RS4 sub upgrade in progress......
06-03-2007, 02:30 PM
#1
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RS4 sub upgrade in progress......
<center><img src="http://pictureposter.audiworld.com/561/dsc01253.jpg"></center><p>
Here are a couple of "in progress" shots of the sub box I'm building for my RS4. The outer "wings" will be covered with black plexiglass/carbon fiber panels that I am constructing. The sub will have a seperate in-cabin volume control, and will feed off the stock sub wires.
Here are a couple of "in progress" shots of the sub box I'm building for my RS4. The outer "wings" will be covered with black plexiglass/carbon fiber panels that I am constructing. The sub will have a seperate in-cabin volume control, and will feed off the stock sub wires.
06-03-2007, 05:08 PM
#5
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Weight of the assembly as shown is 49lbs......
The two cover panels will be 1.5lb each, so total will be 52lbs. I'll post pics in the trunk when the whole thing is done. Funny how the weight adds up once you start building. Anyway, good thing the RS4 has 420hp. I'll also be getting an aftermarket exhaust to add 20hp and drop 30lbs weight, so I will still have a net power:weight ratio gain. I'll post pics in the trunk when it's all done. I still need to identify the wires coming off the bose amp that feed the sub. Can you help??
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06-04-2007, 06:54 AM
#8
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JL amps are robust, overpriced $/watt, often meh SQ - 0 headroom. Amp & sub w/same logos? So?
(Writing pithy subject lines is like writing haiku...)
JL amp are well-built.
They are intensely profitable for JL because:
1 - they use a circuit which adjusts the rail voltage of the amp according to the speaker impedance load measured at amp turn-on.
A good aftermarket amp which makes 50W into a 4 ohm load will make 75-100W into a 2 ohm load.
The JL will make 50W.
This is not right or wrong in and of itself (although it takes careful system design to use these amps optimally). But it does mean that a 50W "typical" amp needs 100W of output transistors, 100W of power supply, and 100W of heatsing (and associated heatsink related transport costs due to its size and weight).
The JL gets by with 50W worth of parts in each of those categories.
2 - they are stiffly regulated. This is also not right or wrong in and of itself. PPI and xtant designed amps (in their original company forms) were very good sounding amps.
Stiffly-regulated amps make the same power with input voltage ranging roughly from 11-16V. These amps don't require (or benefit from) caps. They also, by definition, have 0 dB of dynamic headroom - the ability of an amp to perform above its rating, into a constant speaker impedance load, for some period of time. Since this is true for these amps and not for loosely-regulated amps (nowadays, just about everything else), you need a higher-rated stiffly-regulated amp to sound as good during musical peaks as a loosely-regulated amp (all other things being equal, of course).
Since there is no dynamic headroom due to the power supply design, there is no reason to have higher-capability components on the circuit board (and they don't - seed above).
3- they just don't seem to sound that good. The theories I've heard are that the output transistors (or other components) are very low in cost and speed and quality, but I don't know that for certain.
I've owned JL amps and I wouldn't say they suck. I think there are better choices out there for SQ and I think there are better choices out there for just raw performance.
Oh, and if anyone can tell me how the speaker's voice coil knows what brand of amp the electrons are going through, let me know, k?
JL amp are well-built.
They are intensely profitable for JL because:
1 - they use a circuit which adjusts the rail voltage of the amp according to the speaker impedance load measured at amp turn-on.
A good aftermarket amp which makes 50W into a 4 ohm load will make 75-100W into a 2 ohm load.
The JL will make 50W.
This is not right or wrong in and of itself (although it takes careful system design to use these amps optimally). But it does mean that a 50W "typical" amp needs 100W of output transistors, 100W of power supply, and 100W of heatsing (and associated heatsink related transport costs due to its size and weight).
The JL gets by with 50W worth of parts in each of those categories.
2 - they are stiffly regulated. This is also not right or wrong in and of itself. PPI and xtant designed amps (in their original company forms) were very good sounding amps.
Stiffly-regulated amps make the same power with input voltage ranging roughly from 11-16V. These amps don't require (or benefit from) caps. They also, by definition, have 0 dB of dynamic headroom - the ability of an amp to perform above its rating, into a constant speaker impedance load, for some period of time. Since this is true for these amps and not for loosely-regulated amps (nowadays, just about everything else), you need a higher-rated stiffly-regulated amp to sound as good during musical peaks as a loosely-regulated amp (all other things being equal, of course).
Since there is no dynamic headroom due to the power supply design, there is no reason to have higher-capability components on the circuit board (and they don't - seed above).
3- they just don't seem to sound that good. The theories I've heard are that the output transistors (or other components) are very low in cost and speed and quality, but I don't know that for certain.
I've owned JL amps and I wouldn't say they suck. I think there are better choices out there for SQ and I think there are better choices out there for just raw performance.
Oh, and if anyone can tell me how the speaker's voice coil knows what brand of amp the electrons are going through, let me know, k?
06-04-2007, 08:48 AM
#9
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dead on, only you missed one thing:
Xtant hasn't changed since Mitek bought them out what 4-5 years ago? I guess if you have a good product why screw with it, but at least give us an appearance change.
Xtant hasn't changed since Mitek bought them out what 4-5 years ago? I guess if you have a good product why screw with it, but at least give us an appearance change.
06-04-2007, 01:25 PM
#10
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I was perfectly happy with them in two previous systems......
To my ears, they sounded fine, clean, and were durable for my listening purposes. Also, the audio shop where I bought everything is only 3 miles from my home, so service, install, etc. is very convenient. I also got a great deal on the package.