Thursday, July 20, 2023



The Solid State Logic Bus+ in Aux rack at High on Technology Studio

How will the little company from Texas fare against a legendary name like Solid State Logic?

The latest bus compressor from SSL vs the bus compressor from Warm Audio is important data for consumers of gear. $2899 US vs $799 US. 

Both units share some common ground:

  • Both products are derived from classic SSL console bus compressor designs
  • Both are manufactured in China
  • Both feature balanced inputs and outputs

Is the current SSL Bus+ worth $2100 more?


Warm Audio Bus Comp

Warm Audio is a game-changing company, their WA-76 compressor/limiter put the company on the map and laid out their path forward as THE clone manufacturer to beat. Their products built the company's reputation by delivering low purchase price, reliable performance and high quality sound.

Warm Audio designs their products in Texas and has them custom manufactured in China. Warm Audio inspects every piece of product at their facility in Texas. This attention to detail and quality control has helped them deliver gadgets that work consistently. 


The SSL brand is a company with a rich history in professional recording, their mixing consoles from the 70's and 80's have helped produce mega hit songs for artists like Peter Gabriel; he liked the company so much he bought it. SSL has since changed hands and been acquired by corporate aggregator Audiotonix. 

THE definitive Bus Compressor IN the SSL Console, this is the sound

Today, the SSL company designs their products in England and has them custom manufactured in China. Very few of the current SSL products (in July 2023) are built in the UK. All of their reasonably-priced (under $4,000) hardware designs are manufactured in China. The SSL Bus+ feels like a substantial piece of hardware. 



1 RU hardware size, All Analog Stereo VCA Bus Compressor

Dynamic Range: Greater than 120 dB

Noise: less than -90 dBu

Frequency Response: 18 Hz - 22 kHz

Distortion: THD + Noise, 20-20K @ +20 dBu Input: less than .05%


(2) RU hardware size, Digitally Controlled Analog Bus Compressor

Dynamic Range: 117.5 dB (Compressor In)

Noise: -90 dBu (Compressor In)

Frequency Response: 20 Hz to 20kHz (plus or minus .025dB)

Distortion: THD + Noise, .004% at 1k @0 dBu

What do you buy a Bus Compressor for? When I went looking for an alternative to my API 2500 I wanted a sound that I did not already own. I looked at a lot of hardware products by a range of boutique builders. 

When SSL dropped the Bus+ on the world I had the cash and was ready to pounce. What I really wanted was a classic SSL Bus Comp sound but all the extra features looked nice and the price is not out of line for a high-end piece of equipment. 

The SSL Bus+ has a plethora of knobs and controls on the front. Around back it has detector inputs along with XLR balanced connectors for inputs and outputs. SSL has provided some quick ways to get to the coveted Bus Comp sounds. There were at least two console versions, the Bus+ emulates either plus it has some EQ options to further shape the sounds passing through it - too bad there is NO memory for saving configurations.


In preparation for this review I spent two weeks using the Bus+ in every way I could on a variety of original tracks I'm preparing for an album. I'm an old school, analog, outside the box guy, I love hardware. I used the Bus+ on drum, guitar and vocal subgroups.

On its best day the SSL Bus+ always sounded a little over-done, using the parallel compression mix knob just made the compression disappear but did not result in an improved mix. It was a lot of trial and error, mostly error.

The Warm Audio Bus Comp is true to the original SSL hardware circuit designs from years gone by, at least for components that are available. The VCA chips in the WA-Bus Comp are from THAT Corp. The control layout is simple and effective. You can use it as two mono processors but that's not what it's for. I gotta say, I love the single rack-space, stereo processor layout of the Warm Audio Bus Comp. It's a solid piece of hardware and it feels good mounted in a commercial rack or a home-brew wood rack. 

On its best day the Warm Audio Bus Comp helped pull the mix together, made it speak-like-one and glued all the tracks together into a cohesive sonic landscape. It is easy to bring a mix to life with the WA Bus Comp.

Warm Audio gave their Bus Comp a secret weapon, switchable discrete op amps and transformer coupled outputs. This feature means you can have the standard old electronically balanced outputs like classic SSL designs or you can switch in the big USA Cine Mag transformers driven by discrete op amps and enjoy enhanced sound output; this is an old-school boutique design, built for the artist. It is a bit like adding an API output stage to an SSL Bus Comp and it definitely affects the output in a positive way.


SSL Bus+ Left Channel Controls

The SSL web site is full of more information about all the knobs and controls. If you're serious about adding a Bus+ to your studio then I suggest you go to the Solid State Logic web site and download the manual to learn about all the features in depth. 

Frankly I found the face panel of the Bus+ to be confusing to use in actual mixing situations, the left and right channels are not symmetrical so when I'm working fast I'm distracted by knobs changing position and function from left to right. I'm not a fan of all the detented pots on the Bus+, the feel of these components does not inspire confidence. The square buttons feel more like cell phone or TV remote control quality (which might be great and reliable long term but I don't care for them).

SSL Bus+ Right Channel Controls

The Warm Audio Bus Comp has a neat clean face, clearly labeled controls, and overall the knobs and switches have a professional feel. I have 15 tons of equipment and I appreciate the 1-RU enclosure. 

Warm Audio Bus Comp


The SSL Bus+ is a beast of a piece of hardware with good weight, a lot of switches, stepped pots and two beautiful meters. It's got a lot of ways to tweak, distort and manipulate your sound. If you're a mixing guy that makes his living grinding out mixes for artists this might be a real hardware asset to you. If you're a mastering guy this might offer some fun sonic diversion and exploration. If you're a creative artist looking for a stereo bus compressor to glue your mixes together there are much lower priced pieces of gear that will be indistinguishable in a mix (unless they sound better ;-)

Bus+ has two meters and some shaping EQ

Inside the enclosure, the Bus+ features fiberglass circuit boards and surface mount components, a lot of surface mount components. Surface mount is not bad unless your repair shop does not have the specialized equipment needed to do component replacements (in the event a repair is ever needed). 

I avoided buying the Warm Audio Bus Comp for quite a while, I was sure (for no good reason) I needed something better. I've never been unhappy with my API 2500 since it arrived here years ago but I'm always open to discovering something different that improves my mixes. 

The Warm Audio Bus Comp has been an absolute joy to use, it's hard to make it sound bad and it's easy to bring a mix to the foreground, make it sound like it is meant to be and hold the level in the pocket. The Cine Mag output transformers give the Bus Comp a huge sound.

Inside the enclosure the Warm Audio Bus Comp uses fiberglass circuit boards and through-hole components like gear of yesteryear. 


Ultimately the measure of any piece of equipment is how much you use it. I have the Warm Audio Bus Comp patched to the inserts of my vocal subgroup so I'm mixing with it every day. Makeup gain and threshold are the two controls I use most often. I love how this box pulls a vocal mix together and puts it right in your face (in a pleasant way).

The Warm Audio Bus Comp delivers totally professional performance for an extraordinary price. 

Good Music To You!

Thanks for reading High on Technology. 

©2023 Mark King, It's not ok to copy or quote without written permission from the author.