Are Birthsheet Specs done with the Gain Setting maxed out?

[Mr. Black 10+ year member]

The answer is no, because an amplifier can reach full output with the gain set to minimum if the input voltage is high enough.
What Jack is saying is that the birthsheet figure is rated output into Xohm with X voltage input from the power source (probably 14.4V for CEA-2006). Whether the gain is set to maximum, minimum or anywhere in between depends on what the preamp input voltage is from the source unit.

Thanks...you and a few others have been quite helpfull.

 

[ramos 5,000+ posts]

I'm just curious as to where abouts my T1001bd is getting its full 1485 watts...

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CEA-2006 Primary Rating for Power Amplifiers

There are two Primary Ratings for power amplifiers whether the amplifier is a “stand alone” device, or one built into a source unit. The Primary Ratings will be listed as follows:

Power Output with Total Harmonic Distortion plus Noise

This measurement is designed to indicate the actual continuous power developed by the amplifier, into a 4 ohm load, over the entire design bandwidth, while producing not greater than 1.0% THD+N

Signal to Noise Ratio (A weighted)

This measurement will indicate the amount of audible noise inherent in the product. A major change to this measurement is the level at which it is made, previously, most products were measured for noise at full power, which resulted in amplifiers which had the same internal noise but having power differences, receiving different S/N ratings.

The new method, requires the measurement of the noise at or 2Vrms (1 Watt @ 4W). This makes a true noise comparison possible, since an amplifier that has 20dB more power will not “automatically” have a S/N measurement 20dB better.

Important to note, because the new measurement is designed to remove the additional power (in dB) from the measurement, most amplifiers will report a significantly lower S/N rating, when in fact they have the same performance as the customer is used to.

For example, if an amplifier that made 100 watts @ 4W was measured with the old method, it may have a S/N ratio of -100dB

The same amplifier, measured using CEA-2006, would result in a measurement of only –80dB . The 20dB difference is a result of removal of the 100 watts of power, since the difference between 1 watt and 100 watts is 20dB.

CEA 2006 Additional Specifications

Secondary Ratings may be disclosed as well, providing the measurements are made in accordance with CEA-2006.

For example, it is possible to list a 2 ohm or 1 ohm power spec, as long as it is made in accordance with the guidelines. It is also permissible to advertise Frequency Response, Stereo Separation, etc., as long as the methods used to obtain the measurement follow the guidelines in CEA-2006.

All or any of these secondary ratings are listed at the manufacturers discretion.

Additional Power Output: Additional output power may be specified at loads other than 4 ohms and supply voltages other than 14.4V DC. This allows the manufacturer to indicate the conditions that make the amplifier perform optimally. If you intend to connect the amplifier to a 1-ohm load, look for a power output rating that indicates performance into 1 ohm. If you’ll use the amplifier in SPL competition, and want to provide more than 14.4V DC as a supply, look for an additional Power Output spec that indicates performance with a higher supply voltage. If you’ll bridge the amplifier, look for an additional spec that indicates what the amplifier’s output will be when the channels are bridged. This is the spec that’s intended to indicate what you should do to get all the power that you paid for from your amp. It’s not necessarily an apples-to-apples comparison, unless the reference characteristics between the two amplifiers you’re comparing are the same.

Dynamic Power: This spec used to be called “headroom”. Headroom was an indication of how much power an amplifier could make reproducing short bursts or musical transients. Amplifiers can make more power when reproducing transients than they can sustain for long periods of time. Headroom used to be stated in decibels, but dynamic power is expressed in watts. It’s easier to understand without breaking out your scientific calculator to convert dB to watts. You always carry a scientific calculator when you shop, right?

Frequency Response: The frequency response spec indicates the range of frequencies that the amplifier will reproduce. It’s not different from the old frequency response spec, but, these days, nearly every amplifier made can easily reproduce the full audio band (20 Hz-20 kHz) unless it’s an amplifier designed to drive only subwoofers. Good frequency response is available in almost every

amplifier made now, so the importance of this spec when comparing amplifiers isn’t what it used to be.

Maximum Input Signal: This spec indicates the maximum amount of signal voltage that the amplifier can take without overdriving (clipping) the input section, which increases the amount of distortion in the output signal. If the spec is 5V, it doesn’t do any good to connect a preamp that outputs 9V.

Maximum Sensitivity: This spec indicates the minimum input signal voltage that’s required to drive the amplifier to full output. If the spec is 250mV, a head unit with a maximum output voltage of 100mV won’t allow you to get full power from your amplifier.

Effective Damping Factor: This replaces the old “Damping Factor” spec, which was originally used to indicate how much control an amplifier could exert over the speaker’s moving cone. It’s a hotly debated topic. If you’re used to seeing damping factor specs of 500 or even 1000, you’ll be surprised to find that nearly every amplifier available for use in cars will have a spec between 6 and 7. Why, you ask? Because amplifiers have gotten much better over the years and they all have relatively low output impedance and that’s the characteristic upon which the damping factor spec is based. Effective Damping Factor better indicates the difference in audible performance between amplifiers than the old spec. In other words, it’s really difficult to hear the difference between a damping factor of 500 and a damping factor of 1000. Now that difference will be expressed more accurately as the difference between, say, 6.39 and 6.85.

Output Regulation: This is a more meaningful representation of the effects output impedance. To completely explain output regulation may require another article, but here’s a simple explanation: If an amplifier has high output impedance, especially if it’s close to the speaker’s impedance, the frequency response of the amplifier’s output will no longer be “flat”. Rather, it will resemble the impedance curve of the speaker. Output regulation is an indication of how much the frequency response may change when the amplifier is connected to a 4-ohm load. If the amplifier is connected to a load of lesser impedance, the error will be greater. For most amplifiers, the error will probably be less than a decibel, but if the output impedance is high, the amplifier’s output, and, consequently, the speaker’s output, may be reduced by a dB or more at frequencies where the speaker’s impedance is lowest. An amplifier with a big number in the Output Regulation column may dramatically change the frequency response of the system.

Setting A Standard

CEA 2006 states that "Power amplifiers designed for use in mobile applications include, but are not limited to: separate single and multi-channel, integrated amplifiers, and bandwidth-limited amplifiers that are connected to, and rely solely on, the vehicle’s primary electrical system for power input and have output power ratings of greater than 5 watts when measured in accordance with CEA-2006." Hmmm...you may be thinking, "OK, so what does that mean? Check this out: CEA 2006 defines an integrated amplifier as, "A power amplifier integrated into a device whose primary purpose is not power amplification. An integrated amplifier, for example, may be the amplifier contained in a head unit whose primary purpose is media playback..." That’s right, head units are included in the rating standard. Enough said.

It’s important to remember that manufacturer’s compliance with CEA 2006 is voluntary. The CEA isn’t the Federal Trade Commission and can’t compel amplifier manufacturers to adhere to the spec. CEA 2006 isn’t the law, it’s just a good idea and was designed to help customers make an informed decision about the amplifiers they'll spend their hard-earned money on. Look for the CEA 2006- compliant spec on the amplifier’s box to be sure you’re getting all the power you’re paying for. Only you can compel amplifier manufacturers to adhere to the new rating standard.

 

[Mr. Black 10+ year member]

Good info. Thanks.

 

[JimJ 5,000+ posts]

This measurement is designed to indicate the actual continuous power developed by the amplifier, into a 4 ohm load, over the entire design bandwidth, while producing not greater than 1.0% THD+N

Pshhhhh...//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Because amplifiers have gotten much better over the years and they all have relatively low output impedance and that’s the characteristic upon which the damping factor spec is based.

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[DBfan187 5,000+ posts]

http://www.rockfordfosgate.com/products/amp_watts.asp#power