi where FiiO said USB to LDAC is not currently possible due to a Sony issue (firmware or hardware), but they think their next generation product will be able to handle it.

 

[faheem]

The BTA30 can transmit LDAC for optical input, but not for USB input. I saw on Head-Fi where FiiO said USB to LDAC is not currently possible due to a Sony issue (firmware or hardware), but they think their next generation product will be able to handle it.

Thanks for the correction.

 

[tusing]

For 4 Vrms, why does the Qudelix 5K only offer 210 mW into a 50 ohm load?

https://www.analog.com/en/design-center/interactive-design-tools/dbconvert.html

This calculator says we should be getting around 320?

 

[Fernando]

It would be a great idea to implement the qudelix 5k in a stationary amp, Atom, Topping...

Well, nice and cheap.
In Spanish the 3 B. "Bueno, Bonito y Barato”."

 

[DavidS]

It took some time to arrive and I forgot to report back . It works perfectly. Switching between AAC Bluetooth and USB DAC is not fast enough to make a meaningful AB test. (Subjectively it sounds cleaner). But the main point is that the dongle can be charged from the iPad.

Apologies for coming back to this but which one did you get please?

 

[m_g_s_g]

Apologies for coming back to this but which one did you get please?

EDIT:

P.S.: After some months using it daily, I’ve noticed that when charging it gets hot. I try to not to charge the Qudelix when hearing music (it’s an option in the app).

 

[pwjazz]

Ive just received my Qudeliz and surprised that the max volume is not that much different to the apple usb dongle.

Did you set the unit to high output in the app? By default it operates on low output mode at 1V max.

 

[Lunafag]

The cornerstone of my audio setup. Drives both the IEMs and full-size headphones and contains all my EQ profiles.

 

[Ufasas]

Is Qudelix comparable to discrete sound cards of Asus Strix \ Creative Soundblaster Z \ ae-5 ? Is it even close?

 

[somebodyelse]

Is Qudelix comparable to discrete sound cards of Asus Strix \ Creative Soundblaster Z \ ae-5 ? Is it even close?

https://www.audiosciencereview.com/...and-measurements-of-sound-blasterx-ae-5.9114/

 

[Lunafag]

Some subjective impressions from various codecs and the bitrates Qudelix app reports. My PC only supports SBC and aptx. Qudelix allows disabling the silly high sampling rates for LDAC so I did. They all sound fine with music, without an ABX test I can't say for sure I can tell them apart. But with a sine wave generator there are clear differences.
SBC: the app doesn't show its bitrate. High pitched whine when playing 20Hz tones, "alien noises" when playing tones above 10k.
aptx: smartphone had a higher bitrate than PC but both performed the same - tones above 7k get some rustling noise.
aptx hd: same as aptx except the rustling is quieter and starts at 9k.
AAC and LDAC had no audible artifacts.