AuraSonics KN4.5BT — a new generation of AuraSonics' popular active speaker series
Grigory Liadov
The Russian company AuraSonics continues to develop products for professionals and music listeners. This time, the company has updated its most popular active speaker range, the KN series.
The KN series was developed as an alternative to inexpensive monitors from Western companies that had left the Russian market. It is important to note that AuraSonics speakers are not standard OEM models from a Chinese factory. The speakers were custom-developed to a specification prepared by the AuraSonics team. The first models appeared in 2023 and were convincing products. Only a couple of years later, AuraSonics has introduced updated KN models with better specifications and more features.
The new models keep the original design and now come in two colours: the familiar grey-blue finish and a new white finish. As before, the range has two sizes, now called KN3.5 and KN4.5. The names accurately describe the woofer sizes. According to the manufacturer, the new monitors have an improved low-ripple power supply that reduces noise and improves sound quality. A subwoofer output and a switch for choosing the active speaker's left or right position have been added. Bluetooth versions remain available as the KN3.5BT and KN4.5BT. Their Bluetooth connection has been upgraded from version 5 to 5.3.
KN-series monitors are active two-way speaker systems with the amplifier in one speaker. Although the system does not use separate bi-amp amplification, it offers several connection options. These include professional balanced inputs and, on Bluetooth models, a wireless connection.
AuraSonics KN4.5BT specifications
| Drivers | |
| Woofer | 4,5" |
| Cone | Polymer |
| Tweeter | 1" |
| Driver type | Fabric dome tweeter |
| Amplifier | |
| Amplifier type | Digital, class D |
| Power | 60 W (2 × 30 W) |
| Connections | |
| Balanced | TRS |
| Unbalanced | RCA, minijack |
| Headphone output | Minijack |
| Subwoofer output | RCA |
| Bluetooth | V5.3 |
| Controls | |
| Master volume | Rotary knob |
| Active speaker position switch | L/R |
| Treble | 10 kHz ±6 dB |
| Bass | 100 Hz ±6 dB |
| Other specifications | |
| Frequency range | 70 Hz–20 kHz (±3 dB), 60 Hz–22 kHz (±10 dB) |
| Maximum sound pressure level, SPL: | 100 dB |
| Cabinet | MDF with vinyl laminate |
| Dimensions | 163 × 244 × 180 mm |
| Weight | 4.45 kg |
The cabinets are made from laminated MDF, while the front baffles are plastic. Waveguides around the drivers help distribute sound more evenly.
The monitors use a bass-reflex design. A round port faces backwards near the top of each cabinet.
The lower front panel of the active speaker has the volume control, AUX input, headphone output and power indicator. The monitors have a power-saving mode. With no audio signal, power consumption falls and the indicator turns red. A signal at any input, including Bluetooth, wakes the system and turns the indicator green. If there is no signal for more than 15 minutes, the monitors return to standby.
All KN models use conventional fabric dome tweeters. A metal grille protects the tweeter from damage.
The larger NK4.5 model has a 4.5-inch woofer with a polymer cone. The stated size refers to the driver's standard mounting dimensions. The actual cone diameter, including the rubber surround, is 10.5 cm.
The connection panel and tone controls are on the rear of the active speaker. Balanced TRS inputs are available, along with stereo RCA inputs for consumer audio sources. The subwoofer output also uses an RCA socket. Its level follows the speaker volume, so one knob adjusts the overall system level.
The second speaker connects through spring terminals for bare wire. The supplied speaker cable is 2 metres long. The package also includes minijack-to-minijack and minijack-to-stereo-RCA cables for mobile audio sources.
As before, the amplifier operates in class D. It uses a FourSemi FS2105 integrated chip. This relatively little-known chip combines an amplifier, a DAC and DSP.
The amplifier's rated power is 2 × 30 W into 8 ohms.
The line inputs use a PCM1808 ADC, specified at a 99 dB signal-to-noise ratio and −93 dB THD+N. The DSP supports a 15-band parametric equaliser, which is used to correct the monitors' frequency response. The DSP is programmed only at the factory and is not accessible to the user.
Measurements
For our measurements, we use the hardware and software test system RightMark™ Audio Analyzer PRO. We also use the measurement microphone Earthworks M50, with the following specifications:
- Microphone serial number: 92901C
- Microphone sensitivity at 1 kHz: 26.4 mV/Pa
- Microphone frequency response variation, 20 Hz–20 kHz: 0.2 dB
- Microphone frequency response variation, 3 Hz–50 kHz: +1/−3 dB, with roll-off from 45 kHz
Frequency response measured on the tweeter axis
The measurements show an operating range of 70 Hz–22 kHz. The frequency response is fairly even, with small rises at the ends of the range. These are very good results. Compared with our measurements of the previous generation, the KN4.5BT has a smoother response and significantly lower response variation.
Frequency response at different tone-control settings
Tone adjustment works as before. Bass can be adjusted by about ±4 dB below 300 Hz. Treble adjustment starts at 1 kHz and covers about ±5 dB.
Sound
Sound quality is good and close to that of the previous model. As before, the KN4.5BT has a bright, full midrange and fairly natural tone. Music is enjoyable: individual instruments are easy to hear, and their tone sounds natural, without obvious colouration. In the budget speaker category, the KN4.5BT performs well. It is better than most comparable systems with the amplifier in one speaker.
We have no specific equalisation recommendations for the KN4.5BT. There is enough tone-control range for a more dramatic sound when required. For audio work, the manufacturer has already used DSP to tune the response during development.
We did not find the bass lacking for this speaker size. The low-frequency output is sufficient for the format. However, like other small speakers with cones up to 6 inches, the KN4.5BT mainly provides full coverage of the midrange. A subwoofer is a better solution for the lowest frequencies. The new generation's subwoofer output makes connection and combined volume adjustment much easier.
For audio work, we do not recommend placing the speakers directly on a desk. The fullest, most balanced sound is on the tweeter axis or slightly below it. At other listening positions, treble and upper-midrange output is reduced. Directivity matters less for background music. For professional use, stands or supports are a better option. One example is the AuraSonics FLS-KN, made specifically for this speaker series.
Conclusions
The AuraSonics KN4.5BT continues the Russian manufacturer's successful development of affordable active speakers. The new KN generation keeps the previous models' main strengths and adds a subwoofer output, an active-speaker position switch, a newer Bluetooth protocol, revised amplification and an alternative cabinet finish.
The AuraSonics KN4.5BT is a successful low-cost speaker system. Its good sound can meet the needs of both general listeners and professionals. Convenient volume control, several connection options, a headphone output and an affordable price are further advantages.
Note. This is an adapted machine translation into English. It follows the “In simple terms” approach. Read the original article at https://prosound.ixbt.com/monitors/aurasonics-kn4bt.shtml.