Review: REL Acoustics Strata mkIII Subwoofer

Category: Speakers


I was never in favour of a subwoofer, as I never had heard a well-integrated subwoofer in the system at any place. It is unfortunate that those who had it in their system never achieved a seamless integration, as they probably never bothered to put in the required effort. I got a call one day (few months back) from a buddy informing me that he had opted for the used REL Stantor (the more powerful model in the ST series) that had just been delivered and awaiting installation. I went over and we spent many hours on that Sunday setting up, constantly tweaking and listening to a variety of music. Over the period of a month we had few sessions and finally both agreed that it has integrated well with his Alon Adriana, and Cary tube amps TNT Jr. Turntable and Wadia CD player. This was the first system where I was extremely pleased with the results of subwoofer integration, never before I had experienced so much satisfaction with a subwoofer in the audio chain.


Once I was convinced that REL can be tamed with some effort and has the capability to be tuned to any system, I investigated further about the options available to me. The friends REL Stantor was not on my short list as it was too expensive for my setup at around $4,000 (new) and also its high power rating of 300 watts. REL are reputed to be very versatile when it comes to integration with speakers. I finally decided to take the plunge and opted for the REL Strata III. My audio dealer made special arrangements to send a demo unit to try out for two days on no obligation basis. The demo unit arrived on Friday evening and I spent the following Saturday and Sunday setting it up and doing a bit of listening in the process. Although proper fine-tuning was not achieved but I had a good idea of what to expect if I went for it. I ordered the brand new unit.


The REL manual is excellent when it comes to guidance about how to go about setting up the subwoofer. There is no way one cannot setup the subwoofer if the basic guideline is followed which is a starting point. Once you have setup the system you may need time to fine tune it by listening to your usual music and tailor the sound according to your personal preference by tweaking the subwoofer even further.

When I got my new REL Strata III, I did all the connections at the amplifier end, as the wires were connected to another amp which I was running with a passive pre and the interconnect was directly connected on the other end to the CD player. I was sure I made the right connections. When all looked OK we both sat down (my son and I) comfortably in our listening positions and I asked my son to press play on the cd players remote.

BOOOOOOOOOM! BANG! We jumped in our position trying to run helter-skelter not knowing what and where something went wrong. In confusion we tried to use the remote control of the system to turn down the volume and nothing was happening. So I ran across the room and switched off the mains supply to the whole system. Peace and calm finally prevailed!

I had to figure out what went wrong. We found out soon that the CD player was actually not connected through the preamp but directly to the power amp which made it produce the sound at full volume meaning 140 watts being pumped to the main speaker and the subwoofer blaring at full volume producing earth shaking bass.

Luckily nothing went wrong and all the equipment was safe, but I will never forget this experience for a long time to come. We corrected the anomaly and everything finally was set.

As per REL/Sumiko setup procedure the recommended placement as you may already know is in the corner, but yes, they do acknowledge that if it does not suit you, it can be placed anywhere convenient, albeit with some loss in pressure and extreme low frequency extension. In my case the sub is positioned 3 inches out diagonally from the corner behind the left speaker (the bass is locked here with max loudness). I concluded that a setting of a cut off frequency of 28 Hz (Coarse on A and Fine on 5) is the maximum I can go to before slight boominess creeps in. Seems this setting is "just under the main speakers". The sub rolls off with 12dB/Octave.

Following are the setup parameters that I used on the REL Strata III

Crossover frequency: 25 Hz, Course on A1 and Fine on A3
(The two filter controls are to allow coarse and fine control of the filter settings. The coarse control marked A through D changes the turnover frequency by approximately half an octave per division. The fine control marked 1 through 6 offers a resolution of approximately one semitone per division)
Gain: 12 o’clock
Phase: 0 Deg

The frequency response specified for my Paradigm Reference Studio 40 speakers is 59-22,000 Hz (+/- 2 dB) with low frequency extension down to 34 Hz (+/- 3 dB, in a typical room). The Paradigms are on a rigid metal stands with 6 inch main post filled with river sand and decoupled from the flooring by spikes.

I also own the Chartwell LS/35a’s (15 Ohm version) from the 70’s and was really curious about pairing them with the REL. I had to spend less time with the set up since I had done most of the work while setting up the Paradigms. The difference was that I had to change the crossover frequency and set it at 53 initially, but, later bringing it down to 43 and even lower to mid 30’s. I was very curious about what others had experienced while trying to mate the unit with LS/35a’s.

I found out that according to Richard E. Lord most of the audiophiles make the mistake of setting the crossover point too high and gain too low which actually does not help the overall balance. The other interesting point that I discovered was that the setting between A1 and A3 is somehow workable with all speakers no matter what their frequency extension. I was surprised to find this out but realized that somehow folks at REL know what they are talking about. In my case, I had set it at 28 (initially) and gain between 10 and 11 o'clock, so to a great extent it was not wholly incorrect. I did however change the crossover frequency to 25 Hz and the entire system started to sound wonderful with great extension and depth, without my missing anything in between whatsoever. The most surprising disclosure was that REL tested the LS3/5a's also and they used the same low setting and higher gain and according to them it was subjectively very good integration.


Some of the music I chose to dial in and lock the bass while setting up the system was “Rain” from Madonna’s album Immaculate Collection, Dave Grusin – Migration and Nusrat Fateh Ali Khan and Michael Brook’s album Night Song. Initially after spending almost 20-30 hours spread over 5 days the system started to sound very much listenable with amazing low frequency extension. The sub had actually disappeared so to say. The difference is only noticeable when it is switched off, but who would want to switch it off after knowing what is going to be missing!

I also had a pair of Rogers (LS/35a’s) 11 Ohm version (belonging to a friend) handy and wanted to see what difference it makes when replaced with the Chartwell. Rogers were more upbeat and could handle rock music better than the Chartwell, but, the high frequency of the Chartwell was slightly superior, airy so to say compared to the Rogers. Dire Straits, Roxy Music and like sounded better on Rogers and Ella Fitzgerald, Louis Armstrong, Diana Krall and like on Chartwells.

Most of the music we listen to does not even go any lower than 40Hz as very few acoustic instruments go below this frequency. The double bass goes down to 41.25 Hz, the Harp as low as 33 Hz and finally the piano at 27.5 Hz. All the other instruments have lowest frequencies that are higher than the ones mentioned. The movies, however, have a lot of artificial low frequency sounds induced to give that thrilling effect. We are only concerned with music here and not the effects. Any subwoofer, which can produce the sound of music well, can be considered good for music as well as Home Theatre.

It is also to be noted that when the REL is connected via its hi level input feeding from the amplifiers speaker out put terminal, it only takes in the signal and does not affect the impedance characteristics of the main speaker/amplifier combo. Furthermore, REL takes on the character of the amplifier connected to it, the better the amp the better the output from the subwoofer even though one might wonder how and why it can be since the REL has its own amplifier built-in. I personally tested it and found it to be so. The Perreaux 3150B amp showed a different character in comparison to the Quad 606II that I used for listening sessions. By connecting the subwoofer to the speaker out terminal of the amplifier the exact same signal is fed to both the main speakers and the subwoofer, which in other words means that the character of the bass from the main system is carried forward into the sub-bass.

Many have suggested that folks tend to overload or overdrive their subwoofers. Most likely it will not happen in my case, why? The Chartwell are very inefficient at 82dB and need very little power to produce music, max input stated is 25 watts. I actually play them with a beefier amplifier that might be pumping a lot more than 25 watts into these babies at times. They go to max 95 dB so I cannot increase the volume any further since the woofer bottoms out if I crank the volume. At 15 Ohms they actually turn the amp into a 70 watter instead of 140 specified at 8 Ohms. No question of overdriving here.

As for Paradigms, they are very efficient at 91 dB; hence, I need not crank up the volume to listen to them, as they go pretty loud anyway. So, in both cases I will probably never end up overdriving anything. I know the REL has built-in circuitry that actually will not allow the sub to be overdriven. I also did check the woofer's mechanical movement at fairly loud listening levels and it was barely moving, yet, producing very good and deep bass.

I listen to music 90 percent of the time and the balance watching Concert DVD's and occasionally movies. My system is a two-channel system and will remain so for a long time to come.

I have been listening to the LS3/5A and REL combo on and off for the last few months and I just do not feel like connecting the Paradigms back after the session. The sound is so open, fatigue free, with tight bass, liquid midrange and great low frequency extension that I am afraid if I continue listening to this combo I may waste the Paradigms. The LS3/5a seem to be having the voice coils of God (courtesy B&W ad :-))

As far as breaking in is concerned it might just start to sound better on its own as time passes, not sure if it can be detected by ears over a period of time - say 100 -200 hours maybe more, I have been listening to the Strata since last 5-6 months now and I certainly cannot tell if the bass has improved or not. But, one thing is certain; I have been enjoying it in my system immensely.


Audio Nirvana? Naaaaah! Not possible. Nothing is perfect. My friend who got the Stentor thought his system was amazing and everyone who used to visit his place ranted and raved about his system (and it sure is in many ways), we found out later how much was actually missing before the REL was put in place. It was an incomplete system so to say, even at that price level.

With the sub in place I rediscovered my music collection, to be honest, I was flabbergasted when I realised what I had been missing all these years. Somehow I also feel that it’s not just the bass (last octave) that is added by the subwoofer, the system is now sounding more authoritative so to speak. With the REL in place I feel the mids have more body (even though the sub does not handle that frequency range, but it is somehow contributing there as well). The overall sound quality is soul stirring with excellent low frequency extension that was missing before the REL was put in. I wish I had acquired the REL much earlier. The high price of the unit is more than justified. A truly high-end sub-bass system!

The only thing I believe in is that as long as one is enjoying, it’s worth it. This hobby is going nowhere as I feel that it is a journey with no destination, you just get the kicks from the ride itself.

Happy listening!

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Never installed a sbuwoofer in my own system but have installed a REL Stantor in a firends system. Heard many subwoofers including but not limited to JBL's, Infinity etc
Excellent review Quadophile !! The ONLY sub I ever considered was the REL Strata 3 for my system.
I added REL Strata III to my system after years of thinking about going with a sub. I was able to integrate them beautifully with my Silverline Sonatina II's, and wow, what a difference! Even that the contribution sounds small in absolute terms (when you turn off the main speakers), it changes the character of the entire system and makes it FAR more fulfilling. I cannot see ever, ever owning an audiophile quality audio system without such a sub.

Just imagine those who do not have it in their system, how much they are missing! I have yet to come across anyone who had a complain against the addition of a REL Strata III.

Happy woofing!
I've referred several members (at LEAST two) to this review, which I think is excellent and thorough. I've even posted a link in a couple of threads. Hope you don't mind, but will stop if you object for some reason. (Guess I could have ASKED you first, but...oh well).
I had hoped that's what your thought would be, but it dawned on me AFTER posting the links that maybe you wouldn't WANT someone else posting links to a review that they didn't write. So it's good to hear your response. I do think that the above is quite an excellent discussion, and one that's pertinent for people looking for a good sub that's used. Like, I feel that online CONSUMER reviews are a potential source for relatively unbiased information. Finding a consumer review that competently incorporates technical details is an added bonus.