[redmonddad]

Clicking? I can definitely say there's ZERO clicking of any description on my device. Maybe WiFi or EMI interference? Too close to the phone or powerful WiFi/microwave devices? That will often result in clicking/hum on some devices.

Not a bad suggestion!

Although I've heard examples of WiFi/microwave RFI and this wasn't consistent with that. I'll also note that I do have very good WiFi coverage throughout my house (by design), but I also expect that my AV equipment will be well shielded against such interference. Although building a Faraday cage around my listening room is an amusing idea

By training I'm an EE, but I went into SW and it's been quite a while since I've actually worked on hardware. That said, the noise is close to what I would sometimes encounter when digital and analog circuits are mixed together without proper noise control measures on the circuit board. It had a steady cadence (about every 2 seconds), possibly suggesting something related to the clock (or a subdivision of the clock) or at least synchronized to it. Anything involving the DAC circuit would certainly qualify.

Since many folks seem to have good units, maybe I have some bad caps on the circuit board. Some bad noise suppression caps would not necessarily interfere with QC tests unless they were specifically testing the noise floor.

 

[gLer]

Not a bad suggestion!

Although I've heard examples of WiFi/microwave RFI and this wasn't consistent with that. I'll also note that I do have very good WiFi coverage throughout my house (by design), but I also expect that my AV equipment will be well shielded against such interference. Although building a Faraday cage around my listening room is an amusing idea

By training I'm an EE, but I went into SW and it's been quite a while since I've actually worked on hardware. That said, the noise is close to what I would sometimes encounter when digital and analog circuits are mixed together without proper noise control measures on the circuit board. Since many folks seem to have good units, maybe I have some bad caps on the circuit board.

Improper shielding or faulty caps are both very plausible. Would suck if some units have QC issues, or if this is a wider design problem with certain batches. We'll need more data points to be sure. @Sajid Amit any noise issues on your unit?

 

[sofastreamer]

in the ru7 thread many users are reporting a clicking specially in between tracks. there it is said its normal for a 1bit device, which the cma18 clearly is not. What has been reported in the past though is that questile dongles have had a high proneness to wifi and bt waves. i dont know if it still is the case with the new iterations / products tho.
when noticing a hum, was it connected to a laptop/pc via usb? was the laptop running on batteries or a wall mount? could either be a bad usb connection or even a ground noise if the power supply of the pc isnt too great. does the hum get lower if you touch the questyle?

 

[Menkau-ra]

I would have ignored a slight hum, but the clicking was particularly annoying (and because it drew my attention, I was more aware of the hum). It was almost like the noise you would get on some switching power supplies on a PC...except there isn't one on a device like this. It could very well be a case of too many marginal units making it past their QC checks?

Did you use 4.4 connector? Will 3.5 help with the noise floor?

 

[Premetec]

Have one versus mojo2 vs cma18p?

 

[Menkau-ra]

Have one versus mojo2 vs cma18p?

The problem with Mojo2/Poly is that it’s not a truly portable solution. Using it outside of your WiFi is a PITA.
Also there is no way to turn off the Poly, it always drains your battery. And if you don’t use is for a few weeks and you’re ready to take it for a walk you’d find out that the battery is dead at the last moment

 

[Hanesu]

I just received a Questyle CMA18, purchased through Amazon.

I fell in love with the Questyle M15i dongle-style DAC/amp and got the CMA18 hoping for an upgrade as well as the flexibility of Bluetooth. I really wanted to love it.

It worked marvelously with my Focal Utopia and Focal Stellia. However, I had a poor experience using it with more sensitive IEMs. I tried 3 different IEMs: the 64Audio U4s, 64Audio Volur, and Empire Ears Odin. All three were setup to use 4.4mm balanced. The noise floor was terrible, and they all exhibited a background hum and clicking sound during quieter musical passages as well as when nothing is playing.

Used with my conventional headphones, I had no problem driving both the Stellia and Utopia. There was no evidence of a noise floor problem with them; the sound was clean and to my ear neutral in nature and I was quite happy with that.

Another issue I didn't like is that I needed to set the iPhone at a very high volume before I could use CMA18 (both conventional and IEMs). With the M15i, the fixed output level matches the iPhone levels fairly closely, so it's very intuitive to use with the phone controls. With the CMA18, I have to crank the phone before the amp volume buttons can be used. As a consequence, I have to be cognizant of that volume setting and remember to set it back to a lower volume whenever I'm finished with the amp. Not a showstopper, but irritating.

Re: Bluetooth...it was very easy to pair, but the placement of the "function" button makes it far too easy to hit accidentally, which switches the input selection. So after an accidental press you have to cycle through all the selections to get back to BT. Reestablishing the Bluetooth connection is simple but it takes a moment, which is an irritation since it is so easy to change by accident (and happened frequently during my testing). Also, while the use of circuit board LEDs visible through the glass window is a Questyle signature, it does not serve the CMA18 well. It's quaint and inobtrusive on the M15i, but the CMA18 is far more complex and this interface is very awkward. At this price point and this level of complexity, they should have provided a more sophisticated display. I understand their commitment to their design language, but in this case it is way off base.

If I were using this only with conventional headphones, I might have been fine keeping this as a nice portable, but I started playing with portable amps mainly to support IEMs. For that application, the noise floor is a showstopper.

That said, I don't see anyone else complaining about a noise floor in this in the thread, so maybe I got a lemon?

I was actually just about to write that I am confused that some reviews praise the dark background of the device while others (actually more) write, the device is better being used with headphones instead of (sensitive) earphones, because of the noise floor. All of this really could be a hint there might be units with technical problems? Maybe Questyle can clarify?

 

[gLer]

I was actually just about to write that I am confused that some reviews praise the dark background of the device and others (actually more) write, the device is better being used with headphones instead of (sensitive) earphones, because of the noise floor. All of this really could be a hint there might units with technical problems? Maybe Questyle can clarify?

Could also be that some people are far more sensitive to noise floor and also use very sensitive IEMs. In my case the darker background was obvious, and manifested in better separation, imaging, stage and transient response, none of which would be as notable if noise floor was a factor.

 

[Hanesu]

Could also be that some people are far more sensitive to noise floor and also use very sensitive IEMs. In my case the darker background was obvious, and manifested in better separation, imaging, stage and transient response, none of which would be as notable if noise floor was a factor.

Could be. What earphones did you use it with? And you could not detect any noise at all floor when music was not playing?

 

[gLer]

Could be. What earphones did you use it with? And you could not detect any noise at all floor when music was not playing?

Rn6, Xe6, Z1R, Trifecta, N8. No noise, not even in the quietest passages. My tinnitus was always louder

 

[Hanesu]

Rn6, Xe6, Z1R, Trifecta, N8. No noise, not even in the quietest passages.

But Trifecta is quite noise sensitive, right?

My tinnitus was always louder

 

[Hanesu]

Not a bad suggestion!

Although I've heard examples of WiFi/microwave RFI and this wasn't consistent with that. I'll also note that I do have very good WiFi coverage throughout my house (by design), but I also expect that my AV equipment will be well shielded against such interference. Although building a Faraday cage around my listening room is an amusing idea

By training I'm an EE, but I went into SW and it's been quite a while since I've actually worked on hardware. That said, the noise is close to what I would sometimes encounter when digital and analog circuits are mixed together without proper noise control measures on the circuit board. It had a steady cadence (about every 2 seconds), possibly suggesting something related to the clock (or a subdivision of the clock) or at least synchronized to it. Anything involving the DAC circuit would certainly qualify.

Since many folks seem to have good units, maybe I have some bad caps on the circuit board. Some bad noise suppression caps would not necessarily interfere with QC tests unless they were specifically testing the noise floor.

By the way, have you tried it with a case? Because I have the Aroma Air and it also has a problem with interferences. And it gets way better when you put its case on (I am actually wondering if this is the reason why Aroma provided it "for free" in the box)!

 

[gLer]

But Trifecta is quite noise sensitive, right?

Yes very!

By the way, have you tried it with a case? Because I have the Aroma Air and it also has a problem with interferences. And it gets way better when you put its case on (I am actually wondering if this is the reason why Aroma provided it "for free" in the box)!

Good point, I only use mine with the leather case.

 

[redmonddad]

By the way, have you tried it with a case? Because I have the Aroma Air and it also has a problem with interferences. And it gets way better when you put its case on (I am actually wondering if this is the reason why Aroma provided it "for free" in the box)!

Yeah, I was using the Questyle leather case.

 

[redmonddad]

Did you use 4.4 connector? Will 3.5 help with the noise floor?

I was using a 4.4mm balanced connector. Did not try the 3.5mm as I find my IEMs all sound better using balanced. Super quiet noise floor using balanced on the Questyle M15i with all three of the IEMs I mentioned above (U4s, Volur, and Odin).

CMA18 all packed up ready for return, so I won't be able to try out 3.5mm to compare.