Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Sub woofers, Sub Bass Systems and Crossovers....

I could use some help, please. I'm trying to work out the best way to integrate a sub woofer (Rel Stadium 3) which I've borrowed to evaluate and, from reading (manuals and threads here) and talking to technical support, I'm feeling confused.

As I read it, Rel's philosophy is to connect with both low and high level inputs for video and music respectively. I'd like to be sure I understand it.

From what I understand, the idea for Music is to take a high level signal from the main speakers to the sub and use the on board filters to bring it in just at the low frequency of the mains. For video material they would connect to a line level input, which routes the signal through their filters, or LFE, which bypasses the sub's filters.

So, why take the full signal for music and then filter out anything above, say 22Hz to 55Hz, depending on the capability of the mains? I guess I need to know more about what is carried at line level and what is carried by LFE alone but I've assumed they carry frequencies up into the range that most main speakers work at. Any thoughts and information would be appreciated.

In my system, (596, 568.2 and D5K's) I have configured the subwoofer as one - mono for music, 5.1 and LFE. I have experimented with both the THX and Meridian crossover defaults and with the mains as Small and Large 96.24.

Currently, I have the mains as Large 96.24 and the crossovers set at 40Hz. The intention is to keep the Stadium out of where the D5k's perform well and use it to provide information that they do not - substantively, below 35 Hz. Again, I'd appreciate any feedback on this to help me think it all through more clearly.

By the way, I've now tried the Meridan D1500 and this Rel. I didn't especially like the D1500 because the bass sonded and felt thick and slow to me. The Stadium sounds and feels faster and more musical. I wonder if I shoud try the D2500 in comparison but heaven knows how much I'm missing just because I can't configure the one I've got adequately!

Steve

[This message has been edited by hamblis (edited 01-12-2004).]

Hi Steve

I had a REL Stentor III which I was using very successfully with 5ks (and later, 6ks) and a 568.1. I had it set to 80Hz for LFE and Logic modes and played with settings between 30Hz and about 70Hz for music (mono setting). REL's philosophy (as you'll have read) is to augment the bottom end with the octave that's usually missing, so for music, it should kick in where the mains drop off. Their advice on simultaneous high and low level inputs doesn't apply with a DSP system, so don't worry that it's all connected via the 568 sub out (and consequently the REL low level input). The REL should have it's own filters bypassed (there was a position on one of the Stentor switches for this) so that the 568 does the x-over, and the settings in the 568 set up programme should be used to specify the sub and level of LFE limiting (REL make grand claims about headroom, so I plumped for no LFE limiting). You'll have heard already how much extra info is in the LFE channel, and in my opinion it sounds massively better to do it via a REL than even the 6ks I have. I'd recommend getting a sound level meter to calibrate it all, as subs are pretty tough to do by ear. The next thing is placement, and REL have some new info on this on their newly updated website.

Although I'm without REL at present (had to sell due to lack of room), I will be looking to track down a Stentor III again later this year when I'll have more space to play with!

Hope that's of some help...

Cheers

George

PS Forgot to say, someone here on the forum suggested previously about setting the music Xover to twice the value of the lowest freq your mains will play. It's a good starting point, but I found that anything above around 45Hz was too directional. You may find that changing the polarity of the sub aleviates this problem, and REL suggest that sometimes a dip in the bass can be better than an additive effect with possible boom, at the xover region.

[This message has been edited by Mr Meridian (edited 01-12-2004).]

Hi Steve,

The way Meridian works bass management is mostly as follows

small- allows you to select a cross over and the rolled off bass goes to the sub, or any speakers designated as large if there is no sub present.

large- no roll off at all. You can use the protection circuit for analog speakers. I believe the DSP speakers have a version of the protection circuit in it. what this circuit does is allow the full frequency range to be played- as volume increases, the circuit attempts to limit dynamic range (difference between loudest and softest moments) so as to protect the drivers in the speaker.

Mono sub- this means all the rolled off bass from any speaker designated as small goes here plus any LFE channel

LFE sub- only LFE goes to the sub- nothing else

No sub- rolled off bass from small speakers goes to any speaker designated as large. lfe goes to those speakers as well. no large speaker and no sub, I thnk then you lose that rolled off bass and I dont know where the LFE goes.

so how do we integrate the sub into your system.

First off, you cant do what REL wants since you are using digital speakers.

The Meridian website says the D5ks play down to 35hz. So I think there are a few ways to go. I think you have to give these all a try.

I think you might want to place the sub between the center and one of the mains (eg. Left......sub...center......right)

but room placement is always a tricky thing.

assuming all the speakers are D5ks (center, mains, surrounds)

I would start off with the D5ks set to small, and then pick a cross over frequency.

Configure the sub as mono for all options and then plug the sub into the analog sub output and there you go.

another way to try is
set the d5ks to large and then set the sub as an LFE sub only. Obviously this will only add the sub's output to movies or other sources with a LFE channel (DTS audio, DVD-A, SACD)

A kind of hybrid of this is to set all the D5ks to large except the center, and set that to small. set the sub to mono and then you can define the xover point for the sub- basically youre using the sub as an extension of the center channel and also for LFE. Since the center is critical for movies, and movie soundtracks do not contain bass exclusively in the LFE track, this might get you a good dynamic result.

Im not a big fan of having a sub just for LFE since LFE is so limited (120hz-20hz). and because the 120hz range is high enough for many people to "locate" the sub.

I think by putting it between the center and one of the mains- if you use it only for lfe, it might be easy to believe the bass is coming from one of the main speakers. this also goes for using a crossover in the small setting.

Almost forgot to mention what George said- turn off all the filters, etc in the sub!

George,
That might have been me. This is based upon the usual xover being 1st or 2nd order (6 or 12db/octave). I think M uses a 24db/octave digital xover so I think you can get away with an xover closer to the bottom limit of the D5ks in this case. I think I would try it around 50-60hz and go from there.

[This message has been edited by JerryL (edited 01-12-2004).]

George, Jerry, thanks very much. George, for interest when you start hunting a Stentor 3, Rel told me last week they are bringing out Mk 5 versions of Strata, Storm and Stadium by Easter (missing out Mk 4 as apparently "4" is unlucky in Asia. Mk 5 versions of Stentor and Studio (I wish) follow but with no date. All new versions will "give more and do it better" but major innovation is front panel with digital controls for mode, filters, phase, etc.

You mentioned using a Sound Level Metre to calibrate with. I have one but assumed the 568.2 would not put out a calibration "tone" through the analogue sub connection and I don't have much material putting out a steady bass tone (at least not one that I can play in the evenings...). Have I got that completely wrong?

Jerry, your assumption is right in that all my speakers are D5k's. It seems I'm working with your "hybrid" approach - sub set as mono, main speakers set to large, centre as small. Now I understand more about how bass is rolled of from small mains I'll play with that a bit. Like you, I don't want the sub just for LFE. Actually, it's for music, principally. I'm listening at the moment to Sain Saens Organ Symphony and there are bass tones from the large pipes that the D5k just don't touch. The thing is a real pleasure - I probably shan't relax, though, until I've heard the Stentor 3 like George used to have.

Thanks again to both. I'm having a lot of fun with this and it's nice to feel a better understanding of it.

Steve

PS. Forgot to say that I have the Rel positioned outside the right hand main, not quite in the corner. It does not appear boomy but I will try it inside the main and close to the centre.

[This message has been edited by hamblis (edited 01-12-2004).]

Steve,
just as more info- the 568- if its like the 861- will put out calibration tones for all the speakers. you want to use a sound pressure meter to assist you in calibrating.

you not only have control over the level of each speaker, but also of the phase. what you do is toggle between + and - and which ever setting produces a higher spl reading, thats the setting to use.

Keep in mind that if only the center is set as small, then you need to be using Trifield or similar mode for music otherwise you wont get any sound going to the center, and there wont be any bass to roll off.

also give it a try with all speakers set to small- you never know.

hey

I have 2 subs with my 568v1. Infinity Intermesso. they have RABOS "roomcorection", and I do my crossover at 100hz. all my speakers are analog and set as small, an the subs are left and right, placed in the corner. The rabos is masured out and the sound is very good.
My main speakers are ProAc Responce 2.5 an the are sounding mutch more open in the midle sinse the subs are conected. The hole system are a lot more detaled in the lover midle and the upper bass, and the subs are werry good in the buttom. This vas a big upgrade for me, I prevesly have an Mirage bps210 as lfe.

My next step is maby the DSP33 as front, since my ProAc is a litle hessitating and hard in the top.

Hamblis,

I demo'd exactly what you are doing a couple of years ago. I don't think I knew enough about subs to do it justice then however.
The Stadium was a very cabable unit.

In addition to the very good points made above, I can only add that I think the best result with 5k's was to set them to small and actually take some of the bass music workload to the sub. The 5k's seemed to become more capable in the mids and highs when I did this. I thought this may be even slightly logical as the middle driver is shared as bass/mid.

Placement is critical. If the bass freq's are behaving well in the corner, then, I'd probably leave there. However, test in the centre to be sure. Also, the REL is a big old box so it doesn't score well with WAF if it sits right in the middle of things.

X-over setting will have to be judged by what you like to hear and will be different to , say mine, because of how your room is (mis)behaving. Remember, you can change it on the fly while your fave tunes are playing with the remote.

Cheers

Nick

[This message has been edited by ncpl (edited 01-13-2004).]

and in your testing, if you move the sub, remember, you have to recalibrate it for level and phase.

Jay,
not surprised you had such bad luck with REL, they make two kinds of subs, HT ones which suck and Music ones which blow, hehe.

But seriously, the Q series are absolute distortion mongers, whilst the ST series are a nightmare to integrate with anything more than two speakers. I've been doing some serious research into the behaviour of downward firing subwoofers and have come to the conclusion that whatever gains you get from pressure loading the driver against the floor are wholly negated by the appalling behaviour in the crossover region.
It is the crossover that is the most important part of integrating a subwoofer with 'small' speakers and getting it wrong sounds exactly like what you had - zero midrange.

RELs are great for stereo applications where the built in crossover is a benefit, where you have an incredibly sophisticated and well implemented digital crossover such as in Meridian processors they're a liability.

Before I went to digital speakers, I found I preferred my setup to be large with max setting in protection (that means no protection). I would run the stereo interconnects to my sub, I xovered around 50hz and then I ran the high pass back to my amp which fed my mains. the center and surrounds were set to small at around 80hz xover.

this worked for me- thats the fun and frustrating part of this hobby. you have to tweak with it to get it right. the more time and experience you spend playing with the gear, usually the more youll understand it and have a feel for what will work.

as is mentioned above, unfortunately this doesnt work for a setup with digital speakers and analog subwoofer.

Part of the problem is that the advice given to consumers for sub setup is just plain wrong!
Everyone is told to balance all channels to 75dB using white noise and a SPL meter - this is a flawed method.

The professionals use the following method:
1. Balance the main channels at 75dB with white noise.
2. Create a test tone CD (this is easy to do now with modern PCs and the internet) with alternating tones straddling the crossover point. So for a THX 80Hz Xover, you need 60Hz,70Hz,90Hz,100Hz.
3. Using the sub volume only, try to balance the volume of these tones so that the alternate pairs, 60+100, 70+90 are at roughly the same SPL.

With all speakers set to small it is generally unnecessary to play with the phase control, even more so since the distance measurement to the seating position in the processor also acts as a phase control.

Thats very interesting advice. Can you provide a link to the tones?

Also as to getting to 75db- with digital speakers, the highest level setting you can achieve is 0. In my room, with all speakers set to 0, the rear right comes in at 71db, while the others come in higher- so I have to bring the others down to 71.