New Software Review: Chandler Limited Zener Limiter by Universal Audio
In addition to Chandler Limited’s unmistakable sonic footprint (evident in both the hardware and software versions of the Zener Limiter), the plugin offers added features such as the ability to use it in dual mono, stereo, and Mid/Side mode.
I have had many chances to try out and use gear from Chandler Limited, either in plugin form or with pieces of analog hardware as a guest engineer in commercial studios. I can say without reservation that everything they make is of the highest quality, in terms of circuit design and build. In addition, everything they make does something unique and interesting.
After my recent review of the Curve Bender EQ, I was excited to give the Chandler Limited Zener Limiter a try and run it through its paces. Since I already own a UAD QUAD Satellite, the installation was easy and I was quickly on my way.
Features
Since I had never used the Zener Limiter before, I inserted it on a track, opened the plugin and took a look around. It has all the usual controls one would expect to see: Input, Output, three different Comp/Limit settings, a sidechain filter, plus of course, Attack and Release controls. It also has a switch labeled “Input Gain” (offering selections for “High” and “Low”) and another switch that toggles between “THD” and “Limit.” There are channel bypass buttons, a Mid/Side mode selector and a “Link Channels” button as well.
While most of it seemed like every other limiter, there were a few things that I felt needed some clarification. I could just run some signal through it and play around with the controls to see what it does (and I did), but I felt that a deeper understanding was warranted to really get the most out of this box. Time to consult the manual!
As with everything Chandler Limited creates, there’s a bit of history involved in this offering. The Zener Limiter is based on some EMI limiter designs, specifically the RS168 and the later version of the limiter that was part of the TG 12345 console channel strip. The Chandler Limited version has been updated for modern use, with the inclusion of some new features that contribute to its flexibility while making it attractive to modern music makers.
A few of the controls need some explanation due to the uniqueness of the compressor. It is worth noting that all of the information in the user manual is pertinent to the hardware version, but for the most part, the plugin version behaves and reacts the same.
The Input Gain switch changes the gain and impedance simultaneously. When set to “Low,” the input impedance is 1200 ohms and the signal level is close to unity gain; when set to “High,” the impedance is lowered to 300 ohms and there is an additional 12dB of gain.
The Input control is an audio taper control, so it will not behave as you might expect if it were a linear taper control. Since the Zener Limiter is a fixed-threshold compressor, the amount of compression is set by how hard you drive the input, rather than having an independent threshold control. This is the same as an LA-2A and an 1176, so most users will be familiar with this concept.
The “THD” toggle switch disengages the limiter’s threshold but still runs the signal through the entire audio path, including the sidechain. This adds a smooth distortion and a high frequency bump due to the discrete amplifiers and the zener diode limiting circuit. The amount of distortion depends on how hard you drive the circuit. The manual states that it takes a signal and “gradually triangulates it as you increase the Input control, however importantly, it does not clip the signal in any way.”
[The hardware manual offered something interesting with regards to the “THD” mode and how you drive it. If you boost the Input control all the way up and feed it a unity gain signal, you can drive the unit to 2% distortion. However, if you increase the input level in front of the Zener Limiter to +4dB or +5dB, you can drive it to 5% distortion which (as the manual states) is “many, many times that of tape and without distortion.” In other words, you can drive this unit and get some cool sounding harmonic distortion, which can gently tame transients while increasing the RMS level of the signal. Very cool!]
Understanding the “Comp 1/Comp 2/Limit” switch is pivotal in achieving the tone you want from the Zener Limiter. “Comp 1” has a ratio of 2:1 but emulates the response of the Altec 436/RS compressor, which was subsequently modified by EMI. This setting has the slowest time constants of the three available settings. “Limit” has much faster response times and is much like a Fairchild 660. “Comp 2” is designed to be somewhere in between the two other settings, which further adds to the limiter’s flexibility.
The Attack and Release
The labeling on the faceplate is notable in that some of the values are labeled in white whereas others are labeled in yellow. Specifically, the release values in white with parenthesis are the original unit’s values, while the yellow labels are the added values that Chandler Limited included in their design. This color convention is true for the Attack and Comp/Limit controls as well. This is important to note only if you wish to use the limiter as it was originally designed by EMI. I’m sure for some this is helpful when emulating a particular kind of sound, but as with anything, the addition of more values can only be seen as a benefit.
One unique feature that the plugin version offers is that the limiter can be used in dual mono, stereo, or Mid/Side mode. For dealing with stereo sources, Mid/Side operation gives you more flexibility and can be a life-saver when mastering stereo mixes with too much or too little vocal. It certainly adds to the appeal of this plugin.
In Use
The first thing I usually check when using a new plugin is what kind of CPU hit my computer takes when I drop it on a track. The Zener Limiter uses 6% on my UAD QUAD Satellite in mono and 10% in stereo. This is a pretty significant amount of CPU to allocate to one compressor, but if I use it in only critical situations, it wouldn’t cause a problem at all. This is a pretty unique sounding compressor and is not necessarily perfectly suited for all sorts of tasks, so I can’t see this restriction being an issue for anyone who purchases it.
I have to admit that my first impression of this limiter left me scratching my head a bit—not because of how it sounded, necessarily, but because the gain structure is a little bit odd. Being a fixed-threshold compressor means that the only way to increase or reduce the amount of compression is by turning the input up or down. In theory, this is pretty simple. In practice however, I found that it was hard to get subtle amounts of compression on louder, steady-state sources (like a bass guitar or a full mix). When I would set the gain switch to “Low,” the amount of compression was greatly reduced, but I couldn’t always make up the gain by boosting the output all the way.
The response and compression is highly dependent on the position of the Comp/Limit switch because the attack and release times change depending on how it is set. (To clarify: in “Comp 1” mode, attack position 1 is 28ms; in “Limit” mode, attack position 1 is 5ms.) In other words, the compressor behaves completely differently in different Comp/Limit modes. This switch does not just change the ratio, it completely modifies the character and behavior of the limiter. Add to this the handy sidechain filter and you start to see that this unit requires a bit of thought and willingness to explore in order to get the most out of it.
Once I figured this out, I realized that I was thinking about how to use this limiter in the wrong manner. This is not a “I just want to tickle it” kind of limiter. Nope, this is a full-on “I want to manipulate the sound” kind of limiter.
OK, Chandler Limited… message received. I threw out my expectations, opened my mind to something a bit different and dove right in.
I have to admit, I do not think of compressor/limiters as “crush, kill, destroy” devices as a rule, though I do use this approach with some elements within a project or mix from time to time. I think it has become so common for someone to say: “We got a great drum sound and then crushed it. It was awesome.” It can be cool and is always interesting, but I’ve found this approach really is more effective if there is something dynamic and explosive to offer contrast.
Now having said that, I am not sure that there’s a better compressor for exactly this approach than the Zener Limiter (though the Distressor is pretty hard to beat too!). The first thing that comes to mind when I think of aggressive compression will always be drum room mics. This has become a standard procedure almost, but too often it just makes everything messy and makes the cymbals swell and breathe in an unmusical, noisy way.
When I tried the Zener Limiter on room mics I was stunned. It still pumps and breathes, but there’s something unique about the attack and release relationship that just adds some jump and excitement to the track that I haven’t heard from any other compressor. Even the “all-buttons in” trick on an 1176 wasn’t quite as intense sounding. And, with the wide choice of attack and release times coupled with the Comp/Limit modes, you can really make this thing do whatever you desire, including matching the tempo of the track. For my ear it was best and most exciting in “Limit” mode. Some of that is because of the faster attack and release times, but I mostly loved the shape of the compression envelope. It’s kind of hard to describe how it jumps and grabs almost simultaneously. It was excellent!
When compressing kick drum (something I almost never do), the Zener Limiter was pretty aggressive but did work very well for a vintage, colored sound that accentuated the front end of the kick while giving me control of the length of the decay. On a full drum mix, it was just too aggressive for my tastes. However, I could see it working well in specific situations where a bouncy, noticeably compressed sound is needed. Even though it was more compression than I would typically use on a full drum mix, it never sounded bad, it was just too obvious.
A close-up look at some of the added values (yellow) implemented by Chandler Limited from EMI’s original design.
But when it comes to drums, the highlight was using the Zener Limiter as a parallel compressor. I always have a parallel compressed buss for my kick, snare and toms so I can add some grit, sustain and movement to the drums while keeping the original transients in tact. This limiter was so, so perfect for this. Being able to aggressively compress the tracks and then play around with the attack and release times against the clean, uncompressed drums was an absolute delight. It again added some excitement and made the drums sound more intense. This also helped them take up more space in the mix with a definite air of authority. For the last couple of years, I’ve been using the Lindell 254E for this particular task, but I now think there’s a new sheriff in town.
Next up was trying it on the bass, and again I was pleasantly surprised with the results. What was peculiar to me was that I really didn’t like the way the compressor sounded when the bass was soloed. It seemed too aggressive and messed with the front end of the note too much. It felt kind of spongy and soft without a ton of definition. I kept messing with it and got something that seemed interesting and workable, and then took the bass out of solo. It was then that the strength of this limiter became so apparent to me. The bass sat firmly in place, was clear and articulate and yet still had an edge of excitement to it. It made no sense to me that something that was so plain on its own could be so perfect in the track. Needless to say, I was pleased.
On a vocals, it again seemed overly aggressive but it really could add some presence to an otherwise vanilla-sounding vocal. I don’t know that this limiter could be subtle on a vocal (especially with the gain structure being the way it is) but at the same time, I would never use it on something that needed subtle compression. Even when aggressively compressing a vocal with the Zener Limiter, a nice sense of life and dynamics still remains.
The same was true on an acoustic guitar—there was just no way to subtly control the dynamics. However, it was excellent at creating a colored, forward-feeling sound for the acoustic. Its response was reminiscent of the jangly, bouncy sound that was common for the 4 lads from Liverpool.
The last thing I tried was to use the Zener Limiter as a 2-Mix compressor, which to me is the ultimate test for a compressor/limiter. Not all compressors work well for this important duty, and the complexity of a full mix tends to shine a light on the weaknesses in any compressor.
As I expected, it was a bit too aggressive for my tastes in this application. Full disclosure: I am not a fan of the SSL buss compressor as a 2-Mix compressor, as it always seems to be too apparent and too aggressive. I prefer something that lightly controls the dynamics while adding the “glue” that only a good compressor can. It’s not always the amount of compression applied but can instead be the sound of the audio path in the compressor and its gain reduction type that make some compressors better suited to this task than others.
The Zener Limiter always added some thickness to the mix, and also made things smooth and vintage-sounding. This was however, at the expense of some transients because it was so difficult to get the compression to react lightly. I must say that if you usually use 3-4dB of gain reduction on your 2-mix, I could see this limiter being one of your new favorites. It imparts such a cool character on everything that it touches. I am certain you would never be able to hide that you were using the Zener Limiter on the 2-mix… but that’s a good thing!
Summing it Up
There are so many compressors and limiters in the market these days that the choices can be dizzying. I find that my workflow sometimes gets bogged down by the process of trying out many different compressors in various situations. Since I have so many high-quality plugin choices available, I find it helpful to hear what each may have to offer.
Having said that, the Zener Limiter is so unique that once you try it (which I recommend), you may wonder how you could live without it. It doesn’t work perfectly on everything, but on the things that it does work on, it probably exceeds everything else you may have in your arsenal. Give it a try and don’t limit (pun intended) the sources you use it on. At $299, the Chandler Limited Zener Limiter, designed by Softube exclusively for the Apollo and UAD platform, does not come cheap, but I am confident you’ll end up making the purchase… you won’t regret it!
Mike Major is a Mixer/Producer/Recording and Mastering engineer from Dunedin, FL.
He has worked with At The Drive-In, Coheed and Cambria, Sparta, Gone is Gone, As Tall as Lions, and hundreds of other artists over the last 30 years.
Major is the author of the book Recording Drums: The Complete Guide and is the creator of the video series “The Method to the Mix”.
Please note: When you buy products through links on this page, we may earn an affiliate commission.
Echobeach
September 7, 2017 at 9:13 am (7 years ago)Very helpful review, Mike. Thx!