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rick mcinnis

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  1. Another thing I wanted to suggest to those about to put holes in their K-402s: With a strip of paper - mark it at 9 & 15/16 inches this will be ever so slightly large but is a mark on the yardstick - for the obsessive 9 and 59/64ths is even closer! Use card stock. Connect the two ends with some tape. You can then easily see where you are with your port. There can be an advantage to putting an angle on the port. I am going to try this - to have it continue the 45 degrees I want for the baffle. Not there is a chance in hell of me getting that with any consistency. I am not skilled with a router and my extra layer of baffle towards the mouth precludes being able to use one well. I feel certain getting close is all that is needed. Lots of barrel sanding bands are on hand along with sandpaper. Draw a "circle" around the port -.75" out - (the thickness of the baffle in this case) to see where you need to finish up. I am thinking about, for the sake of curiosity, of going ahead and cutting the holes in the other K-402 while it remains just a high frequency horn to hear and measure what happens. I can use a sheet of paper with a blob of MORTITE on the back until I am ready to install in the second box. It is finished but needs to be shellacked and that will take two weeks. I know I will lose the frequencies in that part of the horn but want to see what happens above that. Main motivation is go ahead and do it while I still remember what i did right with the first horn. Using the epoxy to repair is easy but it does take lots of time to allow it to dry before adding a subsequent coating. I am concerned that putting it on too thick, like BONDO, is a bad idea. With hopes of helping someone not repeat my mistakes ... Take care,
  2. Wreote the above at work and had to stop. One thing about my chair response is that my high frequency response increases. Now this could be since I am not measuring the K402 in its center - a littel bit below - they are sitting up really high in the air and my copper tube is not long enough and it is not that important at this point. In MEH configuration I will be able to measure at the center. The SEISMIC cabinets are 35 inches tall and, as you know the K-402 are mounted vertically. Tall imposing thing! I believe that with the MEH the response at one meter will not be anyhwere near as diminished as it has been with a speaker with drivers VERY far apart - voice coils easily thrity inches away from each other. I have not posted anything of real usefulness because there is no way to post an REW file here - they are too large and my pictures are useless. I tried to email them to you, but again, they are too large. I hope I am missing something and there is a way to do this. One thing I found while measuring at 1 meter which goes along with what you have expanded upon to us from Danley's suggestion (!) to never use a filter with a man's name. I greatly appreciate his male chauvinism in this respect. I can just see more craven folk having to insert the obligatory "man or woman's name" in its place. But, what I found was that with no first order filter I got the expected for the greatest part of the range from 100 to 20,000 Hz a straight line at 0 degrees. Then I used a 100 hz first order slope and zero degrees phase became a much larger number. I went up 100 Hz at a time till 600 hz and by then the line remained just as straight as it was, from memory, but close to -1000 degrees. When i would use the PEQs to get the response I wanted using no added filter, as you have stated, there is no phase growth to speak of. So my feeling is that we should not use the first order filters in the XILICA unless one has no other choice. Will be interesting to see what is required with the woofers. Maybe that shift will be useful? Only measuring will tell. I know what filters I need will be different from yours - I am not interested in copying them but It would be interesting to see your approach. I think I am approaching this as you have since I have tried to use your advice along with the fact I had been trying this many months ago on a whim but with my old system, not the kooky one with the Seismics which actually have some phase linearity the old system did not display the goodness. It shows me in hindsight that many of the things we have done traditionally were bandaids for hopelessly flawed systems which is how I would describe my system when it contained to horrendous EDGAR 75 Hz horn. What Danley said in the old DIYAudio post was the purloined letter. It was right there for all to see but from what I have read Chris A was the only person to see the beauty of it and put it into practice and of course bring it to our attention with his measurements. Thanks again, Chris A. Now to work on those holes. By the 2way if I said I was going to make them smaller I made an error. Mine will be as close to 1/10 Sd as possible. I will err on being a little bit large instead of the other way around. Take care,
  3. I figured yours would be of similar weight. Having a removable back makes the box much easier to deal with. That material is similar to what I applied to the horn. It made a dig difference there and I only used a little bit since it was an experiment. So you really hear less resonance with this on the walls of your box? Sure would make things easy in comparison to any other method I can think of. Have one box assembled and get to see how everything fits inside today. I had to make my boxes wider for the woofers to fit. I think I will have to do some manipulation to get the assembly though the hole in the box. I think the magnets are going to be closer to the walls than I had thought. This will make it easier to use them as a brace but tricky to get in the box.
  4. My walls are also 3/4 inches thick so they will get excited by the woofers. From what I have read DYNAMAT is very effective but really expensive and tuned for use with sheet metal so it seems that multiple layers wold be required for plywood. I had read someone saying that the recycled tire rubber floor matting you see in gyms would make a good damper. I have some of it here so I will try this first. It is about 3/8 inch in thickness and is very heavy as if I want to add more weight to the cabinet. Since my baffles are like sails in the wind I am attaching thick wool felt. Again to placate me wondering if I shouldn't have done it if I don't. For stuffing I am going to use the long fiber wool that has been used in all of my speakers for thirty years when I thought the transmission line was the answer. There is no question (in my mind, at least) it is the best compromise stuffing. I will not STUFF the cabinet. I agree with Chris A that the back volume is not critical along with what is done with the volume; assuming that because of the small entry ports the reflected sounds we attempt to guard against with conventional speakers simply do not find their way into the output to any significant degree. Speaking conceptually since I have no real idea. With a combination of some kind of heavy damper followed by THICK soft felt would probably be ideal taking care of wall damping and absorption without the use of stuffing but that much wool felt will cost lots of money so I am going to hope the wool, by itself, is plenty. Luckily there are many ways to skin the cat and still have the skinned cat you always wanted. RYTHMIK boxes assembled and attaching glue blocks for the 402 cabinets with the hope of having them assembled middle of next week.
  5. Those speakers look great. I am concerned about your unsupported mouth, though. Low frequencies will distort the mouth, I certainly do not know if this will be detrimental to what you hear. Did you do anything different with your ports? What did you do to insure there is no leakage between your baffle and K-402? Getting to that point and would appreciate hearing what you did. If you have already said, forgive me, but I have not read which drivers you decided to use. I am skeptical about photographic wood, especially considering your (very fine) execution. After seeing so much of that stuff used in automobile interiors - I was never convinced. I am wondering if after you go to this trouble she might wish she had never made the request! I do think it would be a shame if you had to do that. Maybe a light sanding with fine sandpaper or a SCOTHBRITE pad to get a dull finish but with some character from the scratches and then use a wax to get just the amount of sheen you would want. I would think you could get a nice dull sheen that could look good. I have seen bespoke furniture fellows use plastics in this way and it can look really good. Romy Bessnow has long speculated that a slightly rough finish on a horn could be advantageous. How to do such a thing with any consistency is the trick. Fun thing to wonder about until the music you are listening to takes you away from those thoughts ... Mine will remain as shipped other than having holes in them.
  6. Got the turnbuckles and bolts to attach the panels and found I ordered turnbuckles that are one-half inch too long. Suitable ones to arrive Wednesday from McMASTER CARR. Hope they will accept the too long ones in return. About to get serious about assembling the cabinet. The pieces are cut. I am going for a bit of overkill since one would rather go too far than not far enough - the front frame is 2.25 inches thick - 3 layers of 3/4 inch plywood - back panel two widths. Tried some 1/8 inch natural rubber matting for sealing the baffle to the horn - too thick - so I have ordered some 0.30 inch material which should be about right. The baffles against the horn sides - even without the tension from the turnbuckles - seriously deadens the walls. Even without the rubber - I figure the rubber will make them as dead as practicable. Making pieces for the top and bottom of the horn which will be padded with MORTITE and then pressed against the horn - hoping I can use the "rigging" to make this easy - I figure a piece of wood perpendicular to the "top pieces" will make this easy using the bolt and the turnbuckle as one side of the clamp. I have found the MORTITE, by itself, does a great job of damping, but there is the danger (not likely but who wants to take the chance?) that it could fall off. Plus I figure some gentle pressure would only make it better. Another thing - I would have liked to epoxy the baffle to the horn but then I would never be able to remove the CDs. The woofer almost touches the throat flange and the baffle is up against the bolt for the CD. The table saw gymnastics refers to chamfering the mouth edge to match the flare of the horn. I had to run the blade high and at a angle (different heights and different angles to achieve this. Don't think the saw liked this that much; keeping the board straight in two dimensions was the gymnastics part. It is not perfect but close enough that the gap left after using the rubber sheet will be easily filled with (yes, you guessed it) MORTITE. The fellows at ADVENT said the MORTITE sealer was part of the ADVENT loudspeaker sound. At age twenty I was following the Pied Piper of audio - Harry Pearson - so I had to have Double ADVENTS. Of course, I could not afford anything better. I continue to be astonished (I use the word seriously) at how good the K-402 sounds. Simply incredible compared to my INLOW horns which made it impossible to return the Edgar's salad bowls which I used for over ten years. So now the only problem is deciding where to put the holes. I worry that i am missing something because i usually am. Chris A says 5 inches from the screen. I am not sure if screen was used in a general sense (always 5 inches from the screen) or just an easy way to illustrate his installation. Here is the BMS driver The screen is right up front - but on the JBL, and I suspect the TAD 4002, if similar to the 4001, the screen is 2.75 inches behind the front of the driver. Using my memory for the 4001s since I sold them years ago. It was over two inches, though. Should I, also, have my ports 5 inches from the screen or from the front of the driver? This would place them almost at the throat of the horn. Though this position would put the ports in a more center of the cone position. The vertical mounting does force the ports to be very close to the suspension if they are placed further "down" axially. I read over the Unity patent again and there is the suggestion that the area where the ports are located should be the same area as the ports. This would not be the case if I used the screen as a reference point. Of course, 5 inches from the mouth does. So hoping for a little MORE reassurance before I make the holes. I know I keep going on about this but I want it to be right Would a Forstner bit work on the ABS? I will post a picture of the baffles tightly coupled to the horn Thursday. Thanks for the help and encouragement.
  7. There is no question your process is scientific and mine is pragmatic. Needless to say I look at this project as way to learn more about these things you know and I do not. Wanted to show that the 2441 with the Be diaphragm can get to 20kHz. There is not an exciting phase plot from eleven feet away. With the whole system playing it is a stair step shaped thing that drops like a rock above 1000 hz - writing from memory. I will go take some more measurements and post the filtered IR. I never save any of the stuff since changes are fairly constant. Take care,
  8. At the beginning of the Chris A project he had mentioned that there could be advantages to vertical mounting of the K402. Since this would make it lots easier to get closer into the corners and generally a less bulky installation I changed mine from horizontal to vertical this morning. I think it works better but there is no question they are too high. I have never had a system that sounded this good while walking around the room but that is not something i normally do. I am not saying it sounds immensely better - it is as much different as better. So the rationale is actually gaining some floor space. So considering it again. What I wanted to do at the beginning but got worried the horn wall was too curved and now I realize it would not be any more of a problem than the other set. It would stiffen the largest wall which needs the stiffening most but I wonder, since I have no idea, if this wall puts the ports in a less ideal place? Looks like the ports are going to be much nearer the surrounds where I suspect the short walls, just by their obvious nature will place them closer to the center of the cone. What do you think, Chris A? I have a bunch or MORTITE and so i applied it to one of the horns - It does make the walls sound duller when you tap them. I am not hearing anything at the moment. More of one of those things you do so you don't have to wonder if you should do them. Wish stainless steel shot was not so expensive - would probably make a good combination mixed into the MORTITE. But not a chance. No lead - does something weird to everything it touches.
  9. Got my plywood today. For anyone wanting 4 x 8 Baltic birch in the Atlanta area - SUWANEE LUMBER is Suwanee - close to Buford - is selling the sheets for $57.00. The price was so good I thought they were confused but it is the good stuff. I have settled on the dimensions of the big box - conditional on whether Chris A thinks i am going wrong - 44 inches wide - 37 inches tall - 16 inches deep. Would there be any deleterious effects from the box being that tall with the horn centered? I could move the horn closer to the top but having it centered would make it a little easier to get the baffles attached to the top and bottom of the box. Since there needs to be a baffle underneath I know the height is not important all to itself. The baffle below will be an enclosure for the RYTHMIK woofers. Luckily they do not require large enclosures to go as low as I would want. As is in my room they extend to 15 Hz with an actual rise in response after EQ. Not that I wanted a rise but that is how it works out AT THE MOMENT to get the flattest response. I got some of this stuff from McMASTER CARR and it seems to do some damping. I suspect more than one layer is needed. i figure this with some way of having contact with the box for the top and bottom of the horn to really settle down the horn? https://www.mcmaster.com/9709T29 With the horns mounted in a temporary 2 x 4 frame I am able to place 12 x 12 concrete pavers (with a thick felt between horn and paver) on the top with pavers underneath making gentle contact. The top and the bottom make a satisfying sound when tapped. The side are much better than when none of this was done but the baffles will make all of the difference in the world. Won't be able to use the concrete in the box but it shows me how much good reasonable pressure on the walls can make. The CD is supported by a stack of wood for the moment. McMASTER CARR is an amazing store! Like the ultimate HOME DEPOT. Another idea is to not remove the ribs entirely but make them 3/8 inch at their tallest - make a corresponding cut in the baflles to get a centering device. The cut would only be as long as needed - not across the board.
  10. A small box attached to the back of the big box to allow the thing to get further into the corner. The small box will be 2 pieces of 3/4 plywood for each side to make a very broad glue joint. T The small box will be the same finished height of the big box and centered on the back. I like the idea of having, initially, two access points to adjust things. The back fo the small box will eventually be glued. The back of the big box will be removable Easiest way to do it and less wasteful of plywood. Along with my inability to make a clean inside 90 degrees cut. As with most DIYers it will be overbuilt since I do not have ability to know what can be done without. I do not think anyone ever went wrong with a box that was too sturdy. I doubt i will be exploring the limits of that!
  11. IAt the moment the horns are supported by the front flange resting on concrete pavers atop a box along with a stack of wood to support the 2441. Tomorrow the CRITES gasket arrive and then i am going to install those with the crude 2 x 4 surrounds. Will be interesting to see/hear if it makes any difference at all. I thought there was some consensus that it is a good idea to keep the mouth stiff - the whole horn ideally, of course.. I will have measurements of both to compare. Whether what I think I am hearing is measurable by REW and my non usb mic - I did get the calibrated one from the folks in Michigan (?) and use a FOCUSRITE Scarlett2 USB box. I know when I cleaned up the throat there was a measurable difference - whether that difference is audible is another thing and whether what we can measure is what we are hearing is the biggest mystery of all. Still measurements are important as a comparative and a map of where you are going. Once you get used to doing it you cannot live without it. This could be both a good and a bad thing - could we start hearing what we are seeing? One has to stay on guard! I have no real idea where what I have called resonances are occurring. They are not audible like a LP tick, of course. More like that stuff we call digital noise - that bit of haziness that permeates everything = but is nothing like it used to be. We have come a long way with digital playback. I am one perfectly happy with REDBOOK since nothing much I am interested in comes in high resolution so I concentrate on that. I have bought a few 24/96 downloads but I did not have the REDBOOK version - namely ABBEY ROAD 2019 mix - I know one thing - the 2019 mix sounds much better than my original CD release which is more unusual than it should be. As it is with any audio component - it does take a while for the excitement of new to wane and one starts hearing things they did not at first. Of course, these are minor in the extreme but that is what all of this audio kookery is about - trying to get a little but closer. To make this clear - I was comparing them to a horn I had lived with for seven or so years. I was well acquainted with their foibles - or more properly their foibles were plainly revealed by the 402s. Every device has its weaknesses. Never for a minute do I not consider I could be dreaming. I was just wondering if others had noticed this, too, over time. There is not a doubt in my mind these are the finest sounding loudspeakers I have ever heard. I am so anxious to get a box built to heare 60 or lower Hz to 18 KHz coming from one source - it is all I am thinking about. (which made me think how strange it is we honor Mr. Hertz by usually writing Hz but not with Mr. Volta. I guess he should have dropped that vowel for a bit of extra infamy? To meet Chris A's advice to get the box within 18 inches of a corner - and knowing the limitations of my woodwoerking abioities i am going to make a box with another box on the back going from top to bottom but about one-third the width. This will get me much closer to the corner with a 45 inches width - my box will be slightly larger in the width and the height - and having a slightly larger internal volume than the KLIPSCH box per Chris A's measurements - assuming 3/4 inch material. The small box will extend 16 inches behind - 26 inches tall and 16 inches wide. I am not worried about those two dimensions being the same since much of this area will be filled with the compression driver and the larger back chamber I use. The chamber is a PVC plumbing cap that is the same diameter as the jbl. Much of the internal area has been filled since it would be too big as is and I have no way to cut it down accurately. I do not doubt this limits its ultimate power output but this means nothing to me since I do not want to know what that would be. The use of wool and wool felt in the enclosure does make an audible difference to me. As long as a placebo works why fight it! The box sides will be sixteen inches which will make it easier to find a way to attach the woofer baffles to the cabinet walls also to add damping stuff. Finding a way to put some pressure on the top and bottom of the horn with the enclosure is something I want to try. All thoughts and cautions are appreciated.
  12. Sorry about all of that wasted space on my last post. I did not do that on purpose. No question drivers having a snout have an easier time - but I found with the studs that it went fine. Thanks for your photographs babadono. Looks like you removed the big cork spacer from the K402? I have removed the stand to make it easier to make measurements plus I did not like all of that intermediary stuff - did not make a smooth transition. As it is i am using a small amount of mortite to fill in the gap hoping this will not be needed with the CRITES rubber gaskets which I have ordered. Very nice people. Sure is much easier checking for alignment with these versus the INLOW which your hand could not fit into. I have found that even a fifteen inches wide baffle will still need to be chamfered at the mouth side - the curve begins just before that.. My baffles will be closer to seventeen inches. Hoping for an intimate contact for damping and strengthening. I see my idea of using threaded rod is not realistic for the front of the baffle. Will have to use a piece of wood and screws. The front piece will be deep enught to make contact with the top and bottom of the horn. I want to be able to remove the baffle easily at the beginning. Eventually I would probably epoxy the baffles to the sides but still retain this to squeeze the baffles into the horn sides. Since I am going to follow what Chris A has recommended: placing the asembly in the corners as close as I can. A bib for beneath the K402s will be needed. Should this extend to the floor or should there be a gap? These bibs will contain the RYTHMIK woofers for the first octave. As I get to know these horns I am beginning to hear the resonances due, mostly I suspect, nothing attached to the mouth. I am going to build a crude frame out of 2 x 4s to use in the interim. Got my cutting list ready. Now to pick up some plywood next week. I had hoped Chris A's heavy duty CA402s would have become available but I could not wait any longer. Reading through the thread AGAIN I found this which told me in no uncertain terms that Chris A is a wise man. These thoughts are extremely appropriate and timely in this era of models and experts: ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- I think that a lot of people make the mistake of believing simulations over real life a great deal. In my experiences I've seen otherwise bright engineers make that mistake periodically over my engineering career, often to the derision of the more experienced engineers that knew better (...from the school of hard knocks). Fortunately, the enterprises that I worked in were guided by these most experienced engineers and those issues of over-belief in simulation were mitigated quite early before other less recoverable decisions were made from those simulation results. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Those are the words of someone I will follow.
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