Deang Posted June 16, 2011 Share Posted June 16, 2011 http://materion.com/~/media/Files/PDFs/Electrofusion/PLS%202011%20PAPER%20FINAL.pdf Note pages 23 - 25 Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted June 16, 2011 Share Posted June 16, 2011 wow you're optimistic, after its fails this will be, what is this your 5th kid? Quote Link to comment Share on other sites More sharing options...
Deang Posted June 16, 2011 Author Share Posted June 16, 2011 Aluminum vs. Titanium IMD http://www.radianaudio.com/index.php?option=com_virtuemart&page=shop.browse&category_id=33&Itemid=40 Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 16, 2011 Share Posted June 16, 2011 I never liked diaphragms. Quote Link to comment Share on other sites More sharing options...
Deang Posted June 16, 2011 Author Share Posted June 16, 2011 Don't even know why I bother coming here anymore. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted June 16, 2011 Share Posted June 16, 2011 [] Quote Link to comment Share on other sites More sharing options...
mikebse2a3 Posted June 16, 2011 Share Posted June 16, 2011 Thanks for posting the Paper Dean mike tn Quote Link to comment Share on other sites More sharing options...
Modified-Tractrix Posted June 16, 2011 Share Posted June 16, 2011 Interesting paper, thanks for the link. It sounds like some used JBL drivers with the new Be diaphragms from truextent could be a good solution. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 16, 2011 Share Posted June 16, 2011 Thanks Dean, its been pretty quite around here lately on the upgrade and modification front. looking forward to the switch to Beryllium reports. Quote Link to comment Share on other sites More sharing options...
Chris A Posted June 17, 2011 Share Posted June 17, 2011 Aluminum vs. Titanium IMD http://www.radianaudio.com/index.php?option=com_virtuemart&page=shop.browse&category_id=33&Itemid=40 Internal damping of the vibrating material is important as you get into the 10-20 KHz region. It's been said that a lot of the measured SPL of compression drivers in that band is measuring the ringing in the diaphragms. This includes more exotic materials, such as Ti and Be. Apparently, what Be does is to push the ringing into higher frequencies than Ti. Aluminum as a diaphragm material is apparently avoided in commercial applications because it yields (goes plastic) and work hardens, etc. In home applications, Al may be preferred.One newer suggestion made in another thread was to look at a pure Mg material for the diaphragm, which has ~5x more internal damping than Al or Ti alloys, and about 2X more damping than typical Mg alloys. Unfortunately that suggestion was immediately dismissed with a rumor of driver beaming. Maybe another look is warranted? Chris Quote Link to comment Share on other sites More sharing options...
Deang Posted June 17, 2011 Author Share Posted June 17, 2011 Hi Chris, O.K., if you want to talk more about that Fostex tweeter, I'll meet you back over in the other thread. :-) Beryllium loaded drivers rule the roost, but they are pretty expensive, and most don't consider them for that reason alone. There is the used market of course, but there is considerable risk going in that direction, since one never really knows anything about the history of the drivers, and the diaphragms alone are not cheap by any stretch. People for the most part base their choice on what they can reasonably afford, and here we basically have phenolic, aluminum, and titanium based drivers. For the midrange, there is another choice: cones -- run in tandem, horn loaded, or alone at the expense of higher efficiency. I think the paper shows fairly conclusively that titanium, though not unsuitable for the home system application, is inferior to aluminum when speaking in the context of lower distortion and better sound quality. Compression drivers are primarily designed for fixed installations, used to fill large areas with sound, and for that you need high output and a high degree of reliability. In these installations, low distortion and sound quality apparently take a back seat to reliability. "In an attempt to address the sound quality issues voiced by some audio professionals, it was decided to look closely at the time domain behavior of each of these diaphragms...titanium ribbed diaphragm shows the worst ringing of the four diaphragms, exhibiting long decay at both the upper two octaves and at 1kHz...the titanium diaphragm with no ribs is the second worst performer on the wavelet decay test, it suffers from the top octave and 1kHz ring...the aluminum diaphragm has good decay behavior, both in the upper two octaves and at 1kHz ... it appears that the aluminum and the beryllium diaphragms have similar decay characteristics, and both are better than titanium in that regard...Although we have done no formal listening tests of this effect, it has long been stated by audio professionals that the titanium diaphragms do not sound as good as the original aluminum ones, but they are prized for their reliability..." Quote Link to comment Share on other sites More sharing options...
Chris A Posted June 17, 2011 Share Posted June 17, 2011 Okay, but just to point out that pure Mg isn't in the same price category as Be diaphragms (about $600/driver), here is an extracted table out of the paper that I linked, above. Note the last row - internal damping: Sound Property Comparisons of Light Metal Materials: 99.9% ‘pure’ Mg Mg-Alloys Al-Alloys Titanium Specific Gravity (g/cm3) 1.74 1.77 2.74 4.5 Young’s Modulus (Gpa) 40 41 65 110 Speed of Sound (m/s) 4760 4880 4880 4940 Bending Strength 2.76 2.72 1.78 1.1 Vibration decline /damping factor 0.01 0.0044 0.0025 0.002 Quote Link to comment Share on other sites More sharing options...
michael hurd Posted June 17, 2011 Share Posted June 17, 2011 I'd wager it has a lot to do with the diameter of the diaphragm, and the compression ratio, IE: how hard the diaphragm is working. There are also many grades of TI foil used, same goes with aluminum. I am not sure that they can all be painted with the same brush so to speak. I found this picture on the AVS forum with a few different compression drivers, and their respective wavelets. Quote Link to comment Share on other sites More sharing options...
moray james Posted June 17, 2011 Share Posted June 17, 2011 Michael: can you give the Cole's Note's comment on what these colorfull graphs mean? Thanks. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted June 17, 2011 Share Posted June 17, 2011 There is also a controversy over what is marketed as Be...... at least from a few manufactuers, notably Usher Audio. See the second post with the truth .pdfas well. what.pdf Quote Link to comment Share on other sites More sharing options...
michael hurd Posted June 17, 2011 Share Posted June 17, 2011 Steve Mowry - Truth. It seems that when the document was converted from .doc to .pdf ( the forum wouldn't let me upload a .doc file ) that a chart was mangled. Let me see if I can get a screen shot of that up. truth.pdf Quote Link to comment Share on other sites More sharing options...
Chris A Posted June 17, 2011 Share Posted June 17, 2011 can you give the Cole's Note's comment on what these colorfull graphs mean? The vertical axis is frequency, the horizontal axis is time. The color of the plotted areas signifies relative intensity at that frequency and time. The idea of the plots is to show the time decay of compression driver/horn combinations to an impulse drive input from an amplifier. A perfect driver will show a symmetric pointed top and a broad base with sloped sides, plus all-blue to the right of the impulse response peak. In reality, compression drivers/horns "chatter", especially above 10 KHz, as shown on the chart. For Ti diaphragm drivers, that chatter can be excessive, and it shows up as a "smeared cymbal" reproduction, whereas Be diaphragm drivers tend to exhibit much more "crisp" behavior. However, there is chatter above 20 Khz for Be drivers/horns, which is usually not plotted--because humans cannot hear it...but your dog might... Chris Quote Link to comment Share on other sites More sharing options...
Speakmeister Posted June 17, 2011 Share Posted June 17, 2011 Where is the proof that Mg is not suitable for a diaphragm? I have been using Mg fixtures in Aerospace for nearly 20 years because it exhibits good damping. the aluminum fixtures are much heavier and tax the digital controllers with all the modes they exhibit. Quote Link to comment Share on other sites More sharing options...
Chris A Posted June 17, 2011 Share Posted June 17, 2011 Where is the proof that Mg is not suitable for a diaphragm? Do any of the articles say that? I didn't say that... Chris Quote Link to comment Share on other sites More sharing options...
Speakmeister Posted June 17, 2011 Share Posted June 17, 2011 Chris, I am not responding to your post as you seem to point out the damping of Mg. I really do not understand why it is not used more as a diaphragm material. Quote Link to comment Share on other sites More sharing options...
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