Dual Monoliths reviewed

[russ.will]

As it says, is anybody interested?

Just for the fun (education) of it, I'd like to try a dual Monolith setup and post my findings here. The only reason I'm suggesting a dual Monolith setup is because I already have one.

To a certain degree, it's about what happens if you buy two cheap subs as opposed to one expensive one. Y'know, we've all seen it, the "I'd buy two Monoliths instead of a PB-12" sort of statement, with no regard to what it actually takes to make two subs work in one room.

I have the room to try a pair in various locations to see what benefits (if any) two subs will produce. Illka (of the field sub tests) has suggested that two Monoliths may be a very intersting combo and as I'm half way there, think it may be a bit of fun to find out what happens if you try this out under 'real world' circumstances.

How hard are two subs to integrate? Will they produce a more even response across a number of listening positions? What are the perceived benefits of stacking/co-locating a pair? Will my windows survive? Will Mrs russ.will ever talk to me again?

[FONT="Comic Sans MS"]<I'm prepared to risk that last one as I just got a corporate invite to the Chelsea Flower Show, for two. >[/FONT]

I have an SMS-1 for EQ purposes and producing basic plots of the measured response at/across various positions. Anybody interested should own a Monolith plus at least 3m of a decent sub cable.

If you don't, then why haven't you investigated the Mark Grant cables in the cables power buys? Shame on you!

I'm prepared to travel and collect sub/owners within a resonable radius (say 50 miles of Cambridge) if transport is a problem.

Early risers, or somebody prepared to stay the night would be prefereable. We've done one test this year and it takes a surprising amount of time to get things moving, which results in 'dead test time'. Believe me when I say, a day passes quicker than you might think when getting involved in such events.

Beer, curry and other inducements are available and Angel Eyes will be invited along as an independent arbiter.

Don't let that last point put you off - he makes great coffee and has better ears than he lets on.

Your offers, if any please,

Russell

PS. DD, make sure you can commit before you offer.

[Phil Hinton]

Russell,
I am already running two Monoliths in my reference system at the moment. I have not quite managed to get them perfect yet in terms of positioning (difficult even in a dedicated room) but running them EQ'd from the Audyssey pro unit. They certainly provide good spl levels and you know there is plenty of headroom, however there is a lot to be said for actually buying a quality single subwoofer. The monoliths are a bargain for the money, even with two running, however I have had higher quality subwoofers through the system which to me added more in the way of finesse and quality and still maintained good spl levels. You will gain maybe 2-4 db extra headroom and a more even sound if placed well but it really will depend on the room at the end of the day. Good luck with your own experiment.

[Dynaudio Desire]

Well russ I will see what I can do. I myself would love to hear both how the Monolith sounds in a bigger room and what 2 of the deers sound like! I would have to probaly go along the early risers route, as staying the night most probaly wont go down well.....

Only trouble is now I have work every saturday so it will have to be on a sunday. Infact next saturday I am off to the strawberry fair so I could drop the beast of on the way or something and let the guys who know what they are doing have a listen.

[Druboo]

Hi Russell

I would be 'up for it' it's just a question of logistics. As I've mentioned before I do have to travel to Cambridge for work commitments fairly regularly. However this is during the working day, aiming to arrive in Cambridge for about 10, get the work done and get as far as I can home again before the evening traffic jams

Weekends are out unfortunately as Mrs Druboo is working and I wouldn't put upon you the company of at least the 2 youngest members of the Druboo tribe.

Will try and sort something out with work, so I either have to overnight in Cambridge or have a guaranteed quick return, i.e drop the Monolith (and 5m MG cable ) off one week have to return the following week or fortnight when I can pick my bits up. At the moment the trips are every 6 - 8 weeks and i dont think I could do without my Monolith that long.

[Peter Galbavy]

I would probably be intereted but can only do weekends and a number of Saturdays in June are already filling up... Most Sundays (with the exception of Sunday-following-a-very-late-Saturday) are OK. Have Monolith, have cheap 2m cable (that works for me).

North London to Cambridge in about an hour - A1 not M11

[russ.will]

Originally Posted by Phil Hinton

Russell,
I am already running two Monoliths in my reference system at the moment. I have not quite managed to get them perfect yet in terms of positioning (difficult even in a dedicated room) but running them EQ'd from the Audyssey pro unit. They certainly provide good spl levels and you know there is plenty of headroom, however there is a lot to be said for actually buying a quality single subwoofer. The monoliths are a bargain for the money, even with two running, however I have had higher quality subwoofers through the system which to me added more in the way of finesse and quality and still maintained good spl levels. You will gain maybe 2-4 db extra headroom and a more even sound if placed well but it really will depend on the room at the end of the day. Good luck with your own experiment.

Cheers Phil,

It really is just for the fun of it. Spending on upgrades is on hold until I've sussed the likely cost of converting my loft into a dedicated room. I thought this would be a bit of fun to keep me occupied and allow me to comment in an informed fashion on a question that often gets raised on here.

I also didn't want to do anything that may duplicate any efforts that may result from our discussions in the 'Free Beer...' thread.

This one looks easier to sort out though. I've just had a PM from Tom at BK offering the very kind loan of a DF to play with.

Russell

[Ilkka R]

If one co-locates two active subwoofers, one gains a 6 dB uniform gain. Both subwoofers will have close to identical frequency responses at the LP.

If one separates (more than ~1-2m distance) two subwoofers, one gains somewhere in between 0-6 dB (depending of the frequency). Both subwoofers will have different frequency responses at the LP which means that in the best possible case they will make the FR smoother but in the worst case they make it less flat.

If your current place for the subwoofer produces fairly flat FR, I would suggest co-locating them. Then you will get the maximum gain and won't have to deal with phase problems.

[Nimby]

Separating subs will sometimes produce a cancellation trough depending on the room.

Trough frequency will depend on distance between the subs.

I tried this with my IB array and my cylinder using REW.

Moving the cylinder merely moved the trough up and down in frequency.

As did playing with the phase of the cylinder.

[russ.will]

Cheers boys,

@Ilkka, I don't have an even frequency response at the listening position. The only positions that provide that, are at the rooms quarterpoints in front of the door or in front of the LH speaker & equiptment rack, both of which are unacceptably inconvenient.

However both of these positions still suffer huge room gain sub 40Hz. As such, it's the potentially smoother response across the two to four main positions, rather than any headroom gains, that I'm interested in playing with.

The other interest I had was to test something I think you once said (and I apologise in advance if it wasn't) which, IIRC, was that two Monoliths would outperform a single PB-12/plus. Given that I already have one Monolith, this would be a cheaper upgrade than flogging it and buying something else.

@Nimby, I recall your experimentations, but in this instance both of the subs are movable, albeit to a limited degree. With the SMS-1 I also have the option of playing with the subs phase individually and globally. I feel this would give some interesting setup options. Of course until they're both in the room, it's rather hard to predict the end result, so only actually doing it will demonstate one way or the other.

I also plan on experimenting with them both at the rooms quarter points (when Mrs russ.will will be induced to be elsewhere). This would give me some, albeit limited, knowledge of likely configurations for the loft conversion I'm looking at.

Of course that room would also be a candidate for an IB...........

Russell

[russ.will]

Quick update. The second Monolith arrives tomorrow, followed by AngelEyes and his PB-Ultra a day later.

Obviously lots of things to try out - Co-location, room quarter points etc and I don't know if any of it'll turn out to be useful but should be fun. I mean over a kilowatt powering three 12" vented subs can't fail to be fun, can it?

Russell

[russ.will]

Russell

[Nimby]

It's bad enough having three big subs in the same room but overexaggeration by using wide angle barrel distortion is just... wicked!

Nice piccy! (apart from the price label still dangling form the SVS)

[russ.will]

The scary thing is, that picture stretches the perspective and makes it look like there is a lot more room than there actually is.

The two Monoliths are placed at the room's quarter points and are actually the only ones working at this moment in time. The SVS PB-12/Ultra was just pushed into place for the shot.

The Ultra works best placed at the same quarter point as either of the Monoliths and in 16Hz tune. After AngelEyes room (which is much larger) we had thought that my smaller room may work best with the 12Hz tune, the lack of headroom being less of an issue in the smaller space. It turns out to be of academic use. It just seems to give a really low hump in the response with a yawning chasm in the response between the port and the boxes natural tune.

The label is instructions for which subsonic filter to use in which combination with the foam bungs.
[FONT="Comic Sans MS"]
Sorry about the fuzzy shot. I'm not geared up for macro.[/FONT]

Interestingly (or perhaps not) the subsonic filter offers a 25Hz option, which is a bit odd for a sub with a 20Hz native tune. Presumably you could use it to increase headroom further although god knows why. We were checking our ears for blood as it was. All listening was condusted at reference level. That's loud after a solid 4 hours.

As with so many issues, there seems no clear cut answer to the one expensive one versus two cheap ones. The SVS does go deeper, and I suspect a bit louder (I think I heard one of the Monoliths starting to compress during the usual Flight Of The Phoenix scenes) but this is only after one day of playing.

The two Monoliths, by comparrison, provide a more even quality of bass across the two listening positions. Still, it's early days and my head is hurting from prelonged pressurisation. Ok, that could be because of excessive beer consumption, but it is a long time since I've had a day of grinning like an idiot due to bass jollies.

Roll on the next two weeks.

Russell

[AngelEyes]

Oi Russell, there is a strange hole in my frequency response for some reason I don't seem to have anything below 80hz...

[russ.will]

Could it be phase related?

Russell