Playing With Subs and Expressions

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ttocs

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Hoping you all are well and safe.

In addition to cutting holes in walls for the ML IW speakers I bought (before being stuck at home) to replace the 4i speakers I had been using for surrounds (which will be repurposed for ATMOS duties), I've decided it's time to play with the subs. I've got two Sumiko S.10 subs, one next to each Expression. I've been content enough to not use the subs for augmenting the Expressions so they've been setup just for LFE and all the Small speakers.

After thinking about this for a while, a long while, I thought the "adding subs thing" deserves some attention, again. I'm really happy with the sound from the Expressions overall, but would like to make the Low Bass present itself with a bit more foundation - if that makes sense, more presence.

Some background of what's in my little brain. I attended just one Pink Floyd concert back in the 1987 at the Rosemont Horizon, Rosemont IL. That place sucked acoustically, but this was the best sounding concert I've ever attended because they used only their equipment and brought in loads of acoustical treatments. It was at this concert that I discovered how "they" want their music to sound - LOTS OF BASS! But great sounding bass, albeit with thunderous impact on my chest!

After running the ARC calibration on the Expressions the result seems to be a pretty flat curve. The graph for the Right speaker showed a pre-calibration bump of about 5dB at 30Hz which had a slightly lumpy slope down to minus 2dB at about 70Hz, the Left showed a 6dB dip at 40Hz. Frankly, to my untrained eyeballs the pre-calibration curves looked pretty good, nothing really horrible like what I had before I removed some walls to create the multipurpose great room I currently have. I had large peaks and nulls with the old setup. Life has been easy with the current audio setup.

This is the current layout.
ATMOS-layout-small.jpg

In the past I've tried using the Left Sub/Left Speaker and Right Sub/Right Speaker, but I wasn't convinced this was working the way I intended. This week I decided to use the Right Sub for the Left Speaker, and Left Sub for the Right Speaker. This is working very well! Of course the concept is using multiple woofer locations to cancel out some waves and smooth out others, vs Sub&Speaker in same location and boosting the problems. I think I know why this is working with so little effort, but I wouldn't be capable enough to explain it to someone else. Now this is without any extra calibration, just seat of the pants adjustments of Subs and Expressions.

I'm using the Speaker Level inputs via Speakon Connectors (only 1 Hot wire used, both hot wires was too much gain) on the Subs, and using Reference Stereo on the preamp so no bass management is in play. The Sub Crossovers are set to their minimum of 30Hz, and the Hi/Low Level is set to about the 8:30 mark - really low level.

I've played with the Mid Bass Switch on the Expressions and tried setting it to the -2dB position, and then boosted the Bass Level dial to +3dB, but that killed too much Mid Bass. ML states the Mid Bass Switch applies +2dB or -2dB between 140Hz to 300Hz, while the Bass Level Dial controls the bass from 75Hz downward.

The settings on the Expressions are back to default, and the Subs are at the 8:30 mark, which if this were a volume knob that went from 1-10 it's at 1.5.

Playing lots of bass heavy music including organ, symphonic, jazz, and progressive rock (the good stuff from the 1970's), it all sounds good and natural. Even playing punk and pop sounds good.

Roberto always says "Trust your ears". I agree. With some combinations of settings I was getting "pressure" in my ears from inaudible bass and it was uncomfortable even though the volume wasn't as high as I'm usually able to handle, so I altered the settings to remove the pressure and my ears are happy.

I'd love to measure some things as a reference point and tweak a bit, but I am not setup for that right now. I've never used REW before and don't have a calibration file for the mics I have that REW recognizes. So if any of you can share thoughts on how I could go about this that would be appreciated. If I order a UMIK it would take 3-4 weeks to get right now, and by then I hope Dirac releases the version that is for the preamp I have.

I'd apologize for the long winded post, but what else do we have to do right now anyway?

Almost forgot to mention this. The bass seems to have more impact with this setup!

Stay safe and well.
 
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kach22i

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If you would like to do some white paper reading click the link below by The Sound Doctor (Barry Ober).

http://soundoctor.com/whitepapers/subs.htm

I do not agree with everything he says, but a lot of it I do.

In short:

1. There is no stereo bass, it just is not mixed that way in the studio.

2. Use preamp interconnects not speaker wires. In my experience M/L's do not like sharing the speaker wire signal, soundstage will suffer.

More info in a thread that went sideways, many opinions out there, just find what works for you - Roberto is right.

https://audiokarma.org/forums/index.php?threads/two-channel-stereo-subwoofer-small-room.907002/

Another link to my system without all the noise of people not well read.

https://www.whatsbestforum.com/threads/kach22is-system.30259/

I agree with many of the people at What's Best, subwoofer bass has localization, perhaps because of cabinet enclosure resonances, who knows.

I use a single sub, but if had two would be inside of the mains, probably pulled forward a tiny bit and possibly out of phase 180 degrees with IC's flipped.

Each room is different, experiment and keep an open mind.

I've discovered a whole new level of enjoyment with nothing in between the speakers but the subwoofer. Moving my audio rack off to the side of my listening position was the best thing I ever did.
 
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ttocs

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Thanks for the reply kach22i. You had me at Gulf! (Porsche fan)

First off, I agree that having little to nothing between the speakers is desirable. I played with this a few years ago when I had a BDI low cabinet for the equipment with the tv panel hanging from a spine attached to the cabinet so the panel is almost in the same plane as the speakers. After chasing some ideas for a couple years I finally just pushed the cabinet back against the wall (the speakers and cabinet were 6' from the wall) and the sound became much better! This is why I got rid of the cabinet and moved all the equipment to the middle of the side wall. Fast forward to now, I've got mono unbalanced amps for the mains and I want short interconnects so now the equipment is again between the speakers - but - the panel is on the wall, speakers are way toed-in, and there is no closed cabinet for the equipment.

Since getting my twin subs 3 years ago, I've played with locations all over my listening area from right in front of my feet to against the front wall. It was kinda freaky that when I used REW that they were within a few inches of where the measurements said was the best, and the biggest tweak was rotating each one to a different angle.

To clarify, I'm not wanting to colocate the subs for stereo effect with two channel music, it's mainly to check for possibilities in improving bass response in general - primarily for two channel, but also for movies. Adding the subs as described above for two channel is really a subtle effect being that the actual level employed is very low. But it is an improvement.

I just did some painting and am reconnecting the components so I'm going to be playing some more in a few days.
 

kach22i

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The frustrating thing for me is the size of my M&K sub. That is why I have the back, top and sides covered in sound absorbing materials.

I did sketches of repurposing dual driver push/pull to be a lower profile teardrop or conga drum on it's side shape. First I will just point the bottom at me with main driver facing up at ceiling to test out if getting the sub lower clears up the front soundstage even further.

It amazes me that so much audio equipment is hard flat boxy surfaces.

It should all be soft round almost aerodynamically shaped in my opinion.

Perforated leather on 1/2" (min.) recycled cotton acoustic mat with generously rounded bio-inspired forms is what everything from turntables to loudspeakers would look like in my redesigned world.

Death to the boxes!

The only boxes would be shipping boxes.
 
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