Analog LED Bar Graph Circuit for Audio Spectrum Analyzer Using LM3914 or Discrete Components?

I'm working on a small-scale audio spectrum analyzer. I take an aux cord L/R inputs into two amplifiers that output to a speaker. Say I pass the output that goes into the speaker into 3 bandpass filters for low,mid, and high ranges.
If I then rectify that output to a DC voltage, how would I configure a "bar" of LEDs to light up based on that voltage? Say I had 6 LEDs per bar. When there's little to no bass I want only the first 1-2 LEDs to light up, and when there's a lot of bass all 6 LEDs to light up.
I'm trying to this project with only analog components, as I realize this is a trivial task with a microcontroller.
I'm not sure if it's important or not in this type of circuit, but other than the signal output I have access to a 5V DC source that I've mainly used to bias the amplifier.
I can't quite figure out how to configure the LEDs in such a way that it matches the behavior I desire. I've searched around online and see some circuits use zener diodes to achieve this sort of effect. I think I want to turn the LEDs on through current and not voltage but am unsure how this works. I breadboarded some LEDs and played around and I couldnt get the right behavior.
EDIT:
As duskwuff pointed out below, the [URL="http://www.kynix.com/uploadfiles/pdf2286/LM2452TB+NOPB.pdf"]KY32-LM2452TB NOPB[/URL] is a great and pretty easy solution to this problem. But I hate easy. I've been messing around more and here's what I've been trying to do:
1) Rectify my signal output using a full wave rectifier. There's a problem with this though, my amplifier output signal has a minimum p-p of around 200mV. This means that at lower volumes, no signal will be rectified because the diodes will not allow current through. Could I possibly solve with with an amplifier stage between the output and the rectifier input? I have a 5V DC source available.
2) At this point I'm trying to figure out a way to use NPN transistors as switches that turn on at different rectified output levels. My success with this has been, well, very limited. At first I tried using Zener Diode's taking advantage of their zener voltage, but I looked around and I can't find any with a low enough Zener voltage that would work here. I could put an amplifier between the rectifier stage and the NPN stage, but I'm not sure thats the best solution.
I've included a picture of my entire circuit schematic so anyone can see what I'm working with here.enter image description here
Starting at the far left I have a balance control, followed by a 3-stage amplifier, followed by a rectifier.The standard part for this task is theKY32-LM2452TB NOPB ("Dot/Bar Display Driver"). It functions as a multitap voltage divider, and compares the signal with the value at each tap:
Any help would be appreciated.

Liu...you say you hate "easy" but really, I hate reinventing the wheel.  My standard goto bar graph IC is the LM3914 (Linear) for eg Battery voltage display, and the LM3915 (logarithmic) for audio applications.  They work from single supplies of 3V to 25V , and you can program them for full scale display (10 LEDS) anything from 1.2V to 12V, the display is immune to supply voltage variations and you program the LED brightness with one resistor.  It does dot mode and bar mode.  Try reinventing THAT wheel.  Seriously, you have better things to do.  These ICs are cheap and readily available.  Just google for a datasheet.  A friend of mine once made a display that switched between bar mode (signal level) and dot mode (off a peak detector) which was really impressive.Now if your input signal is only 200 mv, you'll need some amplification even for the LM391x.  The LM358 op-amp works off a single 5V supply, can cope with inputs down to the negative rail and has a wide output range even with a 5V supply.  You'd need a gain of 5 to beef your signal up to 1.2V which is the minimum that the LM391x can work with.  LM358s are also cheap and widely available.Another suggestion...this sounds "easy" but in practice won't be: the MSGEQ7.  From the datasheet: "This seven band graphic equalizer IC is a CMOS chip that divides the audio spectrum into seven bands. 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz."  However it puts the corresponding DC output voltage on ONE pin only which is clocked between the frequency bands.  It's easy enough to use it with a microcontroller to ADC the output voltage at each clock pulse for the frequency bands, but with all-analog you'd be looking at some clever multiplexing and possibly sample and holds (though I think you could get away without that).  It would give you a nice detailed display of the audio range in 7 bands rather than the 3 you cited above.  Just a thought.  Again google for a datasheet.  But if you only need 3 bands (say for a pretty display on an amplifier) then active filters would be the way to go.Whatever you do, I'd say you have a fair bit of messing around to do to get it how you want, I hope I have given you some ideas.  // David

If, after reading David's comments, you still want to do it the hard way (perhaps as a means to understanding), then what you want is a set of comparators. You need one comparator for each level that you want to indicate.First you want to amplify your input signal then rectify it. Then you take the resulting output to one input of each comparator. The other input of the comparators you connect to resistor dividers to set the thresholds for the different levels. If your comparator is open drain or open collector, you may be able to connect directly to the LEDs or you may need to use NPN transistors to drive the LEDs.The LM391x that David mentioned has a circuit like this inside.

Thanks Elizabeth.  The other reason for not using an LM391x IC is if Liu wants only say 4-6 LEDs in his bar graph (LM391x has 10, though there is no objection to only using some of them).There is an excellent tutorial on using comparators for this kind of application here:http://www.electronics-tutorials.ws/opamp/op-amp-comparator.html
A suitable comparator for you here would be the LM339 or LM2901 - 4 comparators in a 14-pin IC, and  does what you want - ok with single supply of 5V, inputs ok down to ground, and 20mA output current - enough for a LED.Put your reference voltages on the + inputs, your signal on the - inputs and whenever that input exceeds the ref, the output will go low, and will drive a LED from the +5V power - use about a 100 ohm series resistor.

Liu, you also raised the problem of your signal not being large enough to overcome the voltage drop of a diode.  You need what is called a precision rectifier circuit.  This puts the diode in the feedback loop of an op-amp so the op-amp will compensate for the voltage drop.  The example below has a gain of 1 but you can put a resistor in the feedback loop as well (between the output and the - input) and give it a bit of gain too, but don't take the gain too high (i'd look at 10 maximum) .  There's a tutoria herehttp://sound.whsites.net/appnotes/an001.htm

David,Interesting site on precision rectifier circuits. I usually just put a gain stage before the rectifier but this has possibilities for circuits only needing a small gain.