Amps available today ? |
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martinsson
Registered User Joined: 19 June 2007 Location: Sweden Status: Offline Points: 325 |
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It really would help if the amplifier manufacturers could agree on a specific method that is always published, like FTC for instance, then they can add whatever elae the want, like PMPO, EIA or IHF, I do lot know if any such agreement is in effect, or has been, sure does not look like it.
But not only that, it needs to be a method that acually means something for the real world perfomance, it could even be so that they need to publish two different methods in order to show the characteristics of the amplifier, simillar to both peak and rms.
Edited by martinsson - 20 December 2019 at 12:41pm |
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Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/
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Timebomb
Old Croc Joined: 11 October 2004 Location: Lancaster Status: Offline Points: 2716 |
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If an amp can output 1/4 of its rated power into 4 ohms continually, and sustain for a few hundred milliseconds then it will be fine even when playing heavy dubstep. The problem is if you have a modern amp that can deliver 3000W into 4 ohms burst, and 3000W into 4 ohms with a 9dB crest factor (4:1 duty cycle), equivalent "real power" 750W continual sinewave into 4 ohms, if you publish that it can do 750W continual sinewave people will think it is equivalent it to older 750W amps... People seem to think that a continual sinewave output is a good way to evaluate an amplifiers output capability, when in the real world no one plays long sinewaves into resistive loads. |
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James Secker facebook.com/soundgearuk
James@soundgear.co.uk www.soundgear.co.uk |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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This is the old Lab Gruppen method on how they stated their wattage specifications. This may have been the best way to satisfy those who prefer continuous average power ratings and, those who rather have burst ratings.
The chart allows the user to correlate the diversification of music being used the most, to the output power you can expect from the amplifier. Since music material can vary from High Crest Factor to Low Crest Factor, one could gauge the output wattage based on the type of Crest Factor used the most in their music material.
If you understand the Ohm's Law, it is not difficult to attain the Continuous Average rating of an amplifier based on the Peak rating and/or the Peak rating based on the Continuous Average Rating.
With modern Class D amplifiers, the limiter select switches follows the Ohm's Law Rule. So it is a matter of merely converting volts to watts at the given load.
Best Regards,
Edited by Elliot Thompson - 20 December 2019 at 2:14pm |
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Elliot Thompson
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Tonskulus
Registered User Joined: 15 September 2017 Location: Finland Status: Offline Points: 425 |
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Still some amps sounds tighter, more brutal on bass even having less continuous RMS power than another one in comparsion. It has something to do with DF and/or feedback loop, also maximum available current (when pushing to the limits). Speaker is not simple load, far from pure resistive.
So absolute power ratings are not everything we need to know about. Just go and get some amp and try it out. if not satisfied then try something else. Another weird thing is, people usually hear what they want to. And that becomes the truth they believe. If one wants scoop to be the best subwoofer type ever, he only hears the good things about it - discarding all the distortions etc. The best component on paper is not always the best in reality. Edited by Tonskulus - 20 December 2019 at 5:55pm |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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The Tempo of the music will dictate the performance level you've described. The Tempo of the music correlates to the degree of Crest Factor.
Controversy can develop on Speakerplans due to the wide variety musical taste from members. It is similar to choosing a horn-loaded enclosure versus a Bass Reflex enclosure versus a Bandpass design. The best design falls more to wards the tempo of the music that is used the most.
The Mid-Hi cabinets will also play a major roll on the bass performance. Midrange tends to be always overlooked by a good amount of sound professionals. Midrange however, plays a major factor on the bass and treble performance.
The best thing one should do is focus on the primary music material that is used 90% of the time to attain the best sound possible. If the remaining 10% that you rarely play sounds acceptable to you, it will sound fine to everyone else you are catering for.
Have a better understanding of the impedance curve of your loudspeakers in the enclosure. Those who understand the impedance curve of their loudspeakers in the enclosure and, take the Ohm's Law into factor, can get the results right the first time. It will make the task far easier when choosing the best amplifier suited for your loudspeakers. If one takes their craft seriously, they will learn the Ohm's Law. The Ohm's Law not only dictates the amplifier's performance, but the loudspeaker as well.
Best Regards, |
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Elliot Thompson
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3118 |
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erm, no it doesn't |
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martinsson
Registered User Joined: 19 June 2007 Location: Sweden Status: Offline Points: 325 |
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The way an amplifier interacts with the load and how this influences the perception of the sound is a very intresting area, and one so complex I think it deserves a thread of its own as it touches upon output stage design, type of feedback, output impedance, loadcharacteristics and powersupply, (amongst other things) I have asked about this on diyaudio.com but it was never completly resolved, but please share your thoughts, it is a very intresting area.
Regarding the load part, here we have an unfortunate but necesary missmatch between the reality of the load (speaker) and the nice resistive and predictable load used to specify the output power, necesary in the context of the great variation of speakerdesigns and their impedance signatures which is dependent on the driver but even more so on the type of enclosure (loading) in which the driver is deployed. The impedance signature of a speaker can vary grately depending on what type of enclosure used, from the relative simplicity of a closed box to the more complex higher order quarterwave design, but there is more to this than the impedance alone, the amplifier also have to deal with the reactive parts of the load which is just as diverse, and all is varying with temerature.
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Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/
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martinsson
Registered User Joined: 19 June 2007 Location: Sweden Status: Offline Points: 325 |
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Thats very true, and to some extent beneficial in that it makes up all intresting discussions about theoretical and measurable parameters versus the expirience and percieved performance since these rarely go hand in hand, another very intdresting topic. What counts in the end, regardless, is the listening expirience, and I for one is not conviced that we have defined everything sufficiently well to bridge the gap completly between theory and expirience, adding to that we are individual humans with different tastes and hearing, and thats a really great thing. This ties back to my previous "mild and friendly rant" about the lack of diversity in the speakerofferings from the most common brands where bassreflex and other helmholtz based solutions togheter with a predominatly surface mount configured linearrays seems to be the best we can do for the listeners expirienced sound quality, but I don't belive it is, but it sure is predictable, consistant and convinient, which are very important factors as well. Edited by martinsson - 21 December 2019 at 10:45am |
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Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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In Car Audio competition, it is very common to slow down the tempo of tracks to achieve very low frequencies. Not only does it shift the bass frequencies downwards, it also takes more time for the bassline to complete the passage (similar to playing a 45 RPM Record @ 33 1/3 rd speed) compared to playing the track at it's correct speed. This result can be easily shown on an RMS Analogue VU Meter. An RMS Analogue VU Meter will display how long the needle will remain at a certain level before it reverts back to 0 when comparing a slower tempo track to faster tempo track. Peak meters respond too quickly, and can give you the false assumption of a continuous average level. They are not designed for that purpose. However, they work well to determine the peaks.
Low Crest Factor is based on a constant level for long periods
High Crest Factor is based on impulse response for short periods
If you are playing frequencies ranging from 20 cycles 40 cycles per second, it takes more time to complete its period than playing frequencies ranging from 50 cycles to 100 cycles per second.
Best Regards, |
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Elliot Thompson
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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It is a very long, winding and time consuming topic to venture. It requires more of a "Show and tell" to be understood since you are manipulating voltage and current.
Pro Audio Amplifier Manufactures are capitalising on the loudspeaker's variable impedance characteristics but using the "We don't listen to sine waves" as an excuse. Since amplifiers are benched using a dummy load, it is not per say the sine wave being the issue but, the constant current being pulled from the amplifier by the dummy load causing the amplifier to protect itself.
History shows us there were many loudspeakers that were known for offering a constant load in which, created havoc to amplifiers. Because such speakers are not on top of the Pro Audio Amplifier Manufacture's list due to being marketed solely for the High End Home Audio crowd, it does not affect the Pro Audio Amplifier Manufacture in terms of sales.
Absolutely! This is why sound system owners must know their loudspeaker's characteristics. Sound System Design is about getting a better understanding on how your Sound System functions. If the designer is not interested in focusing on how his/her Sound System components work together to create pleasing to their ear result, then they should just buy Powered Loudspeakers punch in a preset and call it a day.
There are many who have gave up on the whole amplifier -
loudspeaker mating scenario and, have moved to wards powered speakers in the
Pro Audio Industry. Best Regards, |
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Elliot Thompson
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