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Author: MichaelRead Big gold star, 5000 posts Feste Award Winner! Old School Fool Add to my Favorite Fools Ignore this person (you won't see their posts anymore) Number: of 10537  
Subject: Re: New sub Date: 10/1/2012 4:40 PM
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So then why did they like to tell you to stick your sub in a corner? I assume they performed all sorts of tests, have they changed the types of tests? What changed their thinking?

RM


Back in the day most subs were large-sized speakers and low-power internal amps. Most had amps of about 180 Watts while those sold today have about 2400 and relatively smaller speakers: the efficiency has increased and the need to use corner echo as a boost is dated. Sure, corner echo emphasizes bass yet, similarly, muddies bass so the differences in bass are hard to notice.

For the heck of it I pulled mine way from the wall and looked in back. It's got a volume knob, variable HZ knob 80-120, a polarity switch for 0 or 180 a set of RCA jacks for Level In (no idea what those are for) and of course, the speaker knobs and on/off/auto switch. Do the new ones still have these things?

Yup. The RCA jacks are there to feed the sub a low-level input from the amp (marked, usually, ‘pre-out’) allowing the sub’s amp to be used rather than the main amp’s power. The frequency knob cuts out all frequencies above its setting allowing the other speakers to handle the higher frequencies.

And now I'm heading off into a tangent...

I bought the Boston Acoustics for my family room back in '97 or '98 (I'm pretty sure Dolby was around then as well as THX). That living room had 9-11 foot cathedral ceilings, wall to wall plush carpet, drywall, a stone fireplace next to the home theater system and a wall of windows. I remember placing the sub in the corner and trying it pointed 90 degrees from the main speakers and then parallel with them. Honestly can't remember which set-up we preferred. But man did it sound GOOD. I think the first movie we tested it on was Air Force One.

Our current house has a totally different dynamic and I've occasionally wondered if the sub's current placement is wrong. It's no longer in a corner but it is against a wall on the bottom shelf of one of my oak cabinets. All speakers are parallel. The room is knotty pine, walls and cathedral ceiling, huge beams, a staircase to the loft behind the sound wall, another stone fireplace this time opposite and no wall at all between the LR and kitchen. Crappy wall to wall and vinyl flooring. I really ought to take a photo!

But I have to say I don't get the same feeling with the home theater here. It's possible I also don't have the switches on the sub woofer set properly for this room and the manual which is missing and I remember being little more than useless anyway.


The difference of the rooms is the reverb time and that’s not that easy to alter without expense. What makes a difference is speaker placement. But first reset the sub’s crossover to 120 Hz if it’s not there already and experiment with the phase switch on the sub – bass is affected if the mains and the subs products are out-of-phase: one setting will give you better bass than the other. Also, toeing in speakers, even subs, can make a difference.

This whole thing on bass management is because most of a room’s character is affected by frequencies below 120 Hz. Above this the waveform is short and measured in fractions of an inch: subs produce a waveform several feet long and are several times more powerful. Highs decay faster while lows just keep on going bouncing off everything in the room.

MichaelR
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