[LinstantX]

We need a direct comparison with quloos mub1. I think the battle will be interesting.

 

[noplsestar]

We need a direct comparison with quloos mub1. I think the battle will be interesting.

I have reviewed the Quloos MUB1 and will compare it to the CMA18P in a few weeks! Stay tuned

Edit: Although I would like to add that the somewhat exotic „Calyx K“ already sounds perceivable better than the MUB1 (for much less money) so I am quite confident, that the CMA18P will have a noticeably better sound than the MUB1. But more of that soon …

 

[lantian]

I think there's a difference between current mode amplification (like Questyle) and curret output Amplifier (like Bakoon HDA5210 for example).

For Bakoon, yes, like you wrote above, can handle Low Impedance Planar better than the regular voltage output amplifier.

However, AFAIK, Current Mode like Questyle means the amplifier read the input data in form of Current as opposed of Voltage (like many others Amplifier), but still use voltage output.

Does anyone actually have any real explanation for this current mode amplification. Have been looking all around and so far nothing. Is it actually anything more than marketing jargon for a nice solid state amplifier circuit. Cause till now have not seen even an attempt of explaining this.
Because there can be no current if there is no voltage and vice versa. Both are partial property of electricity and without one other can not exist.

 

[goaud27]

Does anyone actually have any real explanation for this current mode amplification. Have been looking all around and so far nothing. Is it actually anything more than marketing jargon for a nice solid state amplifier circuit. Cause till now have not seen even an attempt of explaining this.
Because there can be no current if there is no voltage and vice versa. Both are partial property of electricity and without one other can not exist.

Both of them exist of course, but the question is what do you measure to stabilise the amplifier:

Most of the amplifiers, at least in portable gear, are negative feedback amplifiers based on op amps: that is a part of the op amp output is fed back into its input with an inverse phase to stabilise its operation. To determine how much should be fed back in, one needs to measure an error with respect to some reference. When it comes to electricity you can either measure an error in the voltage or in the current value (depending on if you measure in parallel or in series, respectively).

Some drawings are here.

In general, voltage feedback amplifiers (VFA) have lower noise, but current feedback amplifiers have lower distortions and are faster (higher bandwidth), as you can see e.g. from Texas Instrument article here.

Somehow the VFAs seem to get much more love from manufacturers. And there are only a handful CFA designs. Wonder if the differences are actually audible.

 

[lantian]

Both of them exist of course, but the question is what do you measure to stabilise the amplifier:

Most of the amplifiers, at least in portable gear, are negative feedback amplifiers based on op amps: that is a part of the op amp output is fed back into its input with an inverse phase to stabilise its operation. To determine how much should be fed back in, one needs to measure an error with respect to some reference. When it comes to electricity you can either measure an error in the voltage or in the current value (depending on if you measure in parallel or in series, respectively).

Some drawings are here.

In general, voltage feedback amplifiers (VFA) have lower noise, but current feedback amplifiers have lower distortions and are faster (higher bandwidth), as you can see e.g. from Texas Instrument article here.

Somehow the VFAs seem to get much more love from manufacturers. And there are only a handful CFA designs. Wonder if the differences are actually audible.

Thank you so much, finally. Finally and explanation that is not confusing or full of marketing.
I have actually heard and read a bit that VFA amps are a lot easier to get stable and can be done with less parts, while CFA will require more ingenuity and components.

 

[coolhand]

Does anyone actually have any real explanation for this current mode amplification. Have been looking all around and so far nothing. Is it actually anything more than marketing jargon for a nice solid state amplifier circuit. Cause till now have not seen even an attempt of explaining this.
Because there can be no current if there is no voltage and vice versa. Both are partial property of electricity and without one other can not exist.

A definitive reference in respect to the application of current drive (and the multitude of potential benefits of such) have been distilled and well documented by Esa Meriläinen, a well versed exponent of this approach.
Nelson Pass has also expressed much favour of current drive when applied in ideal scenarios.. which in general terms is "full range"drivers sans crossover, as they benefit so much more from current control (rather than voltage control).. and which in practical terms can result in the bass and treble becoming significantly extended amongst other notable characteristics.

 

[Questyle]

Sorry to keep you all waiting; every year around Chinese New Year things get very hectic, and fitting in these improvements into the schedule was tough, but…

I have good news to share!

Thank you to everyone who has given their feedback on the CMA18P in the last few weeks; we have taken this feedback to heart, and I’m happy to announce today that we have adjusted the CMA18P’s firmware to allow for simultaneous charging and audio playback!

Let me explain how this works:

Now with this upgraded functionality, when the CMA18P is turned on and connected to a USB charging source without data transfer (such as a charging brick, power bank, etc), it will charge regardless of what audio mode it is in.

However, if the CMA18P has a USB connection with data transfer (such as a computer, tablet, phone, etc), it will default to “Play Only” mode, wherein it will use data from the USB connection but power from the internal battery. This is to prevent the CMA18P from automatically charging off of smaller playback devices, such as your phone. However, if desired, you can manually enable the “Charge and Play” function in the following way:

To manually enable “Charge and Play” mode when connected to a USB playback device, long press the Function Button for approximately 4 seconds. The Battery Indicator lights will illuminate and flash, indicating the CMA18P is charging, and audio playback will continue uninterrupted.

Once turned on, this “Charge and Play” mode will remain active until the USB cable is disconnected. In other words, every time you switch USB playback devices, the CMA18P will default back into “Play Only” mode.

Please note that when used with some devices, such as iPhones and iPads, it is not recommended to turn on “Charge and Play” mode. In general, iOS devices have a current output limit of 100mA, which is not enough to charge the CMA18P, and could cause a communication failure.

--------------------------------------------

Devices with this upgraded firmware can be purchased from QuestyleShop.com https://questyleshop.com/collections/all-products/products/questyle-cma18-portable or from local distributors in your region.

Unfortunately, the first batch of 100 CMA18Ps which were initially sold in Mainland China do not support this function, and users cannot update the firmware themselves; it requires re-flashing a chip that is not accessible through a USB-C firmware update operation. If your CMA18P does not have this function and you wish to upgrade it, please contact zach.bielak@questyle.com

Please note that here in China, we are about to go into Chinese New Year, and will resume operations and responses starting Feb 19. Thank you in advance for your patience.

--------------------------------------------

I know many of you mentioned other functionality upgrades you'd like to see implemented (desktop mode, skipping tracks by holding volume buttons, APP EQ with 20 parameters). At this time, we haven't implemented them, but are still exploring the possibilities.

 

[Leviathant]

Sorry to keep you all waiting; every year around Chinese New Year things get very hectic, and fitting in these improvements into the schedule was tough, but…

I have good news to share!

Thank you to everyone who has given their feedback on the CMA18P in the last few weeks; we have taken this feedback to heart, and I’m happy to announce today that we have adjusted the CMA18P’s firmware to allow for simultaneous charging and audio playback!

…

--------------------------------------------

Devices with this upgraded firmware can be purchased from QuestyleShop.com https://questyleshop.com/collections/all-products/products/questyle-cma18-portable or from local distributors in your region.

Unfortunately, the first batch of 100 CMA18Ps which were initially sold in Mainland China do not support this function, and users cannot update the firmware themselves; it requires re-flashing a chip that is not accessible through a USB-C firmware update operation. If your CMA18P does not have this function and you wish to upgrade it, please contact zach.bielak@questyle.com

Please note that here in China, we are about to go into Chinese New Year, and will resume operations and responses starting Feb 19. Thank you in advance for your patience.

--------------------------------------------

I know many of you mentioned other functionality upgrades you'd like to see implemented (desktop mode, skipping tracks by holding volume buttons, APP EQ with 20 parameters). At this time, we haven't implemented them, but are still exploring the possibilities.

Thanks for this update. A UK dealer has told me that they already hold stock in their warehouse here in the UK. Are you saying that this stock will have the updated firmware, or, if not, will have the ability to have the firmware upgraded (without needing to send them back to you)?

Also, I appreciate that desktop mode is not a guaranteed future feature but are you saying there’s potential this could also be added on a similar firmware update in time? (Without needing to buy a new unit). This is a near dealbreaker for me so sorry to clarify.

 

[goaud27]

Sorry to keep you all waiting; every year around Chinese New Year things get very hectic, and fitting in these improvements into the schedule was tough, but…

I have good news to share!

Thank you to everyone who has given their feedback on the CMA18P in the last few weeks; we have taken this feedback to heart, and I’m happy to announce today that we have adjusted the CMA18P’s firmware to allow for simultaneous charging and audio playback!

Let me explain how this works:

Now with this upgraded functionality, when the CMA18P is turned on and connected to a USB charging source without data transfer (such as a charging brick, power bank, etc), it will charge regardless of what audio mode it is in.

However, if the CMA18P has a USB connection with data transfer (such as a computer, tablet, phone, etc), it will default to “Play Only” mode, wherein it will use data from the USB connection but power from the internal battery. This is to prevent the CMA18P from automatically charging off of smaller playback devices, such as your phone. However, if desired, you can manually enable the “Charge and Play” function in the following way:

To manually enable “Charge and Play” mode when connected to a USB playback device, long press the Function Button for approximately 4 seconds. The Battery Indicator lights will illuminate and flash, indicating the CMA18P is charging, and audio playback will continue uninterrupted.

Once turned on, this “Charge and Play” mode will remain active until the USB cable is disconnected. In other words, every time you switch USB playback devices, the CMA18P will default back into “Play Only” mode.

Please note that when used with some devices, such as iPhones and iPads, it is not recommended to turn on “Charge and Play” mode. In general, iOS devices have a current output limit of 100mA, which is not enough to charge the CMA18P, and could cause a communication failure.

--------------------------------------------

Devices with this upgraded firmware can be purchased from QuestyleShop.com https://questyleshop.com/collections/all-products/products/questyle-cma18-portable or from local distributors in your region.

Unfortunately, the first batch of 100 CMA18Ps which were initially sold in Mainland China do not support this function, and users cannot update the firmware themselves; it requires re-flashing a chip that is not accessible through a USB-C firmware update operation. If your CMA18P does not have this function and you wish to upgrade it, please contact zach.bielak@questyle.com

Please note that here in China, we are about to go into Chinese New Year, and will resume operations and responses starting Feb 19. Thank you in advance for your patience.

--------------------------------------------

I know many of you mentioned other functionality upgrades you'd like to see implemented (desktop mode, skipping tracks by holding volume buttons, APP EQ with 20 parameters). At this time, we haven't implemented them, but are still exploring the possibilities.

I would also like to see the desktop mode added. PEQ would be a great addition as well.

Meanwhile, since it can be used while charging, is there some kind of battery overcharge protection? Or ideally an ability to set charging threshold? Otherwise if you keep it connected to a laptop, the battery will stay 100% charged while also hot, which will degrade it very fast.

This slowly brings to another natural question, would it be possible to open the device and change a degraded battery later?

 

[noplsestar]

Found a very interesting (and almost poetically written) review about the CMA18P (again only with google translate) with a long sound description:
https://mp.weixin.qq.com/s/1HILVEcf1mcl3ZQsYAxEVA

 

[goaud27]

In case someone finds it as interesting as me, here you can see pics of a complete device teardown

 

[VisalEziomi]

Will we able to purchase battery from Questyle Store? In the future.

 

[The Schraeer]

Yeah but how would you go about disassembling to replace battery?
I haven't spotted any visible screws yet.
Maybe hotgun the glue and pry out the back glass, ala. smartphone style?
That's a bit bothering really.
Style tax.

 

[rhart00]

Any place to purchase this in the US yet?

 

[bsiegler]

Any play to purchase this in the US yet?

I purchased direct from Questyle. No idea when it will actually ship, though. I did email them this evening (American time) inquiring about wait time and am curious to see if/when they get back. Will try to remember to post back here if I get a response!