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About jrhill

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  1. If you've got big open spaces above your ceiling, this might present a difficult problem of another nature if insulation wasn't inserted - in fact, any large undampened volume is an invitation to acoustical problems and some are a real PIA to fix The most difficult frequencies to get right is below 100Hz (hence your subwoofer generated problem) and, unfortunately, you can't rely on the dsp to take care of these sorts of problem completely without 'choking your system badly - if you can get these bass areas approximately right, the overall system sound is just so much better - as has been said so often, get the bass right and the rest is a 'piece of cake' - don't you just love optimists!
  2. Sorry, it's that builder's stuff that comes in a pressure can - you drill a hole on the wall, insert the nose-tip and press the button - expands about a million times - then just reseal the hole in the wall - a version of styrene foam - will be quite goid ro tie the inner and outer wall together that mayn't be perfect but should be a big improvement The acoustic way of fixing the problem is either add another layer of plaster board with a flexi glue as a fastener (green glue for example) or just add mass with one of the heavy damping materials - pro-audio uses a thing called leaded vinyl (no lead in it these days) and this will stop the vibrations in the wall pretty well indeed - there are various other ways of adding mass to the plaster walls and most will do the trick.
  3. I hesitate to be a 'bringer of bad news' but it seems you have exhausted most position variations with the speakers at that end of the room and it hasn't changed the fundamental problem of both the 'twin dips' and low bass 'rolloff'' so, it's time to consider something that mayn't be WAF and that's reverse the room so the speakers (amp and rack) is at the other 'fat' end of the room - maybe there's more chance of getting a better a result - it's a lot of trouble, I know, but it just might be what's required. Those DEQX units are marvels of technology indeed, but there are limits to what they can do and correcting response cancellations (troughs) are at their limit before other side effects appear (to me, anyway) - and you'll always be conscious of the sound deficiencies of the room with the relatively new purchase (plus, as you say, another outlay isn't within the present budget Just looking at the change due to the toe-in tests reminds me of something but just a niggle - the drops in the 'twin dips to a more reasonable response there for dramatic increase of the bass response trough means .... damn, can't quite catch the thought - will see if it comes to me .... Not all is lost, just a hiccup in progress, frustrating as it is Cross post from the other thread -. My B2 fractal diffusers have been finally cut (the 'leanfuser' ones with the extra fine 'fins' on top of the basic units) - not quite following on to the design exactly, but close enough - 10 pieces x 1200 high and 4 x 600 high for $300, which includes the $100 setup fee = $25 ea - the next lot will come down to about the $16 ea for the 1200mm ones - they suck up paint like a sponge, even the thick paint that's used to render the outside of houses - applying the 3rd coat at present and it maybe enough to create a hard, tough sealed surface - it'll be interesting to see if the painting actually makes much of a difference in practice ...
  4. Well that's bloody interesting - haven't seen that before So peak no 135 is touchy about speaker vertical, eh - somehow, there's a cancellation going on here unless it's a change in the microphone's field - try something a bit on the weird side - put a cushion/pillow on top of one speaker and see if this alters anything - then try the other to see if the same change occurs, if at all Another thought ... as the half wavelength of 135Hz is a bit over a metre (3.7 feet, no?), how far are the panels away from the side walls (ignoring the absorbers for now) and are both sides the same? Is the other panel a bit less than a metre (2.8ft) that might correspond to the approx 180Hz trough? You might drop a line to Bob Prangnell at Mad Scientist Audio in NZ - he runs big maggies and has recently moved house so will be going thru a similar process of optimising the speaker position. Who else up there (Brisbane) runs the 20.7's?
  5. Possibly use some expanding foam to tie the gyprock panels down - without stiff studs and battens, hard to stop the low bass from making the walls 'move to their own tune', as they say. You could add some heavy damping material (much heavier than carpet, etc) on them but the cost escalates fairly quickly
  6. I had a brief read up on these Maggies and can't see why you'd ever need a sub at all - but maybe I'm missing something As you mentioned, both the line source nature of the drivers and their size and would probably reduce any ceiling reflection issues - plus the horizontal nature of the diffusers would enhance this too - perhaps this might be part of the problem, unlikely though it may seem - the double dips in the low mid octave appear to be interference but your 'waterfall' doesn't seem to indicate a significant energy imbalance - seems remarkably smooth actually There was a mention of the extended 'break-in' time of the drivers but I don't think that exhibited here No much further to add unfortunately - perhaps the new drivers are creating a mismatch with the amps? (scratching around here!) Back on your first post, the graph shows a large peak in the bass response at a bit below 40Hz and your 'waterfall' indicates a quite pronounced standing wave, if I've read it correctly - looks to be about 10dB - what's creating this? If it's the length of the room resonance problem, you'll need a limp mass, or hermholz, trap to get rid of that, I think, rather than back wall diffusers - absorbers will suck out too much low mid and indirect reflections - my opinion here, mind you ... Is there a dedicated Maggie website and has this problem arisen before?
  7. There are plenty of electronic crossover kits/assembled available and just need to select 50Hz as one of the high pass filters - Madisound sell quite reasonable ones - variable filter slopes, etc - you can setup a simple buffer with a 12dB high pass filter too - lots of options that don't use passive filters and scary components
  8. On the fly, as they say, I'd suggest the 68Hz is possibly the peak created by the room width (1000/68 = 14.7ft or approx. 4.5 metres) just the numbers seem to be too convenient and the narrow width of the trough seems to indicate a cancellation point The 2 dips in the lower mids about 150 and 180 don't seem to be related to anything except maybe the floor/ceiling height (1000/2.54 x 3.3 = 119Hz) unless you've got some humungous couch in the listening position or a large hard topped table maybe - the plots of the 2 speakers are fairly similar so it appears that your room is playing a significant part in the response At the risk of sounding fatuous, maybe get one of those diffuser panels and hold it on the ceiling above one speaker with a stick, 2 broom handles, etc to see if any change in response - also maybe about mid distance between speaker and listening position (on the ceiling again) to create interference to 1st ceiling reflect point. Another silly one but maybe tilt the speaker back about 5 - 10 degrees and see if any change - don't think so, but I sometimes find lifting the speakers off the floor a bit more can be useful too ... Unfortunately, I don't have any experience with any Maggies, so offering just guesswork - 'normal' speakers behave a bit differently You may find it helpful to actually reduce some of the absorbtion and diffusion to see what changes, particularly the wall behind the speakers - if you can produce changes in the freq response without changing speaker position, it's an option or fresh starting point Did you get a good coat of sealer paint on the foam diffusers? The ones here just seem to suck up paint like a sponge and I'm thinking about making up a smooth cream consistency of that wall patching 'polyfilla' to fill the little holes first, or something to that effect
  9. I find the idea that ALL tone controls produce loss of whatever is a bit of a mouthful - not sure where you're going with these statements - not all listeners care about accurate imaging (which is effectively destroyed by analogue tone controls, graphic eqs, parametric eqs and loudness controls). I would respectfully mention that the old analogue MCI recording desks are regarded by many as having the best tone controls ever built and the Neve tone control circuits are emulated in many others - just saying here that tone controls are not the total boogie man and disasters that you suggest even tho these are found in 'pro-audio' gear . Those of us who value fine timing and imaging have long ago dispensed with analogue tone controls. I would suggest if the quality of circuits such as the above mentioned Neve, MCI, Soundcraftsman, Harrison, Otari, Cello, etc, etc were built into modern preamplifiers, there wouldn't be any concerns about loss of fine timing and imaging - Mind you, I'm not sure who would like to pay for them but there's no doubt the 'best' of analogue circuits of 20, 30 years ago could easily be recreated in hifi consumer products ....
  10. I belong to the 'great unwashed' who actually just loves good tone controls - I have no great enthusiasm for Mark Levinson but his Cello Palette was a perfect complement to any system (including top shelf exotics), IMO, despite it's 6 variable band/controls per channel and not being a cheap product. I really regret not 'breaking the bank' and getting one when they were available years ago The DEQX, and similar products are focused on correction in rooms, systems,etc but is quite able to store different freq response curves that can perform the same function as the veritable tone control but without the associated loss of fidelity - the advent of the mini computers like RasberryPi, with appropriate programs are also able to perform 'tone control functions' with no problems - you can even do this on some of the humble units like Berhingers, and so on, altho the loss of fidelity is pretty substantial, unfortunately. Nearly every recording desk ever built contains tone controls,either analogue or digital - the industry couldn't function without them - why it's such a taboo in the reproduction chain has always been a mystery to me - years ago, there were some good quality amplifiers that had adequate tone controls and bypass switches for when they weren't required The ability to alter the sound of the wide variety of recordings at home is a boon to many, and with the return to favour of vinyl systems, I think tone controls will also be resurrected, hopefully with better performances with the rapid improvement in sound quality of dsp systems, for example. For other people, the whole idea of tone controls is anathema and the subject produces quite spirited discussions
  11. Always a problem crossing a bass driver to a mid/FR one - a lot depends on how low a freq that the FR will function in it's baffle - I had a look at the linked websites and in this baffle, on the floor, the Betsy will go down to about 80Hz with approx. 93dB/W which is a pretty amazing performance - the freq response has a bit of a bump up from about 1.5k to about 5k but as this appears to be part of the 'sound', I wouldn't try changing this - on there own when tested in a acoustical test centre, they exhibit a smoother response so playing with the baffle would sort this out if it was a problem - IMO here mind you. Crossover - at 80Hz, you could simply use a subwoofer with it's inbuilt filter and amp - the major difficulty lies in trying to get a clean bass signal out of any of them, including the more expensive ones - it can be done but not so easy On the website, there's mentioned coupling the Betsy up with a 15" driver also on an open baffle and a separate plate amp - this is a fairly well tried and tested approach and the 15" drivers aren't particularly expensive If you were to go the way of passive crossover, rolling off the bass driver will require pretty big chokes so raising the freq response up to maybe 120Hz will make this more manageable - this is known as the FAST arrangement if you want to read up on it - speaker bug has some Jantzen core chokes that work quite well for this 120Hz Xover (and others too) and you could simply add a series capacitor in line with the Betsy to roll them off a bit above their open baffle point of 80Hz - ie, a 12dB/oct rolloff for the bass and a 6dB filter for the Betsy coupled up with the natural 80Hz baffle rolloff would be a reasonable starting point. There are a number of electronic Xovers available that'll be more precise about matching driver efficiencies, etc but I wouldn't do any of this until the Betsy's are up and working in your room - lots of dsp stuff on offer too but suggest you don't rush these either as a lot of easily made errors/traps in their use I'm a 'bit of a nutter' about clean bass and managed to get Lorantz bass drivers (Dandenong) and this has it's own particular requirements that aren't so simple but I think there's a SEAS bass driver that'll do a pretty good job for the lower 2 octaves (30-60-120) and readily available - a caution here in that really good bass drivers cost quite a bit of $s - not easy to get cheap & good quality bass anywhere plus, below the v100Hz point, room and bass trapping starts to become necessary - also, amplifier characteristics make themselves known 'down low' too ... While you're organising some plywood, suggest you grab some of those course hair floor tiles &/or some cork tiles to stick/pin to the back of the baffle - not very sophisticated or anything but quite effective and easily (& cheap!) to try. Welcome to 'better hifi'!
  12. I had a good listen to the video about the small baffles and indeed, it does sound quite good considering the laptop speakers but sadly missing the bass - I'm cutting some ply tomorrow and will knock up a couple similar to the ones on the video - about 22" high, about 18" wide and curved to 12" top/bottom edges with a timber 'foot' - it'll be interesting just where this rolls off with sitting on the floor, and on top of my 15" bass boxes.
  13. I don't mind the GST so much, but when we go to collect the parcels at the PO, or whatever, do we not only pay the GST (still the 10%?) but get slugged by some mysterious handling fee or surcharge? And does it only apply to declared $100+ value, or to everything?
  14. I figure that the small baffle mentioned on the Decware site needs the floor to produce anything like lower mids and bass The official IEC website baffle size for a 6dB rolloff at 100Hz about 56" wide and 68" high - I got the BetsyK rather than the OB version and am in the process of cutting some folded baffles for a 150Hz Crossover that are 1200mm high and the 3 surface widths of the baffle are 18" (460mm - one side) 9" (230mm - centre panel for driver) and 10" (250mm - other side) - the sides fold back at a 45 degree angle altho not critical - so the sizes when added up is 48" high x 37" wide for 150 Hz - if mounted on top of bass box (2 way system) the face of the bass box contributes to the open baffle length I was a bit surprised at that small size and the 'rave' talk, so intended to cut some 12mm ply at 'guess-timated' size to see what happens - not done yet - I estimated something like 18" x 22" from the 8" driver size, I think. When testing, it was thought these drivers were intended as ceiling mounted FR drivers down to about 60 Hz for hotel systems (Rane, etc) and such use - could be quite wrong too. These drivers are a real surprise when checked/measured, and exhibit quite low distortion above 120Hz, and not all that bad below this point either for a freq response that's also rather good too - I added a circular cowl around the magnet (plastic plumber tube) and stiffened the pressed frame (plumbers FerroPrix 2 part glue) and filled the gap between magnet and frame (Caravan putty - similar to the Planet 10 mods) but didn't need to do anything else to the cone/spider/etc - nice driver at a bargain price
  15. These are listed (retail price + postage) at $180 ea, at KrispyA, Mark - what am I missing?