Recommend speakers/amp for cabin?
#16
04-04-2010, 03:45 AM
The question I have is whether the THD listed is at 100% RMS or not - neither the THD or S/N at listed RMS is listed on Crutchfield yet.
Last edited by Wrathernaut; 04-04-2010 at 04:30 AM.
#17
04-04-2010, 04:25 AM
I have the HD 750/1 and HD 600/4 Now on this G, on my old G i used Focal Power 2150 and 1800 powering an all focal system, Both were great, I personally dont notice much of a difference in both of my setups, I spent more on the Focal setup but am just as happy with the cheaper setup I use now.
#18
04-04-2010, 05:00 AM
#19
04-04-2010, 12:53 PM
My $0.02.
http://bcae1.com/
#20
04-04-2010, 05:21 PM
How could an amplifier's clipping point (inducing distortion into speaker voice coils) be frequency dependent?
http://www.bcae1.com/ampclass.htm
# Class A amplifiers are very inefficient and produce lots of heat because there is a large amount of current flowing through the output transistors even with no audio signal.
# Class B amplifiers are more efficient but will have a 'notch' distortion.
# Class AB amplifiers are moderately efficient (depending on bias current) but notch distortion is eliminated by the idle (bias) current.
# Class D amplifiers are very efficient but are generally used for non high fidelity or subwoofer applications.
# Class B amplifiers are more efficient but will have a 'notch' distortion.
# Class AB amplifiers are moderately efficient (depending on bias current) but notch distortion is eliminated by the idle (bias) current.
# Class D amplifiers are very efficient but are generally used for non high fidelity or subwoofer applications.
Class D designs are almost to the point where they are suitable for high frequency and subwoofer use. Most do not have the fidelity (yet) needed for anything above the bass range but they're getting there.
Class D amplifiers produce higher distortion than AB designs due to the high-speed switching on and off of the transistors, but this distortion occurs at high frequencies that are typically removed by a low-pass filter.
Last edited by Wrathernaut; 04-04-2010 at 05:25 PM.
#22
04-04-2010, 05:49 PM
Not targeting a specific class of amps - can you honestly say that impedence is not a factor when conducting THD bench tests?
#23
04-04-2010, 06:09 PM
It's not that I don't believe you, I may just completely numb here - I don't see where bcae1 points out that THD increases with frequency. I just don't.
Not targeting a specific class of amps - can you honestly say that impedence is not a factor when conducting THD bench tests?
Not targeting a specific class of amps - can you honestly say that impedence is not a factor when conducting THD bench tests?
I can't argue that impedance isn't a factor in THD bench tests.
Unless they're CEA-2006 compliant, when it isn't:
CEA-2006 Compliant
On May 28, 2003, the Consumer Electronics Association published standard CEA-2006, "Testing & Measurement Methods for Mobile Audio Amplifiers." This "voluntary" standard advocates a uniform method for determining an amplifier's RMS power and signal-to-noise ratio. Using 14.4 volts, RMS watts are measured into a 4-ohm impedance load at 1 percent Total Harmonic Distortion (THD) plus noise, at a frequency range (for general purpose amplifiers) of 20 Hz to 20,000 Hz. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. This applies to both external amplifiers and the amplifiers within in-dash receivers.
On May 28, 2003, the Consumer Electronics Association published standard CEA-2006, "Testing & Measurement Methods for Mobile Audio Amplifiers." This "voluntary" standard advocates a uniform method for determining an amplifier's RMS power and signal-to-noise ratio. Using 14.4 volts, RMS watts are measured into a 4-ohm impedance load at 1 percent Total Harmonic Distortion (THD) plus noise, at a frequency range (for general purpose amplifiers) of 20 Hz to 20,000 Hz. Signal-to-Noise ratio is measured in weighted absolute decibels (dBA) at a reference of 1 watt into 4 ohms. This applies to both external amplifiers and the amplifiers within in-dash receivers.
Now if the THD and S/N aren't done by CEA-2006 specifications, then you're going entirely by the manufacturer's claims.
Like the "225 watt" Bose sound system in our cars.
Last edited by Wrathernaut; 04-04-2010 at 06:16 PM.
#24
04-04-2010, 06:41 PM
I'm a bit confused as to whether they put a 4-ohm load on it, and once there's 1% THD, they measure the watts, then round down and sell it as that many watts RMS with 1% THD, or a manufacturer says "It's 200w RMS amp" so they put a 4-ohm load on it, pull the RMS watts out of it, and if THD is less than 1% it's CEA-2006 certified at that RMS, and if it's lower than 1%, you can claim ".05% THD at 100% of RMS".
Now if the THD and S/N aren't done by CEA-2006 specifications, then you're going entirely by the manufacturer's claims.
Like the "225 watt" Bose sound system in our cars.
Now if the THD and S/N aren't done by CEA-2006 specifications, then you're going entirely by the manufacturer's claims.
Like the "225 watt" Bose sound system in our cars.
I'll make an assumption here and say that when you talk about "100% RMS", you're referring to the deck's preout V being matched to the amp's input lvl sensitivity. Right? So yeah, I got a CD5000 (measured 7.14V rms @ full unclipped output) in my Maxima, and a TRA560.2 in the trunk which accepts a 'maximum' of 12V rms. Gains being set correctly, when I reach full unclipped output on the deck (72/80 volume in this case), the amp produces "100% RMS" - which could coincidentally be @ 1% THD, but very rarely is. Less work done by the amp (ex: 4 ohm), less of a requirement to dissipate heat = generally, lower lvls of THD.
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