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Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?

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Posted on August 24, 2016 at 19:28:51
andyr
Manufacturer

Posts: 12550
Location: Melbourne
Joined: September 2, 2000
 Having recently added subs to my Frankenpans and swapped out the 3-way analogue active XO on the Maggies for a 4-way miniDSP setup (which includes a LP/HP XO between the subs and the Maggie bass panels - which are from a set of 2.5s), I'm interested to know what XO frequency people have selected for their XO between subs and bass panels.

The guy that supplied the subs and configured my miniDSP unit set the sub-bass panel XO @ 100 Hz (24dB slopes) - because that's what he "normally does" (with cone/box speakers).

But I'm thinking that maybe:
* a 12dB HP slope for the Maggie bass panels would be a better arrangement, and

* I should let the "lovely Maggie bass" extend lower ... so maybe the XO should be set @ 60Hz, not 100Hz?

Hence my desire to know what others have done.


Regards,
Andy

 

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RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 25, 2016 at 07:10:15
guitar slim
Audiophile

Posts: 168
Location: Washington DC suburbs
Joined: May 24, 2012
Hi Andy,

With my T-IVs I ended up with 4th order LR at 40Hz between the sub and the bass panels.

Previously I had a pretty good set-up with an 80Hz crossover point, but the 40HZ choice leaves the character of the bass panels nearly untouched, while still off-loading them from the very bottom part of their range.

Best of luck, let us know what you end up with.

 

RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 25, 2016 at 08:18:36
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Andy, I don't know if what I do is optimal but it seems to work for me. I love the Maggies bass which is tight and musical, so I set my sub to kick in around 38-40 hz (3.7i) with the speakers running full range. Using REW5 I saw the bass drop off around 30 hz and now the subs fill in keeping the curve relative flat to below 20 hz. Unfortunately, I did an upgrade to my computer and despite my best efforts I seemed to have lost the plots so I can not post them.



"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

Found the plot, posted on August 25, 2016 at 08:36:25
neolith
Audiophile

Posts: 4842
Location: Virginia
Joined: February 21, 2002
Contributor
  Since: December 2, 2004
 Here's a link to my Google Drive




"Our head is round in order to allow our thoughts to change direction." Francis Picabia

 

RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 25, 2016 at 10:37:21
Roger Gustavsson
Audiophile

Posts: 2058
Location: Huskvarna
Joined: February 12, 2010
 In theory the acoustic slopes of sub-bass and bass should be mirrored, at least it is a good starting point. If the subs roll-off with the 24 dB/octave acousticly you should configure your bass to do the same. In the case of of planars like Magnepan, they will roll-off with 18 dB/octave below the lowest resonant frequency. Magnepan speakers may have a hump before the roll-off sets in. The Maggies use to benfit from removing the low bass as it increases the onset of compression and lowers the distorsion. The peak in the bass, that is necessary to compensate for the acoustic short-circuit, use to take most of the available excursion available.

 

RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 25, 2016 at 11:35:41
Barry
Audiophile

Posts: 1003
Location: PA
Joined: November 24, 1999
Contributor
  Since: January 18, 2009
 It's trial and error time.

Despite spending a couple of hundred hours playing around with this using different XO settings, DSP EQ, and changing room absorption then measuring with REW, there is no simple answer. If you're taking your measurements from the listening position, every room and set-up will be different.

In my room, I found a smoother frequency response over a range of 40-250 Hz with somewhat higher XO frequency setting in the 80-90Hz range before applying DSP. 40-60 Hz XO settings looked more ragged over that range. No luck at all with 12dB/octave slopes but that doesn't mean you shouldn't try them (and flip phase/speaker connections too). I wouldn't go too much higher than 80Hz because bass sounds start to become directional above that level.

I didn't choose to run the mains full range because I wanted to take some of the bass load off the panels for less distortion.

I over-EQ'd the frequency response (DSP on subs only) to get it flat which screwed up the group (phase) delay (mine's over 50 ms at 60 Hz)because I wasn't looking at it. You may not have that problem, but I'd check it and listen.

Also, note that EQing the listening position can make the bass annoyingly more boomy in other parts of the room.

Oh, my flattest frequency response obtained by changing absorption did not sound the best due to too much reflected sound. As you guessed, measurements don't allow you to skip listening.

Sorry I can't be more helpful. Have fun and good luck!












 

RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 25, 2016 at 13:41:18
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 The 2.5 bass panel is going to be used as a midbass in your setup so has a band pass filter. The max standard LR2 or B2 you want is 2nd order because beyond that you are going to suffer serious phase issues. Magnepan uses slow onset spaced fc where the 2nd to 4th order poles are up to two octaves away so contribute minimally to phase and group delay. You should follow REW to find out the phase behavior you end up getting. Impulse response too.

My personal favorite in sharp XOs is Butterworth 3rd LP with a 1st order. I usually space them to avoid timing issues at the XO rather than for flat FR, which is less significant for me in the bass-midbass regions, +/-3db is fine and +/-5 db is tolerable.+/-2db is phenomenal but anything better is going to have you doing lots of DSP correction. I have used analog EQ to get +/-1 db on the bass- midbass but for the sharp suckout node.I found the phase fluctuation to be more bothersome than the FR ripple it replaced. Doing the EQ on a supposedly phase compensated graphic EQ on foobar2000 did it better but I don't really apply it very often and need to recalibrate with every setup variation I try.
.

LR4 and LR2 are relatively easy to match to each other if you have a time delay option on your DSP. Lexicon Integra and many other HT processors are setup to cut the bass at 24db LP and the mains at 12db HP to avoid phase disruption and compensate with DSP time alignment in manual settings or measured auto setting.
.

 

RE: Is there an optimal frequency to set the LP/HP XO between subs and Maggie bass panels?, posted on August 30, 2016 at 04:29:52
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 I think that blending decent woofer(like scanspeak revelator 10" alu)and crossing it much higher(from 300 to 500 depending on panel size,like Martin Logan are doing )could enhance Maggie's sound in more musical way than trying to mate it with subwoofer.
cheers

 

RE: Mmmm, fundamentally disagree! Do you know anything about Maggie bass? nt, posted on August 30, 2016 at 04:31:32
andyr
Manufacturer

Posts: 12550
Location: Melbourne
Joined: September 2, 2000
 .

 

RE: Mmmm, fundamentally disagree! Do you know anything about Maggie bass? nt, posted on August 30, 2016 at 04:46:09
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 I had been trying all kind of subs years ago starting from velodyne to vandersteen,closed,vented,small and big..never was satisfied with blend(I have 3.7 and 1.7).I used plugin XO in Foobar driving 4ch out. I'm glad however if you are satisfied with your solution.

 

RE: Aah, OK ..., posted on August 30, 2016 at 05:27:28
andyr
Manufacturer

Posts: 12550
Location: Melbourne
Joined: September 2, 2000
 Sorry, don't know what 'Foobar' is able to do but I would say:

* for music - you should only use sealed subs.

* you need software to do 3 things, in terms of sub/bass panel integration:
a) provide the LP/HP filters.
b) provide delay on the HP output - said delay depends on how far away from your ears the subs are, compared to the bass panels.
c) allow PEQ on the sub (LP) side, to deal with room modes.


Andy

 

RE: Aah, OK ..., posted on August 30, 2016 at 06:00:27
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 The same as Minidsp I suppose. Usual computer things like 4way xo,3 types of filters,plus PEQ,delay and room measurements all via 8 channels.Yes Vandersteen and Martin Logan were more suitable but still far away to call it success.Listening to soft drum wack on David Gilmour was more or less OK but jazz---never.In the end that lack of proper midbass-bass drove me almost crazy so I started to switch to dynamic speakers.

 

RE: Don't give up on maggie midbass.., posted on August 30, 2016 at 20:22:51
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Were you bracing your Maggies? The bass - and particularly midbass loses much of the dynamic constriction with bracing. The low bass can stay distorted because you simply run out of excursion despite bracing. Which is where using a subwoofer is a good idea combined with high passing the maggies just above the resonance peak.

But the overall output is still going to be somewhat limited in the 3.x models. If that was your limiting factor in producing a convincing jazz club dynamic performance the solution is an MG20.x or a Tympani, particularly the .T IVA, rather than moving to a dynamic speaker. . And, of course, bracing is very helpful.

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 04:08:49
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 Thanks for suggestion. Don't know why but i was not impressed with 20.7 sound plus being a tube guy I don't want to maintain some 16 tubes in each monoblock to drive them....No,no bracing and not about overall output in recreating Jazz club atmosphere. I was frustrated more about eternal question of truthful reproduction. Try for example for curiosity sake to play some overcooked recordings like Chris Jones/Moonstruck/track#3.Ain't got love. or Sara.K/Water falls/Track#8.All your love. on the same Stockfish records. It is like a demo file and showcase for Maggies, making you believe that no bass reinforcement is needed at all. Switching however to normal recording like Patricia Barber/Verse/track#2.Lost In This Love... will reveal all shortcomings. Kind of torture test. Listen to that track on Maggie and then on good dynamic speakers or simple A-B'ing via something like sennheiser hd650 or similar.That comparison leaves me very frustrated.
Or maybe I will give Maggie a second chance due to some crazy experiment I had a few weeks ago. I cheated on Maggie by bringing home two dynamic speakers for comparison- Kef Blade2 and Wilson Sophia3. While I spent most of the weekend comparing between Blade and Sophia in the end I made interesting test. Wilson can not be biamped but Blade fortunately yes,so I played bass section (6.5" 2x2 per speaker.Two separate enclosures combining dual opposing cancelling woofers with port)of blade with Maggies. It was not bad at all thou not perfect since I was unprepared for fine tuning with that type of test but it gave me a lot of food for thought for combining woofer/s instead of subs.Sure nobody will buy blade2 as woofer for Maggie but probably building enclosure using good driver would be satisfying in the end.

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 05:53:16
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I am intending to do a similar experiment with a friend's Focal Nova Utopia with the mini fridge bass units and my Neo8 + ribbon mid/tweet sections.

Generally speaking, a braced set of T IV bass panels is not uncompetitive with the Focal bass given sufficient power to the maggies they do a very convincing rendition of organ foot pedals. Where they lack in comparison to the well done box woofers is with percussive bass. That pounding sensation just never happens.

I recently tried out my converted Vandy 2c subs with Aura 8" Neo driver and 10" bass using both speakers on one side vs. bass panels on the other. (equivalent to 2 13" bass units) and tested to see where the bass would swing to the Vandy sub's direction, (calibrated level settings at 100hz) and it was only in the lowest contrabass notes and organ. But playing loud bass heavy dynamic music the vandy subs started compressing and rattling while the bass panels were just fine. And the music did not pull to the sub's side at all.

So I think the issue is not having enough radiating area on the 3.x models and the need for sturdy bracing, and really big power (I use a Crown 5002). The difference in bass performance with the big maggies on Mye stands or other bracing and left to themselves is vast. It is like adding a large subwoofer. The dynamic limitations you are speaking of are easily surmounted with bracing and ample power . - and a big bass panel...

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 07:09:25
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 That could be cool. Just try to cross high around 250 for comparison. Unlike pure sub, JL like T-Rex thumping drivers-Focal 13WX inch Audiom woofer is fast and musical, able to sing very high and I think was crossed around 250hz in both WILSON Maxx and Utopia.Not sure about biamping on Utopia though....Some 7 or 8 years ago I helped my friend to build sub with 11WX woofer Focal audiom to mate it with 3.7---was not bad.

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 07:43:31
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I have line level XOs to play with so can tune the same way I have with the bass panels.

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 08:16:59
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 I was thinking of a DIY Neo8 PDR line array coupled to a pair of these subwoofers for woofer/subwoofer duty. They are bipolar like the KEF blades - IIRC.

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 11:38:21
ozzy666
Audiophile

Posts: 9
Joined: August 30, 2016
 Nice options you have:) That's exactly what I was thinking. However I have some doubts and still scratching my head. Martin Logan switched to similar design to their subs recently instead of also kinda canceling tri-drivers approach. Bipolar/cancelling design is very nice idea. I tried B&W sub PV1D with 8" opposing drivers with Maggies but left unimpressed by tiny, yet dominating… not so blending… bass signature. Yes fast and tight and on the paper should match Maggie but…. Don't know how to explain… If you can go to local dealer or nearest tradeshow.. Or friends. Try to compare near best implementation of two technologies---sealed vs ported. Perfect case Magico vs Wilson...Magico while being fast and detailed have that sort of sealed bass notes that leave me personally almost ill with impression of being hit by giant ogr's fist into my stomach/diaphragm dreaming of free air breath. Wilson is opposite.. Bass tuning is perfect and free…(unless you play some Stockfish label samples with tube amp-- it will be distorted) so you don't see the speakers it is percfect cliche phrase of disappearing act.
So I think that superbly implemented ported design is more suitable to my liking. What Kef did is exactly what I was thinking about. Combining two opposing anti- vibration woofers with free breathing port. Actually they even did more…instead of competing with wilson on composite resin material-- super dumping heavy and expensive they did cheaper lighter version but they added some nice stuff as dumping carbon absorbing particles to deal with vibration and resonance.Four light and fast midrange/woofers provide speed and grip while doubling add needed bass and no distortion---NICE. The only thing stopping me from trying it now is cost of total 8 drivers only for trying/pilot project. Going into Wilson approach is cheaper.. Only one 10" driver like Scanspeak.. Ah don't know… a lot of thinking… Personally if not that crazy price increase steps like Wilson Maxx2-50k---Maxx3-75--Alexx(Maxx4)--109k that makes me sick I would go for second hand at half the price but again wonderfully sounding Alexia is around 30k used. Jesus why there is no competition at all??????? Returning to 5k Maggie 3.7 is a relief but again that bass!!!!!! ¡!

 

RE: Don't give up on maggie midbass.., posted on August 31, 2016 at 13:27:40
Satie
Audiophile

Posts: 5426
Joined: July 6, 2002
 Yes, I thought the percussive bass from the Magicos was very impressive but only happens in real life on rock shows and inside Kodo drums.

The Focal does bass like the Wilsons with a big enough driver and cabinet with slot loading. Still knock the breath out of you if called for.

I can only suggest that you try and hear a big maggie with proper bracing on it before you treck over to the immovable damped boxes. Perhaps press a magico against the woofer side of an mg20.7 at the dealer's to brace it with the mass 1/2 way up. It really makes a big difference.

Another approach is the LS9 with its lines of sealed woofers and open Neo8PDR.

 

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