Dbx 286s

The Dbx 286s is a Channel Strip preamp with two specific and separate sections. One to pre-amplify the sound and the other to process the signal before entering your audio interface via a compatible mixing console or sound card. The Dbx 286s is better equipped than a transistor preamp since it allows you to preset the sound before mixing and processing it.

As efficient as a transistor pre-amp, the Channel Strip Dbx 286s preamp offers everything to meet the requirements of audiophiles wishing to optimize the sound quality of their vocal or instrumental recordings in studios. Let’s take a detailed look at the features and functionalities of the Dbx 286s to find out if purchasing it can really be a worthwhile investment.

Dbx 286s Mic Preamp Overview

In the box: we find a Power supply , a user manual, screws to install it in a rack since the preamp is 19 inches. As a result, it can fit perfectly in a classic rack. Of course, there is also the essential Dbx 286s preamp which will also be the subject of this test. So what characterizes this effects preamplifier?

First, it must be recognized that the Dbx 286s is a Channel Strip microphone preamp that is quite easy to use compared to its peers, to name only the SPL Goldmike 9844 among many others. It allows you to carry out refined sound processing of all types of studio recordings in an almost intuitive way.

Be careful, however, because its ease of use does not make it any quicker to learn than other preamplifiers. It requires a certain amount of time to adapt to optimize its use .

The Dbx 286s microphone preamp from HARMAN also meets very versatile uses . This is what makes it more compatible with home studio use than with streaming.

Although it may be ideal for sound recording vocals and acoustic instruments , the Dbx 286s can also be used for acoustic and electronic sound sampling.

Associated with a power amplifier, this preamp for dynamic moving coil microphone and condenser microphone can therefore be used in a variety of ways. This could go far beyond the sole framework of a home studio sound recording. Thus, it can also be used for sound purposes .

The Dbx 286s provides concise and precise control of the sound preprocessing of studio microphones and various other musical instruments (acoustic and electric). The same applies to the sound preprocessing and preamplification of various types of common audio, video and multimedia devices:

• CD player or DVD player with RCA output,
• Blu-Ray player,
• Vhf and UHF reader (for digital audio processing),
• Vinyl record player or electro turntable with phono cartridge and phono input (for preprocessing and preamplification of sound to be digitized),
• Disk Jokey vinyl turntable (if you wish to pre-amplify the sound already processed on a DJ mixer in order to liven up and add sound to a room),
• Gaming PC with HDMI port, USB audio port, and Stereo jack port (output preamplification if you want to use your gaming computer to broadcast music or to add sound to a room),
• Video game consoles (preamplification of video game sound effects during a major tournament).

We can clearly see that the Dbx 286s can allow effective processing of electronic instruments and devices, mixing consoles, but also various other sound sources. In any case, you should still avoid exposing this preamp to very high frequency (MHz) sound sources in order to prolong its lifespan.

On the other hand, we can bring out the bass sounds emanating from the Dbx 286s through a subwoofer (to make them resonate better) and by taking care to mix it on a dedicated digital console. This will allow you to have a refined and more nuanced compared to the sound renderings obtained by processing via analog consoles.

You can also enjoy richer, high-definition sound in Stereo by bringing out the Dolby sound through a powerful home theater speaker or other types of wired speakers or even a loudspeaker. -Bluetooth wireless speaker.

As an alternative to the subwoofer, you can also choose between several high-performance power amplifiers, to name only the high-end Tuner amps The advantage with preamps and amps from Universal, Cambridge audio and Pionner lies in the fact that they integrate a very efficient amplifier module .

The Dbx 286s remains as efficient as these amps, because unlike a simple Class-B amp which only amplifies half of the input signal, the Dbx 286s preamp optimizes pre-amplification and full processing . Remember that the Dbx 286s has two sections ( preamp and sound preprocessing ) that can be used jointly or separately.

Equipped with great audio power , the Dbx 286s integrates two processors isolated on either side. The Dbx 286s has a section dedicated to mic and another section dedicated to sound preprocessing . Depending on your needs of course, you can use these sections combined or isolated.

In this case, if you wish to use only the preamp section, you will simply deactivate the other section (dedicated to sound preprocessing) by pressing the BYPASS . This is located at the front of the Dbx 286 s preamp. Conversely, you can also choose to preprocess the sound before pre-amplifying it .

We will therefore have to activate the preprocessing section (alone) before we can tweak the sound exactly the way we want to hear it. In addition, this specific section dedicated to sound preprocessing provides 4 possibilities for processing (or purifying) sound signals, namely:

• Compression (to modify the audio gain in relation to the level of the sound signal at the input) ,
• “ De-essing ” (to reduce or even eliminate sibilants),
• Embellishment or “ Enhancement ” (to give a nice timbre to the sound or to color it more or less like a pre-amplifier with tubes or replaceable tubes) ,
• And the expansion/Noise Gate : to better control the line level (i.e. the level of sound signal perceived at the line input).

Access to this sound preset section also allows you to combine these four functions according to the desired sound rendering. Still with the aim of optimizing , processing and purifying the sound signal before it reaches the input of the audio system or the audio interface of a PC, we can also use various Dsp processors ( external digital signal processor):

• Mixing tables, mixing console or sound card with integrated amplifier,
• Channel strip dedicated to audio mixing,
• Analog console,
• Mixing console or digital mixer, etc.

Depending on the type of analog connection that we wish to make for the preprocessing of the sound to be digitized, we may also need to use an adapter, a specific connection cable, one or more converters.

To bring out the pre-processed and pre-amplified sound, you can connect either your sound card, your equalizer or your mixer to the INSERT input located on the back of the Dbx 286s.

To give you a much more precise idea of ​​the different sound processing possibilities available from the Dbx 286s, I invite you to discover the overview of its different functionalities just after this line.

Note : You can also discover our complete test guide for the Telefunken U47 . This review guide gives you the full overview of this condenser microphone, its sound quality, as well as our review and some demos of using the mic.

Dbx 286s Preamp Features Overview

The Dbx 286s succeeds its predecessor DBX 286A. The Dbx 286s microphone preamp benefits from an innovative and quite specific design on its front panel. It also incorporates new electronic circuits with more recent components.

In terms of audio power , sound quality and preset options , the Dbx 286s remains as efficient and reliable as its big brother DBX 286A. The Dbx 286s microphone preamp has been designed to meet various uses in home studios. It thus makes it possible to obtain:

• quality of pre-processing and sound recordings.
• Easy-to-operate audio compression ( notably thanks to “ OverEasy ” mode)
• A significant reduction in “ hissing ” sounds via access to its De-esser which can be set to variable frequencies.
• A more than satisfactory sound enhancement from the pre-processing phase thanks to the “ Enhancer ” function to accentuate the detail of the audio rendering and to better define the sound to be recorded (or broadcast) at both the bass and high levels. frequencies.
• Optimal line level correction at Expander/Gate preset function .
• processing in output (i.e. externally, at the output) by providing a dedicated insertion jack port.
• A better overview of signal transmission and sound flow in real time thanks to the complete display of their levels by specific status LEDs.
• Optimal usage compatibility with all types of condenser microphones and studio condenser microphones thanks to the provision of a dedicated 48V phantom power supply.
• High-precision sound pre-mixing with its notched adjustment potentiometers.

Zoom on the technical features of the Dbx 286s preamp

The Dbx 286s preamp can work with (almost) all types of microphone at low (rate or) sound signal level at the input. This can be a ribbon mic or a dynamic magnet and moving coil mic.

The same goes for all types of devices with line input , but you must be careful to only connect them to the line input. To pre-amplify or pre-process the sound of a microphone, simply connect it to the Mic Input .

Depending on the type of microphone, we can then activate the Phantom power supply (if we are dealing with a condenser microphone) or leave it deactivated (if we are dealing with a dynamic microphone like a Yeti type microphone from Blue for example) . On the other hand, you can connect line level devices such as mixing consoles, DSPs ( or digital signal processors) and electronic musical instruments (such as effects synthesizers) via the line input.

As for the “ Line output ”, it can be dedicated to connecting a sound recorder. The 6.35 mm Stereo Jack port accessible on the back of the Dbx 286s and on which we find the indication “ Insert ” will be used to connect a signal processing device or external sound effect in analog mode.

Still on the back of the Dbx 286s, you can easily connect a Power Supply (or mains power cable) to the power port designed for this purpose. The Dbx 286s can also be placed in a rack dedicated to it for greater precautions.

Furthermore, you will better avoid exposing yourself to feedback by making sure to set the MIC GAIN potentiometer to minimum (i.e., to the left) before switching on the power. Now that we have more or less covered all the features of the Dbx 286s microphone preamp, it is time to take a complete look at all its technical specifications.

Technical specifications of the Dbx 286s preamp

First, at the level of the Dbx 286s microphone preamp section: we find phantom power , a high-pass filter as well as an input gain adjustment button . Note that these main settings are applicable to the input signal. We must therefore use it to pre-amplify the sound before switching to the other section intended for audio pre-processing.

You will activate the 48 V by pressing the corresponding button located on the front of the Dbx 286 s to power a condenser microphone or an electrostatic microphone like the Rode NTG1 for example. There is no need to activate it, however, when dealing with a dynamic microphone, otherwise there is a risk of damaging the moving coil transducer.

Be careful, however, because for certain types of condenser or condenser microphones like the Rode NT5, these transducers may require the use of a specific adapter or .

We also have access to a high-pass filter, to reduce frequencies to less than 80 Hz with a slope of approximately 18 dB per octave . To do this, just activate the High-Pass Filter button . This will reduce any noise pollution likely to be generated by proximity effects, microphone handling noise and unwanted background noise .

Mic Gain setting , we can use it to better define the gain of the sound signal at the input . The microphone preamp is capable of providing up to 60 dB of sound gain without manifesting distortion.

The sound that emerges gains more transparency and detail in almost all frequency ranges: Bass, midrange and treble or (treble). This gain setting boosts the low signal level at the input to make it clearly audible and much more easily exploitable in the pre-processing section including: compressor, de-esser, enhancer and expander/gate.

If you only want to use the preamp section of the Dbx 286s, you can press the BYPASS button. This will have the effect of deactivating the processing circuits . This section allows you to use phantom power, the active high-pass filter and the “Mic Gain” setting without having to pass the audio signal through the pre-processing circuits in the dedicated section.

As mentioned, the processing section of the Dbx 286s provides four settings: compressor, de-esser, enhancer and expander/Noise Gate. They can be combined in multiple ways so that we can really obtain the desired or desired sound rendering .

The compressor is used to change the gain relative to the level of the input signal. If this level is low, the compressor gain will be fixed. If the signal level at the input exceeds the compression threshold, the gain will drop.

For signals with high sound pressure, the gain will tend to gradually decrease . We will use the DRIVE potentiometer to reduce the gain (i.e. to compress or condense the signal at the input).

We will use the DENSITY Potentiometer to increase or reduce the signal recovery time . This is to provide dynamism to the progression of the sound signal flow during audio recording. Compression is particularly useful for:

• Homogenize the sound rendering of a vocal take of the song,
• Add punch to the sound of a bass drum or a tom,
• Offer more nuances to the sound of a snare drum,
• Give a specific timbre to an acoustic or electric instrument (acoustic guitar, electric guitar, electric or acoustic bass guitar, etc.).

The de-esser reduces the high frequency sound intensity of voices, particularly sibilance . This is an annoying whistling sound that can be perfectly reduced, or even eliminated by accessing this setting. On the Dbx 286s preamp, we can perfectly define via which frequency we must reduce or eliminate these sibilants.

The FREQUENCY knob sets the frequency of the high pass filter. For the de-essing processing of the singing voice, it can be set around 4 to 8 kHz . This function is also very useful for better processing of the sound reproduction of certain types of instruments.

This is the case when you want (for example) to eliminate the noise of sliding on the strings of an acoustic, electric or electro-acoustic guitar in order to obtain better sound reproduction. The “ enhancer ” which is also called “ spectral enhancer ” adds more clarity and detail to the sounds we record or broadcast by “ingeniously” amplifying certain frequencies.

The HF ( High Frequency ) DETAIL allows you to boost high frequency sounds to the input signal. As for the ( Low Frequency ) DETAIL potentiometer , it gives more clarity, breadth and dynamism to the definition of sounds whose frequencies are located below the spectrum.

HF DETAIL circuit of the Dbx 286s works using a dynamic rectifier to perfect the adjustment of equalization , however complex it may be. The equalizer's dynamic operation and variable frequency work to allow high-frequency enhancement to be applied only when necessary.

HF DETAIL function of the Dbx 286s is ideally used to configure and or instrumental recordings . It also provides more clarity and better sonic detail to drum and percussion tracks.

For signals already rich in high frequencies, you can deactivate the HF DETAIL setting or reduce it as much as possible. This will ensure that the sound reproduction is improved and that any parasitic noise likely to alter the audio quality of your sound recording is eliminated.

By slightly boosting the LF DETAIL , on the other hand, we can better accentuate the low frequencies to give more roundness, fullness, clarity and detail to bass vocals and most instrument sounds when played. in the bass or in the low/high mids.

Expander/Noise Gate preset option , this function acts much like a gate. In simple terms, this function allows you to control the level of an input signal by “opening” or “closing”.

The illuminated “ THRESHOLD ” LED indicator under the two potentiometers lets you know when the Noise Gate should activate. If the signal level is high, the Noise Gate is “open”, allowing all of the signal to pass through. If the level is low, the Noise Gate “closes” and the input signal is attenuated.

Note also that the signal remains intact even when the level of the input signal exceeds the chosen threshold. The expander/Noise Gate of the Dbx 286s allows you to attenuate the signal in a much smoother and progressive .

This gradual expansion also works perfectly with signals whose attack time and recovery time remain quite difficult to predict. Likewise, this function remains greatly useful for eliminating background noise likely to be generated by an amplification stage or other stages of the Dbx 286s.

Zoom on the sound quality of the Dbx 286s microphone preamp

At the back of the Dbx 286s preamp, we find:

• An XLR microphone input:

The MIC INPUT of the Dbx 286s allows you to connect (almost) all types of XLR microphones via balanced or unbalanced connections. With a high impedance microphone , however, you will need to use an impedance adapter. To be able to connect a condenser microphone like the Rode NT1000 or a condenser microphone to this MIC INPUT , or will also need a Stereo Jack socket adapter which outputs in XLR.

• A line entry:

The rear of the Dbx 286s can also receive at its input ( LINE INPUT ) or “line input” all sources of line input sound signals and only these sources (this input is therefore not intended for microphones!). You can only connect instruments that have a line input: mixing console, effects synthesizer, keyboards, etc.

Just like the Mic Input dedicated specifically to XLR microphones, the LINE INPUT can receive balanced and unbalanced signals. For unbalanced signals, the input impedance is equivalent to 10 K Ω while this impedance will be equivalent to 20 K Ω for balanced signals.

• A line output (or “LINE OUTPUT”):

The line output of the Dbx 286s receives balanced and unbalanced 6.35 mm jack plugs. The nominal output signal level starts from zero dBu at 600 Ohms . As for the maximum signal level at the output, it exceeds 21 dBu at 600 Ohms . The output impedance being 100 Ohms for asymmetrical signals if this is established at 200 Ohms for balanced signals.

• An INSERT input: it allows you to recover the sound signal at its output.
• An input for mains power: we will connect a Power supply cable to power and operate the Dbx 286s preamp which must be connected to the audio system or to the audio processing interface via a dedicated mixing console.

On the front of the Dbx 286s microphone preamp, there are LED indicators for MIC GAIN (in dB) and LEVEL (in dBu) as well as a CLIP LED.

This gain potentiometer is used to accentuate the gain of the microphone input signal or the line level input depending on whether it is a vocal or instrumental jack. For the case of a microphone connected to the XLR input like the Slate Digital ML-1 , we can obtain a gain of between 0 and +60 dB . For that of an instrumental jack (operated by connection to the LINE INPUT), this gain can vary from -15 to +45 dB .

To avoid damaging the device, you must adjust the MIC GAIN potentiometer to minimum and reduce the volume adjustment of the monitoring headphones while taking care to turn on the preamp or activate the PHANTOM button (when you need to use a condenser microphone).

The red CLIP LED is a light indicator which allows you to be alerted when the gain level saturates the circuits . If this occurs, you will need to reduce the GAIN by setting the MIC GAIN potentiometer to its lowest level. As for the light level indicators, these LEDS allow you to control the flow rate, that is to say the progression of the level of the input signal.

• An activation button and phantom power LED indicator:

This button is used to activate the power supply of a condenser microphone at a voltage of 48 V via a specific XLR connection cable. If you are using a microphone that does not require phantom power (this is the case for example in the case of a dynamic microphone) it will be better to leave it deactivated to avoid damaging the moving coil microphone.

• An adjustment button with LED indicator HF (Highpass Filter):

The HIGHPASS FILTER attenuates frequencies below 80 Hz that have a slope of 18 decibels per octave . We can very well ensure that this function is activated when the Highpass LED lights up.

• A Bypass mode activation button with LED indicator:

In Bypass mode, the gain and filter settings of the preamp section remain operational. The red LED lights up when this function is activated.

• A DRIVE potentiometer for the compression function:

We can turn it to the right to increase the input level. In the OFF position, the compressor lets the signals pass and can even condense them, without modifying them. By operating high DRIVE settings, on the other hand, we can boost signals at low input levels with a gain that can be up to 20 dB .

• A DENSITY potentiometer for the compression function:

It is used to increase or reduce the recovery time of a signal . The recovery setting ranges from 0 to 10 . There is no real “good” or “bad” DENSITY setting; you will mainly have to rely on your listening skills.

• A gain reduction indicator (in dB) in the compression function:

It is used to indicate the reduction setting made on an input signal in decibels. When the attenuation is at its maximum, the LED indicator which lights up on the far left turns red.

• A FREQUENCY potentiometer for the De-esser function:

This potentiometer is essential for adjusting high frequency sounds. It acts as a high-pass filter and can be configured from the De-esser. A setting between 4 and 8 kHz will be ideal for processing vocals , while higher settings may be better suited to instrumental takes.

• A THRESHOLD potentiometer for the De-esser function:

This potentiometer is used to adjust the sensitivity of the de-esser in relation to the input signal perceived by the Dbx 286s. The two LED indicators next to the THRESHOLD potentiometer ( 1 dB and 6 dB ) illuminate when the de-esser is active. These LEDS express (in decibels) the sibilant reduction that is applied via this second de-esser adjustment potentiometer.

• An LF (Low Frequency) DETAIL potentiometer for the ENHANCER function:

This potentiometer of the Dbx 286s allows you to accentuate low frequencies at 80 Hz and attenuate them at 250 Hz . This will have the effect of increasing the low frequencies without them losing their sound quality. The sound remains clear and does not show any distortion despite the accentuation of the bass and low-midrange tones.

• A DETAIL HF (high Frequency) potentiometer for the ENHANCER function:

This potentiometer allows you to correct and optimize the processing of the sound input signal during its continuous transmission, but at high frequencies. This will allow you to , rich and sound in the treble without harming your hearing.

• An Expander/Noise Gate function:

This remains inactive when its THRESHOLD potentiometer is set to OFF mode.

• A THRESHOLD potentiometer and two corresponding LEDS (in dB):

This adjustment potentiometer is used to set the maximum threshold above which the expander/Noise Gate can open to allow the input signal to reach the output. We can also set this potentiometer to the OFF position, to allow the signals to pass without having to modify them.

This THRESHOLD adjustment button also has two LEDs (+) and (-). The LED (-) of the THRESHOLD button is placed to its right and lights up when the input signal is lower than the predefined threshold. As for the LED (+) placed to the left of the THRESHOLD button, it lights up when the input signal level exceeds this threshold.

• An EXPANSION RATIO potentiometer:

In the Expander/Noise Gate function, there is also a second potentiometer which allows you to define the attenuation applicable to a sound input signal when it is below a certain threshold. We will opt for fairly low settings for expansion while higher settings may be better suited to the Gate.

• A Gain potentiometer in the OUTPUT GAIN function:

This “OUTPUT GAIN” adjustment button (and therefore output gain setting) simply allows you to better define the level of the line output . This adjustment may especially prove useful to compensate for possible drops in signal level due to preprocessing carried out on the Dbx 286s.

Additionally, you can also check out our complete Blue Microphones Snowball microphone . Discover in this guide the complete overview of this condenser microphone with its 3 directivity settings, as well as its sound quality and technical characteristics

Technical characteristics of the Dbx 286s microphone preamp

• Microphone input: balanced
• Impedance: ≈ 4.2 kΩ symmetrical
• Gain: 30dB
• Gain adjustment range: +0 dB to +60 dB
• Phantom power: 48 volts
• Equivalent input noise: –125 dBu (22 Hz to 22 kHz, 150 Ω source impedance)
• Line input: Balanced
• Impedance: 10 kΩ unbalanced, 20 kΩ balanced
• Maximum Level: > +21 dBu (balanced or unbalanced)
• Gain adjustment range: -15 dB to +45 dBINSERT input: (Stereo 1/4” jack)
• Ring: impedance >5 kΩ
• Tip: impedance 100 Ω
• Total harmonic distortion: <0.01%, 20 Hz to 20 kHz, +10 dBu
• Line Output: (6.35 mm Stereo Jack) balanced/unbalanced
• Impedance: 100 Ω unbalanced, 200 Ω balanced
• Frequency response: 20 Hz to 20 kHz (+0.5 to -0.5 dB)

Compressor:

• Threshold range: -40 dBu to +20 dBu
• Maximum compression: 30 dB
• Attack time (depending on the signal): >1 s for a small increase in level, up to 10 ms for larger increases
• Recovery time (depending on signal): adjustable from 1 dB/s to 75 dB/s

De-esser:

• High pass frequency range: 800 Hz to 10 kHz, 12 dB/octave
• Recovery time (depending on signal): approximately 1 ms/dB

Enhancer:

• Characteristics HF DETAIL (signal dependent equalizer): approximately 15 dB of high frequency gain
• LF DETAIL (Low Frequencies Detail) characteristics: Bell filter boost at 80 Hz, Bell filter attenuation at 250 Hz,

Expander/Noise Gate:

• OFF threshold range: +15 dBu
• Expansion rate adjustable from 1.5:1 to 10:1
• Maximum depth: >50 dB
• Attack time (depending on signal): approximately 2 ms (at maximum attenuation)
• Recovery time (depending on signal): approximately 10 ms/dB
• Dynamic Range: ≈ 105 dB
• Power: 15 Watts
• Operating voltage: 230 V
• Dimensions: 45 x 175 x 485 mm
• Net weight: ≈2.05 kg

Our opinion on the Dbx 286s microphone preamp

We would have really liked that this microphone preamp was equipped with a phase inverter to allow the polarization of various sound sources at a single point. This is not possible with the Dbx 286s since it only allows one microphone to be used at a time.

And the same for the other input dedicated to line input. This can only receive one instrument or sound device with line input at a time.

Aside from this fact, the Dbx 286s is rather good equipment to use in the studio if you want to sing, rap or record the sound of various instruments (acoustic, electric, electronic effects). We can even optimize its use with a wide choice of amplifiers for professional use in order to obtain better sound quality in output.

This studio equipment also has the advantage of being more affordable compared to most Channel Strips preamps available on the market, including those from major brands such as: Universal, Cambridge audio and Pionner.

This Dbx 286s preamp also has the advantage of being compatible with a professional Focusrite sound card in addition to being able to be used perfectly for home studio sound recording needs.

The Channel Strip Dbx 286s preamp from Harman can even be used for PA purposes if you really intend to broadcast impeccable sound whether in a room or outdoors. This preamp also constitutes powerful analog studio equipment.

Of course, if you want to find a better alternative you can turn to a digital mixing console, but to do this you will really have to pay a certain price. So it's up to you to see!

Dbx 286s mic preamp demo

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