What is Questyle's 'Current Mode Amplification'
Feb 7, 2024 at 7:24 AM Thread Starter Post #1 of 10

Questyle

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Over the past decade since its establishment in December 2012, Questyle has consistently incorporated founder Wang Fengshuo's groundbreaking "Current Mode Amplification" amplifier technology into all of its products. This unwavering commitment to innovation has earned Questyle numerous prestigious audio awards on a global scale.

“Current Mode Amplification,” a technique used in audio amplifiers based on current mode technology. This type of amplifier, known as a current mode audio amplifier, differs significantly from traditional voltage mode amplifiers in several key aspects. Here, I’ll elaborate on these aspects to provide a comprehensive understanding of current mode amplification.

Understanding Current Mode Amplification
Basic Concept: Current mode amplification represents a shift from the traditional voltage mode approach. In this method, the core amplification process occurs in the current domain, which involves processing the signal as a current rather than a voltage.

Circuitry and Components: These amplifiers utilize transistors (typically bipolar junction transistors) in a fully discrete architecture. The input and output remain in voltage mode, but the essential amplification happens in the current domain. This design ensures the amplifier operates constantly in a pure Class A state, known for high fidelity but less efficiency.

Differences from Voltage Mode Amplifiers: Unlike voltage mode amplifiers, which may include differential input stages and common emitter voltage amplification stages, current mode amplifiers have a distinct circuit structure. This unique structure allows for certain performance benefits, particularly in terms of speed and bandwidth.

Advantages: One of the main advantages of current mode amplification is the reduction of transient intermodulation distortion (TIMD), a common issue in traditional amplifiers. Moreover, these amplifiers can achieve extremely high bandwidth (up to 500 kHz at full power) and very low distortion levels (as low as 0.0002%). This performance challenges the limits of human auditory testing.

Versatility: Current mode amplifiers are versatile in their application, suitable for various power levels (ranging from 10mW to 2000W) and sizes (from a few square centimeters to professional-grade amplifier sizes).

Implication for Audio Quality: The low distortion and high bandwidth capabilities of current mode amplifiers suggest they can provide superior audio quality. They are particularly effective in delivering clear, accurate sound without the artifacts that often plague traditional amplifiers.
 
Questyle Audio Engineering Stay updated on Questyle Audio Engineering at their sponsor profile on Head-Fi.
 
https://www.facebook.com/questyleaudioeng @Questyle_Technology https://www.questyle.com info@questyle.com
Feb 7, 2024 at 11:12 AM Post #2 of 10
Over the past decade since its establishment in December 2012, Questyle has consistently incorporated founder Wang Fengshuo's groundbreaking "Current Mode Amplification" amplifier technology into all of its products. This unwavering commitment to innovation has earned Questyle numerous prestigious audio awards on a global scale.

“Current Mode Amplification,” a technique used in audio amplifiers based on current mode technology. This type of amplifier, known as a current mode audio amplifier, differs significantly from traditional voltage mode amplifiers in several key aspects. Here, I’ll elaborate on these aspects to provide a comprehensive understanding of current mode amplification.

Understanding Current Mode Amplification
Basic Concept: Current mode amplification represents a shift from the traditional voltage mode approach. In this method, the core amplification process occurs in the current domain, which involves processing the signal as a current rather than a voltage.

Circuitry and Components: These amplifiers utilize transistors (typically bipolar junction transistors) in a fully discrete architecture. The input and output remain in voltage mode, but the essential amplification happens in the current domain. This design ensures the amplifier operates constantly in a pure Class A state, known for high fidelity but less efficiency.

Differences from Voltage Mode Amplifiers: Unlike voltage mode amplifiers, which may include differential input stages and common emitter voltage amplification stages, current mode amplifiers have a distinct circuit structure. This unique structure allows for certain performance benefits, particularly in terms of speed and bandwidth.

Advantages: One of the main advantages of current mode amplification is the reduction of transient intermodulation distortion (TIMD), a common issue in traditional amplifiers. Moreover, these amplifiers can achieve extremely high bandwidth (up to 500 kHz at full power) and very low distortion levels (as low as 0.0002%). This performance challenges the limits of human auditory testing.

Versatility: Current mode amplifiers are versatile in their application, suitable for various power levels (ranging from 10mW to 2000W) and sizes (from a few square centimeters to professional-grade amplifier sizes).

Implication for Audio Quality: The low distortion and high bandwidth capabilities of current mode amplifiers suggest they can provide superior audio quality. They are particularly effective in delivering clear, accurate sound without the artifacts that often plague traditional amplifiers.
Ok so if understood it correctly, input and output are "voltage buffer stages" while the actual gain is done in current gain stage instead of voltage.
In either case am very thankful for this description and explanation.
Could we perhaps then hope to one day see a pure headphone amplifier from you.
 
Feb 16, 2024 at 12:18 PM Post #3 of 10
@Questyle I've read all the advantages, but this technology has no cons?
There's a conversion from current to voltage: it's completely transparent without any quality loss?

And why there aren't other manufacturers that use it, if it's so good?

I am sincerely curious about it, I'm not trying to underestimate your work.

Indeed I am looking for a desktop dac/amp and I'm looking forward to try the new Eighteen Master ☺️
 
Feb 16, 2024 at 12:41 PM Post #4 of 10
Current mode amplification can achieve high slew rates (voltage and current change over a period of time). Think dialing down the time divisions on a scope and getting greater detail on the waveform. This gives greater detail in an amp. The legendary Mass Kobo 465, uses this along with a high voltage swing (32vPP) at the output. You do need to convert back to voltage at the output. It likes lower impedances and does not like impedance swings from my uderstanding.
 
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Feb 23, 2024 at 8:00 PM Post #5 of 10
@Questyle I've read all the advantages, but this technology has no cons?
There's a conversion from current to voltage: it's completely transparent without any quality loss?

And why there aren't other manufacturers that use it, if it's so good?

I am sincerely curious about it, I'm not trying to underestimate your work.

Indeed I am looking for a desktop dac/amp and I'm looking forward to try the new Eighteen Master ☺️
Perhaps this article might be able to answer some more of your questions. Gary Barker has summed it up quite nicely.

https://headphone.guru/questyle-aud...mplifier-peer-into-the-black-depths-of-music/

I'll repost the pertinent points here:

"Questyle Audio is not the first company to use Current Mode Amplification, several ultra high end amplifier companies such as Halcro and Krell have used Current Mode Transmission in their top model amplifiers and preamplifiers for a while now, and most microwave communication is dependent on Current Mode Amplification as Voltage Mode Amplification is not capable of sufficient bandwidth, but what is completely unique to Questyle is their application of Current Mode Amplification, completely eliminating the basic issues of Current Mode Amplification.

The primary drawback to Current Mode Amplification is that it requires a fixed impedance load, which makes it entirely inappropriate for use with speakers (or headphones) which are a dynamic impedance load. To deal with this, Questyle developed a multi-stage amplifier topology. The first stage converts the incoming Voltage Mode signal to Current Mode (in Voltage Mode the signal is created by modulating voltage, whereas in Current Mode, current is modulated). The second stage is a fully discrete pure Class A amplifier operating in Current Mode, all signal amplification takes place here (Gain). The third stage is the negative feedback loop also operating in Current Mode (the negative feedback loop is employed to improve stability, IE: limit Total Harmonic Distortion [THD]). The final stage converts the signal from Current Mode back to Voltage Mode thus making the amplifier compatible with dynamic impedance loads. I hear you saying, “Well that’s fine and all, but what’s the benefit?” The benefit is speed. Questyle Current Mode Amplifiers have a linear bandwidth (linear bandwidth refers to the frequency response at all power levels from 0 to full rated power) in excess of 500 kHz, and by having the negative feedback loop operate in Current Mode, they produce no Transient Intermodulation Distortion (TIMD – that slight harshness and metallic sound associated with solid state amplifiers)."
 
Questyle Audio Engineering Stay updated on Questyle Audio Engineering at their sponsor profile on Head-Fi.
 
https://www.facebook.com/questyleaudioeng @Questyle_Technology https://www.questyle.com info@questyle.com
Mar 6, 2024 at 11:42 PM Post #6 of 10
@Questyle I've read all the advantages, but this technology has no cons?
There's a conversion from current to voltage: it's completely transparent without any quality loss?

And why there aren't other manufacturers that use it, if it's so good?

I am sincerely curious about it, I'm not trying to underestimate your work.

Indeed I am looking for a desktop dac/amp and I'm looking forward to try the new Eighteen Master ☺️
In the realm of audio, "Current Mode Amplification" acts as an embellishment to an already splendid tapestry. If one were to discuss its shortcomings, they would include its higher cost and the significant design challenges it presents.
 
Questyle Audio Engineering Stay updated on Questyle Audio Engineering at their sponsor profile on Head-Fi.
 
https://www.facebook.com/questyleaudioeng @Questyle_Technology https://www.questyle.com info@questyle.com
Mar 6, 2024 at 11:50 PM Post #7 of 10
Yep, Current Mode Amplification features an ultra-wide bandwidth and ultra-high-speed signal response, with their signal response speed being approximately 50 to 100 times that of Voltage Mode Amplification.

Current mode amplification can achieve high slew rates (voltage and current change over a period of time). Think dialing down the time divisions on a scope and getting greater detail on the waveform. This gives greater detail in an amp. The legendary Mass Kobo 465, uses this along with a high voltage swing (32vPP) at the output. You do need to convert back to voltage at the output. It likes lower impedances and does not like impedance swings from my uderstanding.
 
Questyle Audio Engineering Stay updated on Questyle Audio Engineering at their sponsor profile on Head-Fi.
 
https://www.facebook.com/questyleaudioeng @Questyle_Technology https://www.questyle.com info@questyle.com
Mar 11, 2024 at 10:41 AM Post #8 of 10
@Questyle I've finally bought the Eighteen Master 😍
Where can I find the Windows driver? Is it the same of the Fifteen?

TY!
 
Mar 22, 2024 at 4:35 PM Post #10 of 10
No driver is needed for Windows XP and Vista. Which version of Windows are you using?
Windows 11.
But I installed the fifteen driver and all works fine 😅
 

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