Dynamic Headroom

It refers to the ability of an amplifier to deliver a greater amount of power on brief musical peaks than the amount of power it is rated to deliver continuously.

That can be good in the sense that the peak power levels required by a lot of music can be vastly higher than the average levels that are required. Classical symphonic music is one of the most extreme examples of that.

However, high dynamic headroom can also be an indication that the amplifier's power supply and/or its thermal design are "weak," because it indicates that the amplifier cannot sustain its maximum power capability for very long.

Regards,
-- Al

Note that I said that "high dynamic headroom CAN also be an indication that the amplifier's power supply and/or its thermal design are 'weak.'" I did NOT mean to imply that a high dynamic headroom figure NECESSARILY means that the amplifier is deficient in terms of its power supply design or its thermal design.

For instance, an el cheapo mid-fi receiver with a poorly regulated power supply, minimal storage capacitance, and marginally adequate heat sinking may very conceivably provide more dynamic headroom, relative to its continuous power rating, than a 200 pound $20K class A monster.

Keep in mind also that besides being a function of design, the dynamic headroom numbers are functions of specmanship. The more conservative the continuous power rating is, the greater the dynamic headroom number will be.

Regards,
-- Al

Take a 100wpc amplifier that doubles all the way to .5ohms; That is Dynamic Headroom, at its very Best.
Or another 100wpc amplifier, that produces 140wpc.@4ohms, and maybe 150wpc. @2ohms very briefly. The second amp. does NOT have ANY Dynamic Headroom.

While I agree with the general sense of your post, this statement reflects an incorrect definition of "dynamic headroom."

Re-stating what was said earlier in the thread, in slightly different terms, "dynamic headroom" refers to the ratio, usually expressed in db, of an amplifier's short-term maximum power capability to its rated continuous (long-term) maximum power capability.

An amplifier that can double down to 0.5 ohms is designed to be able to supply very large amounts of current. In many cases that kind of amplifier will have very little if any dynamic headroom based on the proper definition, because its maximum output power will typically be limited by the voltage range that its output can encompass.

At the other extreme, quoting Kijanki's accurate restatement of my earlier posts, "within given power supply size (wattage) you could design for higher output voltage (getting better headroom) sacrificing output current and making it weaker for average power demand."

Since the dynamic headroom of an amplifier is based on the proportion of short-term maximum power to long-term maximum power, it will be improved if the design (or the specmanship!) does one of the following:

1)Increases the short-term maximum power, without significantly affecting the long-term maximum power. This basically means increasing the voltage range that the output can swing without clipping.

2)Decreases the long-term maximum power without significantly affecting the short-term maximum power. This is why I mentioned that amplifiers with "weak" power supplies and/or marginal heat dissipation provisions can often have good dynamic headroom numbers.

3)Obviously, some combination of (1) and (2).

Mlsstl & Kijanki -- thank you for your excellent posts.

Regards,
-- Al

Magfan -- No correction needed. You don't need any dynamic headroom provided that brief musical peaks do not approach the 500 watts. Keep in mind, though, that 500 watts is only about 12db louder than 30 watts.

Best regards,
-- Al

A much larger power supply is required to add headroom to an amplifier and the power supply is where the money is.

Although as I indicated earlier, headroom can also be "added" by subtraction. Either by underspecifying the continuous power capability of the amplifier, or by designing it such that its continuous power capability is reduced relative to its short term power capability. Doing the latter would likely reduce the cost of the amplifier, rather than increasing it.

Regards,
-- Al