[jaylevine]

For those of you with Magnepan 3.7 and subs I am curious what crossover point folks use to dial in their subs?

I was using a Anti-Mode 8033s but have decided ditch it and go back to using the Rel in 'native' mode using the speaker outputs and the hi-input.

[WGH]

PM David (DAE), he has 3.7's with a REL sub. I'll be seeing him in a few weeks when he gets back in town and let him know about this thread.

Wayne

[SteveFord]

40 Hz w/ SVS sub if that helps any.

[Bardo]

I use 40hz with my 3.7's myself (Velodyne). For me, that puts it to where when the sub is on I can't tell that it's on, but once the sub is off, I can tell it's off... Hope that made sense.

[richidoo]

Don't know your experience with integrating subs, so forgive me if this is elementary to you, or OT... maybe it will help others.

Aligning the sub phase accurately will have more effect on SQ than crossover frequency. Panel speakers have such clear bass that adding a sub that is out of phase usually does more damage than good. To get the phase aligned, the sub needs to be same distance or closer to you than the Maggies. Subs that are behind the speakers can't be in phase because the sound can never catch up with the sound from the mains, and sub phase can usually be delayed, but never advanced. If your REL has only two position phase switch, then it needs to be set at 0 (no delay) and placed at the same distance from you as are the speakers. Fine tune phase for clarity by moving the sub closer or farther away. If your sub has a proportional phase knob, then you can set the sub anywhere between you and the main speakers and adjust the delay to match the arrival of the maggies at the crossover freq. The closer you get the phase aligned, the faster, clearer bass you will have. Even though the wavelength of 40Hz is many feet long, adjustment of a few inches of phase is audible with speakers like Maggies. Only sealed subs should be used under a fast bass speaker like Maggies. Once it is aligned, then it's easy to adjust the crossover freq to taste for a feeling of fullness. Adjusting the low pass filter (crossover) freq will change the sub's phase a little, so readjust the distance for optimum clarity again. Volume does not affect phase.

With Quad 2805, the lowest freq setting was best in a small room, with REL 8" sub, about 35Hz, I think. A bigger room doesn't concentrate as much LF energy, so would need more support from the sub with slightly higher crossover. Not much though, it is easy to go too high then you start "hearing the sub." Most "hearing the sub" is phase. It's not easy, but worth the fiddling.

[jaylevine]

I understand what you are suggesting, and it does make sense. But it does conflict with what Rel recommends (corner placement) in their manual, and while I don't understand the basis for their recommendation they are emphatic about it in the manual.

My subs are Rel Strata III, not that this makes a difference. Just curious if others share your view regarding dialing in a sub by starting with equal to or closer than listening position w/respect to speakers?

[richidoo]

REL is emphatic about corner placement because in the corner the sub radiates into smallest possible volume, giving it much more dynamic headroom, and easing stress on cone, voice coil and amp. Most people use the subs for HT LFE and they like it loud. REL doesn't want anybody disappointed with SPL during the big LFE events, nor do they want warranty claims of broken subs from people overdriving them trying to make them loud enough for the big LFEs without the acoustic support from the walls. A HT receiver can synchronize the arrival time of all speakers, no matter where they are placed, and LFE is more about SPL, less about tonal detail anyway. In high end music system we usually don't have electronic phase adjustment and bass detail is what we're after. 
Sorry to hijack your thread Jay...   

[jaylevine]

Not a problem; I started this thread to learn about 3.7 and how to optimize my sub. Apprici ate you taking the time to throw some knowledge my way.

[SteveFord]

Richidoo is spot on and Bardo's post makes perfect sense to me. 
You want it where it blends in but you don't notice it until it's missing.  This does not require very much in the way of volume.

[clin36]

hi folks,

I am thinking of upgrading my Magnepan MG IIIa to 3.7i.

First of all, how big a difference do you think is there between the IIIa and the 3.7i?  Couple years ago I auditioned 3.7 (not the 3.7i yet back then) at local dealer, driven by Classe gears.   It sounded very nice - clear, smooth and no listening fatigue.  My current system is also very old (Accuphase C200 pre, modified Adcom GFA-555 and old CD players), so it's hard to make a comparison between my IIIA and the 3.7.

Also, if I upgrade to the new 3.7i, I am thinking of also adding subs.   Someone recommended that I should use two subs as that would be much easier to integrate the subs with the Maggie.   Do you agree or think it necessary?

As for subs, I am thinking of REL sub, such as T5, R218, or R-528SE, all mentioned by Absolute Audio in Editors' Choice.   The R218 is class D-amp.   I have not been following closely with the discussion of D-amp, but it had bad raps for a long time, so not sure how it works in REL subs.

Absolute Audio says that the R-528SE has uncanny ability to integrate with main speakers ...

thank you in advance for any advice

[SwamisCat]

I upgraded from a IIIa to 3.7i about three months ago. I really need to write up a full review. If I do, here are the highlights:
1) the old speakers were built better. New models seem flimsy.
2) I always hated the external crossover until I lost it. I didn't realize how much extra length it gave me on speaker placement over just the eight foot speaker wires.
3). The IIIa has substantially lower bass. High twenties in my room, vs high thirties for the new guys
4). The new model has substantially more and better upper bass and lower midrange. It rocks better. Considering how easy it is to add a sub for low bass, the tradeoff seems well worth it to me.
5) the new model looks a lot better than the old model (though I had refurbished the old one by painting feet, getting new socks and staining the wood cherry.)
6). The midrange quality is clearly better on the new model. Less grain, less glare, less irritating upper midrange emphasis.
7). The more laid back upper mids result in some important differences though, not all good. First, the speakers need to be positioned optimally in totally different ways to address this change. The i's need to be aimed right at me, whereas the IIIs preferred a Limage set up. In addition, I think absent perfect setup, the old model may have imaged better due to the increased upper midrange emphasis. The new model is trickier to optimize. I suspect the tape on the back of the model attenuates rear midrange energy thus reducing some of the the bounce back magic of the old model.
. Highs are probably better on the new, if you aim the tweeter directly at your ears as per the manual.
9). New model seems fussier and more demanding, but pays off in the end.
10). I would NOT say they are more dynamic, sound better at low volume or are more coherent in my room. I might need to compare them again though to refresh my memory.
11). I do not know how the new models stack up against a bi amped IIIa. Certainly is a path to consider if you love your current sound.


Hope this helps a little.

[SwamisCat]

Btw, I own a pair of DWMs and a single Rythmik sub.  I set the XO at around 50 (plus or minus depending upon placement) and run the Maggies full range.

I totally agree with the above old comment that timing and phase is absolutely critical. For best result I found I need the sub closer to me than mains and have to pay careful attention to phase (Rythmik has a dial for phase for fine tuning.) some day I will buy a second sub.

[Jimf42]

I am pretty late to this thread..but just found it. I am on the fence re getting a sub for my MGIIIa setup.  They seem to provide sufficient bass (as they are not in HT setup).  I am biamping with Bryson 3b amps.  I may look at the DWM Mag bass panel