5-channel amp

[LoneWolf]

This is really just a couple general questions that I haven't found the answers for yet. I would appreciate if anyone could give me some insight or point me in the right direction.

Here is a little back round info and my loose plan for the sound system.

Skip to the bold if you just want a crack at the questions.

I just picked up a 318is and the stereo system was murdered. I think what happened was that the previous owner installed an aftermarket head unit but did not make the proper connections to use the stock amp.

My car has aftermarket speakers in the back, Boston Acoustics. They look fairly new, so for the sake of saving cash to invest into the other little things with the car, I will keep them for a bit. The front speakers look aftermarket as well, but I haven't popped them out to check yet. (gonna do that in a few minutes) My car also has tweeters in the door.

I am looking to add a new after market head unit, Pioneer 6300-BT. I have this unit in my DD and I really like the blue tooth feature being built in. The wiring all seems pretty straight forward thanks to all the info here.

I am probably going to be using a 5-channel amp, Rockford Fosgate R600-5.

Now, using that amp it makes mention of different power levels because of the Ohms.

Would I be able to use a 2 ohm woofer while the rest of the speakers are 4-ohm?

And how would I tie the tweeters into this amp?

Everything else seems pretty straight forward on this install, not my first time doing head unit and sub hook up, but I have never messed with tweeters or multi-channel amps.

Thanks.

[StereoInstaller1]

Do NOT buy that amp, it is a very poor choice for an E30. Especially combined with that deck, you will have no midbass at all.

The high pass filters are not adjustable. 80Hz is a stupid choice for crossover points for most any car out there. Ideally, in an E30 you want to see about 120hz@12db/oct for the front and 100Hz@12db/oct for the rear...80Hz is just dumb.

The deck has only 80Hz or 125Hz, but it changes both front and rear crossovers, not separately adjustable. BTW: the new model is the DEH64 and is virtually identical.

I HIGHLY recommend you follow the "Killer $500 Stereo" guide, that Jensen shown there is a far superior choice, or any other 5 channel that has proper variable high pass filters.

GL!

Luke

[LoneWolf]

Well that makes this all a lot easier lol

Would you have any recommendations for a deck with blue-tooth capability and those specs you mention?

I love the feature of having it built in versus having a stupid ear piece when driving. I guess I could always go back to using my Jabra Blue-tooth speaker....

Thanks big time for your input!

[StereoInstaller1]

Yes, there are several. I have a JVC, the KD-R900. Easily the worst menus this side of Alpine, but overall terrific performance. Very very impressive SQ, but the hands free is underwhelming, but adequate.

I currently have a big hard-on for the Pioneer DEH64, which may or may not be the replacement for the DEH 6400. Both are BT and do hands free and A2DP. I highly recommend buying it at WalMart, they have a great price on it ($135 locally) and an amazing return policy.

BTW, if you plan on using one of my sub boxes, let me know. We are already trying to gear up for the "show season" and are currently sold out (again) on E3010 boxes, but plan to do yet another run in a couple of weeks. We have lots of other projects on the front burner, so every time I do a run, I keep thinking I will have 2 or 3 available...but people keep buying them!

I suppose that would be a great problem to have, right?

Luke

[LoneWolf]

Yes, there are several. I have a JVC, the KD-R900. Easily the worst menus this side of Alpine, but overall terrific performance. Very very impressive SQ, but the hands free is underwhelming, but adequate.

I currently have a big hard-on for the Pioneer DEH64, which may or may not be the replacement for the DEH 6400. Both are BT and do hands free and A2DP. I highly recommend buying it at WalMart, they have a great price on it ($135 locally) and an amazing return policy.

BTW, if you plan on using one of my sub boxes, let me know. We are already trying to gear up for the "show season" and are currently sold out (again) on E3010 boxes, but plan to do yet another run in a couple of weeks. We have lots of other projects on the front burner, so every time I do a run, I keep thinking I will have 2 or 3 available...but people keep buying them!

I suppose that would be a great problem to have, right?

Luke

Thanks again for the input!

I actually looked at that head-unit (pioneer DEH64) after I bought the other Pioneer already.

I plan on building a box a lot like yours, I am just unsure about the porting. I have never built one ported and never really researched the effects.

Curious though, why do you point your sub forward in that design? Is it because of the porting?

The only reason I ask is because I had heard from "car audio guys" you point them towards the back for better sound.

[dwvw]

His points forward so it fires through the ski hole. It is sealed to the back seat so 100% of the sound go to the cabin and none is wasted vibrating crap in the trunk. It really is one of the best designs for these cars. As for pointing subs back, I have excellent resuts doing that with hatchbacks and SUV's, for any other vehicle it's a pretty poor choice unless there is a lot of open area in the rear deck.

[StereoInstaller1]

I plan on building a box a lot like yours, I am just unsure about the porting. I have never built one ported and never really researched the effects.

Curious though, why do you point your sub forward in that design? Is it because of the porting?

The only reason I ask is because I had heard from "car audio guys" you point them towards the back for better sound.

I don't really know how to answer your question without sounding like an ass, so here goes: those "car audio guys" basically know dick about actual acoustics or proper box design...or how to interface a box design to a car's interior. There is a whole bunch of misinformation out there, and very little actual knowledge.

Basically, as said above, if you don't get 100% of the boxes output into the cabin, fire it backwards and rattle your trunk. Seriously, that are the only 2 options.

One of these days I will find a way to make spiffy little drawings and show the acoustic principles I use, and explain the "why" of my designs...but likely not this year either, I just cannot seem to find time. My website is a perfect example of that...all I have to do is find time to make words and pictures appear, but I can't find time for that either.

As far as the porting, what it does is one of two things: it flattens the impedance curve shown to the amplifier to allow the amp to make its full power at virtually all frequencies and it acts to control cone motion at very low frequencies preventing excessive excursion...assuming it is designed properly.

Oh yeah...in the hands of a hack, ported boxes can sound very shitty, as in just terrible. Sloppy "one-note" bass, horrible "overhang" where the woofer cannot track an input signal, loud "thunk"-like mechanical noises, port noise, just all kinds of crap. It takes about 2 minutes to design a sealed box, while a proper vented box can take hours to nail down specific goals.

However you slice it, I recommend you look at it like this: the goal is not which direction the woofer faces, nor the whole "ported vs sealed" argument, but look at the real goal: 100% of the output of the box actually sealed into the cabin.

Does that make sense?

Let me know if I can help with the box design. Much of what I have to say flies in the face of what the so-called "car audio guys" say, but I have solid math and solid engineering behind what I say, and over 30 years experience as a professional high-end installer to back that up.

Well, that and well over 350 boxes sold on just 1 forum for just 1 car, right?

Let me know if I can help.

Luke

[gasgasrider]

Huh?

Wait, since WHEN do you care about sounding like an ass? That's half the fun of reading your replies man!

[mrgraphics]

To answer your two bold questions:

Would I be able to use a 2 ohm woofer while the rest of the speakers are 4-ohm?

You can, but you must insure that the amp is 2 ohm stable. Each channel on an amp is handled individually. But for maximum amp efficiency, you really should run all speakers including the sub at the same ohm (usually 4). Get a dual coil 2 ohm sub. Then that gives you options by running the coil in either series or parallel. That way you could run the dual coils in series and get 4 ohms. If you decide to run another sub later, you can run a second dual coil 2 ohm sub in a series / parallel combination and still net out 4 ohms.

And how would I tie the tweeters into this amp?
The tweeters run off their own crossover that connects to the 6.5" (or whatever size your running) speaker. When you buy a component set of speakers, it will come with the crossover that you hide in the door. http://www.alpine-usa.com/product/view/spx-17pro

If your really skilled, you can do it the cheap way using a capacitor: http://www.carstereo.com/help/Articles.cfm?id=1

[LoneWolf]

I don't really know how to answer your question without sounding like an ass, so here goes: those "car audio guys" basically know dick about actual acoustics or proper box design...or how to interface a box design to a car's interior. There is a whole bunch of misinformation out there, and very little actual knowledge.

Basically, as said above, if you don't get 100% of the boxes output into the cabin, fire it backwards and rattle your trunk. Seriously, that are the only 2 options.

One of these days I will find a way to make spiffy little drawings and show the acoustic principles I use, and explain the "why" of my designs...but likely not this year either, I just cannot seem to find time. My website is a perfect example of that...all I have to do is find time to make words and pictures appear, but I can't find time for that either.

As far as the porting, what it does is one of two things: it flattens the impedance curve shown to the amplifier to allow the amp to make its full power at virtually all frequencies and it acts to control cone motion at very low frequencies preventing excessive excursion...assuming it is designed properly.

Oh yeah...in the hands of a hack, ported boxes can sound very shitty, as in just terrible. Sloppy "one-note" bass, horrible "overhang" where the woofer cannot track an input signal, loud "thunk"-like mechanical noises, port noise, just all kinds of crap. It takes about 2 minutes to design a sealed box, while a proper vented box can take hours to nail down specific goals.

However you slice it, I recommend you look at it like this: the goal is not which direction the woofer faces, nor the whole "ported vs sealed" argument, but look at the real goal: 100% of the output of the box actually sealed into the cabin.

Does that make sense?

Let me know if I can help with the box design. Much of what I have to say flies in the face of what the so-called "car audio guys" say, but I have solid math and solid engineering behind what I say, and over 30 years experience as a professional high-end installer to back that up.

Well, that and well over 350 boxes sold on just 1 forum for just 1 car, right?

Let me know if I can help.

Luke

I could care less if you come off as an "ass". From what I have seen while lurking on the forums is that you are a respected member with a lot of experience. That is all that matters to me.

Like I said, these were supposedly car audio guys. Course they never installed their own systems either haha. Never considered what they said about audio to be the bible, that is for sure.

I appreciate the input big time. I have that Jensen 5500 on order. I may choose another sub, not sure though. I mainly just wanted the amp on order because I had seen it discontinued on a couple sites?

I should have it next week.

I have a couple mechanical projects to handle first. But sound is very important to me.

[LoneWolf]

His points forward so it fires through the ski hole. It is sealed to the back seat so 100% of the sound go to the cabin and none is wasted vibrating crap in the trunk. It really is one of the best designs for these cars. As for pointing subs back, I have excellent resuts doing that with hatchbacks and SUV's, for any other vehicle it's a pretty poor choice unless there is a lot of open area in the rear deck.

You say sealed to the seat? You mean just pushed up tight with the "center platform" (where the subwoofer is) not actually glued right???

[StereoInstaller1]

Yes, exactly. I use 1/4" closed cell foam on the face of the box, then upholster over that.

When you screw it in, it forms a complete seal...that is why you have to remove the trunk tar too, as the thickness of it would not allow a seal.

[LoneWolf]

Yes, exactly. I use 1/4" closed cell foam on the face of the box, then upholster over that.

When you screw it in, it forms a complete seal...that is why you have to remove the trunk tar too, as the thickness of it would not allow a seal.

Ooooooh ok. I see what your saying. The closed cell gives the cover some cushion that allows it to seal.

Awesome.