Review: Neptune Audio's neptune EQ - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 2 Old 02-23-09, 11:09 PM Thread Starter
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Review: Neptune Audio's neptune EQ

When the folks at NeptuneEQ asked product reviews, I immediately volunteered. I had heard of their magic box and the wonders of EQ to help fix minor speaker and room problems before and wanted to see the results for myself. Having had a lot of experience using the venerable Behringer Feedback Destroyer (BFD) to EQ subwoofers, I figured I could relate this experience to the NeptuneEQ and offer some insight into the units performance.


The NeptuneEQ is an 8 channel fixed-band digital equalizer. Plenty of channels for an entire 7.1 system. It uses 24bit, 96 kHz D/A conversion steps, and does all of its EQ magic in the digital domain. It has a sleek aluminum faceplate and buttons, with a nice blue vacuum fluorescent display. What sets it apart from other equalizers on the market is its completely automated setup procedure. More on that later, but it really is a plug-and-play system. This is a good time to mention one way this unit excels above its competition: the microphone jack is on the front of the unit. That seems like a no-brainer, but some of Neptune's competitors hide the mic jack on the back, meaning you have to fumble around the back of the unit whenever you want to make a new measurement. Not in this case -- having the mic jack in front eliminated that hassle every time I made a new measurement.

The hookups on the back offer both RCA and XLR inputs and output for every channel. They even allow for mixing and matching, so if your preamp has XLR outputs, but your power amp has RCA inputs, you can use XLR inputs to the NeptuneEQ and RCA outputs from it to the amp. Internally, the output voltage can be set to match sensitivity with your power amp, which is another great feature.

Noticeably absent is an RS232 port or 12V trigger input. Since the unit does have multiple presets from which to select ("Flat" and "Movie" to name two), an RS232 instruction port to switch among them would be nice. I imagine most people who can afford a product at this price point have some degree of automation in their system and the RS232 port would make integration that much easier. The 12V trigger would help by allowing the unit to be turned off and on automatically from the preamp. In my setup, this was not necessary since my power unit can turn preamp banks on separately and then delay for the power amps. But in some setups triggering may be necessary and I believe more and more people are wary of leaving their electronics on all the time when not in use. But in the grand scheme, these were both minor nits, as I left the unit in "Flat" mode most of the time and had my power distribution unit handle the on-off functionality.

But overall the fit and function of the unit is well done. It is heavy and obviously overbuilt, good traits for piece of gear to have.

Full range EQ is kind of a double edged sword. On the positive side, if you have a bright room or your speakers start acting weird around the crossover region, it can boost or tame the response. But like all gear, it is putting another unit in the signal path, and in this case, another A/D then D/A conversion. Some purists argue that this is a recipe for noise and other unwanted artifacts in your sound path. Neptune gets around this by using quality 24 bit, 96 kHz DACs and very good build quality. I listened closely for hum, hiss, or other noise when the unit was in the equipment rack, but none was there to be found. A quiet unit indeed.

Setup
Installation was simple, as I had plenty of extra RCA cables laying about. My setup is a Marantz SR-18 receiver being used as a preamp, and an Outlaw 950 amplifier driving the main speakers, Magnepan MG10.1s. The NeptuneEQ simply went between the preamp and power amplifier. Neptune recommends using the XLR connections whenever possible for higher signal quality, but alas, none of my gear has those connectors. Also, my cables were only about 2 feet long, so the potential to pick up noise is very small.


The unit ships with a calibrated microphone, cable, stand, weighted bag, manual, power cord, and a delicious pack of Orville Redenbacher's microwave popcorn. To start the setup procedure, the manual instructs you to put the mic on the back of your primary seating position and be oriented vertically. The included stand and weighted bag help in this regard. In my case, we have high-backed LaZBoy couches for our theater seating. Not ideal, I know, but sometimes furniture is picked more for the wife than the acoustics. In any event, the microphone would have been way too high in this arrangement, so after consulting with Neptune's very responsive technical support, they confirmed that the mic should be at ear height for all the listening position measurements. So I constructed a quick stand out of throw pillows and the measurements began.


The procedure for initial setup was very simple. First, I zero'd out all the gains/cuts in the Marantz preamp. I also set the distance to 10 feet for all the speakers and set the mains to large, and subwoofer to yes. At the sub amp, I disabled the sub crossover and zero'd the single parametric cut/boost functions, so that nothing interfered with the Neptune's auto-setup calculations. Then it was just a matter of scrolling through the menus on the Neptune -- which I found very intuitive and easy to navigate. One of the functions was setup, and the first sub-menu item was Auto-Calibrate all.

The unit starts by doing pops and chirps to determine which speakers are present and their distance from the center point. This is done at the first position, which the manual instructs to be the most central. After that, it does a pink noise burst to measure for the EQ and level for all the speakers. It then prompts you to move the mic, hit a button, and then vacate the room. This is all repeated for a minimum of three, maximum of five positions. I believe this is to average the responses so that one bad microphone location (like a null at a particular frequency) will not skew the filter selection. In theory you could leave the mic in place for all five measurements, although even if you have only one seat, I would advise moving the mic a little bit for the aforementioned reasons.

The whole procedure from the first microphone placement to completion took less than 5 minutes. The room clearing delay was nice as it allows you to get completely clear before the measurements happen. The time is adjustable in the settings, in case your room is very large.

I then looked at the setting it changed. Distances were spot on and measured in inches instead of one foot increments like the Marantz. Levels were almost exactly what I set manually with the pink noise and a Radio Shack SPL meter (a.k.a. the old fashioned way). The exception here was the subwoofer. For some reason, it liked setting the sub 10dB lower than my manual setting. At first this seemed like a mistake, but upon further measuring I figured out why -- I have a dipole subwoofer, which has a steep roll-off below 70 hz and a peak at 120 Hz. Best as I can determine, the Neptune was attempting to keep the peak in line with the mains, which sadly is too narrow bandwidth and not centered on one of their bands. Please note, this is a unique problem to my setup. Very few people will have these kinds of issues in their setup.

But despite all this, the NeptuneEQ is also manually-configurable, so I decided, via trial-and-error to boost the sub by 5dB, which got me the extension I wanted and did not let the peak in the response boom too badly. A compromise that still sounded very good.

Listening Impressions
So, the obvious question: "how did it sound?" Overall, I liked the results. I have a concrete floor room (basement with tile, rugs, and padding), so as you might expect, the room can be overly bright. The NeptuneEQ tamed that with some filter on the top octaves that took some of the harshness out of it. Also, mid bass was cleaned up quite a bit. The Magnepans roll off quite steeply at 80 Hz, and have a a bit of a low point in the 100 to 200 Hz range. Couple this with an 80 Hz subwoofer crossover and you can get an interesting response. The NeptuneEQ added some boost in the 100 to 200Hz range and through boost and cuts in the mains and subwoofer, really smoothed out my overall response in the crossover region. You can actually see the changes in the measurements section below.

For test material, I streamed a lot of FLAC music of various genres. One of my favorite test pieces is Blue Man Group's "Audio" CD. Very percussion heavy, but not necessarily deep bass all the time. It gives you a feel for resonances and tonal balance. Also in heavy rotation was Fleetwood Mac's "Rumors", which has a lot of acoustic guitar numbers and both male and female voices -- again good for testing the tonal balance. For music, I found the NeptuneEQ tamed some harshness in the higher octaves, which can cause listening fatigue over time. Cymbals and distorted guitars did not sound harsh and tinny and I found my listening sessions could continue longer. The other major area of note was the mid/high bass. As mentioned earlier, my room and speaker combination has always had a bit of a dip around 100 and 200 Hz, and a peak at 130 Hz. This being around the crossover frequency for the sub can make the integration tricky at best. Sad to say, I've learned to live with much of this. However, the NeptuneEQ did a great job of smoothing out this region as well. It was apparent from the very beginning and was definitely the biggest "wow" factor of the gear.

For movies, I have a few I always rely on for gear testing. The Lobby Shootout scene in "The Matrix" is great for low music and crisp gunshot effects. "Master and Commander" is good for testing voices amidst massively loud cannon fire. Finally, "The Fifth Element" is a fantastic movie all around for audio testing. Deep electronic score, explosions, dialogue, and the famous aria scene on the flying hotel tests the entire range. The diva singing hits almost every frequency your speakers can produce (if you also include the score and fight sequences). Again, the reduced high end made watching movies with crash and gunshot effects less fatiguing and I definitely noticed more clarity in deep male voices. The effect of the NeptuneEQ was noticeable and significant. I have to say I was impressed.

Measurements
Subjective observations are one thing, but one of the reasons I was asked to do this review is that I have experience measuring responses with Room EQ Wizard. For the uninitiated, Room EQ Wizard (REW) is a free software tool developed by John Mulcahy and supported at the Home Theater Shack (www.hometheatershack.com). It allows the user to take measurements of in-room response of speakers and subwoofers, and has tools for selecting and optimizing parametric equalization channels to help smooth out frequency response and tame resonances. The most common application of the software is to use the inexpensive Behringer Feedback Destroyer and set the recommended EQ channels. The BFD has some limitations. The DAC modules are not the best quality and introduce noticeable noise into the system at higher frequencies. Because of this, its use is usually limited to subwoofer equalization only. REW records the impulse response of a known test signal, and from that can calculate and display frequency response, waterfall/spectral decay, and reverberation time. Plenty of tools to analyze a new piece of gear and its effects on the room acoustics.

For measurements, I used a Behringer ECM8000 microphone run through an M-Audio MobilePre USB sound card. Measurements were taken on a Gateway Tablet laptop at the central listening position. For simplicity all measurements are of the Left main speaker with the sub woofer active when indicated.

Below is a measurement of just the left channel. Green is the original and blue is with the NeptuneEQ engaged. There are three major items to note. First is the cut in the top octaves. The response graph shows a steep fall-off. My measurement microphone probably needs a new calibration, but the important thing of note is the relative difference. The NeptuneEQ did a minor cut in the top two octaves. This was what was described earlier as taming the brightness and contributing to the reduced listening fatigue. The second item was the slight cut in the midrange (800 to 7kHz). This was not as noticeable as the other two regions, but worked to smooth out the overall response and further reduce listening fatigue. The final region was the major boost given in the upper bass region. This was obvious from the first song and movie. It cleared up male vocals and dialog. Sadly, it excited the peak at 120 Hz a bit more, but the trade was worth it.


The next plot shows the full range measurements. Orange is the bypassed measurement and purple is with the NeptuneEQ. Here you can see my "issues" with the subwoofer. Believe it or not, as bad as the measurements look, it sounds very natural. My sub does not produce the low extension of thunderous explosions; instead it has more of a natural integration with the Magnepans, which was its intended purpose. I am working on building a passive 1st order low pass network to compensate for the dipole roll-off (and extend the response lower). However, this was not completed at the time of test. I was interested in how the NeptuneEQ would attempt to compensate. It applied two major filters to the subwoofer, a boost around 80 Hz and a cut around 175 Hz. The first raises the response to be more inline with the natural peak around 120 Hz. The second squashes the cabinet resonance in the sub, which can actually rise through the sub crossover and muddy up the crossover region. Both of these helped clean up the response in the crossover region, which was readily apparent. Other than the aforementioned disparity in the levels, I was impressed with how the NeptuneEQ picked the filters for the subwoofer.


It would have been nice to have the main peak at 120Hz suppressed, but that is a narrow bandwidth peak and this is not a parametric EQ (nor does it claim to be). So while good at cleaning up larger anomalies like a bright room or mismatched crossover region, the NeptuneEQ will not fix a narrow bandwidth resonance. However, there are other avenues to treat these such as traps and Helmholtz resonators. So not a negative on the NeptuneEQ, just understand what job this tool was designed for.

Conclusions
Overall I was impressed by the NeptuneEQ. The biggest takeaway I had from it was how easy the setup was. It truly is a fully automated setup, but not stubbornly so, as you can tweak the values later to suit your needs. As it is rather expensive, it will not be the solution for everyone -- but when you figure for 8 channels of high quality DACs, calibrated microphone, laptop, and time spent manually figuring out filters and settings for all eight channels -- the value starts to become apparent. Their customer service was also very responsive with all my inquiries, most of which were informative questions, not problems with the setup. If you are in the market to get the most out of your home theater system, you should definitely give the NeptuneEQ a look.


What: NeptuneEQ 7.1 Channel Automated Equalizer
Where: http://www.neptuneaudio.net/
Price: $3995

Test System:
Marantz SR-18 Receiver (Preamp)
Outlaw 950 Amplifier
Dayton HPSA-1000 Subwoofer Amplifier
Magnepan MG10.1 (Left/Right)
Magnepan MGMC1 (Surround)
Dual Exodus 15" Subwoofer (Dipole Linkwitz Design)
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post #2 of 2 Old 02-24-09, 01:06 PM
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Re: Review: Neptune Audio's neptune EQ

Please post any comments in the review thread over in the Neptune Audio forum.

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