Luke Box + existing aftermarket amp questions

[kung fu jesus]

I have an Alpine MRP-F300 4/3/2 Amplifier with a pair of pre outs connected to an an Alpine 147bt HU. I run Infinity 509CS components in the front, Infinity Reference 5032cf in the rear (might replace with something that fits better). I am very happy with the sound and it is plenty loud with the gain set at 50% for the F & R channels.

I plan to add an 8" Luke box.

If I power the the rears off the HU, leaving the fronts and sub powered off the amp, will the sound be unbalanced, or will I have some flexibilty adjusting the gain on the fronts and sub?

Another option would be to add a small one or two channel amp just for the sub. If that is the case, I would look for a smaller unit, attach it to the box. Should I connect it to the sub pre ots on the HU or the preouts on the existing sub?

Would I be better off just going with a 5 channel amp like a Kenwood KAC-7005PS?

[StereoInstaller1]

I have done almost that exact same setup several times.

My general recommendation is running about 3X the rear power for the fronts, so since your deck makes about 12W X4 (12 watts RMS is typical deck power, that "35X4" is pure bullshit) you will have an honest 25 watts on the rear using deck power.

The important part is the deck having a high pass filter so you can take the bass out of the rear speakers, that is a critical part of getting the best sound. I am 99% sure your deck does.

Since your amp does have high and low pass filters, your front stage will have roughly 70 watts RMS (real honest power) and your sub will have roughly 140RMS. You would use a 4 ohm woofer, be it SVC 4 ohm or DVC 2 ohms/coil, whatever it takes to have a 4 ohm load.

If you are looking for a nice, fun, well balanced sound, this will do it perfectly...no giant boom (but you wont be ashamed to play hip hop either...) and plenty of kick for rock, jazz, blues, whatever.

Here is the catch: if you decide for whatever reason you need more power and decide you want a 5 channel, you would have to change woofers. Most all 5 channel amps need to see a 2 ohm load on the bass channel, so you would need a DVC woofer to get that 2 ohm load.

You could also just add a 2 channel amp on the 4 ohm woofer and use the 4 channel on the mids and highs...but that takes a little more space.

All about personal preference, right? I listened to the exact same thing: 4 channel amp and SVC woofer for about 18 months. It really does do just fine, it is absolutely amazing to me considering he weight and size....but to be honest, I always wanted just a little more.

I say to get really happy bottom end, feed a decent 8" (Type R is incredible SQ, ask Robrez, his is stunning) around 300 watts RMS and you should just about never want for more.

If I were looking to build a tidy little system with some great sound quality, I would do the Soundstream STL6.620. It is a 6 channel, so the same 4 ohm woofer will work perfectly. The bass channel makes 300 watts RMS, it comes with a sub level control (you have an Alpine, sub level is easy to use, so it is not necessary, but still a nice touch)

I have seen that amp sell for as little as $175 out on the web, but soundstream shows it as $339: http://soundstream.com/store/car-aud...s/stealth.html

Hope that helps!

Luke

[kung fu jesus]

Luke, that_is_AWESOME. Thanks so much! I knew the output labels on HUs are garbage, but wasn't sure if the power increased running 2 off line outs vrs 4. Very good information!

I am getting too old for bawdy sound, but I like reasonable quality over quantity.

I figured if I needed/wanted more like you mentioned, I would add a sub amp. Not the cleanest install, but I think it could work. If I went that way, should the sub amp take it's input from the 4 channel amp or the 5/6 channels out the back of the HU?

One more question... With the four channel, I would run channel 3/4 as bridged, then if I used a DVC sub, i need that to be 2 ohms and wired in series to make 4 ohms or a SVC @ 4 ohms, correct?

Given I will be a little down on power while utilizing the rear channels of the 4 channel amp for the sub, which do your recommend for a cleaner sound, SVC or DVC?

I appreciate your time for responding!

[StereoInstaller1]

Not a worry, thank you for asking!

SVC vs DVC is a non-issue. Same performance. You get wiring options with DVC is all.

The only goal is getting the proper impedance woofer so you show the amp the proper "load" that makes the best power.

Bass needs power and proper impedance matching is a critical system design criteria. You need not get a ton of power, the 140 watts you will have running the bass will flat blow your mind.

Listen to the Joe Walsh track "Ordinary Average Guy"...its fun.

Oh: while you are getting ready, go tune your system using the tuning guide. Even with no sub you can get some nice improvement in clarity by filtering the fronts about 80Hz and maybe even using a little bass boost on the rears.

Let me know when you are ready for the box ahead of time, BTW. We do not have any 8" LTWs in stock, we need to get some built...your car would be a good excuse.

Luke

[kung fu jesus]

Excellent! I read the am tuning tutorial and I need to complete that.

I generally use a few songs for testing my tuning; LCD Soundsystem "Tribulations", S-Tone, Inc. - "Verao" , and Social Distortion "Story of my Life". If I want to test the bass, I use Theivery Corporation 38.45. For location, I'll move onto Dave Brubeck "Timeout" to see if I can place each instrument in the quartet. There is always some compromise, but with the material you have written on here, it has been extremely satisfying and easy.

I am sorting steering refurbishment now. When I get the steering coupler and tie rods in, I should be ready to place the order.

[kung fu jesus]

Another question: I took your advice and looked up the Alpine SWR-843D Type-R. I like what I am reading in the spec sheets. I see the mounting depth is 4.5" (top mount) and the sub box is 5" deep (on your site) with an angle to match the rear bulkhead. Will I need to look for another speaker with a shallower depth to fit? I am estimating you use 1/2" or 5/8" MDF for the boxes (mounting depth would be 4.375 4.5" +/- carpet thickness)

[StereoInstaller1]

It fits, I have done that particular woofer myself.

We have got to find a way to describe mounting depth better. One of the challenges, inventing wording to explain how it works when it isn't "cut and dried"...but the woofer does fit.

Luke

[kung fu jesus]

Excellent! Thanks for the follow-up.