Improving your bottom end with REL's Strata III sub-bass system!


Hon. Acoustical Engineer
Mar 16, 2002
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Home theatre and audio buffs, mainly new comer’s, invariably add a subwoofer to their systems just because it is a fad to have one installed and also everyone else is doing the same. Not wanting to be left behind they go for it, thinking they will improve their bottom end, little they know that the subwoofer if not properly set up can actually become a boom box. A properly set up subwoofer can raise the goose bumps, unlike an improper set-up that can help only produce bumps in the audio spectrum. Meaning, the subwoofer creates nothing but boomy (unwanted echoing) effect in the room, a very undesirable trait one can have in a system.

Setting up a two-channel system properly is in itself a daunting task. One has to understand the exact requirements of the room and what equipment could be suitable in a given room. Too much power and larger speakers in a small room can have detrimental effect; on the other hand too little power and small speakers in a large room can never sound fuller.


Many serious two-channel listeners tend to stay away from installing subwoofers in their system. Why? Sometimes it is very difficult to seamlessly integrate a subwoofer with the speakers. Generally the best integration is achieved in a single speaker that produces the entire spectrum of sound (based on the capabilities of the speaker in question and from lowest to highest frequency). The manufacturer usually takes care of the nitty gritty of installing proper crossover, size of the midrange, woofer and tweeter so that good sound can be had from a speaker with multi driver array from lowest to highest frequency the speaker is capable of producing. It is possible to buy a reasonably good speaker below $1000 which produces sound down to 40Hz, the better the quality the higher the price, but it is impossible to buy a reasonably good speaker capable of producing the frequency down to 20Hz below $1000, such speakers cost 10’s of thousands of $$$. This is where a subwoofer comes in which can be had at much less amount of money to achieve low frequency extension.

It is almost impossible to demo a unit in the store due to different setup, different equipment and acoustics of the environment. The best bet is to evaluate one in the room and system you have. Many cheaper subwoofers do not have the facility to fine tune and integrate the woofer with the existing system. A good subwoofer must be flexible enough in providing fine tuning capabilities so that it can be integrated into the existing system as well as accommodate any change in the future, if you upgrade your existing 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. The ST series starts with the REL Strata III (100 watt amplifier built-in) at a humble $1,395 and ends with the REL Studio at $10,000 (with a massive 500watt amplifier built-in)! 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.

REL sub-bass systems (as REL calls them) are not cheap in comparison to what is available in the market. I have come across some good brands with very high power amplifiers built-in (as much as 500 watts) selling at much lower prices than REL Strata III which is having just a 100 watt power amplifier built-in. Few are aware of the fact that REL sub-bass systems are hand built in the UK and use highest quality components in every subwoofer they built. The entire series uses same quality components whether it is the REL Strata III or their flagship model selling for $10,000. All the sub-bass systems in their range have the same fine tuning facilities which can be adjusted from as low as 22 Hz to as high as 96 Hz through the controls provided on the back of the unit. With the two controls provided one can precisely adjust the crossover in 24 steps from 22Hz to 95Hz, this gives great flexibility when pairing it with any speaker be it a small bookshelf or multi-array six feet tall floor standing models. The Strata’s in-room low frequency extension is specified at 18 Hz (-6 db) and their flagship is capable of going down to bone marrow penetrating 9Hz! All subwoofers have the facility of connecting via the RCA jacks (lo level) direct to subwoofer out on the preamplifier/AV amp or the ideal choice of connecting the subwoofer (hi level) directly from the output of the power amplifier’s speaker out terminals. This is done through the Neutrik Speakon connector (10 meter cable with connector is provided with the unit).


ENCLUSURE TYPE: Sealed box design
VOLUME: 30 Litres
INPUT CONNECTORS: 2 Neutrik Speakon and Twin Phonos
AMPLIFIER: 100 watts RMS, 200 watts Peak , DC Coupled Mosfet
DRIVE UNIT: 250mm Long Throw Cast Chassis
PHASE: 0 and 180 Degrees
PROTECTION: Internal PCB Mounted Fuses with Set-Safe®


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.

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) the famous BBC monitors 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. This led me to embark on a fact finding mission on the web and trying to get some feedback from like-minded fellow audiophiles who had the ear as well as knowledge about pairing a sub seamlessly.

I got some excellent tips from fellow members/audiophiles on the forums and clubs where I am a frequent visitor. I found out that according to Richard E. Lord (man behind REL) 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. 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 has 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. When it comes to music reproduction at very low frequency, I found REL to be excellent.

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.

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.

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 (on your bottom) from the ride itself.

Happy listening!

REL's Website


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Feb 3, 2004
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MMMMMmmmmmmmmmmmmmmmmm........ Sub........ I play bass guitar. I love my bottom end :) hehehe

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