aechmea

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About aechmea

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    Aechmea recurvata

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    Hunter Valley
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    Australia

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  1. I haven't given up hope for you yet Bill. Forget the 150 and 180 for the time being; lets look at the big suck at 70Hz Time to get the subs out of the far corners and trial them along the side and back walls. Behind the chair worked for me as did one sub out in the room away from walls, but that proved to be an annoyance for walking. This little gem can give some ideas. http://www.hunecke.de/en/calculators/loudspeakers.html It won't work for planars due to the reverse polarity backwave but will for the subs. So just use it to trial some possible sub positions. I have this ATM, which has doorways, furniture etc. taken into account. Not really to scale, but close enough. [Remarkably similar rooms, by the way.] Yes, the left sub is in the back right of the room. ------------------------------- When I measure close to and with my (leather) chair in situ then I get all sorts of funnies, mainly in the mid range. Might be worth trying without the chairs to see whether some lumps and bumps disappear. I doubt it, but one never knows. ------------------------------- Hmmmmm. A speaker (sub) 1.2m away from a wall will have a null at 70Hz when the direct wave and primary reflection combine. Since both subs are the same distance from the front wall and about 1m-ish away, both are producing a 70Hz null. The Maggies look to be 2m-ish from the front wall. The backwave has to travel an extra 5m-ish, a wavelength which is equivalent to a freq of 70Hz. Because the backwave and directwave are reversed polarity, when they combine, this gives another null. So all 4 speakers (2 maggies and 2 subs) are producing a null at about 70ishHz. Worth investigating. Time to get the subs on the move.
  2. Well, yes and no. It helped considerably in my case. Despite the attention given to room modes in the literature and internet chatter, modes were not the cause of the peaks and troughs I had in the low freqs in my room with my speakers. Instead my 'problems' were actually comb filtering (aka SBIR) rather than the standing waves of modes. In short SBIR is the interaction of the direct wave with a strong reflection. If it is half a wavelength (or odd multiple thereof) out of phase there is a cancellation at that frequency. Planar speakers have an equal amplitude and opposite polarity backwave, so when that interacts with the direct wave after a bounce or two off the front and back walls then a typical comb filtering response might be seen. The typical comb response graph can be obscured by other reflections from floor, ceiling and side walls. I used an Excel spreadsheet, room dimensions and some trigonometry to calculate path differences from speaker to chair via various wall reflection paths. These calculated path differences matched pretty well with many of the peaks and suck-outs. So I moved both subs to unusual places around the room. The sub that I placed at the wall behind the chair (rear wall) filled in the suck-out that was caused be the Maggies bouncing off the rear wall back to the chair. Rear wall to chair = 2.5m ==> path difference = 5m ==> frequency of that as half wavelength (cancellation) = 35Hz-ish. I place the mains and chair for the best soundstage, imaging, clarity and that sort of thing then place sub(s) to fill in the bass 'holes'. Sub positioning is never anywhere near where the mains are, but maybe that is just my room's geometry. My use of subs has nothing to do with bass reinforcement as such which seems to be the HT approach, rather a way to even out the bass in support of the room geometry and mains. ---------------- @Bilbo Hi Bill I would think that your suck-outs at 150Hz and 180HZ would almost certainly be room geometry/positioning/reflection/SBIR. But what exactly is the culprit. 180Hz is approx a path difference of 0.95m. 150Hz is a bit longer at 1.14m. So the reflection from what surface/object is able to give a 1m-ish path difference. Unlikely to be floor bounce. Floor bounce for a 3m listening position 1m off the floor is about 300Hz and higher freq for seats further away. Ceiling bounce is a possibility but only if the ceiling is 2.3m or less and even then planars don't have anything much off-axis to contribute to floor or ceiling bounce. Planars have a natural null at 90º and 270º so normally side walls don't matter much either, if at all. Its really all about the directwave and the reverse polarity backwave. Hmm, so I would be looking at something roughly 500mm from the speaker or the mic that the positive direct wave might be reflecting from or something 1m away that the reverse polarity backwave can reflect off. [how far from the front wall are the bass panels?] --------- On a different tack but all effectively changing the direction of the first reflection of the backwave and the directwave. 1. You might try crossing the speaker axis in front of your chair. This has the effect of angling the back wave in a different direction and maybe reflecting off an entirely different set of walls. 2. Point them directly down the length of the room. Same reason. 3. Somewhere in between. 4. I tilt mine downward significantly, so that the top and bottom of the speaker are equidistant from the ears. Somewhat disconcerting to look at. They are very tall and my ears would be below half way were the speakers upright. However it's unlikely that such a small path difference between top and bottom would be anywhere near 180Hz. But it does change the path of the backwave and directwave. 5. I have the ribbon on the outside. Effectively the bass panels are close together and the backwave bounces off the front wall first and then off to the side, rather than the side wall first and back to the middle. 6. Unless the absorption is quite thick and plentiful it won't have much affect in the freqs that we are considering. Similarly dispersion is a mid-high freq thing unless the 'skylines' are enormously huge blocks. 7. Have you tried absorption immediately at the back of the speaker to kill the backwave as best you can to see if the cancellations are due to the backwave or not. ------------------ Having said all of that I am not sure that the 2 major suck-outs would be audible. There is a shallow dip from 60Hz to 200Hz, then a low hill from 200 to 1000Hz. I guess that this would give a mid range prominence to the sound, which is sort of what you describe. The overall look is not unlike mine but in my system I could hit that with a bit of gentle EQ. Maybe if you reduce 200 -1000Hz by a dB that will make 80 - 200 more wholesome. One of those supplied ceramic-resistor-things across the mid range panel might help. Are they meant for the mid range panel, I don't know; the sockets are there. Tis all I can think of for now. A plan view of the room and positioning as suggested by Frank will help.
  3. OK, I'll fess up. I have been playing Cds since they first came out; couldn't relegate records to the garage fast enough. I have no reason to change to anything else. I don't play vinyl, I don't download, I don't stream, and I don't listen to radio. Its just me and my CDs. As far as new music is concerned, I take an occasional hint from Amazon (who says "you might like this, based on previous purchases") and from the 'prog' thread. My system can be turned off for weeks on end, such is my love of music (ha ha a bit of self deprecation there, but true nevertheless). One should never assume that your version of the hobby is the same as anyone else's.
  4. Yes indeed .... I would have to pick the time very carefully to avoid weather, wildlife and freeway and aircraft noise. All too hard really which is why it's still just a thought bubble.
  5. I measure my tall wide speakers (2m x .75m) at 3m. ie. about 1.5 times the largest dimension. It just seems right in an effort to get some sound from the top, bottom and sides of the speakers. Whether it makes any difference or not I don't know. I seem to recall Alan saying that it doesn't matter much. The current manual says something along the lines of, measure further away with large speakers. One day I will do an almikel and measure outside, off the ground for the best pseudo-anechoic measurement. The logistics of such an exercise though is a bit impenetrable. Currently I have passive XO speakers and they are amplitude and time corrected as well as anything. Active enables you to do your own XOs, but if that is done sufficiently well by the manufacturer with their passive ones then nothing gained nor lost, IMO. I have never been able to detect the presence of any XO and its anomalies either by ear or by graph, but that's just me. Even though I once did active bi-amping, I am happy being passive. Room reflections in the low frequencies (modes and SBIR) , integrating the sub(s) with mains, and room positioning in general is the most difficult aspect to get right.
  6. The CD layer on the Brothers in Arms SACD is a great example of the damage that can be inflicted by mastering engineers re dynamic range compression. The CD layer on this is also HDCD encoded but they didn't use "peak extend" which is the whole point of HDCD. What were they thinking. Like everything else in life - it depends. There are always, from any era, good/bad recordings, good/bad mixing, good/ bad mastering, good/bad pressings, good/bad replay equipment/environment. The trick is to get them all right. As far as CDs are concerned, I tend to buy the ones with a good DR value. Stuff with a bit of contrast is preferable (for me) than dull and loud ones which tend to sit in the rack unplayed and unloved. I can always correct bass/treble imbalances with thoughtful use of EQ.
  7. The info in the Rhino link is misleading. The release that they are talking about is a second version of the 40th Anniversary release. It is not a 45th anniversary release. Chrysalis is the publisher of mine, not Rhino, so I don't know what that is about. Released in 2016. Book format + 2 x CDs and 2 X DVDs. The mixing was done by Steve Wilson - exceptionally as always. However there are 2 releases of this 40th anniversary set. The first is the Wilson mix, mastered by some bloke that essentially stuffed it up. The details of the stuff-up are well documented. Disappointed, Wilson then decided to do the mastering himself. This resulted in the second release which is called Jethro Tull Aqualung 40th Anniversary Adapted Edition Remixed and Mastered by Steven Wilson Mine has a bar code: 0825646487080 Ensure that you get this version, because the poor release and the good release look very similar.
  8. Yes. I was never able to find any official figure, either from Sanders or from a reviewer (who would probably only reprint what Sanders told them anyway). I did come across a forum-poster like us that said 150amps. Who was he? and where did he get that figure from?, is it right?; who knows.
  9. Active digital bi-amping is over there waving its hands enthusiastically. "pick me" " pick me" "pick me".
  10. Very interesting/unusual. I would keep them and investigate further; especially for the sake of $300.
  11. Hi Lost, Welcome aboard. We hope you enjoy your time here. Please contribute whatever and whenever you can.
  12. Hi John, Welcome to Stereonet. The first task is to demonstrate that you are not a bot. That's done. Now you should be able to post in the forums, which seems to work for you. So, welcome. Some knowledgable people will be along soon to help you with your problem.
  13. I worked backwards (mathematically) from the amp specs, room size, preferred SPL, to see how mine stacked up. I like 80dBSPL, the Maggies seem to come alive about there, but maybe that is just my hearing and my preference rather than some electrical or mechanical properties of the speaker. I have always thought though that you need some oomph to get the panels moving and the figure 8 pattern acoustic null at 90º and 270º doesn't help. So I did my sums at 3meter distance, 83dB/watt speakers, 20dB dynamic range above average level, amp gain, amp input sensitivity, 2 speakers. Then added a bit because of the large (6 x 7) treated room. [A German magazine measured my model of Maggie at 77dB/watt! All very curious.] Anyway the sums confirmed that an amp of 450w (roughly) is required for 83 dBSPL average, which is roughly what my amp produces and why the amps that I had tried previously (250w ones) didn't sound quite right when being played like that. Sure most of the time you only need say 10-20 watts but it goes up exponentially for even just small increases in SPL or for peaks. The amps get hot too, confirming that they are actually working hard. 20dB of headroom is quite a lot, so that could be scaled back to say 15 and if one plays at say 75dB average then you are only talking 20 watts. Then there is the question of whether one can hear small amounts of clipping - probably not. Most amps could therefore cope. None of this takes into account the low impedance, so I suggest that one needs power commensurate with the SPL and current capability. Current requirements will decrease as SPL decreases - Ohm's Law and all that - but I personally don't think that the Maggies show what they are capable of at lower SPL. Maybe that's just deaf old me.
  14. Omnia "Crone of War" (2004) Neo-celtic pagan rock. Omnia is a Dutch band comprising 3 long term members with a changing line-up of others/guests. Harp, whistles, pipes, horns (the animal kind), hurdy-gurdy, dulcimer, a few chants and limited vocals with any number of percussive things, and of course a didgeridoo. Not nearly as 'dark' as one might expect from the 'pagan' description and the album cover. Recorded 'raw' without electronic gimmickry or compression of any sort. 20dB or more of crest value. (= max - RMS average). A bit niche but that's what you find at the bottom of rabbit holes.