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Post by deltadube on Apr 15, 2013 14:37:32 GMT -5
A better source for audio information than Wikipedia is the Rane Reference Library: www.rane.com/digi-dic.htmlThey define damping factor as: damping factor Damping is a measure of a power amplifier's ability to control the back-emf motion of the loudspeaker cone after the signal disappears. The damping factor of a system is the ratio of the loudspeaker's nominal impedance to the total impedance driving it. Perhaps an example best illustrates this principle: let's say you have a speaker cabinet nominally rated at 8 ohms, and you are driving it with a Rane MA 6S power amp through 50 feet of 12 gauge cable. Checking the MA 6S data sheet (obtained off this website, of course), you don't find its output impedance, but you do find that its damping factor is 300. What this means is that the ratio of a nominal 8 ohm loudspeaker to the MA 6S's output impedance is 300. Doing the math [8 divided by 300] comes up with an amazing .027 ohms. Pretty low. Looking up 12 gauge wire in your handy Belden Cable Catalog (... then get one.) tells you it has .001588 ohms per foot, which sure ain't much, but then again you've got 100 feet of it (that's right: 50 feet out and 50 feet back -- don't be tricked), so that's 0.159 ohms, which is six times as much impedance as your amplifier. (Now there's a lesson in itself -- use big cable.) Adding these together gives a total driving impedance of 0.186 ohms -- still pretty low -- yielding a very good damping factor of 43 (anything over 10 is enough, so you don't have to get extreme about wire size). [Note that the word is damp-ing, not damp-ning as is so often heard -- correct your friends; make enemies.] " ABig Thank you Sir for this post!I now have to go shorten my L/R front speaker cables..I knew there was more too this Dampn-ing thing..But really thanks I found a Thread where on a HarmanKardon site the two where talk just about this everything too consider when Factoring the Damping of an amp.Your spot on Bro! is that you fox hole joe! yeah man shorten the cables... what awg guage cables you running bro?
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Post by deltadube on Apr 15, 2013 16:21:51 GMT -5
cool thanks... Dy...
ok if you bi wire 12 awg dose that double the impedance of the run vs going to 10 awg which would lower the impedance of the run?
thanks
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DYohn
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Posts: 18,347
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Post by DYohn on Apr 15, 2013 16:43:40 GMT -5
cool thanks... Dy... ok if you bi wire 12 awg dose that double the impedance of the run vs going to 10 awg which would lower the impedance of the run? thanks Using two 12 AWG wires is the same as using one 9 AWG wire.
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Post by jjmatrix on Apr 15, 2013 17:45:15 GMT -5
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Post by deltadube on Apr 15, 2013 21:58:53 GMT -5
saw a link at the top of the amp thread page like this one.. missing the damping factor too.. thanks tho... well maybe it is dependant on the rain eh..
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Post by audiohead on Apr 16, 2013 2:15:33 GMT -5
ABig Thank you Sir for this post!I now have to go shorten my L/R front speaker cables..I knew there was more too this Dampn-ing thing..But really thanks I found a Thread where on a HarmanKardon site the two where talk just about this everything too consider when Factoring the Damping of an amp.Your spot on Bro! is that you fox hole joe! yeah man shorten the cables... what awg guage cables you running bro? That be Me! ;D..Running 12 AWG on the L/R mains and C the surrounds are 14 AWG I had forgot that you want to keep speaker cable runs as short as you can get them I read that somewhere back in the 70's don't know if or how true that is today?The littlest thing can and will mess up your system.I had Plugs on all of my speaker cable runs from the amp and to the speakers don't use speaker plugs at all now took them out cause for some dam reason I lost low end on my set up now I just use the Old 1/4 cut and into the lugs they go.So yeah buying cheap Banana plugs can and will F-up your system.
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Deleted
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Post by Deleted on Apr 16, 2013 8:31:08 GMT -5
Thanks for that EmoVault link, very informative. From what I can discern, the RPA-1/2 were some *killer* amps. AND, they have those very cool meters. I wish Emo would bring back the meters...
-RW-
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Post by ocezam on Apr 18, 2013 12:03:30 GMT -5
Thanks for that EmoVault link, very informative. From what I can discern, the RPA-1/2 were some *killer* amps. AND, they have those very cool meters. I wish Emo would bring back the meters... -RW- Agreed! ...
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Post by mrranting on Oct 9, 2018 8:27:34 GMT -5
Xpa1 have a DF>500.
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Post by vcautokid on Oct 9, 2018 8:33:29 GMT -5
Correct Keith had posted that information to that a while ago.
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KeithL
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Post by KeithL on Oct 9, 2018 9:44:20 GMT -5
I provided a bit more of a detailed explanation about what damping factors does and why it matters here: emotivalounge.proboards.com/thread/44528/damping-factor-8ohm-4-ohmThe bottom line is that VERY low damping factors - between 1 and about 50 - sound audibly different. However, any damping factor above a few hundred is high enough that the differences are negligible. (Also, actually measuring damping factor above a few hundred accurately is somewhat difficult.)
All of our current amp models have a rated damping factor of 500 or >500 - which you should really read as "high enough that making it any higher wouldn't gain you anything".
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Post by donh50 on Oct 12, 2018 10:21:53 GMT -5
The AES has done studies along with many others... As has been said several times DF = Zload / Zsource or for us speaker impedance divided by amplifier output impedance. While to an EE it is complex (magnitude and phase), most just use magnitude and it's close enough. Note output impedance rises with frequency and thus damping factor drops with frequency. The rise is a combination of feedback factor and the way devices behave (device physics). For most speakers anything above 20 or so is inaudible IIRC (do not have the AES study at hand). I personally shoot for about 100 from a SS amp. Tube amps are often in the 5-20 range which explains why they are so much more sensitive to the speaker. Larger, as in higher-power, amplifiers tend to have higher damping factors as a consequence of the multiple output devices and (sometimes) higher loop gain (feedback factor) since they need more gain to produce full power with a reasonable input voltage. Speaker impedances vary wildly, with large peaks and valleys, so the simple equation is rarely accurate. I tend to use the lowest speaker impedance number ratioed to the amplifier's damping factor (or output impedance) at the specified load impedance (typically 8 ohms) to see if the worst-case DF is better than 20~50 or so. I am less concerned with high-frequency damping since the drivers are much smaller and typically exhibit much less back-emf compared to a woofer. DF is very low on the list of specs I check as important to amplifier performance. I expect tube amps to be low, and SS amps to be high enough to be irrelevant except in a few special cases (typically very low-power amps). I think about DF along with the speakers I plan to drive and decide if I care at all. Note speaker cables degrade the DF the speaker "sees"; look at this Wikipedia article for resistance: en.wikipedia.org/wiki/American_wire_gauge With a big SS amp it is not uncommon to halve the DF due to the wire run (remember the speaker cable has (+) and (-) wires so double the resistance for a given length). Add the wire resistance to the amplifier's output impedance to get the effective resistance seen by the speaker. FWIWFM - Don
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