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Amp Power Question |
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opus jody 
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Joined: 06 June 2006 Location: United Kingdom Status: Offline Points: 1244 |
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 Posted: 12 June 2022 at 9:55am |
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IDK the answer, but speaker impedence isn't actually constant, it's frequency dependent.
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Improvised Hardware Music http://vimeo.com/user9389813/videos
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Randy Bohannon
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Joined: 29 May 2022 Location: London Status: Offline Points: 107 |
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Posted: 12 June 2022 at 10:45am |
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What I meant was that when comparing power delivered into a speaker, impedance is a constant.
At whatever frequency, providing you are using the speaker and the same box, the load presented to the amplifier is the same. Edited by Randy Bohannon - 12 June 2022 at 4:33pm |
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snowflake
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Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3061 |
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Posted: 12 June 2022 at 1:48pm |
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isn't a music signal crest factor of ~10db on the POWER of the signal not the voltage. this seems to say so under 'test signals' section where they talk about a 12dB crest factor on power Loudspeaker SPL Expectations and Reality | Danley Sound Labs this suggests a range of 6dB-20dB on power - but surely 20dB is on stuff like classical recordings not rock or dance music Understanding The Nuances Of Crest Factor - ProSoundWeb |
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toastyghost
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Joined: 09 January 2007 Location: Manchester Status: Offline Points: 10883 |
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Posted: 12 June 2022 at 10:14pm |
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No it isn’t. The electrical impedance changes with the acoustical load, including temperature increase and other non-linear behaviours of the transducer and cabinet. Regardless of this; you also need to consider the difference between apparent power and real power. This is super important since loudspeaker power ratings are calculated from the measured voltage and nominal (or lowest) impedance in the passband - depending on the testing standard used. 20dB crest factor is also very prominent in popular music, at the high frequencies. I suggest reading the AES75-2002 standard document and the papers related to the M-Noise test signal. |
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sam012
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Posted: 14 June 2022 at 12:34am |
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The Blue Aran Jam amps are £1250 for the K16, I understand there's difference in quality between K16 + FFA6004 but my inexperience fails me completely in which would be better at this price point. The JAM amps haven't cropped up as being problematic from my googling? Would running 8ohm @ 1600w not be better than FFA which is 4 ohm @ 1500w? To answer my own question after some thought, the only benefit really is the extra ~100W of headroom for £700 less but opting for a chinese made amp (numbers below) over picking say a FFA 6004 The main amp picking issue I'm having is seeing anecdotal comments saying stuff like the "k10 sounds bad imo, the k20 is better" so I sort of have ADHD on which amp to finally decide on - as the search goes on the budget goes up and up, bringing me back to maybe I should just get the cheaper JAM amp K16 £1250: 4 channel mode: 8 ohm: 4 x 1600W 4 ohm: 4 x 2800W 2 ohm: 4 x 3500W Soundgear Saturn 16 £1080: 8ohm: 4 x 2100w 4ohm: 4 x 4200w FFA - 6004 ~£1800 ebay - 8ohm: 4 x 900W 4 Ohm 4 x 1500W Edited by sam012 - 14 June 2022 at 1:10am |
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VECTORDJ
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Posted: 14 June 2022 at 4:24am |
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QSC Amps are A+
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KDW32
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Joined: 09 April 2010 Location: Green Hell Status: Offline Points: 403 |
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Posted: 14 June 2022 at 8:28am |
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I couldnt find any info on a void V12 1000 did you mean 18 or have I missed so something googling?
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Randy Bohannon
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Posted: 14 June 2022 at 4:42pm |
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Thanks for taking the time to explain it further. :) The impedance load that a particular speaker presents, in a particular box and assuming the same programme material is a constant if all that is being varied is the amplifier(s) testing it, surely? Thanks you for the references, I couldn’t track down a public domain copy of that paper but read up on The idea behind the M tone and it makes sense to me. The ran a few tracks through a spectral analyser and can see how they arrived at their conclusions. The 20 dB crest factor you mentioned makes more sense l, being primarily a function of high frequency content, as the average power content of this portion of the musical spectrum is lot lower in power than than the lower frequencies. So, if I have understood correctly, if the average programme rms if the woofer is 200w, the tweeter might be getting 10w and the 20dB crest factor on 10w seems more realistic. Why does that mean quoting power in voltage, which is independent of impedance and voice coil/cabinet reactance, is that preferable to power, which accounts for impedance by factoring in current, or indeed VA and phase which would be needed to calculate real AC power?
Edited by Randy Bohannon - 14 June 2022 at 4:42pm |
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Randy Bohannon wrote:
the thing is the Watts aren’t what you’d really want more of. The peak voltage capability is what makes the speaker move and handle the peaks for dynamic, good music. Bridging was / is a way to get an amplifier to be able to handle the exceptional peak voltage demands for unclipped music transients.