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Bilbo

Speaker Position Problems Magnepan 20.7's

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Posted (edited)

I have a DSP for the subs - DSPeaker Antimode 2.0 and it works well to manage the subs and room modes.

My objective here is to try and find the right position for my Maggie 20.7's without a sub because I would actually prefer not to use them.

I'm also trying to achieve this without expending more money and adding to the complexity of the system.  I have a very strong slant to the KISS principle.

 

I'm hoping the combined knowledge of others may lead me to find a good speaker position.  So far I'm very grateful for the suggestions, so I try them (if possible) and have made progress.

I can now see that an extreme toe in position addresses some of the problems so I'll need to try that amount of toe in on all the positions in my grid to see if there is a spot where the frequency response improves further.  It may be incremental but that's the only way I know how. :)

Edited by Bilbo

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I do understand your desire to maximise your Magnepans and minimise (or not use) your subs.  I had the same intent for my SGR Audio CX3Bs, but MSO (Multi Sub Optimiser) did such a good job of integrating the SVS subs in my untreated family room that it became a non story.  MSO flattened the bass response way way better than what I tried with REW.

 

MSO gives you the ability to determine how much influence the subs have on your setup by constraining the subs gain and the crossover.

 

Given that you know REW, why not try MSO (which is free)?

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Because I run a HDD direct into a SOtM SMS-200 then into my DAC.

I prefer the sound compared to running it from my PC via Ethernet.

I might try MSO later down the track but my focus is on cracking the code of my listening room.

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Posted (edited)

Bilbo,

 

the boing in the bass is a harmonic much higher than the modes you are trying to sort.

Slam, often felt with drum kits, is also a harmonic around 8kHz !  Nothing to do with bass.

You can toe the speakers as much as you like, it will make minimal difference to bass. Bass is "the room"..

You are fighting the room dimensions. Work with them, learn to love them...

Move the mic around the room, find several locations that measure bass well, then decide which of those possible listening

positions allows the main speakers to be moved to an isosceles triangle. (My isosceles is v close to equilateral).

 If it can't be done, it can't be done, you will never get the flat freq response, like 98% of everyone else's systems.

 

Edited by Nigel

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9 minutes ago, Nigel said:

 If it can't be done, it can't be done, you will never get the flat freq response, like 98% of everyone else's systems.

 

 Quite true but I haven't exhausted all possibilities yet.

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Posted (edited)

Hi Bilbo, just found your thread...

 

As soon as I saw your schematic, I said " turn your system round".

I still own Maggy 1.7's with twin SVS sealed subs...then upgraded to Sanders Sounds 10c with twin Sanders amps and a DEQX hp4.

It took  2 years, a house move, a room tear-down and lots of Superchunk traps but finally I am ecstatic! But that is another story.

The DEQX is a wonderful piece of kit, but I hear you re. $$$. Now Roger Sanders likes DSP gear, but never offered the DEQX in his "kit" as it moved him into a different market. He stuck with Behringer gear for quite some time. His latest 10e offering includes combined xover and DSP machine and I was so curious I search for a long time to find it. He offers a DBX Venu360.  http://dbxpro.com/en-US/products/driverack-venu360 Worth a ponder, perhaps.

Also, Roger Sanders encourages an asymmetrical setup...Dipoles largely remove side and ceiling refections and he reasons asymmetrical bass causes asymmetrical nulls and we wont hear that as much.

Oh yes, I have 2 friends with 20.7s. 1 built stands out of car engine hoists !!!!! and the other bought stands off Bill Mclean in East Gosford. NSW. Both grip the wood cheeks to at least 1/2 way up. And elevate. And tilt. All good, IMHO.

Of all the dipoles I have owned, I have always tilted forwards, never back. Same with the current set up. Square up to the ear.

Phil

 

Edited by smiledon
spelling base to bass

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I thought long and hard about which way to orient the system when we first moved in two years ago.  I did some basic REW sweeps with the system the other way round but the peaks and dips were more accentuated so I settled on the current orientation.

If I can't achieve a reasonably smooth response below 400hz then I may have to resort to full range DSP.  But not just yet - more position & toe in moves to make before the white flag gets raised.

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On 22/06/2017 at 12:06 AM, Bilbo said:

I thought long and hard about which way to orient the system when we first moved in two years ago.  I did some basic REW sweeps with the system the other way round but the peaks and dips were more accentuated so I settled on the current orientation.

If I can't achieve a reasonably smooth response below 400hz then I may have to resort to full range DSP.  But not just yet - more position & toe in moves to make before the white flag gets raised.

@Bilbo Just wondering if you've achieved any improvements recently? Clearly you have a difficult room shape to deal with. I am just going through a similar process with 3.7i's in an irregular room space with some unusual wall geometry, Particularly looking at getting the bottom end right, mids and hf are already excellent.

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32 minutes ago, mjs said:

@Bilbo Just wondering if you've achieved any improvements recently? Clearly you have a difficult room shape to deal with. I am just going through a similar process with 3.7i's in an irregular room space with some unusual wall geometry, Particularly looking at getting the bottom end right, mids and hf are already excellent.

Yes the mids and hf sound wonderful - it's just that pesky region below 300hz that the issues occur.

 

I've taken a radical approach just yesterday by giving the "Limage" setup a go. I was expecting it to sound totally weird but it's not that bad.

I haven't got it set up properly yet because it will involve some furniture moves to facilitate the 40% position plus the listening position closer to the back wall.

It certainly gives a wide & deep soundstage plus the bass is enhanced but the imaging is a bit off.  I'll post more once I find the "Focus" point in the room as per the setup recommendations.

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Why not try some of the diffusers that I’m selling in classified section? I’m using Maggie 1.7i and these diffusers really help open up the sound stage and smooth out the highs : )

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On 9/28/2017 at 7:55 AM, steven365 said:

Why not try some of the diffusers that I’m selling in classified section? I’m using Maggie 1.7i and these diffusers really help open up the sound stage and smooth out the highs : )

Thanks for the offer but I already have diffusers and absorbers through the room.  My problem is with the actual dimensions of the room and the resulting modes.

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From your initial freq sweep in that room the 1.7 is operating nicely in the more audible 40hz bass umph region vs the 20.7 in less desirable 70hz region, translating to what you are not happy with. 

 

The speakers on the narrow end of the room with only 4m odd width is not enough for any panel speaker unless a narrow one, the Magies are too big in width each with not enough distance to side wall and your listening position, based on your first illustration, is too far away and not forming the recommended equidistant stereo triangle. 

 

With the listening chair out in the middle of the room there is less bass reinforcement and in a suck out bass zone. Try re-orienting speakers to the right wall 3m apart (inner edge of speakers) with toe in so tweeters fire 10cm wide of ears, tweeters on the inside, with about 2m to left corner or similar in another part of the room, speakers 1m from rear wall and listening chair against opposite wall to get rear wall bass reinforcement. This will put you in a 3m equidistant listening triangle that should get ideal imaging plus wall bass reinforcement behind listener. If the 3m distance is not enough because the speakers sweet spot is further out, then relocate to the largest part of the room to achieve the stereo triangle larger than 3m.

Edited by Al.M

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Well the Maggie 20.7's are certainly a wide speaker and giving them room is essential.

I did consider the alternative sideways layout but I don't think the Maggies sound as good if you have to sit close to the back wall.  I have tried the equilateral triangle layout which works reasonably well but I find I get a better soundstage size with a bit of extra distance to the listening position.  To my ears that helps the soundstage take on life size proportions for instruments and vocals.


At the moment I am trying quite a radical layout with the panels almost 1/3 into the room and the listening position 3/4 of the way into the room.  The interesting thing is the extreme toe in.

The panels are at almost 45 degrees to the side wall and only 300mm from the wall.  The panels are focused about 1m in front of the listening position. The distance between inside edges is 2.5m.  This results in minimal first reflections when viewed via a mirror as you mostly see the narrow side of the panel, plus, all other lateral reflections are at least 6ms behind.  The rearward panel excursion reflects off the side wall and then into the front wall before traveling onward to the listening position.  I shall give this position a bit more time as it does sound very good.

I'll put some REW graphs up soon.

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Chair against wall will definitely increase bass and doesn’t affect imaging in my setup. 

 

Panels at 45 to side wall crossing in front of listener is very weird. Tweeters should be on inside normally. 300mm to side wall is normally to close. What you are trying to do is fit a very wide panel speaker into an odd narrow and long room, but the option to try is position speakers against the longest wall, i.e 90 degrees to current setup. No harm in trying to confirm or discount that unless it totally upsets the furniture layout functionality.

 

Speakers on the narrow end of a narrowing long room is not good in my experience.

Edited by Al.M

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As I previously said, I used the long wall layout (in my previous house) but front and rear wall reflections were a problem due to proximity/boundary effects.  I do have the tweeters on the inside at the moment but that may change.  The problems created by the close proximity to the walls were worse than the ones I'm trying to deal with in this case.

As you say - this setup is quite weird (to me also) but strangely enough it works quite well.

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Here is a picture of the current setup with the Maggies at almost 45 degrees to the side walls.  I'll get some measurements up soon.

 

IMG_0665.thumb.JPG.6a2c3a34a12aa0b2e0673506f05cf4f8.JPG

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