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Disclaimer: We are a distributor of Antimode products. As such this is not an objective review. However, we do use the Antimode X4 actively in our demo / test room, and this is a summary of our impressions of the product.

Introduction

The Antimode X4 is a high-end preamplifier, DAC and advanced EQ / room calibration device. That's a lot in one box. What makes it different from other preamplifiers is obviously it's DSP (Digital Sound Processing) capabilities. We'll get back to that soon. 

It also has 4 individual output channels (all 4 supports both RCA and XLR), which makes it one of the few high-end devices out there that can properly handle a setup with one or even two subwoofers. It can be configured to run with dual subwoofers in either dual mono or stereo, and crossovers can be defined either manually or automatically.

Initial listening impressions and sound quality

The X4 uses top-shelf Burr-Brown PCM1792A DAC chips that are individually measured and hand selected. It's THD is 0.0008%. And boy can you tell. Before we even get to the DSP capabilities of this device, it's immediately obvious that the sound quality is extremely good. Many are reluctant to add DSP to their expensive stereo systems, worried that it will reduce the overall sound quality. You need not worry with an X4 in your setup. We've had 4,000USD preamps in our setup before, and the X4 easily sounds as good or better.

Antimode Room Calibration / DSP

One of the major selling points of the X4 is the advanced onboard room calibration. It's extremely easy to set up, and everything you need including microphone and microphone stand are included in the box. As opposed to the other Antimode products, the X4 operates in the entire frequency range. The main focus is still on the bass/midbass area, and rightly so. Due to the way high frequency reflections work in a room, it's almost impossible to properly correct for room issues in the higher frequencies. The result after running the calibration process also shows that the Antimode makes few and very light touches above 1khz. If you want to actively limit how high the X4 attempts to correct the response, this is user selectable. The entire process is fully automated, and takes 5-10 minutes to complete. The included quick start guide is easy to follow.

In our room with two Sigberg Audio SBS.1 active speakers and dual Sigberg Audio 10D subwoofers, the result is an almost ruler flat response from 20-120hz, and above that some peaks have been evened out. Otherwise the response has been left largely as is. The resulting sound was breathtakingly good, with tight, dry bass and clear mids. 

The Antimode X4 also offers many options for manual tailoring of the sound, including bass tilt / treble tilt, 9 band parametric EQ and individual adjustment of the subwoofer level. After the automatic correction, we used the bass tilt feature to add a bass shelf that restored some of the bass level that was lost after straightening out the response. We also spent some time applying individual EQ filters in the parametric EQ to fill out some of the dips in the midbass area that Antimode had decided to not fix. After a few rounds of listening, it turned out that it actually sounded better when it was left alone, the way the automatic correction initially did. So we ended up dialing back on the manual EQ. We finally settled on a configuration that was pretty close to what the X4 did automatically. The careful approach of the X4 obviously works, and this is the first time we've tested an automatic room correction device that we couldn't easily improve upon with manual adjustment.

Summary

The Antimode X4 is the perfect companion for a high end system (with or without subwoofers), and the room calibration capabilities will without doubt vastly improve the sound of your system.

The Antimode X4 is available for purchase directly from Sigberg Audio

Subwoofer specifications may be difficult to understand. In addition, manufacturers don't necessarily follow the same standards. That means this guide may not help you compare between subwoofers, but it will at least help you understand what any given spec sheet can and can't tell you.

Frequency response (How deep can it play)

One of the main questions many ask themselves when looking at subwoofers, is how low will it go. What is the deepest bass notes (or explosions) the subwoofer can reproduce? This is actually surprisingly hard to find out, as this may be specified very differently. 

Here is a typical specification: 

25-160hz (-6dB)

The first is the frequency range which the subwoofer can play. From the deepest to the highest frequency. So we are looking for the first number to be as low as possible.

But what does the "(-6dB)" mean? A subwoofer will typically aim to be "flat" through the entire frequency range, which means all notes the subwoofer can play are of equal volume. But in practice any subwoofer will have a natural (or artificially enforced) roll-off towards the lower frequencies. The specifications often indicate this with "-3dB" or "-6dB". In our example, the specs indicate that the subwoofer has started rolling off significantly at 25hz, and at this frequency, the volume will be 6dB lower (half as loud) compared to the main frequency range where the subwoofer has a flat response. So if two subwoofers both are specified with the same frequency range, but one is -6dB and the other is -3dB, the latter will go deeper. 

Sometimes the "-x dB" isn't specified at all, and then it's anyone's guess. 

But how low is low enough? Most music rarely dip below 40hz, and very few tracks dip below 30hz. So if the subwoofer response is in the 20s, you're probably good for most music. If you want to be sure that you have a subwoofer capable of reproducing any and all music including room ambience from things like live recordings, you should be looking for a subwoofer that can reach 20hz. If you are looking for a subwoofer for movies, you may want it to go even deeper. But then you are typically looking at quite expensive subwoofers, and/or relatively large ones. 

A final problem with the frequency response specification is that often isn't linked to SPL (how loud it can play). So the specifications may imply that it can play 20hz, but it doesn't say how loud it can reproduce those frequencies, and that's pretty essential. So you may come across very small subwoofers that claim to go very deep, but in practice these frequencies will be inaudible. 

SPL / dB (Sound pressure)

Not all brands will include this specification, and if they do, it's often unclear exactly what the number means. Sound pressure is typically measured in decibel, and a specifiaction can look something like this: 

Max SPL: 100dB

This still leaves us wondering about a few things. At what distance was this measured? Typical distances are 1 or 2 meters. 100dB at 1 meter, equals 94dB at 2m. At which frequencies? Lower frequencies are progressively harder to reproduce at high volumes. If a subwoofer can reproduce 100dB at 30hz, that same number may be down to 90dB or even less at 20hz. Finally, at what distortion level? Is it reproducing this sound pressure level quite comfortably, or is the subwoofer about to bottom out?

And what is decibel anyway? 

If you want to have any chance at comparing this between subwoofers, you may try looking for something called CEA2010, which is a measurement standard for determining maximum SPL levels. It typically includes information about the distance, frequency or frequencies, and distortion level. Without this information, it's hard to compare SPL across brands. 

A small note is that even with a CEA2010 measurement, we only learn about the final "breaking point" of the subwoofer, where the distortion gets too high. It does not say anything about the distortion at moderate playback level. So two subwoofers with similar CEA2010 results, may show very different distortion levels at moderate levels. This is often what separates a more expensive subwoofer from its cheaper cousin. 

The type and number of drivers

To be able to make sound, a subwoofer needs one or several subwoofer drivers. The size of the driver is typically specified in inches. So you will see something like 12" driver - indicating that it has, not surprisingly, a 12 inch driver. 

In theory, a bigger driver will be able to reproduce the same SPL (sound pressure) with less distortion. The same is true if the subwoofer has multiple drivers. As you may suspect, in practice it's a bit more complicated than that. The quality and abilities of a driver is determined by a host of different parameters. So two different, equally sized drivers may have completely different qualities depending on how they are built. Which is why you may find a 12" subwoofer for anything between 100 and 10,000USD. So the size and number of drivers gives you an indication of the subwoofer capabilities, but it's not the whole truth. 

Cabinet / Enclosure type and size

There are a number of different cabinet types, but for this guide we will stick to the two most common. Sealed and ported. As a general rule, sealed subwoofers will be more precise and is often preferred for more music-oriented subwoofers. Ported subwoofers on the other hand, may be more effective - and is often the preferred design for cinema-oriented subwoofers. Ported subwoofers are also larger than sealed. Note that expensive, ported subwoofers with low port tuning may rival a sealed subwoofers in sound quality - but will still typically be significantly larger. 

So if size is a factor, a sealed subwoofer is probably the way to go. If you want as much sound pressure as possible and don't care about the size, ported might be best. If you want your cake and eat it too (have a small, precise and high capacity subwoofer) it will be expensive.

And finally, Power ratings!

I saved this for last because contrary to popular belief, this is actually the least important specification. The power required by a subwoofer is heavily influenced by the cabinet size and the driver parameters. This means that two 500 watt subwoofers may have a maximum sound pressure level and overall capabilities that are very different. It has also become somewhat of a marketing fad to boast impressive numbers. If the power figure sounds too good to be true, it probably is. The easiest advice here is to simply ignore this part, and trust that the manufacturer has fitted the subwoofer with an amplifier that is the right size (very likely). 

Hope this helps, and happy subwoofer hunting! 

Back to Sigberg Audio subwoofers

In this guide we go through the basics of running Audyssey room calibration and making sure it is configured for the best possible sound. This is a topic with lots of nuance and edge cases, but if you don't want to spend hours and hours on figuring it all out, this guide should get you off to a good start!

It's understandable that some write off our Inkognito subwoofer range as "design speakers", assuming you have to pay a premium for the looks and size rather than sound. Nothing could be further from the truth. 

A good subwoofer can improve not just the bass, but the entire experience of music listening. Unfortunately, lots of people who buy subwoofers are left unsatisfied. Not because there's anything wrong with the subwoofer they bought, but simply because they didn't have the time or knowledge to set it up properly. This article aims to help you dial in the sound of your system by making sure the basic settings of both your subwoofer and receiver is configured correctly. 

Most of the article is written with the assumption that you have an amplifier / receiver / processor with a dedicated subwoofer output and crossover capabilities, but there's a small section towards the end for those who don't - so scroll down if that's you! It also assumes you have a decent subwoofer that has the capability to keep up with the rest of your system. 

Also, the first thing to do is to try to find a good place for your subwoofer, this article gives some guidance on that subject. 

Note: This is all general recommendations. It's always a good idea to experiment, and of course choose what you think sound the best. If you have the equipment and knowledge to measure the results, even better.

Initial setup of your subwoofer

Before running the room setup procedure on your receiver, let's check the settings on your subwoofer. We'll go through the most common controls likely to be present on your subwoofer. 

Volume / Gain: Set this straight up or half-way to max (12 O'clock).

Crossover: Set this to max (typically 160 or 200hz). Your receiver will control crossover.

Phase: Leave this at 0 degrees for now. This will also be handled by your receiver.

If you have any other controls or settings on your subwoofer, leave them at their default setting.

Running room setup / calibration software

All modern surround receivers have pretty advanced room calibration systems that will automatically set distance and levels to all your speakers, including the subwoofer. Most also do a decent job at applying EQ to correct for standing waves in the room. This makes the life of your subwoofer a little easier. Follow the instructions on-screen and/or refer to the manual of your amplifier / receiver for this point. 

Note: Whenever you move any speakers, your subwoofer, or move the entire system to a different room - this procedure needs to be run again.

Checking the configuration after room setup

There are a few things that surround receivers often get "wrong". Let's walk through them and adjust as necessary. Please refer to the manual if you are unsure how to find these settings.

Crossover: Crossover is the frequency at which the receiver starts to roll off the bass, and hand it over to the subwoofer. This can typically be configured as one setting for all speakers, or individually for each speaker category (front, center, back, etc). Your receiver measures what your speakers are capable of, and configures the crossover accordingly. That's not necessarily the best choice of crossover. Typically, you will get a much better bass response if you relieve your speakers of the deepest bass, even if you have pretty large speakers.

You should never choose a crossover that is LOWER than what your receiver selected, but often it's a good idea to go higher. Even if you have large speakers and your receiver set the crossover to 60 or even 40hz, the THX recommendation of 80hz is a good choice most of the time, even with large speakers. You can even try 100hz.

Speaker settings: You typically have this setting for each speaker category, and it can be set to either "small" or "large". What this really means, is whether the crossover you configured in the previous point is active or not. If you set it to "large", the speaker will play the full range of frequencies, and not send anything to the subwoofer. As a general rule, this should be set to "small" regardless of how large your speakers are. 

Note: When watching movies, the soundtrack typically have a dedicated subwoofer or LFE channel. If all your speakers are set to large, this channel is the only thing that will be sent to the subwoofer. When listening to music, your subwoofer will be quiet. A workaround for this is selecting a subwoofer setting called "LFE+Main" if you can find that in your settings. This will have the subwoofer and main speakers both play bass during music. Typically this gives poor integration, and is not advisable. So set all them speakers to small.

Volume: You may need to adjust the subwoofer volume after room setup. Many find the need to turn the volume up by 3-6dB. Here you just have to try what sounds best. This can be done either with the volume control on the subwoofer, or in your receiver settings.

But what if I only have a stereo amplifier?

If you don't have an amplifier with crossover capabilities or room correction software, you can still benefit from adding a subwoofer to your system. It may however be a bit more difficult to integrate with the main system.

Since you will be unable to cut any bass from your main speakers, you will need to select a lower crossover frequency than you'd otherwise would. You also need to set the crossover on the subwoofer. You need to experiment to find the right crossover frequency, and having a look a the specifications of your speakers might be helpful. Slightly above or below the lowest they are specified to reproduce, might be a good starting point for the crossover. Let's say you have monitors rated at 69-20,000hz. Then a crossover of 60hz might work. But 80hz may work too. Your room affects the response, so you just need to test what works.

You also need to dial in the volume manually. Try to increase the volume until you can clearly hear the sub, and then dial it back again a little bit. 

 If your subwoofer has a phase control, you can experiment with this too. Have a friend test different settings, and choose the one that sounds best (not necessarily the one with the most bass). 

That's it!

There are other settings to look into, but those are different depending on your receiver brand, so that's beyond the scope of this article. Hope this was helpful!

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