MJ Acoustics Ref 150 MkII Subwoofers

MJ Acoustics Ref 150 MkII Subwoofers 


150watt AQctive Sub speaker with MOSFET Amplifier
250mm (10”) Driver
Speaker and Line Level inputs.
Neutrik Speakon connector.
Unbalanced RCA (phono) connectors
Twin crossover circuits
Digital Display
Remote Control with ‘out-of-sight’ RM Eye and 4 user-presets
Phase Control infinitely adjustable between 0º and 180º
Frequency response 13hz to 200hz
18 & 25mm MDF cabinet
300mm X 355mm X 300mm
Weight 20.85kg (46.3 lbs)
Black Ash finish or Wood Veneer.


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[Jan 26, 2008]
Audio Enthusiast


ok build


poor in all area. the actual thing vibrates when it tries to reproduce loww bass which it cant do at all.

i made the mistake of buying a mj sub for use in a high end system. big mistake. sounds so terrible its not able to produce music at all. maybe ok for movies i guess as thats just so easy to produce. awful bass. my main speakers did a far far better job. dont listen to the reviews. how many bad reviwes would mj post on their site? none. there subs are not suitable to enhance the sound of high end systems like they claim. take my advise stick to the big boys like american subs like zu if u want musical reproduction of bass and not just quantity regardless of quality of the bass sound.

build is ok but i dont think it could fare better in a budget system either really. mine was sold on and i actually told the buyer what i thought as i dont like to disappoint bargain hunters.

Customer Service

not known, didnt bother to tell them what i thought of their sub

Similar Products Used:

zu, far far better, light paper woofer, not some monstous rubber thing that distorts.

[Sep 13, 2007]


True audiophile product offering very flexible integration with almost any stereo system. Probably the best performance foir buck available. Discreat, and real wood veneer finshes. Tunefull and fast, full frequency responce down to 13Hz.


Unstated looks for some. Takes a full day to set up.

This is a personal review of the MJ Acoustics Ref 150 mkII as owner of this product.

I have run an Audio Note valve SET system for a couple of years now, having migrated from Solid State and huge power amps and tower speakers to the flea powered world of valve amplifiers and efficient horn/hybrid speakers.

Thus this review is primary based on observations in my own valve system which consists of components of a pretty high quality to start with.

Setting up. Allow a full day to do this, a weekend or whatever.

The sub arrived in substantial box, well packed, and is supplied with: RCA lead (5m), Speakon lead (5m), power cord, 4 x optional floor spikes, remote, separate remote eye sensor, user manual.

I set up the Ref 150 to run from the RCA pre-out connection, preferring this to the high level Speakon connection. I did try the Speakon connections, but found it difficult to discern any change in performance, so stuck with the more convenient for my rig RCA connections.

Fist thing, power everything off, plan where you are to place the sub. A corner placement can work well, both visually and sonically, as long as you experiment with distance from the walls to avoid any unnatural emphasis. Lay out all the connections before hooking up. If you have 2 pre out connections, fine. If not you can buy a simple 2-box RCA connector.

On the back of the Ref 150 are 5 main rotary buttons. Main one is for function selection, the other 4 are for gain and frequency tail off on RCA or Speakon, and 2 more for gain and frequency tail off on LFE (low frequency input from a sub out on an AV amp). This arrangement allows maximum flexibility for either stereo or AV usages.

After double checking the cables, switch everything on. Next, check the gain is set to lowest setting on the sub -99db, and then slowly raise the volume on the pre amp to a normal listening level. Now raise the sub gain to in my case -24db. You should now be hearing some sub activity.

Now the fun starts! Play a CD with a tuneful bass, preferably prominent in the mix. I used a level 42 track (running in the family) You will trash this track forever but ignore that. You now will need to play the same track on repeat many many times while you start the fine-tuning process. With the Ref 150 you have very sensitive control over actual 1hz steps for the upper frequency cut off. The big digital display on the rear panel shows all the setting, output level, frequency cut off, phase and gain. Believe me, this is worth the effort, subtle changes are everything here.

My main speakers are good quality Zingali Overture 2's, with horns and 8 inch bass units. I initially guessed the frequency roll off at 45 hz, but quickly realised it needed to be set much higher, bearing in mind the roll of slope of the Ref 150 is set at 24db cut off at the displayed setting. Thus 60 hz setting starts the roll off at 36hz. After about 2 hours of constant experimentation, I stuck with 86hz. This was producing the best lower bass details and at the same time the mid bass was now merging very closely with the Zingali's. Getting excited now.

Next, another 2 hours playing with the gain and also the phase. On phase, generally a down firing sub will need to be set to 90° phase to match a forward firing main speaker, which is what I ended up using. Some rooms can alter this a bit, so it is good to have this as a setting.

Now gain. It took quite a while to settle on this. I got a setting on the level 42 track, but when I swapped to another CD, Faithless for instance, or some live Eric Clapton, the mix shifted a bit.

This is where I came to the conclusion I would need all 4 presets available on the Ref 150, mainly for the gain levels. And it comes down to the subject matter. Lets face it, a pumping Faithless disco track will fill a room with a lot of energy, but a live unplugged gig, or some classical not so much. The different gain levels also restored a lot of the atmosphere and subtle lower registers almost lost in the last 2 types of music.

So, enough of the setting up, what the hell did it sound like? Well, I must admit, I am a bit of a bass fan. Sorry, used to be a mobile DJ (not famous far from it). And I have owned many large solid-state amps and big speaker set-ups over the years. What I have finally settled on is an Audio Note valve system with a CD front end. And I absolutely love it, beautiful midrange, superb treble, micro dynamic, vocals, all the usual valve pros in spades. But I love live music, and my system was lacking that final finish, the ambiance and foundation you normally only get with huge SS amps or crazy priced £40K+ esoteric custom set-ups.

This sub was, I admit, a revelation. It was not a one-note boom box, or a muddy rumbling thing in the corner. Technology has moved on so much in the last few years with many subs, and what we have here is a serious piece of true hi-fi sub frequency transducer! I was amazed at the expansion to the sound stage. The ambience was suddenly more natural. The dynamics had moved up, and the extra information I was hearing right down to a true sub 15-13hz was amazing. And a pleasant surprise was the attack and speed of the output. It kept pace perfectly with the Zingali's, showing the MJ Acoustics speaker to be of very high quality and the on board amp likewise. Plus it did all this without smearing the all important holy grail of 300b amps, the sweet midrange. In fact it added an extension of ambiance and depth to what was already their.

My initial reaction on set up was to add bass to the mix, to actually really notice the sub.
Because the Ref 150 is so fast and punchy, you can get carried away. But this is not the way to go. I found after a day’s careful adjustment, the best (for my ears) setting was to extend the response, not change the balance. This marriage of the main speakers and the sub system is crucial to create a seamless and realistic sound stage with a full audible frequency response. And the way to test you have got it right, is a few days later, try switching it off while playing a favourite CD, and you will hear exactly what you were missing without it. I for one cannot go back. And frankly I find it hard to find a more crucial and cost effective way to bring a valve system into the hi-end. I have spent more on 4 valves than this sub.

There are other subs out their, I listened to REL, B+W, Velodyne. The MJ beat them all at this price point on performance and integration..

Addictive! A fantastically recommended product and made in Britain to boot!

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