Drew in the desert Posted October 12, 2004 Share Posted October 12, 2004 This should be a simple question. How is the size of a driver measured? The reason I ask is I have RF-35's which have 8" drivers. I got out the measuring tape and came up with only 7" from the outer edges of the surround. Does the 8" specification come from the surface distance of the driver, perhaps? Quote Link to comment Share on other sites More sharing options...
JohnA Posted October 12, 2004 Share Posted October 12, 2004 It's usually and largest diameter of the frame. Quote Link to comment Share on other sites More sharing options...
Scp53 Posted October 12, 2004 Share Posted October 12, 2004 drivers are usually measured by frame diameter as already stated. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted October 13, 2004 Share Posted October 13, 2004 Yes, largest dimention. Actual cone size is only specified in detailed specs. Quote Link to comment Share on other sites More sharing options...
Drew in the desert Posted October 13, 2004 Author Share Posted October 13, 2004 Thanks for the help guys. Easy question, Easy answer. Quote Link to comment Share on other sites More sharing options...
kenratboy Posted October 13, 2004 Share Posted October 13, 2004 No problem - A/V gear related questions are ALWAYS welcome! Quote Link to comment Share on other sites More sharing options...
cc1091 Posted October 15, 2004 Share Posted October 15, 2004 You'll never guess where my mind was when I opened this thread. Returning from the gutter for a moment... Interesting how when I purchased my Heresy's (1981) I would have sworn the literature said they had a 10" woofer. Now I see all the info I find on this website says 12". The measured dimension seems to verify what is being said in this thread though. Has the way they measured the driver changed? Seems to me that I remember as a kid that the television industry suddenly changed how they measured the viewable surface of the television screen. Quote Link to comment Share on other sites More sharing options...
dantfmly Posted October 15, 2004 Share Posted October 15, 2004 ---------------- On 10/15/2004 12:03:20 AM cc1091 wrote: You'll never guess where my mind was when I opened this thread. Returning from the gutter for a moment... Interesting how when I purchased my Heresy's (1981) I would have sworn the literature said they had a 10" woofer. Now I see all the info I find on this website says 12". The measured dimension seems to verify what is being said in this thread though. Has the way they measured the driver changed? Seems to me that I remember as a kid that the television industry suddenly changed how they measured the viewable surface of the television screen. ---------------- when heresy first came out they were 10" woofers (i know that), later models of the heresy i think were 12". i don't know that for certain . i do know for certain the heresy II's have always been 12" Quote Link to comment Share on other sites More sharing options...
lynnm Posted October 15, 2004 Share Posted October 15, 2004 On 10/15/2004 12:03:20 AM cc1091 wrote: You'll never guess where my mind was when I opened this thread. Returning from the gutter for a moment... That must be a pretty lousy golf course! Quote Link to comment Share on other sites More sharing options...
TheEAR Posted October 16, 2004 Share Posted October 16, 2004 As was posted the outer edge of the frame. Some 6.5 woofers have a larger piston than "larger" 8" woofers.The frame and sourround size will eat away at cone size(effective size of the speaker).Speaker comanies should start listing piston(cone)size,like Velodyne. To me speaker size starts at the outer edge of the sourround,as some companies make very wide frame edges to max the specs and claim a 20" driver where its in reality a 18".Like Magnat Quote Link to comment Share on other sites More sharing options...
ricktate Posted October 16, 2004 Share Posted October 16, 2004 Im going to have to disagree with dantfmly about the Heresy woofer,,,,i think its been 12 inch all the time. We may need HDBR,,Andy to confirm this but i have seen some very old ones and they all are 12 inch woofers. Rick Quote Link to comment Share on other sites More sharing options...
dantfmly Posted October 17, 2004 Share Posted October 17, 2004 ---------------- On 10/16/2004 11:43:23 PM ricktate wrote: Im going to have to disagree with dantfmly about the Heresy woofer,,,,i think its been 12 inch all the time. We may need HDBR,,Andy to confirm this but i have seen some very old ones and they all are 12 inch woofers. Rick ---------------- i have seen heresy's for sale all over the place and the older ones always have 10" woofers in them. that is where i got that from. Quote Link to comment Share on other sites More sharing options...
John Warren Posted October 17, 2004 Share Posted October 17, 2004 ---------------- On 10/16/2004 7:53:19 PM TheEAR wrote: As was posted the outer edge of the frame. Speaker comanies should start listing piston(cone)size... They do indirectly. The effective piston area of the cone is Sd so solving for the diameter is then d = SQRT < 4 Sd / pi> (where pi ~3.1416) To me speaker size starts at the outer edge of the sourround, That's how the effective piston diameter is defined which, as you point out does not correlate entirely with frame size (remember the Advent!). as some companies make very wide frame edges to max the specs and claim a 20" driver where its in reality a 18". That's why Sd is a better indicator, it considers the actual piston area of the cone, not the frame size. Sd, Xmax and Fs determine the maximum linear acoustic power (Watts) a transducer is capable of achieving. ---------------- Quote Link to comment Share on other sites More sharing options...
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