My new twins!!
Evolving Member
Joined: Aug 2007
Posts: 127
Likes: 0
From: Columbus, Ohio
Some things to consider. Your choice in amps and components for your frontstage is excellent, but your sub-stage configuration is flawed. If you're interested, here's why, and it's more complicated than the rating on the box.
First, a Class A/B amp is less efficient than a Class D because of it's power supply configuration.
The capacitors, filters, power supply and components built onto that amplifier's board aren't designed for booming bass, they're designed for higher musical frequencies. Some transistors can 'stick,' or stop switching at low frequencies. That's bad.
A bridged multi-channel amp isn't optimal for a mono soundsource like a subwoofer, and the excellent sound-quality potential of an amp like that is wasted at low frequency.
Watts are a thermal measurement, and as consumers we've been conditioned to equate watts with volume levels; We've been shammed. Look at the audiophile tube-amp guys; They're running 16, 25, 50 watt amplifiers, and getting plenty loud. The ratings on those boxes, and almost all boxes, are worthless to determine volume.
Why?
A subwoofer is a reactive load, and the amp will almost never "see" the 2 ohms it's not rated for when the sub is playing hard. The danger is still there, however -- the coils on your JL sub probably read a 3.4 to 3.7 DCR, not 4 "whole" ohms. This means less than two ohms in parallel at rest. Think of it as TDC.
As the woofer plays, these figures skyrocket. A subwoofer is a reactive load, the birthsheet and thd figures come from a dummy load. During normal use, the amplifier may "see" [far] upwards of 30 ohms, depending on your choice of enclosure, the temperature of the coils, the frequency the woofer is playing and etc.
Guess how much power that amp does into 30 ohms?
Not much, by comparison to the 300 watts it promises.
sqrt(1000*4) = 63
To do a thousand watts into a 4 ohm load, we need to output 63 volts.
sqrt(300*30) = 94
To do three hundred watts into a 30 ohm load, we need to output 94 volts.
We're never really putting out that 300 watts the amp is rated to do, because it's rated to do only 34 volts into a 4 ohm test load. About sixty volts short, or 1/3 as much power.
So though your speakers are getting loud, and the box says 300, you're really only listening to ... about twenty watts. Twenty watts isn't gonna get that W6 moving very much.
If you set your gains properly with a multimeter, (by using the formula above: sqrt(300*2) to make 300 watts into 2 ohms) (note: the amp isn't rated to do that much, so it may clip, and your voltmeter will read higher. You can probably get it to read 100volts, but that doesn't mean it's doing it without clipping) the sub will not be very loud. You're gonna crank the gains up into clipping to get the volume level you expect.
That's how people blow thousand-watt woofers with 75 watt amps.
So, if you're stuck on the brand, buy ARC's mono offering instead. It'll perform better, be safer for your equipment, you'll get more juice, and cause your charging system less distress.
Class A: Sundown SAX100.2
Class D: Sundown SAZ-1500.1D
See the difference?
Hope it helped.
BTW, still nice amps. Might I suggest a woofer from SoundSplinter? (http://www.soundsplinter.com) Mike, the owner -- he'll even autograph it forya. They're made by TC Sounds (http://www.tcsounds.com), the same people that made the Infinity Titanium woofers.
First, a Class A/B amp is less efficient than a Class D because of it's power supply configuration.
The capacitors, filters, power supply and components built onto that amplifier's board aren't designed for booming bass, they're designed for higher musical frequencies. Some transistors can 'stick,' or stop switching at low frequencies. That's bad.
A bridged multi-channel amp isn't optimal for a mono soundsource like a subwoofer, and the excellent sound-quality potential of an amp like that is wasted at low frequency.
Watts are a thermal measurement, and as consumers we've been conditioned to equate watts with volume levels; We've been shammed. Look at the audiophile tube-amp guys; They're running 16, 25, 50 watt amplifiers, and getting plenty loud. The ratings on those boxes, and almost all boxes, are worthless to determine volume.
Why?
A subwoofer is a reactive load, and the amp will almost never "see" the 2 ohms it's not rated for when the sub is playing hard. The danger is still there, however -- the coils on your JL sub probably read a 3.4 to 3.7 DCR, not 4 "whole" ohms. This means less than two ohms in parallel at rest. Think of it as TDC.
As the woofer plays, these figures skyrocket. A subwoofer is a reactive load, the birthsheet and thd figures come from a dummy load. During normal use, the amplifier may "see" [far] upwards of 30 ohms, depending on your choice of enclosure, the temperature of the coils, the frequency the woofer is playing and etc.
Guess how much power that amp does into 30 ohms?
Not much, by comparison to the 300 watts it promises.sqrt(1000*4) = 63
To do a thousand watts into a 4 ohm load, we need to output 63 volts.
sqrt(300*30) = 94
To do three hundred watts into a 30 ohm load, we need to output 94 volts.
We're never really putting out that 300 watts the amp is rated to do, because it's rated to do only 34 volts into a 4 ohm test load. About sixty volts short, or 1/3 as much power.
So though your speakers are getting loud, and the box says 300, you're really only listening to ... about twenty watts.
Twenty watts isn't gonna get that W6 moving very much.If you set your gains properly with a multimeter, (by using the formula above: sqrt(300*2) to make 300 watts into 2 ohms) (note: the amp isn't rated to do that much, so it may clip, and your voltmeter will read higher. You can probably get it to read 100volts, but that doesn't mean it's doing it without clipping) the sub will not be very loud. You're gonna crank the gains up into clipping to get the volume level you expect.
That's how people blow thousand-watt woofers with 75 watt amps.
So, if you're stuck on the brand, buy ARC's mono offering instead. It'll perform better, be safer for your equipment, you'll get more juice, and cause your charging system less distress.
Class A: Sundown SAX100.2
Class D: Sundown SAZ-1500.1D
See the difference?
Hope it helped.
BTW, still nice amps. Might I suggest a woofer from SoundSplinter? (http://www.soundsplinter.com) Mike, the owner -- he'll even autograph it forya. They're made by TC Sounds (http://www.tcsounds.com), the same people that made the Infinity Titanium woofers.
Last edited by theCybe; Aug 20, 2007 at 02:09 PM.
FYI, I run Morel in my car as well... Thery are REALLY nice. With the sub, I would consider something along the lines of Focal... I run their 27KX. With the Morels, my car sounds very balanced. Also, take a look at Image Dynamics. My buddy is a dealer with them and ive heard several installs. They sound very good. It seems as if you have the budget for this type of equipment; I wouldn't short yourself by getting anything from JL...
Evolving Member
Joined: Aug 2007
Posts: 127
Likes: 0
From: Columbus, Ohio
FYI, I run Morel in my car as well... Thery are REALLY nice. With the sub, I would consider something along the lines of Focal... I run their 27KX. With the Morels, my car sounds very balanced. Also, take a look at Image Dynamics. My buddy is a dealer with them and ive heard several installs. They sound very good. It seems as if you have the budget for this type of equipment; I wouldn't short yourself by getting anything from JL...
Image Dynamics has been a fixture in the sound quality arena for a long time. Focal, DLS, and CDT aren't to be missed either.
I run a CDT frontstage.
