Andyr: All things being equal ( ha ha ha ), when you go from an 8 ohm load to a 4 ohm load with an SS amp, you double the current capacity or "ampacity" of the circuit. The only problem is, since you've cut the impedance in half at the speaker, current demand is doubled at the amp. As such, IF the amp actually "doubles down" as impedance is halved, you've "theoretically" gained since the amp now has more voltage headroom for peaks. Here's where the reality factor comes in.
Since most amps DO NOT double down as impedance is halved, going to a lower impedance speaker can actually reduce the sonic potential of the system. This is due to increased voltage sag that the amp experiences under heavy loads due to the lack of available current. When you pull more current due to having a lower impedance, you generate more heat. The hotter a device gets, the less efficient it becomes. On top of that, if you're pulling more current, the device also becomes limited in how much voltage it can pass. You have to remember that each device in the circuit is rated to pass a specific amount of wattage. Since wattage equals volts x amps in the circuit, pulling more current means that we have to reduce the available voltage. Lack of voltage means reduced dynamic headroom with more potential for compression or clipping.
Besides all of that and to re-state what i mentioned earlier, the lower the impedance, the more likely the speaker is to "modulate" or "distort" the amplifier's output. This is why i said that one is ALWAYS better off with a higher efficiency, higher impedance speaker. Less heat with less current demand equals an easier load on the amp.
So long as the amplifier has enough power potential at the higher impedance that it is loading into, leave well enough alone. That is, unless you have an amplifier that is capable of delivering as much voltage and current that you would ever need into any given load at any given time at any given frequency. This is a VERY tall order and most amps will fall flat on their face trying to do so, especially with wildly reactive speakers.
For those that want to learn, i would HIGHLY recommend reading the "amplifier white papers" that Bob Carver wrote. His writing is very simple to follow along with and may help you better understand how / why some amps seem to run out of steam when being throttled faster than other amps of similar power ratings but with different design topologies. If it is one thing that i will give the Sunfire amps, they never get "gritty" even when throttled beyond belief. This explains why that is so.
Newbee: Yes, you did good. Then again, you already knew that : )
Depending on the output impedance of your amp though, even 5 ohms may be kind of low. I have to assume that you took that into consideration when arriving at suitable figures though. You don't strike me as being careless in your decisions, so i have to assume that you left enough of a "fudge factor" in play to cover all bases. Sean
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Since most amps DO NOT double down as impedance is halved, going to a lower impedance speaker can actually reduce the sonic potential of the system. This is due to increased voltage sag that the amp experiences under heavy loads due to the lack of available current. When you pull more current due to having a lower impedance, you generate more heat. The hotter a device gets, the less efficient it becomes. On top of that, if you're pulling more current, the device also becomes limited in how much voltage it can pass. You have to remember that each device in the circuit is rated to pass a specific amount of wattage. Since wattage equals volts x amps in the circuit, pulling more current means that we have to reduce the available voltage. Lack of voltage means reduced dynamic headroom with more potential for compression or clipping.
Besides all of that and to re-state what i mentioned earlier, the lower the impedance, the more likely the speaker is to "modulate" or "distort" the amplifier's output. This is why i said that one is ALWAYS better off with a higher efficiency, higher impedance speaker. Less heat with less current demand equals an easier load on the amp.
So long as the amplifier has enough power potential at the higher impedance that it is loading into, leave well enough alone. That is, unless you have an amplifier that is capable of delivering as much voltage and current that you would ever need into any given load at any given time at any given frequency. This is a VERY tall order and most amps will fall flat on their face trying to do so, especially with wildly reactive speakers.
For those that want to learn, i would HIGHLY recommend reading the "amplifier white papers" that Bob Carver wrote. His writing is very simple to follow along with and may help you better understand how / why some amps seem to run out of steam when being throttled faster than other amps of similar power ratings but with different design topologies. If it is one thing that i will give the Sunfire amps, they never get "gritty" even when throttled beyond belief. This explains why that is so.
Newbee: Yes, you did good. Then again, you already knew that : )
Depending on the output impedance of your amp though, even 5 ohms may be kind of low. I have to assume that you took that into consideration when arriving at suitable figures though. You don't strike me as being careless in your decisions, so i have to assume that you left enough of a "fudge factor" in play to cover all bases. Sean
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