Home Theater Forum - View Single Post - Why all amps and receivers aren't the same.

Seth=L · 09-26-2006, 01:11 AM

I don't know if this is relevant, or if this thread will even stay open, but I am going to give this a shot anyway.

So you might ask yourself, what difference is there between my Kenwood 600 watt receiver and his H/K 225 watt receiver. The difference is truth in ratings. The FCC doesn't regulate these things closely enough, maybe they don't have the resources anymore, who knows. So many audio manufacturers bloat their power ratings with a little cunning, or they just straight up lie. Some of you may have seen the white van scams before, those guys are straight up lying. Not much of their specs are real, they quite literally pull numbers, numbers that look good, out of thin air.

Many factors can be looked at when considering a new receiver or amplifier. One of the most popular is reading user reviews or maybe specifications. Just know that what you read isn't nearly as usefull as listening to something for yourself. People have different listening needs. An individual likes to listen to heavy metal probably won't have a very usefull review for someone who listens to classical and jazz. Not to say reviews are bad, they deffinitely are usefull to find reliability and maybe erganomics.

Things to be aware of when looking at amplifier or receiver amplifier performance specs:

The wattage: I will show you a bad example of a power rating.
110 watts RMS per channel 6 ohms (1khz at 0.7 THD)

Then a good one:

95 watts RMS per channel, all channels driven 8 ohms (20hz-20khz at 0.06 THD)

The problems with the first rating are:
The (1khz), this is the frequency that they tested the amplifier's power, This single frequency is not a difficult one to produce. A more accurate rating will tell that it is able to provide that amount of power at any given frequency between 20hz (being the lowest and most demanding frequency to reproduce) and 20khz (the highest average frequency audible to humans).

Another thing to look at is the load impedance. Some of these specs aren't offered in great detail for many manufacturers. They should have the wattage ratings for each impedance(resistance to electron flow), measured in ohms. If the ratings for the 8 ohms vs. the 4ohms are higher then make sure your speakers don't have lower ohms before buying many budget brands, lower ohms means more resistance.

Another important factor is continuous output and all channels driven. These manufacturers are very carefull in how they word things. If the specs say something like this [100 watts per channel RMS] that could mean that the receiver is theoretically capable of delivering 100 watts RMS on just one channel, were the RMS of all the channels together may be in the neigborhood of 20 watts RMS. A rating like this [100 watts RMS, all 5 channels driven] would indicate the amp is capable of delivering 100 watts of power RMS to each channel at the same time.

One very simple way to evaluate most receivers and amps without listening to them to find what they are really packing is size of parts (weight), power consumption, and some internal #'s. Not all these methods will always work. Manufacturers have found many ways to make things more eco-friendly. Digital amplifiers operate very efficiently. They run cooler than analog amps, and weigh much less. They have their short comings and upsides as well. Some have boomy bass and reticent highs.

Large power supplies (transformers), large capacitors (round can shaped objects) and hefty discrete output stages (transistors) are all characteristics of a quality amp. If the caps are the size of a spool of thread, the transformer the size of a rubix cube, and a couple large transistors might get moderate performance in a receiver. Though a transformer that weighs 10 pounds, and caps as big as pill bottles, and lots of transistors on a nice heatsink might indicate a more powerfull amplifier

Anyone feel free to add your opinions, and correct possible mistakes. I really hope that this can help someone in the quest to buy a receiver or amplifier.

09-26-2006, 01:11 AM	#1 of 68
Seth=L *Seth L* Member Location: I live over there. Join Date: Jul 2006 Local Time: 12:19 AM Local Date: 12-02-2008 Posts: 1,294	Why all amps and receivers aren't the same. I don't know if this is relevant, or if this thread will even stay open, but I am going to give this a shot anyway. So you might ask yourself, what difference is there between my Kenwood 600 watt receiver and his H/K 225 watt receiver. The difference is truth in ratings. The FCC doesn't regulate these things closely enough, maybe they don't have the resources anymore, who knows. So many audio manufacturers bloat their power ratings with a little cunning, or they just straight up lie. Some of you may have seen the white van scams before, those guys are straight up lying. Not much of their specs are real, they quite literally pull numbers, numbers that look good, out of thin air. Many factors can be looked at when considering a new receiver or amplifier. One of the most popular is reading user reviews or maybe specifications. Just know that what you read isn't nearly as usefull as listening to something for yourself. People have different listening needs. An individual likes to listen to heavy metal probably won't have a very usefull review for someone who listens to classical and jazz. Not to say reviews are bad, they deffinitely are usefull to find reliability and maybe erganomics. Things to be aware of when looking at amplifier or receiver amplifier performance specs: The wattage: I will show you a bad example of a power rating. 110 watts RMS per channel 6 ohms (1khz at 0.7 THD) Then a good one: 95 watts RMS per channel, all channels driven 8 ohms (20hz-20khz at 0.06 THD) The problems with the first rating are: The (1khz), this is the frequency that they tested the amplifier's power, This single frequency is not a difficult one to produce. A more accurate rating will tell that it is able to provide that amount of power at any given frequency between 20hz (being the lowest and most demanding frequency to reproduce) and 20khz (the highest average frequency audible to humans). Another thing to look at is the load impedance. Some of these specs aren't offered in great detail for many manufacturers. They should have the wattage ratings for each impedance(resistance to electron flow), measured in ohms. If the ratings for the 8 ohms vs. the 4ohms are higher then make sure your speakers don't have lower ohms before buying many budget brands, lower ohms means more resistance. Another important factor is continuous output and all channels driven. These manufacturers are very carefull in how they word things. If the specs say something like this [100 watts per channel RMS] that could mean that the receiver is theoretically capable of delivering 100 watts RMS on just one channel, were the RMS of all the channels together may be in the neigborhood of 20 watts RMS. A rating like this [100 watts RMS, all 5 channels driven] would indicate the amp is capable of delivering 100 watts of power RMS to each channel at the same time. One very simple way to evaluate most receivers and amps without listening to them to find what they are really packing is size of parts (weight), power consumption, and some internal #'s. Not all these methods will always work. Manufacturers have found many ways to make things more eco-friendly. Digital amplifiers operate very efficiently. They run cooler than analog amps, and weigh much less. They have their short comings and upsides as well. Some have boomy bass and reticent highs. Large power supplies (transformers), large capacitors (round can shaped objects) and hefty discrete output stages (transistors) are all characteristics of a quality amp. If the caps are the size of a spool of thread, the transformer the size of a rubix cube, and a couple large transistors might get moderate performance in a receiver. Though a transformer that weighs 10 pounds, and caps as big as pill bottles, and lots of transistors on a nice heatsink might indicate a more powerfull amplifier Anyone feel free to add your opinions, and correct possible mistakes. I really hope that this can help someone in the quest to buy a receiver or amplifier.