KRK ERGO – Room Correction System

Recently, I decided to undertake a small project to turn a spare room into a mixing space. Acoustically, it is definitely a problem space. It is almost the classic worst case scenario of a box room. I decided to use what was at hand to help treat the room, so duvets covered with sheets (for aesthetics) were used in the corner of the room where the office desk would have to be placed, for various reasons.

For monitoring, near-field is the way to go as I would want to keep as much of the room out of the mix as possible. For this purpose I am using the VXT6 series of monitor from KRK and the fantastically tiny 6010a monitors from Genelec (now replaced by the 8010). All of which have all been placed on stands, measured, height adjusted and angled used laser pointing protractors. To help me judge the space, I used Room EQ Wizard and an omni-directional measurement microphone to measure the room response. The figure below shows the response of the room with the KRK monitors as the source in green and the Genelec units in purple. It certainly is not flat, at all and there is a particular issue around 90Hz. As well as acoustic issues, you can see the differences in how the speakers perform as the Genelec has low end roll of from about 70Hz, due to their pocket size.

Basic Room Response

 I managed to source a KRK ERGO room correction system for a good price on the used market. This system uses an outboard DSP unit to play specific sound patterns out of each speaker, into the room. The unit comes with its own calibrated measurement microphone, and the system then analyses what the microphone “hears” compared to what is actually being played back, similar to Room EQ Wizard. The difference is that the ERGO then tries to rectify the issues. The ERGO analyses the sweet spot and the room, as two separate entities.

In sweet spot mode, or “Focus”, all of the ERGO DSP power is used to process frequency and time domain based issues in the sweet spot listening zone, rather that the whole room. In the Global mode, the DSP power is used to help fix the whole room, but only in the frequency domain. I am only interested in the Focus measurements so with the calibration done for the KRK and Genelec monitors, I decided to find out exactly what the ERGO is doing. Handily, the ERGO is a monitor controller which allows two stereo monitoring setups to be plugged into it, so it was as simple as doing some A/B measurement testing.

The figure below has two plots. The blue one is the measurement is of the ERGO in bypass mode, meaning no room enhancement DSP is being done. The red blot is with ERGO in Focus mode. It can be clearly seen that ERGO is sorting out issues found in the room calibration. By the way, ERGO only operates up to 500Hz, or around 542Hz in my test. ERGO is designed to be used with acoustic treatment, which would help deal with the higher frequencies. Also, it is interesting how detailed the red plot is, meaning ERGO is taking care rather than broad brush stroking the issues.

ERGO bypassed (blue) and activated (red).
ERGO bypassed (blue) and activated (red).

The next figure is the same again, but for the Genelec speakers. The bypassed signal is again blue, and the processed signal is in bright red. Here, ERGO cuts a chunk of the 94 to 500 hertz range, which is very significant, as I will mention later. There is also a lot of low end boost.

3
ERGO bypassed (blue) and activated (red).

With the soundcard test finished, my attention turned to the room itself. I carried out some sweeps of the room in the sweet spot position. Since ERGO does not deal with things above 500Hz, the figures from now on will just look at the area that it does deal with. Below is a figure of the ERGO on (blue) and ERGO off (green) measurements of the room with the KRK monitors. Here, ERGO deals with the low end at the problem area of 90Hz, and besides that, not much else; at least in the frequency domain.

4
The KRK speakers with the ERGO off in green and on in blue.

However, the result of the Genelec test is much more interesting. The bypassed signal is purple and the enhanced signal is green. To be fair, for such a small speaker they perform exceptionally well but in this particular room they have a honky, congested sound to their low-mid and mids. ERGO seemed to notice these issues as shown in the previous figures. Interestingly, it made the issue at the rough 90Hz mark worse, but perhaps there is a troublesome room mode hanging around the general area I had the microphones placed. After that, ERGO begins cutting frequencies up to the 500Hz mark. As alluded to earlier, this was the most significant ERGO result. The congestion had totally disappeared. The stereo image was more defined yet smoother. A slight harshness was toned right down. Perhaps it is a significant example of the phase correction which this unit is capable of carrying out.

5
The Genelec speakers with the ERGO off in purple and on in green.

Conclusion

There is only so much that I can go into the ERGO operation and the brief and basic analysis above is just in terms of frequency content. In the focused mode, ERGO plays around with the time domain, which I think plays a huge role in the processed sound. In my project room, my normal main monitors would have been the VXTs but the Genelecs are now performing very, very well; but, to be fair both sets of monitors sound a lot better with the ERGO system in use.The main point is that I was surprised just how much of an improvement the ERGO was capable of making. I was sceptical that it was just going to give a low end boost to appeal to our ears love of bass, but the ERGO has clearly done more as things sound a lot more detailed, which allows for mixing decisions to be made with confidence.

Other plus points are the fact that it can be used as a monitor controller for two 2.0 stereo speaker setups. Alternatively, you can use it in 2.1 stereo as there is a special sub mode. It also has two firewire 400 ports at the back, so you can plug other gadgets in. I have my Focusrite Liquid Mix plugged in and I was happy to see that it will get its power from the ERGO too. A down side is that it does not have a proper microphone input, it would have been handy to have for certain scenarios.

So, should you pick one up? Well, it can cost a lot of money when bought new and you can buy a lot of acoustic tiles or raw materials to make your own treatment for the same money, and that would seem to make sense given how the ERGO “only” works on a small part of the frequency range, but the significance is that it works on the most difficult part of the spectrum, from a project studio acoustics point of view. I would say it is certainly worth looking into as part of a complete acoustic treatment package, especially if you need a monitor controller too!

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