[Questyle]

@Feischmaker @ra990 I think I actually misunderstood your original question. The engineers have told me the CMA Fifteen doesn't oversample natively; the internal DAC in the CMA Fifteen doesn't perform any oversampling operation.

Are you experiencing a situation in which you feed it 192k, and the light on the CMA Fifteen shows 384 or 768? If so, tell me more about the setup, this shouldn't be happening per my understanding.

 

[Feischmaker]

Are you experiencing a situation in which you feed it 192k, and the light on the CMA Fifteen shows 384 or 768? If so, tell me more about the setup, this shouldn't be happening per my understanding.

Clear, so CMA15 behaves like a NOS DAC.

And no, i am just a potential buyer
I really like what I hear when I demoed it last week, and is curious how CMA Fifteen does things

 

[ra990]

@Questyle we are using software called Hqplayer to upscale all our audio to the max 705/768k sample rate before feeding it to the CMA. We want that upscaled signal to be processed by the DAC natively, without the DAC chip doing any more internal oversampling, thus avoiding another filter between our upscaled content and the DAC output.

 

[kmmbd]

@Questyle we are using software called Hqplayer to upscale all our audio to the max 705/768k sample rate before feeding it to the CMA. We want that upscaled signal to be processed by the DAC natively, without the DAC chip doing any more internal oversampling, thus avoiding another filter between our upscaled content and the DAC output.

As long as you are using the ASIO driver, Questyle DAC-Amps will play "bitperfect" audio, so basically it will just play back whatever signal it gets without any further oversampling or processing.

To my knowledge, apart from Chord DACs, most don't do oversampling internally for a number of reasons. R2R DACs do that for anti-aliasing reasons but that's another discussion entirely.

A simple way to check if the DAC is not oversampling is when you are playing upscaled and non-upscaled audio. HQPlayer upscaling should light up the higher sample/bit-rate LEDs, whereas non-upscaled (say, 44.1 or 48kHz audio) should only light up that respective LED. That way you are sure that the DAC is not upsampling on the hardware side (which would be nifty for a number of reasons but alas you need a Chord M Scalar for that).

 

[ra990]

As long as you are using the ASIO driver, Questyle DAC-Amps will play "bitperfect" audio, so basically it will just play back whatever signal it gets without any further oversampling or processing.

To my knowledge, apart from Chord DACs, most don't do oversampling internally for a number of reasons. R2R DACs do that for anti-aliasing reasons but that's another discussion entirely.

A simple way to check if the DAC is not oversampling is when you are playing upscaled and non-upscaled audio. HQPlayer upscaling should light up the higher sample/bit-rate LEDs, whereas non-upscaled (say, 44.1 or 48kHz audio) should only light up that respective LED. That way you are sure that the DAC is not upsampling on the hardware side (which would be nifty for a number of reasons but alas you need a Chord M Scalar for that).

Most delta sigma DACs use internal oversampling. This is different from the concept of feeding the unit a bitperfect signal. You wouldn't see this oversampling on any of the indicator lights on the unit. Those will only show the incoming signal rate, not any internal DAC filter being used for oversampling before output.

With Hqplayer, I am using Asio and sending a 705/768k sample rate, which shows correctly on the sample rate indicator lights.

What happens after that signal goes into the ESS DAC chip is what we're asking about.

 

[kmmbd]

What happens after that signal goes into the ESS DAC chip is what we're asking about.

If I understand you correctly, then you are probably referring to oversampling digital reconstruction filters (ODFs). I am fairly certain that Questyle is using that, and there is no way to turn that off (would love to have more input on this from the engineers on @Questyle side if possible).

Questyle used an IIR filter on their QP1R, not sure if that's changed into FIR on the desk products. From the sound alone, I'd assume they are using IIR still which is unique for them. Some DS DACs do offer a NOS mode, but as the filter is not selectable on Questyle, I am not sure that's an option.

 

[ra990]

If anyone is interested in buying this amazing device, I have recently put mine up on the classifieds. It has served me very well and even replaced the Chord TT2 for me. I've got the Utopia as my main headphone now. It can be driven by much less powerful devices and I'm going to be trying some of those. The link to the classified is in my signature. Thanks

 

[Questyle]

@ra990 @kmmbd @Feischmaker Alright guys, I think I finally understand what you're getting at here. I've asked the engineers and will let you know what they say. This is the first time I've encountered this question, so my apologies about my confusion at first.

 

[Questyle]

Alright everyone, I have an answer from the engineers.

The CMA Fifteen does indeed do an oversampling filter — my apologies for not mentioning that from the beginning. The engineers told me the CMA Fifteen, like the QP1R, uses an IIR internal oversampling filter in the ESS DAC. And apparently, it still uses the IIR filter even at 705/768k sample rates. Unfortunately, there's not a way for the user to turn that off; it is programmed into the ESS DAC when the unit ships.

I'm guessing that isn't the ideal answer you're looking for. I understand that you wish to bypass any internal oversampling filters in the ESS DAC, but I'm afraid that isn't possible with the CMA Fifteen. Sorry about that guys.

 

[betula]

My encounter with the CMA Fifteen.

 

[ra990]

I'm really enjoying the Fifteen with the 2022 Utopias. Even on low gain, I'm never past 50% on the volume knob. The bass is visceral and has grunt and the treble is bright without being shiny. The OG Utopias out of the Fifteen were too sparkly and zingy for me.

 

[TheMiddleSky]

I'm guessing that isn't the ideal answer you're looking for. I understand that you wish to bypass any internal oversampling filters in the ESS DAC, but I'm afraid that isn't possible with the CMA Fifteen. Sorry about that guys.

No need to sorry actually, that's indeed a normal case for delta sigma dac, I don't think any Chip (Sabre/AKM/ROHM based) DACs that able to do pure non oversampling.

 

[Menkau-ra]

Alright everyone, I have an answer from the engineers.

Can you help me with BT pairing? I connected my CMA15 to my macbook pro, but it's not being recognized as a sound device, just a generic BT. Same with iPhone.

 

[ra990]

Can you help me with BT pairing? I connected my CMA15 to my macbook pro, but it's not being recognized as a sound device, just a generic BT. Same with iPhone.

I think the Fifteen only supports LDAC and the most basic BT, so your mac might not like it.

But, in your case, it looks like it's not even being recognized as an audio device, so I'm not sure.

EDIT: Specs do show AAC support, which the Mac should be happy with.

 

[Menkau-ra]

I think the Fifteen only supports LDAC and the most basic BT, so your mac might not like it.

But, in your case, it looks like it's not even being recognized as an audio device, so I'm not sure.

EDIT: Specs do show AAC support, which the Mac should be happy with.

Yes, CMA15 has AAC support. I guess it's a FW issue. I just spoke with another CMA15 owner in a Telegram chat and he has a BT issue too.