Epik Empire Data-Bass test results

Here it is The results for the final subwoofer out of the 5 commercial subs I tested early in the spring of this year. The Epik Empire!



Let me go ahead and say that this one was saved for last due to there being quite a bit of extra effort and work involved with reviewing it. Most of this due to it being a dual opposed subwoofer. I wanted to make sure it was right. Not soon after I mentioned that I would be testing one I received a pm from Chad the founder of Epik wishing to speak with me about what would be taking place. He was justifiably concerned about it getting a fair shake in the tests due to the dual opposed design of the subwoofer. I already had some concerns about this myself and had been talking with some notable subwoofer designers about how to handle it.



At this point let me explain the issue simply. A dual opposed subwoofer will always have one or both of the drivers further away from the microphone than a regular subwoofer which usually has a single driver and maybe a port or 2 radiating from a single surface. If you take 2 drivers and mount both on a single face of the subwoofer you can then aim that face at the microphone and the drivers end up roughly 2 meters (In our case) away from the microphone. Now take the same 2 drivers and place one of them facing the other direction on the back of the enclosure and about 20 behind the other. Its contribution at the microphone will be somewhat diminished. Even though you have the same 2 drivers, amplifier, and enclosure volume and alignment the SPL delivered to the single measurement point will be less than the subwoofer that is allowed to aim all or at least most of it's radiation at the microphone. If you have both drivers side firing so that they are equidistant from the microphone you will have the same issue still with advantage maintained by the subwoofer that can aim most of its radiation directly at the microphone. Now this holds true, if you take a single point measurement. However if you take many measurements at various points around the subwoofer the results will even back out as the dual opposed subwoofer will have more uniform 360deg power distribution. Unfortunately there is simply no feasible way for me to do a full polar response work up on every sub I test. It would be ideal but will simply be way too much work. Any subwoofer with radiation from multiple faces is subject to this issue. However ports or passive radiators contribute most of their output over a fairly narrow range, while a dual opposed sub has all radiation from both points covering the entire useful range of the device, so this is a much larger concern in that case. After quite a few emails back and forth with various people I decided on a course of action to investigate the issue and if need be develop a compensation factor for the Empire and other dual opposed subwoofers. What followed was a large amount of work that eventually lead to me becoming convinced of the necessity of and the development of a compensation file for the Empire in order for it to get a fair shake in the output testing. That effort is far too involved to go into here. It will end up being an article unto itself that I will put together in a few days time and will end up hosted on Data-Bass.



One other thing that delayed things a bit was that the first Empire that I purchased ended up developing a buzz or rattle somewhere along the line that was excited by frequencies near 90hz at loud output levels. I determined that it was not the drivers, a driver dust cap, a loose mounting screw or 2, or anything to do with the amplifier. Nor was it some internal wiring or other part making contact with the back of the cones. It appeared to be the enclosure itself although I found it to be very inert and solid feeling and I could not find any obvious issue with any bad seams or anything loose inside. Thankfully Chad sent a replacement under warranty, which technically he did not have to do since I had disassembled it while looking for the problem. (I never did hear what it was.) The second unit was without issue. Kudos to Epik for standing behind their product and honoring the warranty. Thanks.



Alright with that out of the way let's get down to the tests and review.



The Epik Empire is a sealed subwoofer design utilizing 2 long throw 15 drivers in a dual opposed configuration that places one driver on each side of the enclosure. Epik calls this Parallel Drive. Both drivers operate in phase with each other and cover the full useful frequency range of the subwoofer. This type of driver configuration has one large benefit in that the opposing forces of the 2 drivers on the enclosure cancel out each other which results in an almost vibration free subwoofer even when the subwoofer is working very hard. The amplifier is an efficient class D design rated at 600w rms and 1500w short term. It features the usual controls: On/off/auto switch, adjustable crossover 50-150hz, a crossover bypassed LFE input, a phase control and input gain adjustment. It also features balanced XLR inputs which I particularly like and even offers both 120v and 240v operation. It does not however have onboard user adjustable EQ or room compensation. Many subwoofers rely on today's advanced software built into a receiver to take care of that though. The enclosure is 1 thick material as are the cloth covered detachable grills. Both sport a nice looking 1 radius edge. The finish is a simple black laminate. The whole deal weighs in at a hefty 120lbs or so and the external dimensions are 22H x 18W x 24 D. It is not a comfortable 1 man dead lift and carry for most due to not only the weight, but also the size and large smoothly rounded over corners. There is a user applicable Epik logo that comes with the subwoofer and it is listed as designed and assembled in the good old US of A. Epik lists the response as 20-300hz +/-3.5db The price is $799 in singles or you can get a solid discount if you buy in multiples. My cost to my door with freight shipping came in at $799 plus $139 shipping for a grand total of $938. The subwoofer is delivered by freight truck and the packaging is very thorough, with little likelihood of damage occurring in transit, barring some catastrophic event or pure negligence by the shipper.



The overall build quality of the cabinet and the amplifier were very good. The amplifier in particular had a solid and high quality look and feel. The cabinet is heavy and inert. The drivers I examined and they appear to be of good quality as well. They are not particularly flashy with modest foam half roll surrounds, black Kevlar impregnated paper cones, a stiff inverted dust cap, and a stamped steel frame, but the motors are fairly hefty and of large diameter. There is what appears to be a 2 diameter voice coil and a single moderate sized spider. There is no pole vent since the drivers are virtually back to back once mounted in the cabinet. These are cost effective drivers but it seems that the money in them was spent where it counts, a strong motor with plenty of force and the cone and suspension system. Of course the other thing to note here is that there are 2 of the drivers in the cabinet. Multiple drivers can many times outgun a single much more expensive and heavy duty driver simply because the sharing of the load reduces the demands on each tremendously.



Overall the first impression I got from this subwoofer upon receiving it was that it was a solidly built and engineered product, using quality components, with the money spent where it counts most.





Please excuse my photography skills or lack thereof everyone....

All measurements were taken at a distance of 2 meters from the nearest enclosure face in an outdoor ground plane setting as per the usual Data-Bass test procedures.



Here is the compensation file that was developed for the Epik Empire in order to better represent its true output. This compensation is added to the CEA2010 results and also the max long term output and power compression results. Again i will be doing a short article on the how's and why's of this later...










This is the response of the subwoofer with the drivers side firing versus front and back firing towards the mic. There is less than a db of difference between the 2 orientations below 80hz. The side firing orientation provides 1-3db of extra output at the mic above 80hz so I decided to keep with that orientation.











This is the effect of the crossover control on the basic subwoofer response shape with it set at minimum, 12 o'clock, maximum and with the crossover bypassed using the LFE input. All tests were done with the crossover bypassed.










Here is the basic response as tested for the Empire. This is a sealed subwoofer and should exhibit a smooth corner transition into what is ultimately a nominally 12db octave roll off if there is no electronic manipulation of the signal. We can see that this is not the case so there is some shaping of the signal. It looks like there is some boost centered at about 22hz or so. There is also a high pass filter inserted below 20hz. It appears to be an 18db octave filter which combines with the natural 12db roll off to result in roughly a 30db octave final acoustic roll off. The measured response fits within a roughly 9db window from 19-300hz, which is fairly close to the factory published spec.











Time domain measurements.

During the power compression sweeps the sub acted fine up until the second highest sweep level at which point there was a hint of over excursion flutter from the drivers between 16-25hz where they were being asked for a lot of excursion due to the EQ boost. The next higher sweep level produced more exaggerated grumbles from the Empire's drivers over the same frequency range and there was virtually no improvement in output in this band, so this is where the test was stopped. The Empire exhibited very good compression performance indeed, up until the last and loudest sweep level, which produced a very large amount of compression where there is EQ boost used to extend the response.









Spectral Contamination 100db





Spectral Contamination 105db




Spectral Contamination 110db










Looking at the THD measurements taken at the same levels as the power compression sweeps the Empire remains very clean and low distortion above 30hz even at the loudest levels. There is an increase in distortion below 25hz followed by a reduced level again once below 20hz before the response falls down in level to the point that the noise floor is corrupting the results excessively at the lowest frequencies. The increased distortion centered near 20hz corresponds with the EQ boost. Examining the harmonic make up of the distortion reveals that above about 30hz the distortion is dominated by the second harmonic, which is good. Where the EQ boost takes effect and results in much higher driver excursion the 3rd harmonic is the predominant one. Overall I'd consider it a pretty good performance still despite the higher levels near 20hz. If you aren't driving the sub to its limit it even has decent THD at 20hz.










103db THD Alone





103db THD sweep by harmonic component






108db THD Alone





108db THD sweep by harmonic component






113db THD Alone






113db THD sweep by harmonic component

Looking at the maximum long term output which is derived from the highest level sweep completed during the power compression tests, the Empire tracks right about the center of the all time results in the low bass range and then trends closer to the all time maximum recorded levels once above 63hz.





Maximum Long Term Output Comparison








Maximum Long Term Output Excel Comparison Chart and Averages




Attachment 218984

Here are the CEA2010 output results. This sub has good output levels if not huge ones over the 25-50hz octave where it will many times be compared with vented subs which will often be tuned somewhere in this range. At 20hz and below the maximum recorded levels are pretty good and in room this sub could probably provide a real and useful 16hz if called upon to do so. I could not get a clean 10hz result to pass CEA2010, partly due to the high pass filter built in and the difficulty in getting enough 10hz level to get up out of the background noise floor. I should have captured the maximum output result even with excessive distortion just to show what the sub would do dynamically, but alas I did not. I will do this with future sub tests though. Up above 50hz this sub will get very loud indeed and does so cleanly at the same time.













CEA2010 Distortion Results at Each Center Frequency.


















CEA2010 Output Comparison and Averages Excel Chart





Attachment 218985

To wrap up this reviewThis is a pretty good sub. I spent a little more time actually listening to this one at home compared to some of the others and I thoroughly enjoyed doing so. One thing I really like about this sub is the fact that the drivers used have a very good top end without the typical roll off above 50-60hz that can sometimes be severe in subwoofers with a lot of inductance and a heavy moving assembly. I don't know if they employ shorting rings in the drivers but the signs point towards that probably being the case. The drivers also have a pretty light cone and voice coil from what I could tell which also helps out too. It seems that they are sort of a cross between the light moving mass and high motor force of a pro woofer and a long throw woofers increased xmax, which is a difficult thing to pull off well especially in a cost effective design. To see what sort of difference this makes look at the CEA2010 or the max long term output composite graphs and compare the Empire's max output above 50hz with the black trace indicating the minimums, which is a sub with a peaky rolled off response. At 50hz the difference isn't that big, but by the time you follow them both out to 125hz the difference is huge. This is not only max output but an indicator of efficiency as well. You might think that you don't need all of that output but I am a fan of as much headroom as possible and 50-125hz is a very critical response range. Anyway this extended response and high output capability, combined with the very good distortion performance above 30hz, tells me that the Empire has the potential to be one very good sounding unit once integrated well. No MBM is needed here that is for sure. The sub also has enough headroom to provide useful output down to probably 16-20hz in most rooms.



If I have a gripe it is with the 20hz boost. There is nothing wrong with including it and in fact the resulting response will probably match up with typical room gain pretty well, but I wish that it was defeatable, for smaller better sealed rooms, or simply to increase headroom for those that like to really crank their system up. Other than that from what I could tell the Empire could stand to either lose the high pass filter all together or at least have the sharpness of the slope decreased to maybe only 6db octave. The drivers are operating in a very small airspace which should control the driver excursion very effectively already and the sub has shown itself to be capable of pretty good output even recording a passing CEA2010 result at 12.5hz.



The build quality and components of the sub are good as is the performance. It isn't the prettiest or flashiest subwoofer I have seen, but that sort of thing costs extra money. It is also a robust subwoofer that overloads predictably and without damage. The 20hz area is the weak spot in headroom due to the EQ boost built in but when the sub reaches it's limit there there is some overload noise from the drivers but otherwise the sub clamps down and compresses further output. With the discounted price a pair of these is a cost effective deal that should handle even a large difficult space or a cranker if you are one of those types , very well.



That is all for todayTill next time.