3.7s w/ Poor Sound in Small Room, Suggestions Appreciated

mrlittlejeans · « **on:** 28 Jun 2012, 03:08 am »

The question about room size is a good one. I had 3.6's for years in a room 15' x 25' with the 3.6's on the 15' wall about 3' out from the wall and with about 8' between the insides of the speakers. Tweeters on the outside. The sound was divine and I still consider it my reference.

I was transferred by my employer and moved up to Canada and into a much smaller house that had absolutely no room for Mags so I sold the 3.6's. I then bought a house that has a room in the basement that is 12.5' x 23'. I struggled with whether this might be too small still but took a chance and got a pair of 3.7's.

Well, I'm sorry to say that I've been moving the speakers around for almost a week now and have yet to find the perfect spot for them. Either the bass is right and imaging is out or imaging is fine but the midrange sounds veiled or midrange is clear and something else is wrong. I am sure this is the room and not the speakers as I know just how wonderful a properly set up pair of Mags can sound having owned various pairs for all but the last five of the past 20 years. Compounding the issue I think is that I've got a shallow built-in in the front right corner of the room and the left wall of the room has a fireplace and built-ins sticking out a foot or two starting around 6' from the front wall. I've got absorption at the 1st reflection points and used to have absorption on the front wall but found the sound better with it gone.

Do you guys think I'm screwed or should I try something new? I've tried just about every configuration between 2'-5' out from the front wall. Tweeters in or out, speakers betwee 4-8' between them and can't get the sound right. Are there rooms that just aren't right for Mags?

Here is a pic of the room with the 3.7's in it. The persian rug starts about 39" from the front wall. The ceiling is only 6.5' high and where the soffet is on the right, the 3.7's have less than an inch of clearance. Looks like more in the pic but that's just light playing tricks with the velvet. The room is covered in black velvet because this doubles as an HT as well. (AT screen leaning up against the right wall at the moment)

SteveFord · « **Reply #1 on:** 28 Jun 2012, 10:05 am »

I can see a couple of things but I'll be late for work.
Try no toe-in for starters (3.7s have more bass than the 3.6s) and further away from the side walls.
That weird cieling will give you some grief.
Is the room open on the r/h side?

berni · « **Reply #2 on:** 28 Jun 2012, 11:54 am »

You should't overdamp the side walls and even the low ceiling with this black cover. In such a small room you erase a great area. Better you make a combination of absorbtion and difusion on the front wall, leave all other wall blank...Side reflection isn't such a problem... Also tweeters in, no toe in and pull them further out.

mrlittlejeans · « **Reply #3 on:** 28 Jun 2012, 01:30 pm »

Quote from: SteveFord on 28 Jun 2012, 10:05 am

I can see a couple of things but I'll be late for work.
Try no toe-in for starters (3.7s have more bass than the 3.6s) and further away from the side walls.
That weird cieling will give you some grief.
Is the room open on the r/h side?

Thanks for the response Steve and sorry for hijacking your thread. I probably should haver started a new one but it was late and I got excited reading about my problem.

I have tried the no toe-in but will try moving farther from the side walls. The farthest I've gone is 2' out from the side walls which only leaves 4' between the 3.7's. I can try even closer - what can it hurt?

The room is closed on the right hand side and the wall has no annoying protuberances.

Quote from: berni on 28 Jun 2012, 11:54 am

You should't overdamp the side walls and even the low ceiling with this black cover. In such a small room you erase a great area. Better you make a combination of absorbtion and difusion on the front wall, leave all other wall blank...Side reflection isn't such a problem... Also tweeters in, no toe in and pull them further out.

I realize I mispoke a bit about the ceiling. The part without the soffet is actually 7' tall rather than 6.5'. I can try taking off the absorption at the first reflection points again. It is hard to pull the speakers out further as my screen hangs down 50" from the front wall so I can only pull the Mags out that far. I'll give it another shot pulled out that far and with no toe-in to cross off the list. The black velvet on the ceiling is to combat reflections from the screen. ANSI contrast gets destroyed on my unity gain screen without them so I really need to keep that up. It is thin though and I would not expect it to have any significant effect on the sound. The velvet on the side walls is actually on a motorized track so the curtains can be pulled back - I'll try that to see what difference it makes.

I really appreciate everyone's help. I've got a long weekend and at least another month before any possible replacement speakers get here so I've got plenty of time to try to get this right.

berni · « **Reply #4 on:** 28 Jun 2012, 07:10 pm »

If I see right, your curtain is about 1 feet from the side wall?? This makes it alltough thin, a good absorber( ok, don't know in which region ). The sound is absorbed once it get through it and the second time when it is bounced from the side wall. This is good, but too much absorbtion not well balanced or only in some regions, can destroy the sound, especially in small rooms like this one.
I would also put them further out and even in front of the screen...
Describe your bad sound more...

SteveFord · « **Reply #5 on:** 28 Jun 2012, 11:01 pm »

I moved this to it's own thread so if anyone can help, please chime in.
From taking a closer look at that picture I think 1.7s might be the cure for that room. I did something similar years ago and I just could not get big Maggies to work right in a small space.

josh358 · « **Reply #6 on:** 29 Jun 2012, 01:31 am »

There does seem to be too much HF absorption in that room. If pulling the velvet back doesn't work, you could try removing the carpet. Also, you don't want absorption behind them, not usually. Try diffusion at the first reflection points between the speakers on the front wall. Ceiling height shouldn't matter. If they're too close to the side walls, you'll get boomy bass, but you don't want the speakers to be too close together. Then -- set the speakers up for best imaging and EQ the bass. They're never right in the same place even under the best of circumstances, and in this room, I think that's going to be even more true. Bass should be EQ'd anyway, it always sounds better that way.

kevin360 · « **Reply #7 on:** 29 Jun 2012, 03:04 am »

What size is your screen? When I designed my dedicated room, I calculated a minimum workable width for 3.7s and a 92" screen to be 16'. I rolled the dice and hoped the math was right. 12.5' is going to be difficult. Have you read about the Rooze arrangement? It may work for you - in short, you go for some serious friggin' toe (the 'null' will be aimed squarely at you). Also, don't be afraid of sitting fairly close to them.

rw@cn · « **Reply #8 on:** 29 Jun 2012, 02:42 pm »

Quote from: josh358 on 29 Jun 2012, 01:31 am

There does seem to be too much HF absorption in that room. If pulling the velvet back doesn't work, you could try removing the carpet. Also, you don't want absorption behind them, not usually. Try diffusion at the first reflection points between the speakers on the front wall. Ceiling height shouldn't matter. If they're too close to the side walls, you'll get boomy bass, but you don't want the speakers to be too close together. Then -- set the speakers up for best imaging and EQ the bass. They're never right in the same place even under the best of circumstances, and in this room, I think that's going to be even more true. Bass should be EQ'd anyway, it always sounds better that way.

Exactly. They can be made to work pretty well in your room you just have to work harder. There are several companies that have relatively inexpensive kits for rooms (GIK for one) that you should contact.

I am not saying that they will sound as good as in a well treated large (whatever "large" means

) room, but you can get superb sound. Better than in a poorly treated large room.

Since all of the x.7s have internal crossover doing bass EQ probably means doing full range EQ which a lot of folks don't like, BUT you have to do what you have to do.

rollo · « **Reply #9 on:** 29 Jun 2012, 03:36 pm »

A retangcular room is most desireable for Maggies actually. With the length of approx 23 Ft. you can use the rule of thirds to start with. Take advantage of being away from the rear wall as much as possible. Try setting the Maggies 1/3 into the room. Place them 6' apart no toe-in with tweeters on outside [ may require sidewall dampening] first. Then set your listening distance [ start 1/3 of room length ].
Once you have the desired sitting distance then toe in both speakers a 1/2" at a time until you like what you hear. The other way is with tweeters on inside to start.
This set up was used by Scot Markwell to set up Harry Pearsons Maggies which IMO are the best set up I have heard to date, well except mine of course, just kidding

Not an easy task, time consuming but worth every penny in Gold when right. Have fun trying.

charles

josh358 · « **Reply #10 on:** 29 Jun 2012, 09:37 pm »

Quote from: rollo on 29 Jun 2012, 03:36 pm

A retangcular room is most desireable for Maggies actually. With the length of approx 23 Ft. you can use the rule of thirds to start with. Take advantage of being away from the rear wall as much as possible. Try setting the Maggies 1/3 into the room. Place them 6' apart no toe-in with tweeters on outside [ may require sidewall dampening] first. Then set your listening distance [ start 1/3 of room length ].
Once you have the desired sitting distance then toe in both speakers a 1/2" at a time until you like what you hear. The other way is with tweeters on inside to start.
This set up was used by Scot Markwell to set up Harry Pearsons Maggies which IMO are the best set up I have heard to date, well except mine of course, just kidding Not an easy task, time consuming but worth every penny in Gold when right. Have fun trying.

charles

Agree that that would be a great way to set them up, though I thought he said he could only bring them out 50" because of the screen?

Line source dipoles have an unusual property -- if you sit the same distance from the rear wall as the speakers are from the front wall, room modes are cancelled below a certain frequency.* Which I think is why the HP-type setup works so well. The effect requires a rectangular room, though.

I used to use my 1-D's in that configuration, back when I had only a partial understanding of how it worked. I calculated that the rear wall reflection would cancel the front wall reflection at my ears, and indeed it did. What I didn't understand then was that the wall, floor, and ceiling reflections were creating a plane wave, which is why the cancellation was complete as long as the woofer was parallel to the front wall. It also works better with LP's than CD's, since they have mono bass.

*The spatial Nyqist frequency, as established by the distance between the woofers, and between the woofers and their reflected images.

josh358 · « **Reply #11 on:** 29 Jun 2012, 09:43 pm »

Quote from: rw@cn on 29 Jun 2012, 02:42 pm

Since all of the x.7s have internal crossover doing bass EQ probably means doing full range EQ which a lot of folks don't like, BUT you have to do what you have to do.

A perennial problem. The Behringer is inexpensive and excellent, but many people don't want to put high frequencies though its converters. And the DSPeaker is also apparently excellent, but I think it's just designed to sit between the amp and a sub. One solution would be to feed the woofer separately but that isn't easy with the series crossover in the .7's.

TONEPUB · « **Reply #12 on:** 29 Jun 2012, 11:09 pm »

If you have a McIntosh dealer nearby, try and get an in-home demo of their MEN220 room correction processor. They've licensed the technology from Steinway/Lyngdorf and the box is fantastic. Works wonders with any speaker, but particularly well with maggies and ML.

And, it's super easy to set up too.

kevin360 · « **Reply #13 on:** 30 Jun 2012, 03:13 am »

Quote from: josh358 on 29 Jun 2012, 09:37 pm

Line source dipoles have an unusual property -- if you sit the same distance from the rear wall as the speakers are from the front wall, room modes are cancelled below a certain frequency.* Which I think is why the HP-type setup works so well. The effect requires a rectangular room, though

Well, that explains it: my 3.7s are 9' off the front wall and I sit 9' from each of them (measured at the central points (of the speakers and my head)). The wall behind me is 16' back, but 8' back is a plush (read: absorptive) sofa on the riser. The bass from the 3.7s became amazing. I steered more bass their way and they responded magnificently. The reduced range of the sub permitted a bit more level from the subs without triggering 'fat spots'.

All I can say is that it works. It put a smile on my face; see

josh358 · « **Reply #14 on:** 30 Jun 2012, 03:56 pm »

Quote from: kevin360 on 30 Jun 2012, 03:13 am

Well, that explains it: my 3.7s are 9' off the front wall and I sit 9' from each of them (measured at the central points (of the speakers and my head)). The wall behind me is 16' back, but 8' back is a plush (read: absorptive) sofa on the riser. The bass from the 3.7s became amazing. I steered more bass their way and they responded magnificently. The reduced range of the sub permitted a bit more level from the subs without triggering 'fat spots'.

All I can say is that it works. It put a smile on my face; see

For this really to work, you have to be same distance from the rear wall as the front. The reason is that the positive-going bass plane wave strikes your ears, then the negative-going reflected bass plane wave does, delayed by the time it takes to travel from the rear of the speakers to the front wall and back to the speakers again. The idea is to line this up temporally with the reflection of the front bass wave from the rear wall, so that they null, and to do that, your distance from the rear wall has to match. Then the effect is the same as that of a single bass array, the difference being that in an SBA the speakers are omnis radiating into half space and the cancellation is produced by an electronically delayed inverted signal. In a double bass array, the cancellation is from a second set of speakers mounted on the rear wall, again fed a delayed inverted signal.

The other thing is that the woofers have to be parallel to the front wall, otherwise you're going to excite lateral modes and those don't cancel in this setup.

Here's a write-up of a double bass array, check out the spectacular measurements:

http://www.avsforum.com/t/837744/double-bass-array-dba-the-modern-bass-concept

SteveFord · « **Reply #15 on:** 30 Jun 2012, 04:19 pm »

You guys spurred me into breaking out the tape measure and what I had finally decided on (by eyeballing the room, listening and shoving stuff around) ended up being exactly 52" out from the front wall, 52" out from the rear wall.
I've got an idea for the MMGs I've got hung up in the air but that would derail this thread.
Nevermind.

kevin360 · « **Reply #16 on:** 30 Jun 2012, 04:45 pm »

Well Josh, my setup partially meets more of that criteria. The riser has a bar-height rear wall which is precisely 9' behind my head. I assume the sofa acts as something of a bass trap, however (there are also bass traps in the front corners (been contemplating the addition of more)). I tried my 3.7s without any toe and prefer them as they are. The subs fire in three directions. I started with them on the side walls, but they ended up in the front corners. Thunderous depth isn't a problem, but more importantly, the lower mid-bass bloom issues have been practically ameliorated.

I have a sub that's not being used (well, it's a side table in my bedroom). I've been thinking about deploying it in the rear of the room, but there are a number of complications.

poseidonsvoice · « **Reply #17 on:** 30 Jun 2012, 04:50 pm »

Unfortunately, your current room is just a series of multiples. Room modes will be compounded instead of spaced.

Anand.

kevin360 · « **Reply #18 on:** 30 Jun 2012, 06:29 pm »

So it would seem, and I assure you that the original plan was quite different. In fact, I was very careful about the overall room dimensions – made sure that the modes along each axis didn't coincide with those of the others. The original positioning of things was calculated with minimization of modal influence in mind. My only discontent persisted to be a couple of small ranges of bass that over-bloomed, while not having quite enough deep weight (where it's called for – listen to Stanley Clarke bow his upright bass in the opening of 'Romantic Warrior' and you better hear some seriously deep weight (and it's beautiful)).

I didn't plan to have a 'series of multiples'. I planned for precisely the opposite. It is reasonable and prudent to aim in the opposite direction. It also seems reasonable and prudent to expect one's system to sound like crap with the speakers arranged such that one faces their nulls – experience demonstrates otherwise. Properly executed, the Rooze and the sideways are both brilliant – shockingly good. Arranging things with such evenly divided spacing violates my 'common sense'. Oddly enough, it works amazingly well. This is the smoothest and deepest bass I've been able to obtain in this room. It is very satisfying – nay, it's friggin' addictive. Without a properly calibrated measurement system, I can not do more than make a perception based claim, and I can blame nobody for regarding such a comment with a few grains of salt (or more).

I've been through at least a hundred different arrangements. The room is mine to do with as I please – no WAF. The room also features video, but everything is secondary to the sound of stereo at my seat. Believe it or not, I have a solid foundation that doesn't feature any nasty modal behavior – at least, not as far as I hear (which is what matters to me). It costs nothing to try some things, except for a little time. I have time and it's fun to fool around with this stuff. Every now and then, things like this really surprise me.

I suspect the objective with this arrangement is to to use the modes against the modes. If one can't eliminate the damn things, why not work with them? Make some lemonade.

*Scotty* · « **Reply #19 on:** 30 Jun 2012, 07:22 pm »

From the OP original post he has the classic conflict between good bass and good imaging the cure is to be found here. http://vbn.aau.dk/files/12831869/AC-phd.pdf
CABS can be implemented with almost the same effectiveness using only two subs.
See these threads in the Bass Place for more info.
http://www.audiocircle.com/index.php?topic=106838.0
http://www.audiocircle.com/index.php?topic=106756.20
http://www.audiocircle.com/index.php?topic=107243.0
Scotty