September 15, 2020

The surprising reason why you might need a sub in your studio

This is an issue that comes up often in a studio consult session. Usually my services are engaged to give advice on acoustic treatment for a studio. The first thing I will do after an initial discussion is test how the monitors are performing in the mix position. This is where it's quite common to find a problem that looks like this:

The mic was placed in the mix position to show how the monitors measure in the room, as they will be used. Clearly there is no bass response. In general this is not necessarily a good reason to add a sub. Decent quality monitors are not necessarily very expensive and it's not hard to find monitors with adequate extension for most music. 

In this case, the monitors themselves were a limiting factor. We brought in a 12" sealed woofer to test the bass response. This woofer had already been calibrated for a flat anechoic response with plenty of bass extension. Here is the nearfield measurement:
Next we tested in the mix position, with comparison to the existing monitors:

We see a similar response without the early roll off. Clearly there is a room related dip of around 17 dB. This is far too much to resolve with EQ due to the headroom required. We need an acoustic solution. 

The first solution is to optimise the position of the monitors and the mix position. This tends to offer limited improvement and normally we don't effectively resolve a dip related to room modes in this way. We can reduce the depth of a null with bass traps but typically this won't remove a null this deep. In situations like this, the most effective solution is usually a sub in an optimised location.

We used the same woofer to test every feasible sub position in the room. One of the better positions is shown here. You can see that a sub with a little EQ removes the problem entirely. Just a little EQ is required to shape the response into a flat overall trend.  

One way to know

Not every studio needs a sub. The most important factor is how your monitors measure in your particular room. If your monitors have adequate extension and headroom and a reasonably flat response in your mix position, there is no great need to add a sub. It's a solution that I recommend only where it's required. When it comes to buying a sub, many studio owners have a tendency to first try a cheap sub. Whilst it's true that you can actually get decent monitors for a modest price, the same is not true with subs. Generally speaking, most subs below AUD $1500 are not up to the task. This is why I advise people to have the room tested and implement a sub only where it's needed.


May 18, 2020

Why you don't need two subs

By now you've heard it said many times "two subs are better than one." So it might come as a surprise to hear it's not always the case. Quite often it's the wrong advice. The answer is not quite as simple as the one most audiophiles seek. People like simple ideas that make intuitive sense. This is why myths in audio are so prevalent - they are simple ideas that seem to make intuitive sense, so they spread on forums. When something makes sense, people are reluctant to change their minds. My aim with this post is to arm you with the information to help you make a better choice for your particular situation.

The case for more than one subwoofer

There are only two technical reasons for more than one sub:

1. Output - you want more clean output than a single sub can provide
2. Smooth response - no single sub position can provide a smooth response in the seats that matter

There are many non-technical reasons, but I'm going to stick with what provides an audible benefit for your dollar.

If your goal is to increase output, it's worth keeping in mind that two subs can work against each other. Here is an example:

These two sealed subs have a different response due to their positions. How do they sum when measured together?

Here you can see that in the low bass range, below 43 Hz they actually  provide a less smooth response and lower output than just a single sub in the blue position!

This is where things work against those who buy subs, put them in the room and hope for the best. The point to take away here is that the benefit is not automatic. You can't simply put multiple subs into a room and get the benefit so many are talking about.

So you might be wondering when I'm going to present the case for more than one. Here it is. There are many rooms where one sub isn't enough. Here is a good example of a room that requires two.

This was a fairly typical dedicated rectangular room, with one row of seating in a good sized room. This client came to use looking for the missing midbass punch. The interesting thing here was that they didn't put it quite that way. They initially believed that they were missing bass depth. They had one sub up the front of the room:

The large peak around 26 Hz is provided by the room and it allowed a small sealed sub to punch beyond its weight. It achieved good output to near 20 Hz. But the real problem was in the midbass. There is a large recess around 30 - 45 Hz. In movies a great deal of the action lies in this range. I'd argue this region is more important than 20 - 30 Hz. We tested every possible position in this room. No single position could provide a smooth response. Hence we changed our focus to finding two positions that would work well together.

Along the front of the room, we found a better position:

Moving this sub, we removed a dip to achieve smoother upper bass. Then we found a position for a second sub that just happened to be under an existing coffee table that was large enough to hide a sub.

The second position solves the midbass punch issue. With these two positions, we now have a chance to fix the bass.

The final result was a dramatic increase in bass authority and dynamics. Movies delivered a more visceral experience that was lacking before.

The case for just one subwoofer

For audiophiles who just want the best bass in one listening chair, I've found that about half of the rooms we test need one sub and the other half are better served with two. Here is an example of one room that suits just one sub. All the positions we tested:

As you can see, the positions vary enormously. Here are a few positions that are interesting:


This client had many subs in the room, most of them in positions that aren't effective. One of them was in the blue position, which performs very well for 2 channel. The orange position is one of the worst. I've shown it here to give an idea of how badly the room can impact the response. The black position is similar to one that he was using, but you can see it provides a lot more free output. In this room, only one sub is required with moderate EQ.

This room is one of the best I've seen for using just one sub. Yet surprisingly, they had many subs running in the room. The message here is clear - always test the room before you decide how many subs you need.

It's surprisingly common for people who just need one sub to have several. If your plan is to buy a sub then hope for the best, I always recommend just one sub. Where you want to take the next step, my advice is always the same. Test the room. This means either learning how to do it, or engaging a service like ours to do it for you.

June 21, 2017

Rythmik 12" flat pack

We now have a standard flat pack for the Rythmik 300W kit:

This is designed for the 300W Hypex amp version, which has a slightly larger enclosure than F12. The height is increased to gain extra volume.

Rythmik custom curved sub prototype

We're offering this prototype build for sale. Contact us to express interest.

CAD diagrams show the design details which might not be as clear in the photos.

June 17, 2017

JV60 crossover upgrades

It's not unusual for us to receive numerous emails each week asking if we still offer upgraded crossovers for JV60. This is one that we built yesterday:

These are hand made with quality parts and the modifications I used as a JV60 owner. The mods were make or break in my case, resulting in keeping my JV60 speakers for many years. I actually found the sound to be more enjoyable than many high end speakers, priced well above $10k. The sound is smoother and more refined.

Crossover upgrades

We actually offer crossover upgrades for any speaker.  This includes:

  • Hand built crossovers using the same design but upgraded parts
  • Design mods to adjust the sound to your preferences
  • Modified designs to suit new drivers
  • Custom crossovers for custom speakers

June 13, 2017

Emerald Rock Studio

In most cases, our services are engaged after a client has already purchased acoustic treatment. Very often we are called in when there is a specific and objectionable problem they were not able to solve with generic and free advice on the internet. Here we started working with the client before the studio was built and so this meant we could ensure a great result right from the start.

Bass traps

Most bass traps on the market are best described as "low midrange" absorbers. Their effectiveness is typically very limited. Here we built custom bass traps, running floor to ceiling. The traps are 340mm deep and 1000mm wide. One in each corner.
The bass traps are resistive and operate deliberately into the mid and treble regions. The advantage here is that they serve a dual function and actually reduce the amount of midrange absorbers that would otherwise be required. The traps were built as 8 modules, which were then bolted together once delivered onsite. A further advantage of the large depth is that they are more stable. These traps were made with Polymax XHD which we also sell as raw panels for DIYers. 

Vicoustic Wavewood panels are mounted either side of the rear corner bass traps. This space is also a band practise space. It was important to create a neutral sounding room which was not overly dead. Part of creating this balance was mixing diffusion and absorption.

Vicoustic Multifusors are installed on the ceiling. These are very cost-effective panels and we like how easy they are to install. Being a light weight polystyrene panel, they can be installed with self adhesive picture hanging strips. It's an easy DIY install, which avoids the extra cost of a professional install job. 

It was actually this product that first prompted us to become a Vicoustic dealer - it was clear that many of our clients needed an easy to install low cost diffusor.

SVS SB1000 subwoofer set up under the mixing desk. We consider this sub to be a value leader. It's a capable sub with very good performance for the price of a raw driver and amp. Many studios install a cheapie sub and most of them are simply not worth using. The temptation is often there to buy a sub in the $500 - 700 price range. These can only be considered "junk subs." It's a very good idea to spend just a little more for a sub that is far superior. We provided the sub along with calibration. We tested every feasible sub location, finally opting for the most practical placement with the best performance. Here a nearfield location worked best.

Very often the placement of the monitors and their relationship with their surrounds can create issues. A very accurate monitor is easily undermined with poor setup and a hit and miss approach. We worked through various options with placement to determine the optimal setup.

Products and services included here:

  • Consultation on design and layout of the space prior to construction
  • Acoustic treatment design
  • Custom acoustic treatment
  • SVS sub
  • Sub integration 
  • Audio calibration

June 4, 2017

Point source mini - realising a compact point source speaker

This is a speaker we've wanted to create for some time. Perhaps our most versatile ever. We wanted to create a compact point source speaker. It would cater to some unique situations:

  • nearfield monitors
  • a small room where a deeply involving sound stage is desired
  • valve and lower powered amplifiers
  • a centre channel speaker that can be placed on its side
  • a surround speaker with equal horizontal and vertical dispersion to serve more than one row of seats
  • a premium Atmos ceiling surround speaker (which doesn't measure so badly the response plot has to be hidden)

These are quite diverse situations but all of them benefit greatly from a point source speaker. We decided to commence working on this project and the first step was finding the right driver.

One promising driver was the Eminence Beta8CX. The parameters were quite useful and initially it seemed quite appealing that any compression driver with a thread could be tested. We're quite fussy on which compression driver we use as they are very often make or break with HE designs. Price was also an attractive feature. We know that people don't tend to spend big on surround speakers, so this was a key issue.

The Eminence driver has useful sensitivity and works well in a reasonably compact enclosure. However, when we tested various compression drivers, we noticed a serious problem.

There is a broad 15 dB valley from 4 - 11k. We tried various compression drivers but all exhibited a similar problem. Even with the benefit of a DSP active crossover, the sonic result was poor. One of our requirements was the ability to use a passive crossover, where we don't have the option to simply add EQ to a valley this large.

A further challenge with coaxial drivers is that they tend to be expensive. Money does not necessarily buy you exceptional performance. The reality is the coaxial drivers are difficult to get right.

Here is an example of one of the better units:

This woofer is mounted in a different enclosure so it's not directly comparable in all respects, however, the far superior response in the treble region is clear. Despite being one of the best, we can still see some obvious problems. Numerous dips in the woofer response above 1k where we are likely to want to cross to the tweeter. A peak just above 4k which is very audible. We can also see that the compression driver has very limited bottom end response.

The Game changer

Here we have a driver that changes the game. Without this driver, this project would not get off the ground.

In contrast to the cheaper stamped steel frame of the Eminence, we have a very solid cast frame. There is no dust cap here. An accordion cloth surround ensures very long life and very control of the cone edges.

The compression driver is integral to the design. Shown above is the back of the phase plug and you may also notice the copper shorting ring. This arrangement provides much better alignment of the acoustic centres.

Here we can see the best of both previous drivers. The woofer has a well behaved response, free from the problemmatic dips and breakup of the pro coax. We also have a very nicely extended top end without a falling response that needs to be corrected - this makes for a simpler crossover. Overall, a much more usable driver. Our first trial with a very crude crossover revealed a musical result - this is a very good sign.