Description
AMPER851T is a fully digital audio stereo amplifier with Bluetooth and USB-C DAC inputs.
With AMPER8, a new dimension of sound quality, design and engineering has been achieved.
The operation and readability of the touch display are extremely easy to use thanks to the ergonomically shaped housing.
Such ergonomically sloped housing for touchscreens can rarely be found, even with significantly higher-priced comparable products.
The case made of solid brass - a material used in musical instrument making - exudes timeless elegance and is a small gem on any desk.
With a sound experience in 111dB signal-to-noise ratio and 111dB dynamic range, AMPER8 sounds as if the orchestra or band is very close, almost directly in the room.
If the speakers or their placement can't quite keep up, AMPER8 also knows the right answer in such situations:
With the 7-channel, fully parametric EQ, not only unpleasant resonant frequencies can be reduced.
Frequency ranges, which may be a little weaker, might also be raised with the EQ.
And the special thing about it: without touching the color or localization of the original sound: see Linear Phase EQ below.
Numerous dual- and triple-core 32-bit controllers work in AMPER8 for instantaneous and convenient control, each for its dedicated tasks.
For full power AMPER8 can be operated by a modern GaN USB-C PD power supply.
But even for room volume, AMPER8 delivers crystal clear sound when operated from common USB bus.
The result is a state-of-the-art, small and compact power amplifier.
Direct Digital Link - an audible experience
While conventional amplifiers usually send the digital audio signals via a digital-to-analog converter and only then switch to an analog output stage,
in the AMPER8, the audio signal is transported completely digitally right down to the final stages.
There is no NF stage, which is otherwise particularly susceptible to many disturbances.
For this purpose, the 32-bit triple-core Qualcomm Bluetooth and USB-C transceiver in AMPER8 is operated completely separately from other components on its own board.
This is the only way to achieve its high-end properties, which are highly praised by many audiophile experts.
The Direct Digital Link technology developed for AMPER8 detects the sampling frequency present in the input and switches it 1:1 to the Texas Instruments amplifier IC.
When the equalizer function is activated, up to 2x15 BiQuad filters are also loaded with parameters that have been selected in mathematical methods in such a way that musical
timbres and phase shifts are excluded.
The amplifier circuit is also responsible for volume control and power amplification for speaker control.
With Direct Digital Link, a sound is created that is neither affected by analog interference nor affected by data loss on the I2S interface.
Fabulous 111dB SNR signal-to-noise ratio and 111dB dynamic range - from the digital signal source to the loudspeaker's chassis - and not just on a short
way in between: this is an audible experience.
Microcontroller Details
Texas Instruments Amplifier with DSP audio processor:
The TAS5825/TAS5828 is a stereo high-performance, closed loop Class-D amplifier with integrated audio processor with up
to 192-kHz architecture. After startup with Software Control Mode, TAS5825/TAS5828 not only implements classic BQs, 3-Band DRC,
AGL, but also a TI properitary algorithm called Hybrid-Pro. The Hybrid-Pro algorithm detects the upcoming
audio power demand and provides a PWM format control signal for the former DC-DC converter via
the Hybrid-Pro feedback pin (HPFB). The TAS5825/TAS5828 suppports up to 4 ms of delay buffer of audio signal
for predictable envelop tracking, which significantly helps to prevent audio clipping due to DC-DC voltage
adjustment.
USB-C DAC-function and Bluetooth:
In AMPER8 Audio input is based on a Qualcomm
® Kalimba
™ audio DSP High-performance 24bit tri-core processor.
Advanced audio algorithms including aptX Adaptive, aptX HD, SBC and AAC audio codecs are all supported.
The flexibility provided by the programmable applications processor plus the ability to configure the audio processor
enabled us to easily implement all required features.
Touchscreen Control and Operating System Processor:
Touchscreen Processor and firmware reside behind the TFT Display and hold all the necessary operating system applications,
which are required for a fast and responsive user experience. You should watch one of our videos to see, how smoooth it works.
All realtime critical tasks related to audio quality are completely independent from the user interface.
USB-C Power Delivery Processor:
AMPER8 embeds a USB Type-C receptacle which implements a USB Power Delivery application single port device.
USB Type-C is intended for a wide range of applications while USB-PD allows many advanced features,
such as: power role negotiation, power sourcing, consumption level negotiation, electronically marked cable identification and alternate-mode negotiation,
allowing different communication protocols to be routed onto the reconfigurable pins of the USB Type-C connectors.
The USB Type-C receptacle covers all the features provided by the previous generation USB plugs in a single
connector, rendering USB usage easier and more flexible.
The USB-C Power Delivery Processor implemented in AMPER8 always requests the highest voltage available by the USB-C PD Power Supply between 5V and 20V.
When connecting a 20V capable USB-C PD power supply, AMPER8 will run at 20V. When connecting a simple 5V Power Source - AMPER8 will detect this and run at 5V.
Even at low voltages, audio clipping is largely prevented due to DC-DC voltage adjustments.
Linear Phase Equalizer
7-Band Equalizer
An equalizer or EQ is a filter that controls the volume of a frequency or range of frequencies within an audio signal.
A special phase-linear 7-band EQ is available in AMPER8, which initially controls the treble and bass up or down and thus adjusts the coloring of the speakers in the room.
In professional audio circles, such control has developed into an art with which the sound of instruments or the position of an orchestra in the room is formed.
Regardless of its application, good equalization is critical. When used correctly, the EQ in AMPER8 can give the impression of nearness or distance.
The listening room can be enlarged or reduced; the acoustic response of a loudspeaker in the room can be reduced, balanced or increased.
Parametric EQ
However, the EQ in AMPER8 is no ordinary EQ. It is linear-phase and parametric. It therefore becomes a mainstay of optimization,
because it offers continuous control over every parameter. Not only does it offer control over the gain (boost/cut) for each frequency band,
but also the control of the bandwidth, which determines the range of frequencies affected.
Understanding Q
In equalizers, Q is the ratio of center frequency to bandwidth.
If the center frequency is fixed, then the bandwidth is inversely proportional to Q.
This means that if you increase Q, the bandwidth decreases. Q is by far the most useful tool that a parametric EQ offers.
The Q setting allows you to attenuate or boost a very narrow or very wide frequency range within each EQ band.
A narrow bandwidth (high Q) is particularly useful for removing unpleasant sounds.
Let's say the speakers in the room are in the corners and have well-formed bass.
However, in a certain frequency range - often between 100 and 200 Hz - an unpleasant resonance frequency develops: a hum or boom,
which occurs again and again - with every piece of music - and impairs the listening experience.
On the one hand, you could now reduce the bass across the board. But the result would be an overall reduced hearing quality.
If you localize the fundamental frequency of the resonance and only reduce it in a narrow band in this range,
then the overall impression of the piece of music is retained and the overall experience is noticeably enhanced.
The problem was solved by tuning out the offending frequency.
A narrow bandwidth is also useful for enhancing desirable components of a speaker's sound where the speaker may have its weaknesses.
Smaller speakers often show such weakness below 100Hz or above 6000 Hz. By setting a narrow bandwidth, more powerful sound spectrums can be produced -
and this can be achieved without drowning out the rest of the room.
Linear Phase Parametric EQ
So a parametric EQ is a powerful tool for audio processing.
However, unlike other EQ types, the parametric EQ in AMPER8 maintains phase coherence.
This means that changes in a frequency band won't significantly affect the phase relationship between different parts of the audio signal.
Remember that while parametric EQs are powerful tools, it's essential to use them judiciously.
Overusing EQ can lead to unintended consequences, such as unnatural tonal changes.
Always trust your ears and make subtle adjustments to achieve the desired sound without compromising audio quality.
For a direct A/B comparison with/without EQ, AMPER8 offers the option of switching the EQ on and off directly: without cracking and without changing the volume.
Having this in mind will guarantee achieving balanced and transparent sound.
Solid brass case
Brass - a material used in musical instrument making - and a perfect material for housings of high-end audio amplifiers.
It is an artisanal malleable material that has high strength and hardness.
The sound characteristics of brass can be transferred to the visual and auditory experience.
Our brass is made of a pure copper-zinc alloy and can be 100% recycled and reused.
It is brushed, feels wonderful to the touch, is easy to maintain and environmentally friendly.
