Review: SSL SiX CH channel strip


With the SSL SiX CH, Oxford-based Solid State Logic introduces a channel strip for API’s 500 rack format packed with features. Its circuit design is based on the channel strip of the successful SSL SiX and Big SiX mixing consoles. With a simple EQ and a compressor section, the SSL SiX Channel offers all the features needed to make great recordings. Its low price tag makes the SSL SiX CH very attractive for beginners and professionals alike.

SSL SiX CH 500 Series

No less than nine buttons, four knobs, two LED chains and a 6.3 mm input jack find their place on the front panel that is only 3.6 × 13.7 centimeters wide. There is currently no other manufacturer on the market that packs a full-fledged channel strip into such a small space.
What used to take several kilos and at least one unit in a 19″ rack got shrunken down by SSL to a single 500 module weighing only 183 grams. Yes, that’s right: 183 grams! Of course, this is only made possible by the transformerless design and a circuit based on SMD technology.

SSL SiX CH 500 Series

The SSL SiX CH preamp at a glance

Fortunately, SSL has not lost sight of ergonomics despite the various functions. As with the SSL SiX console, the channel strip of the SiX CH is divided into three sections. At the top is the preamp section with a gain control surrounded by three push buttons for +48V phantom power, phase inversion, and a high-pass filter.
The preamp offers freely adjustable gain for microphone signals between +6 dB and +72 dB.
With such a wide range, the SSL SiX CH should be particularly suitable for mics with low sensitivity, such as ribbons or dynamics like the Shure SM7B. SSL specifies the self-noise of the preamp as -129 EIN, an excellent value that is comparable to the very low-noise API 512c preamps, for example.
Line signal can be amplified in a range between -3 dB and +63 dB, so here too, the gain is plenty.

The high-pass filter starts at 75 Hz with 12 dB/octave, making it easy to handle the proximity effect. A five-stage LED chain indicates the signal strength between -21 dBu and +24 dBu. It is important to note that this meter shows the output signal, not the input.

The preamp section includes an additional 6.3 mm jack at the bottom of the front panel. So, line signals and instruments via Hi-Z can be directly connected. The input impedance can be switched between 10 kΩ (line) or 1MΩ (Hi-Z), so there’s no need for an external DI box. You can connect any Instrument directly to the SiX Channel.

Another great feature: If the input on the front is active, the microphone input on the rear is deactivated automatically.

SSL SiX CH 500 Series

SiX CH got an equaliser with an s

The circuit design has its roots in the equalisers (the Brits write it with s) found on the SSL E-series consoles. With two bands for high and low frequencies, the SiX CH’s EQ section is simple in design. But one should not be fooled by its simplicity because it’s got a lot to offer.

Each band can be switched from “Shelf” to “Bell”, which changes the mode of operation and dramatically increases the flexibility of EQ. For example, the shelving frequencies are set to 60 Hz and 3.5 kHz.
When the “Bell” switch is active, the frequency values change to 200 Hz and 5 kHz. In both modes, each gain control allows increases and decreases between +15 dB and -15 dB so that the signal can be strongly adjusted to the user’s wishes. And the two modes sound very different indeed.

If you don’t want to use the EQ, it can be removed entirely from the signal flow thanks to its own switch. Other manufacturers often use the mid-positions of the gain knobs, which would then lock at 0 dB.
The knobs of the SiX CH also lock in the middle position, but according to SSL, tolerances of the pots would still have to be expected and could influence the neutral frequency response of the preamp. So, as they didn’t want to make any compromise in sonic quality, the decision was made to add the on-off switch, which is a lovely detail.

SSL SiX CH 500 Series

The compressor on board the SiX CH

Attention to detail continues with the compressor section. It also has a dedicated on-off switch and can therefore be completely removed from the signal path.
Its controls are absolutely minimal. A single threshold knob with settings between +10 dB and -20 dB defines the amount of compression. A three-stage LED chain in the colors green, orange, and red provides information about how strongly the compressor changes the sound.

The internal circuitry is designed to adjust release and attack times to the applied signal dynamically. As a starting point, the attack time of the circuit is set at around 5 ms, and the standard release time is set at around 300 ms. The ratio is fixed at 2:1, and the integrated over-easy/soft-knee circuit, as known from DBX compressors, should lead to good results, even for users who don’t have in-depth knowledge of compressors.

SSL Quality in every way

The workmanship of the SSL SiX CH is excellent. Despite the low price, this is still SSL quality. The brushed gray metal plate is excellently processed and painted.
All printed fonts and values are easy to read due to the high contrast, even in darker lighting conditions.

SSL SiX CH 500 Series

Despite the big variety of functions, the layout is clear and the operation easy. Every potentiometer and every push button offers enough space for control. The knobs themselves are identical to those that you find in higher-priced SSL equipment.
All controls sit firmly, and the pots are screwed to the housing, which serves longevity and reliability. Also, the input jack is screwed on the front and made of metal instead of plastic.

The logical design of the SiX Channel makes you feel at home instantly, every function is self-explanatory, and the names of the controls are clear and meaningful. The pots can be turned with good resistance, and the switches engage reliably.
Despite the thirteen controls on the front panel, the operation of the SSL SiX CH is a breeze.

The SSL SiX CH in use

For this test, the SSL SiX CH faces competition from my beloved API 512c, the Electrodyne 501, and the built-in preamps of an RME UFX. Before heading over to the instruments, I tested the noise values. These correspond to the manufacturer’s specifications and are on the same low level as the API 512c I mentioned before.
Also, the specification of +72 dB gain seems to be correct, as the SSL SiX Channel has the highest gain reserves across all preamps mentioned above.

Furthermore, the gain increases continuously and not only on the last millimeters, which can sometimes be experienced with cheap preamps. Also, the vast gain range of 66 dB makes a pad switch superfluous in practice.

SSL SiX CH 500 Series

To put the preamp through its paces sonically, I used different types of microphones such as ribbons, condensers, and moving coil dynamics. Right from the start, I was excited by the speed at which the perfect sound could be dialed in with the SSL SiX.
For example, many ribbon mics have a strong proximity effect, so the low frequencies can often be reduced. A push on the Six’s HPF improves the sound immediately and emits lower rumble.

Also, if you want to add a little more sparkle to the upper frequencies of the signal of a ribbon mic, you can do it in the blink of an eye with the Hi-EQ in “shelf” or “bell” mode. With my old Melodium 42B ribbon mic, I turned the knob just before the 2 o’clock position, and I was instantly happy with the result.
On the other hand, this range can also simply be attenuated with very bright-sounding condenser mics to reduce the S sounds. Working with condensers, I also find it practical that a red LED lights up when phantom power is activated. This avoids sending 48 volts to passive ribbon mics by mistake.

For the following audio samples, I positioned a Melodium 42B ribbon microphone in front of my tube guitar amp. I recorded a DI-sample that I sent to the amp for each take. As for the guitar take, the position of the amp and mic is exactly the same, the preamp is the only difference. For comparison, I used the preamps of the RME UFX, the API 512c, and the Electrodyne 501.

In the last audio sample I engaged the high-pass filter to get rid of the lower rumble.

Here’s another take, this time with the Shure SM7B:

As you can hear, the differences are subtle. When driven hard, preamps like the API 512c and especially the Electrodyne 501 can introduce a bit of sonic color and character with their massive transformers in the signal path. The SSL SiX CH is more neutral in comparison. However, its clarity accurately reproduces the characteristics of the individual microphone.

SSL SiX CH 500 Series

According to SSL, the one-knob compressor design’s circuitry has been updated compared to the SSL SiX.
As a result, its range differs slightly from the console, but with the update, the compressor is now even more flexible.
While the compressor of the SSL SiX console works great on voice and vocals, it doesn’t handle well slowly decaying instruments. Sometimes you can hear the compressor acting automatically, even if you don’t want it to.

Fortunately, the updated circuit design of the SiX Channel compressor works well on signals with longer decays. Still, it’s perfectly suited for vocals, which is probably its main use. In most cases, it’s already enough if the green LED lights up only occasionally. This gently thickens the signal and rounds off the transients.

And even on drums, like for snare or kick, the automatic preset works well if you don’t overdo it. Here’s an example on kick drum, in which you can hear the compressor working:

Thanks to the Hi-Z input, the SiX CH is great for bass DI recordings. The lower frequency range can be easily adjusted thanks to the EQ. The compressor can also be useful for bass, of course. Here’s a clean example comparing the UFX’s DI with the SSL SiX and just a tiny bit of compression:

For those of you who use one of the classic broadcast mics like the SM7B or the RE-20, the SSL SiX Channel is a great choice. I’ve tested the preamp with both mics, and the SSL CH offers all the tools to adjust the sound to the specific conditions of your studio. Also, there is no need for an additional inline preamp because the SSL SiX simply delivers enough gain.

If you would like to listen to high-quality samples, download our high-resolution audio files.


The SSL SiX CH is a flexible channel strip that instantly delivers professional results. It is packed with many features: a high and noise-free preamplification of up to +72 dB, a high-pass filter, phase inversion, Hi-Z, and line input, as well as a surprisingly flexible EQ section and even an easy-to-use compressor!
Despite the high feature set, the layout is clear and easy to use. It’s easy to dial in a great sound that needs no post-processing at all.

SSL also makes no compromises when it comes to quality.
With an actual street price of 383 €, the SSL SiX Channel is a no-brainer, especially since it revealed no weaknesses in the test.

Gear & Sound rating

gear & sound rating



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+ Great sound, massive amount of gain
+ Workflow and speed
+ Flexibility of the EQ
+ Full featured channelstrip
+ Craftsmanship

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Where to buy

Price: from 383 € (Sept. 2022)

(Affiliate links)

technical specifications

  • Preamp gain: variable from +6 to +72dB (Mic), -3 to +63dB (Line)
  • Channel strip with SuperAnalogue microphone preamplifier and 5-fold LED display
  • +48 V phantom power
  • phase and HPF switch
  • Separate instrument/line input on the front panel with Hi-Z switch (1MO)
  • Switchable 2-band EQ with bell and shelving characteristics per band
  • Switchable “Single Knob Compressor” with threshold control and own 3-way LED display

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