djk Posted April 7, 2012 Share Posted April 7, 2012 I would start out trying a 38hz tuning, then add more mass and try 32hz. At this point you should be able to compare the frequency response data of both and decide which direction you should take. If 32hz seems to work OK, I would use a high Q filter at 32hz. This will give a bit of boost (depending on the Q) and offer protection from out-of-band signals. Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted April 7, 2012 Share Posted April 7, 2012 Can't wait to see the pictures and I'm sure the panel saw is going to save you a ton of time on the cutting. Indeed. CAD data is always perfect, but to actually MAKE something in the real world requires impefections knowns as "tolerance" which is a very good word indeed, from all aspects of philosophy, human temperance, and mechanics, LOL. Glad to see you are taking a careful approach with good tool and PRACTICING your technique. Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 7, 2012 Share Posted April 7, 2012 This is to prevent the music from driving the diaphragm and motor beyond its linear region. This is not a problem when the driver is in a sealed box because the acoustic spring of the box prevents the diaphragm from moving too much. Just as a sanity check, I'd like to point out the sheer number of ported speakers on the market, including all those made by Klipsch too. They're not all blowing up....even the pro sound stuff. Below tuning, you still have the mechanical damping of the driver. In all reality, a typical home listening session should not be pushing the system anywhere near its limits anyway. Not that I can disagree with The Doctor (who might well have a sonic screwdriver, smile). OTOH, "T. Rex" from Telarc (yup, Telarc gives warnings) did something bad awful to my EVM 15 in a Bigger Belle (not vented of course). It could have been the amp going crazy. I like to tell the story of doing and Exato knife post mortem on the voice coils of some sealed box 8" Speakerlabs woofers. I suspect they were taken outside for a party, with loudness and bass boost applied. Sorry, I should have taken pictures but it was before the days of a camera in every smart phone. There was charing of the former as well as physical distortion, and some melting of copper. The above does not really address Dr. Who's comment. But I've come to the conclusion that eventually some soul will find a way of staging a train wreck for a speaker. WMcD Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 7, 2012 Share Posted April 7, 2012 W.C. and anyone else. The book is pricy. No question there. Let me say the book is excellent and not too technical. it is very highly recommended by me. People may not know that just about any book in the U.S.A. can be obtained for you through your local public library -- even if it is an unassuming operation in a hamlet. You may have to apply for a library card, but that is just a matter of paperwork. Everyone doing research needs a library card! The mechanism is an interlibrary loan. Go to the reference librarian with the title of the book and author -- also an ISBN (International Standard Book Number, which you can find at Amazon for current books) if there is a question of identity of the book. In my situation: I went to Chicago Public Library downtown, Harold Washington library and they obtained Eargle's book for me from University of Illinios at Urbana. It took about two weeks to arrive and then I had it for three weeks. BTW University of Illinois has one of the largest libraries in the world and can be used by Illinois tax payers. But you can get books through the system. You may not know it but you also probably have on line access to WorldCat. http://en.wikipedia.org/wiki/Worldcat. It shows the location of any book at a subscribing library in the world, Any proud holder of a Chicago Public Library card can get on to the CPL website and get access to WorldCat. It may well be true for you through your local public library. So, do not underestimate the Far Side ladies (or gents) at your local library reference desk. They are waiting for someone to come in and ask for an Interlibrary Loan. The cost to you? It is all free! WMcD (once a reference librarian) Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted April 7, 2012 Share Posted April 7, 2012 In all reality, a typical home listening session should not be pushing the system anywhere near its limits anyway. Sez the man who used to say we should add a 30 db (1,000X) for "crest factor" Quote Link to comment Share on other sites More sharing options...
DrWho Posted April 7, 2012 Share Posted April 7, 2012 In all reality, a typical home listening session should not be pushing the system anywhere near its limits anyway. Sez the man who used to say we should add a 30 db (1,000X) for "crest factor" Haha, self-destruction is quite a bit different than maintaining the utmost in fidelity [] Quote Link to comment Share on other sites More sharing options...
DrWho Posted April 7, 2012 Share Posted April 7, 2012 There was charing of the former as well as physical distortion, and some melting of copper. The above does not really address Dr. Who's comment. But I've come to the conclusion that eventually some soul will find a way of staging a train wreck for a speaker. lol, great story - I love your descriptions [Y] Ya, I agree - there's always a way to blow stuff up. Shoulda ported those poor speakerlab woofers [] Quote Link to comment Share on other sites More sharing options...
Marvel Posted April 7, 2012 Share Posted April 7, 2012 But I've come to the conclusion that eventually some soul will find a way of staging a train wreck for a speaker. You can't make something foolproof, because fools are too ingenious... [:#] Quote Link to comment Share on other sites More sharing options...
Panacea Engineering Posted April 7, 2012 Author Share Posted April 7, 2012 Library...? What's a Library...? I thought they all closed down when Al Gore invented the Internet...! Anyway, great advoice...! I think I even I have a Library card around here somewhere, I believe it is with my Voter Registration Card....GUESS I had better dust both of them off....![H] Thanks for jogging my memory...see, two heads are better than one...hence why I need help on the testing...Come on guys.......think of it as a damn vacation...all expenses paid...I can certainly afford one of you cheap bastards....! Quote Link to comment Share on other sites More sharing options...
Panacea Engineering Posted April 7, 2012 Author Share Posted April 7, 2012 Sorry, Double...... Quote Link to comment Share on other sites More sharing options...
djk Posted April 7, 2012 Share Posted April 7, 2012 "The cost to you? It is all free!" My library expects a 'donation' whenever I ask for an inter-library loan, they seem to suffer from cranial-rectitius disease. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted April 7, 2012 Share Posted April 7, 2012 ...hence why I need help on the testing...Come on guys.......think of it as a *** vacation...all expenses paid...I can certainly afford one of you cheap bastards... how about some pictures of the local watering holes.... Quote Link to comment Share on other sites More sharing options...
WMcD Posted April 8, 2012 Share Posted April 8, 2012 I'm up for it. Right now I'm taking a class and that takes up basically all my free time for the next six weeks. Then I'll be signing up for a sumer class. I don't know that schedule, presently. There should be a break in between. Then I have some dates which I'm committed to. So I'll keep everyone posted. WMcD Quote Link to comment Share on other sites More sharing options...
ClaudeJ1 Posted June 27, 2012 Share Posted June 27, 2012 Is there a progress report in the near future?? Quote Link to comment Share on other sites More sharing options...
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