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I'd like to relate the further escapades of a friend of mine, and then some observations of my own. You may remember a post of mine last year when we treated his rear wall with panels made from ply, batting and colored pleather. It did a great job both helping the room and tightening and deepening the maggies bass. He owns an old pair of I's, but they have new panels and have had the full crossover and wiring tweaks plus gold binding posts. So they're old I's but sound as good as is possible.He was happy, so he stopped there, despite my protestations. The problem is his room is a perfect 13 foot cube (with 8 foot ceilings). I wanted him to treat the other walls more, do the ceilings and the ceiling corners. He didn't.
For a year now I have heard him complain about the sound he's getting, he's tried other speakers, amps etc.. and it had gotten so bad it was actually putting me off of maggies. He was about to try another pair of speakers when I finally went ballistic on him and forced some tweaks. I told him until the room was as good as it could be, he couldn't take anything for granted and should not be swapping gear so much. He had finally become that desperate and relented. (He's an odd breed of audiophile. He wants great gear and sound but at no work, or even thinking on his part. He knows very little about the hobby and cares less, he just wants the best sound in the world, that's all : )
As he is cheap as well it meant we had to make the tweaks, not buy them. While it wasn't my first choice, it was easiest, so I had him do the ceiling corners first. He said he had a sheet of styrene at his boses warehouse they didn't need, so we got that and then went to get fabric. It is the saddest thing in the world to be at a fabric store on a saturday night with another guy and have the girl at the counter say "How are YOU guys doin tonight?" I supressed the urge to yell "We're not gay, we're audiophiles! Not that there's anything wrong with that."
I decided to make the panels 2 foot a side. They need to be equilateral (60 degrees a side) so I laid out a 2 foot line, and used a large compass from each end to scribe the other point and connected them. (I have one, I'm a period cabinetmaker) You probably don't, so the easiest way is to lay out the first line, then tie 2 pencils on a string so their ends touch the ends on that line when stretched. You can then use them to find the third point arcing a line from each end.
I wanted to bevel the cut 45 degrees so I cut it out on my large 3' Oliver bandsaw which you also probably don't have. I found the material did not want to cut lets say "predictably" with a razor knife, so be careful if you use that. The fabric was then stapled on. Yes, the staples come out easily if pulled straight out, but under tension they held fine for this purpose.
Total costs were $10 (for the fabric) the styrene was free. A panel large enough at a home center would be about $7. Look where the plywood and insulating boards are. It's basically an inch thick styrofoam board used for insulating. The fabric we used was excellent, with alternating raised ribs much like you'd find on a commercial product. We adhered them in place in the corners with double sided tape which was fine as they weigh almost nothing. The finished product looked like this:
From a distance
Up close
All 4 corners were done. This shows the wall treatment as well.
Yes, it's very Space 1999. Sounds that way too.
We decided to put them up with the gap for the trim at the top instead of allowing for it, because we thought that a completely sealed corner might become it's own problem and "boom". Allowing the gap prevents them from becoming drums in the corners and the slot probably catches it's share of bad waves as well. He has round paper lamps from IKEA in the corners at floor level doing the same job.We also finally re-drilled his maggies bases and put new, longer screws in. They are now rock solid. I also had him hang quilts on 2 walls. We did not get to the ceiling at this time and as I was expecting that to be what this room needed I was dumbstruck at how much the room changed. The maggies finally focused, like an old man who finds his prescription lenses. The lack of width is still unfortunate and hurts slightly of course, but the room has never sounded better. Problem solved, the maggies stay.
Most notably, he had a problem anywhere out of the sweet spot. The sound literally vanished if you stood up before. I could stand in the doorway and barely even hear them play. That is now gone. They are still best in the spot of course but sound very good anywhere in the room now.
The gear in question is: Conrad Johnson PV-8, Ah! 4000 with upsampler and Siemens tubes, Pass Labs X250, Signal Cable power cords and interconnects and Zu speaker cable.
We tried to do the ceiling with egg crate foam this weekened, but it did virtually nothing, which is good because we couldn't get it to stay put. I'm thinking because the room is a small square and not a rectangle, and because the maggies beam and not radiate, the short distance of the room does not allow for the ceiling to become a problem. So if you find yourself in this fix with a similar room, my suggestion would be to do the corners and damp the walls first. It was easy, cost almost nothing, and it looks good as well. It also performed well beyond our expectations.
Now for my input. I was planning to turn my attic into a room last year but the project got delayed to this year. My purchase in the meantime of a Hovland HP 100 threw a towel in my works. I love maggies, but his didn't do they detail this thing can manage thru full range monitors. I did a lot of listening last year (you may remember my notorious RM-40 post) but it became a nut I couldn't solve. His room sucking wasn't helping matters.
But after this fix, I inserted the Hovland for a day. Previously, I could not even tell it apart from his PV-8 on his rig, which in fact sounded better (which pissed me off to no end). That has now ended. I listened to both for a few hours in this more ideal setup. The inability of the room to accomodate the soundstage the Hovland was trying to throw was it's only flaw, and one belonging to the room, not the Hovland. Some aspects of some recordings suffered a "suck out", as you could hear a ghost of where things were supposed to be, and they sounded distant and muffled. That didn't happen when the PV-8 was in. It threw a slightly forward, but very 2 dimensional soundstage. It had width and height,but no depth. At first this did sound more appealing when it replaced the Hovland. But only a few tracks in, I realized the Hovland sounded much better and I missed it being in. The PV-8 is a fine peice for the money used, and without the comparison one could be quite happy with it. My worry had been, if I go back to maggies will I lose the delicious things the Hovland does. Apparently not, which has eased my mind.
What's more, I discovered that when the Hovland came back home to the cabinet jobs I have to use now, they did indeed impart a lot more detail, but God, I HATED the sound. Maybe the maggies did roll some things over a bit, maybe the N'th degree wasn't there, but what was there sounded SO DAMNED GOOD I didn't care. The naturalness, the air, the lack of "edge" (not resolving everything is actually a blessing) made it a joy, and my monitors a rude wake up call.
I will probably go hear a few more things as a lark, but I will most likely settle on the 1.6's this year. To quote George Constanza, "I'm back baby, I'm back!". I can hardly wait to join the club again, I've been away too long.
If you got this far I hope you found something of use in it
Follow Ups:
2 words: "inverted polarity"CJ products are notorious for this. This is easily rectified. Just simply swap the polarity back at the speaker terminals, or turn the speakers around. The latter option mayn't be the most aesthetic course, but you'll get more treble extension & resolution.
PS: I usually recommend corner placement for acoustically problematic rooms. It automatically diffuses many room interference patterns through oblique reflections.
♪ moderate Mart £ ♫ ☺ Planar Asylum
Working the bugs out of this square room has been new to me, all mine were rectangles. What applies in those situations doesn't seem to hold the same weight here, and yes, the corners are the real culprits.Thanks for the tip. It proves if I don't know my physics at least my ears work. We reversed the cables and there was an improvement. It didn't move back any further (except for some of the lowest frequencies), but it did finally extend beyond the speakers outer edges. It had previously pretty much stopped there with the PV8, but now it goes about a foot past which definetly improves the over all sound. Many thanks!
square rooms will always be tough. check out this room mode calculator. my guess is if you plug in the room measurements you'll get 3 modes at very close to the same frequency. (ouch) the corner treatments will help with the Tangential and Oblique modes but the axial modes are the hard ones. even worse when you "stack" the modes decay time gets worse. i've found a narrow cut at the exact resonant frequency with a parametric eq does the job. you don't have to move the speakers and the chair around (much) so you can fine tune for imaging.
I really appreciate your post but....We all have an achillies heel, and even though I have a rather high IQ, math and I have never seen eye to eye, especially in regards to anything to do with electricity, amplitude, wavelengths, trig or calculus etc..... I could learn it for a test, but forgot it a week later, entirely .
I plugged my dimensions into that thing, hit enter and sat there mystified. What's worse, I cannot even understand your post. I don't even know what the difference is between a tangential and oblique mode frankly, let alone how to stack them. (Wow, you can stack them?)
I've always relied on common sense and my senses, and will have to keep doing so. I always swore I'd get a book one day and really try to learn the "guts" of this hobby better, but the problem is, I really don't want to. I'd rather be listening, not crunching numbers. Even if the room is not 100%, I've always managed to get it pretty good and ignorance is bliss in this regard for me at least. I have observed that engineers are never happy people. (or rather, should I say satisfied people? : )
I'm already dreading having to do the crossover upgrades to my new maggies. One look at the jargon, the scribbling diagrams electricians call "schematics" with all the crytpic numbers, values and signs, and I don't have a damn clue where to begin. I don't even know what to buy.
Thanks for trying!
i don't enjoy the math either. what drives me crazy is the things you can't see. sometimes math helps me understand what i'm after at least, and sometimes the solution is more evedent. when you plug the dimmensions into the room mode calculator look first for frquencies under 100hz that match pretty close (within 3hz) in the axial mode. these are thre most powerful modes and are the frequency that resonate on the height, width, and length of the room. for example if your room is 8 feet tall take the speed of sound (1130 feet per second) / height (8 feet)= frequency of resonant wave (141.25hz).if you have two axial modes very close to the same resonant frequncy (stacked) the resonance will be reinforced. since we can't move the walls around we move the point of origin of the wave (speaker) and the point of reception (chair) to get an "inbetween" spot that is acceptable. with 2 or 3 stacked axial modes it is almost impossible. cancellation or equalization are about the only two options. running a sub out of phase and positioning it so that the offending mode is out of phase at the listening position. this can be accomplished with time delay and actual placement. here's a graph of a measurement taken in my listening room that used to have serious bass issues. notice the quick decay and even response. i used a combination of all these tricks - parametric eq, cancellation with sub, active bass absorbers and foam corner treatments - to obtain these results.
♪ moderate Mart £ ♫ ☺ Planar Asylum
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♪ moderate Mart £ ♫ ☺ Planar Asylum
Maybe you don't like it but you have the fundamental knowledge of it's use. I could learn math in school long enough to pass a test, but it was gone in a month. I got an A in advanced algebra in 11th grade but I got a 57 on the final. Forgot it entirely.
The picture you posted didn't come thru, but I doubt it would have helped me get this post any more than the last one.
I do understand cancellation, but apply it with my ears and common sense. If parametric eq means creating a sound to negate a sound, I get the concept, but will never take that route to solve this problem. In any case, it's my friends problem : )
What really confuses me is how people throw out frequencies like they do. "Yeah, I have a problem at 400 hrz" How the hell do they know that? Not everyone can own test gear. I have no idea what 400 hrz sounds like. If there's a suck out at that frequency I'll hear it, but I won't be able to identify it, and frankly, I don't see the need to to solve the problem. Would I be better served by getting a clue? If so, how? Do you listen to test signal discs all day? The pic above is really how I feel about all this.
you can produce a graph like the one i tried to post and mart helped me out with for close to nothing (except for time which you will save later)if you already own the following equipment: a computer (i assume you have one since you are posting here)with a 16 bit sound card, a radio shack spl meter (used as an amplified mic), and the demo version of etf5. the demo version is fully fuctional except you can't save anything. it's kind of a pain to keep restarting the program if you're taking alot of measurements. i found it useful enough to buy the license. you can see the huge difference a small adjustment makes without listening to your entire collection. even if you end up listening to your entire collection anyways, you'll know why each adjustment made this or that sound better or worse. it will at least help the decision making process and keep you going in the right direction.
those room modes are a tough nut to crack. sometimes you get lucky, but in my experience if you want extended bass in a room that's not perfect more equipment and lots of head scratching is needed.
It was an impeccable description of "inverted polarity".
♪ moderate Mart £ ♫ ☺ Planar Asylum
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