High Output Alternator

[shorterthanrich]

Anyone know anything about high output alts for the b5? I have a 2000 and am considering a 160 amp alt. Is the alt buried deep in there and impossible to get to? I may do a big 3 upgrade and possibly a new alt for some audio.

Thanks

[complacentsee]

I've never had an issue with electrical at peak on my amp. Somewhere around 1450W peak I think. But then again I've never maxed out it. Just my hearing. Are you thinking of going with a Ultranator?

It's not the most terrible thing to do. But if you were doing say a timeing belt or an engine pull it would be eaiser. Have to remove the front clip if i recal.

[shorterthanrich]

I've never had an issue with electrical at peak on my amp. Somewhere around 1450W peak I think. But then again I've never maxed out it. Just my hearing. Are you thinking of going with a Ultranator?

It's not the most terrible thing to do. But if you were doing say a timeing belt or an engine pull it would be eaiser. Have to remove the front clip if i recal.

What is the RMS of your amp and what subs are you running? Have you done a Big 3 upgrade?

I'm going to use an AudioQue 2200D amp, which is 2200 Watts RMS. I'll be powering two 13Ov.2 subs, which are happy with about 800+ watts RMS each in the small sealed box I'll be putting them in. So, I'll need at least 1500 watts RMS.
W=V*A
1500= 14*A
A=107.

Come to think of it...maybe I can get away with the stock alt. 1500 watts is a ton, so I really won't need more than that. Getting that 0/1 AWG wire up front will be tough though ;)

So really all I'll need is a big 3 upgrade. How deep down is that alt? Do you think I can get to it to add the new wires?

[complacentsee]

You know. I don't even remember what the RMS of my amp is. I'm guesses it is 800 RMS range. It has been ages since I installed it around 5 years ago. 2 12" Infinity Kappa Perfects... no big 3. I do see voltage drop on really hard punches though. Not even that I care to do any more work to the system.

Are you doing a compition vehicle that your so concenred about the electrical system? I think any thing over what i have is overkill.

[shorterthanrich]

You know. I don't even remember what the RMS of my amp is. It has been ages since I installed it around 5 years ago. 2 12" Infinity Kappa Perfects... no big 3. I do see voltage drop on really hard punches though. Not even that I care to do any more work to the system.

Are you doing a compition vehicle that your so concenred about the electrical system?

Nope, I'm just very into it. I don't want to try to draw more than it can give because it's a waste of money/dims the headlights. Just trying to do it right is all :)

Did you replace your head unit or just use a Line Out Converter? What else have you done to the stereo? I just started planning it out today. I'd like to leave the head unit stock, since if I replace it I'll have to replace all of the speakers since they're all 2 ohms. I don't want to make that kind of investment into the car stereo, since I'd rather put that kind of money into performance.

So I'm thinking I'll add in the ipod adaptor that I've seen through the CD changer and run the subs with a LOC.

[complacentsee]

I replaced the head unit and all the speakers and added the subs.

I ran the bose speakers to an aftermarket head unit fine for 3 years. The issue I had is they run too effieicent and cause your subs to sound quiet relative to your mids and highs.

If your using the bose system you'll need to go with line level converters, Although the bose headunit has low level out, the amp does signal processing.


If were to do it all over again.. I would probabaly put in a nav changer. Put in 1 good 12 into a differant custom enclosure and remove the smaller rear seat.

[shorterthanrich]

Well, since you can anecdotally confirm that the aftermarket HU ran 2 ohm speakers alright, I may install a double din aftermarket HU, leave the speaker stock, take out the two rear deck speakers to vent more bass into the cabin, and build a small custom 2x12 box. I'm not worried about the speakers ever overpowering the subs. I will never, ever have that problem with these subs :D

[wdbdy2000s4]

You know. I don't even remember what the RMS of my amp is. I'm guesses it is 800 RMS range. It has been ages since I installed it around 5 years ago. 2 12" Infinity Kappa Perfects... no big 3. I do see voltage drop on really hard punches though. Not even that I care to do any more work to the system.

Are you doing a compition vehicle that your so concenred about the electrical system? I think any thing over what i have is overkill.

You're more like 600 watt RMS, the Perfects are rated at 350RMS@14volts each, the peak is high though at like 1200 each IIRC. I had 3000watts RMS power on my amps in my jetta, 8000Peak. The headlights would flicker when the subs hit hard.

Well, since you can anecdotally confirm that the aftermarket HU ran 2 ohm speakers alright, I may install a double din aftermarket HU, leave the speaker stock, take out the two rear deck speakers to vent more bass into the cabin, and build a small custom 2x12 box. I'm not worried about the speakers ever overpowering the subs. I will never, ever have that problem with these subs :D

2200watts RMS in the trunk is plenty to "BUMP" as the kids say these days, haha. I blew the trunk latch open on my jetta with 3000. Why not reinforce the rear deck and top mount the subs if you're really concerned, then you save your trunk room.

[shorterthanrich]

You're more like 600 watt RMS, the Perfects are rated at 350RMS@14volts each, the peak is high though at like 1200 each IIRC. I had 3000watts RMS power on my amps in my jetta, 8000Peak. The headlights would flicker when the subs hit hard.

I assumed him to be doing around 1/2 of his peak power, as is often the case.

2200watts RMS in the trunk is plenty to "BUMP" as the kids say these days, haha. I blew the trunk latch open on my jetta with 3000. Why not reinforce the rear deck and top mount the subs if you're really concerned, then you save your trunk room.

With my 13Ov.2s in my 3cf ported box and given 1000 watts RMS (Cadence TXA-1000D) that was more than enough to bump. It was way more than I needed...it made my roof flex 1/4" at least, and was enough to set off nearby car alarms. Most importantly, the SQ was outstanding...the box was tuned perfectly for those subs.

So, I'm very sure that the AQ2200D will be WAY more than enough to give those subs some life in a small (1.4cf) box.

I guess I could support the deck and mount them there, but then I lose the ability to take the box out of the trunk for snowboarding trips, etc. It would probably be better for 99% of the time, but for those few times I just want to pop the box out...it's not worth it.

Besides, a box as small as I'm going wont take up too much room. I'll go mostly vertical on it, so it should really only be about 8" deep total...tops. I'll angle the back to match the seats, etc. Not too bad of a footprint. I might hunt for a slightly smaller amp since I really will only need to give them 7-800 watts each...

So...again, any one have any info on the big 3 upgrade? Impossible to access or what? I'm going to have a helluva time getting that 0 AWG wire to the trunk :D

[complacentsee]

You're more like 600 watt RMS, the Perfects are rated at 350RMS@14volts each, the peak is high though at like 1200 each IIRC. I had 3000watts RMS power on my amps in my jetta, 8000Peak. The headlights would flicker when the subs hit hard.


2200watts RMS in the trunk is plenty to "BUMP" as the kids say these days, haha. I blew the trunk latch open on my jetta with 3000. Why not reinforce the rear deck and top mount the subs if you're really concerned, then you save your trunk room.

Yeah it might be 600 RMS. It was one of those RF 4 channel amps, so 75x4, 150x2, 300x2 4ohm.. yep checks out. I was going for quality over volume. I guess that would make since on why in installed 4 gauge wire. Jesus, you can forget alot of shit over 5 years.

Even at this the trunk really shakes and the rear deck can move over an inch. I added deadening to both of them.

Although I love having the subs, and finally have them working just the way I like it. I hate the amount of trunk space they take up and kind of wish I would have cut up the rear deck and done custom boxes mounted thier.

Unless you really really really just want it loud.. I wouldn't go to nuts. These cars are pretty small on the inside. If I ever do pull my engine to the the 6pd conversion and turbos, I'll pull a jibberjive and do an Ultranator.

The aftermarket deck worked fine for me. Just get a good one with a decent power rating. Mosfets usually don't have trouble driving lower impedence speakers. If it were old school BJT forget about it thermal overload and all that. Just understand that your whatever watt deck will be cut in half on the power output based on the current output. And the bose ones are like some miniscule wattage handling anyway. I would sugest hunting for some ebay deals for speakers.

I mixed and matched wierd speaker combos to do mine. 1 set of MB quart 2 ways (could have been 3 way but I usually don't go for that kinda think so I doubt it) for the rear speakers. And then a set of expansion speakers for the rear. These are like the add on to convert 2 way component to a 3 way. Then I used the factory bose tweeter, and the midbase. Sound is way better than stock. My guess is the bose speakers will start to go pretty quick once you start driving them hard.

[complacentsee]

Also, I might be bias as I'm only 23 and relize how much my hearing has been damaged by these damn addicting subs.

[jibberjive]

Sounds like you're going to have a sick system! I'm still working on my system for my B5 S4, but I'm going to be putting in a Pioneer AVIC f90-bt, 2 Critical Mass UL12's, Powerbass XA-3000D, Alpine PDX-4.150 for the speakers, and I haven't decided which components to run up from yet. I haven't bought the PDX amp nor front speakers yet, so that'll prob come with time as I'm out of money because of my performance build. And BTW, nice on the Audioque. I was going to be running two of their HDC3 12's, but I found these crazy light UL12's.

I'm also going to be doing the big 3 and relocating my battery to the trunk. If you haven't already bought your 0ga wire yet, the cheapest (and excellent quality) kit you can buy is the Kicker PKD1.

http://cgi.ebay.com/KICKER-PKD1-0-1-...lenotsupported

It comes with 20+ feet of 0 ga and a good amount of 4 ga as well as a battery fuse and some distro blocks (non-fused) if you are going to run two amps. I got it for like $100 shipped on ebay from Sonicelectronix's or whatever IIRC. Or if you want to go as budget as possible, find a local welding supply shop and get flex-a-prene. I hear it's the most flexible welding cable and is actually quite manageable. You'll also want to get your ring terminals from the welding supply shop as well because the car audio ones are pretty expensive. You'll also want this to crimp the ring terminals on wires that big (or a big table vice or something). I'm actually going to buy that right now ha.

http://cgi.ebay.com/ws/eBayISAPI.dll...lenotsupported

As for the big 3, I'll let you know how hard it is when I tackle it in a couple of weeks. To take out the alternator the general consensus is that you have to take off the front clip to take off one of the bolts, though a couple of people have said that they were able to get it off without taking the nose off. Others say they tried with the front on and it's impossible. However, once the front is off and the accessory belt is off it's really easy to get off, just a couple of bolts.

I'm going the upgraded alternator route because of the current draw of my amps (3000W RMS + 600W RMS.) I'm going the Ultranator route and he rewinds it to 150 amp and replaces the voltage regulator with a slightly higher Bosch one (14.8 vs 14.) I'll still be quite underpowered with that alternator, but it's not like I'm going to be having it at competition volume levels all day, so I should be fine daily driving. You can't really go that much higher than that with just a rewind of the alternator that will go back in to the stock place because cooling/reliability would be compromised. If you or anyone else is interested in the Ultranator that will bolt right back in, contact Avi at [email protected] and tell him Mike Romney (jibberjive) sent you. Good prices and one of the only ones around to do these Audi alternators. I think the email address on their website is wrong though, so use the one I posted above.

Ultranator Website

If I were you though with your setup I'd just do the big 3 and see how it fares. If it dims too much or just straight pulls too many amps, then go for the upgraded alty. I've got a B6 A4 that I'm currently running 1600W RMS to a RE SX15 daily and my car handles it surprisingly well.



If I'm bumping it super hard and have the map lights on they do dim a little, but normally I don't notice any dimming on my dash board and whatnot like I did with my jeep. I haven't even done the big 3 in my A4 yet either, so I bet you'll be fine. Also, for the ipod in my A4 I'm running a dension ice adaptor that is hardwired and I've custom run to the folddown center console. Sound quality is awesome and I'd do that if I were you (assuming you can find one, because they went out of business a little bit ago.) The placement in the center console is awesome too (I can grab some pics and details if you want.)

As far as using the stock deck with your subs, I wouldn't run a line output converter because the stock bose HU already sends a low level signal to the rear where the bose amp is. You can just straight up splice your RCA's into that line before it reaches the amp and get a really good, clean signal before it's processed at the amp. This is exactly what I did in my A4 (I'm running the stock HU.) Though if you just want to make the install easier you can tap into the leads to the sub just below the rear deck and run a LOC. Fact of the matter, if you decide to go that route I've got one of the highest quality LOC's made (Richard Navone LOC) that I'll sell you. I bought it to use in my A4 but figured out how to get that low level signal, so I've just had it sitting around.

And just so people know that my advice is somewhat legit, I used to be a sponsored car audio competitor.

I'm not worried about the speakers ever overpowering the subs. I will never, ever have that problem with these subs :D

I thought most people worry about having their speakers keep up with the big bass they install, not vice versa

[complacentsee]

It was a limitation of the gain on my amp, not the wattage. Using the "super high efficency" bose speakers my subs would sound rather pethedic. My subs would just chill there not being driven and the bose would be screaming loud. They were simply too high of efficiency drivers and worse, had a very low power rating.

I doub't you will have an issue like mine running that kind of wattage. But if your going to try and get the stocks to keep up with that much sub... you'll blow them out pretty quick

Once I finally got those bose speakers out, I ended up destroying one one night while I was bombed and had some one drive me in my car to get some taco bell. I was finally able to bring that +15 back to zero. Just one of those issues that arrieses when trying to integrate POS stock equipment with a decent deck. Even with some low cost drivers the sound will be improved alot over the bose stocks.


Just figure $100 extra for new drivers in the doors and do it right. No point in going half ass with that much sub.

[jibberjive]

Edit: Now that I see that you may go with a smaller amp, I'd for sure do the big 3 and try it before you go nuts with the alty.

Also, if you haven't bought your amp yet and are considering going slightly smaller, I've got an amp that I'm going to be taking out of my A4 because I'm selling the car that I'll sell you for a killer deal. It's a Cadence Daytona DCA1600, true 1600W RMS and one of the smallest footprints for that powerful of an amp. It's also really efficient, so maybe that's why I don't have any dimming issues with it in my A4. I'll give you a really good deal, so shoot me a PM if you're interested.



(Forgive the sloppy install, I wanted it easily removable as well so I mounted it on that piece of MDF that I covered with carpet and put velcro hooks on the back, which sticks to the rear of the seat.)

[jibberjive]

It was a limitation of the gain on my amp, not the wattage. Using the "super high efficency" bose speakers my subs would sound rather pethedic. My subs would just chill there not being driven and the bose would be screaming loud. They were simply too high of efficiency drivers and worse, had a very low power rating.

I doub't you will have an issue like mine running that kind of wattage. But if your going to try and get the stocks to keep up with that much sub... you'll blow them out pretty quick

Once I finally got those bose speakers out, I ended up destroying one one night while I was bombed and had some one drive me in my car to get some taco bell. I was finally able to bring that +15 back to zero. Just one of those issues that arrieses when trying to integrate POS stock equipment with a decent deck. Even with some low cost drivers the sound will be improved alot over the bose stocks.


Just figure $100 extra for new drivers in the doors and do it right. No point in going half ass with that much sub.

Yeah, I see how you could have issues like that with running the stock speakers with an aftermarket deck. With my stock HU and stock speakers though I'm able to get it to blend rather nicely with my crazy sub setup. Also, since I tapped the low level output for the rear, I can control the volume of my sub with the stock fade control. I'm surprisingly pleased with the mids/highs of the stock bose in my B6 A4. Can't necessarily say the same about my B5 though, and if I were him and were to spend that much on my sub stage, I'd definitely at least get those cheaper Infinity stock replacements that everybody bolts in for less than $100 (like you said.)

[complacentsee]

Jib, do you recomment Caps or not. My math tells me it would probably be approximately usless I had a really big one. But you see enough people swear by them and enough other people do the math and say nope.

I should just start designing amps and effects again instead of reading yours and gurus build every day... You guys make me want to spend wayy to much money.

[jibberjive]

Jib, do you recomment Caps or not. My math tells me it would probably be approximately usless I had a really big one. But you see enough people swear by them and enough other people do the math and say nope.

I should just start designing amps and effects again instead of reading yours and gurus build every day... You guys make me want to spend wayy to much money.

NO, DO NOT GET A CAPACITOR. Simple

[complacentsee]

NO, DO NOT GET A CAPACITOR. Simple

Thats what my math and logic said. But I figured I would ask a guy that has set up more systems than myself.

[jibberjive]

No prob, and that advice is for everyone, don't waste your money on a cap.

[Karl]

This thread is pretty interesting to me. I have 2 tens and a rockford amp that I think is around 700 watts. Thursday I was sitting in traffic in DC, hot as hell, the fans running, my headlights on, my AC on, and the stereo pumping. I scanned my gauges and the voltage gauge was at 12 volts. DEAD ON 12 volts. Not a hair above 12. I've never seen it much below the mark between 12 and 16. I turned all my garbage off and it rebounded to ALMOST normal (normal as in where I normally see it)

I started thinking my alternator was getting old/weak (if that happens when they're going bad) or that I needed a bigger one.

[complacentsee]

This thread is pretty interesting to me. I have 2 tens and a rockford amp that I think is around 700 watts. Thursday I was sitting in traffic in DC, hot as hell, the fans running, my headlights on, my AC on, and the stereo pumping. I scanned my gauges and the voltage gauge was at 12 volts. DEAD ON 12 volts. Not a hair above 12. I've never seen it much below the mark between 12 and 16. I turned all my garbage off and it rebounded to ALMOST normal (normal as in where I normally see it)

I started thinking my alternator was getting old/weak (if that happens when they're going bad) or that I needed a bigger one.

Yeah, I've noticed mine drooping a bit more this summer with the AC/condenser fan running. That ultranator is pretty interesting with 150A @14.8 thats an over 500 watts more of usable power. And a pretty affordable to compared to a rebuilt.

[jibberjive]

This thread is pretty interesting to me. I have 2 tens and a rockford amp that I think is around 700 watts. Thursday I was sitting in traffic in DC, hot as hell, the fans running, my headlights on, my AC on, and the stereo pumping. I scanned my gauges and the voltage gauge was at 12 volts. DEAD ON 12 volts. Not a hair above 12. I've never seen it much below the mark between 12 and 16. I turned all my garbage off and it rebounded to ALMOST normal (normal as in where I normally see it)

I started thinking my alternator was getting old/weak (if that happens when they're going bad) or that I needed a bigger one.

What Rockford amp do you have? I ask because the class A/B amps are way less efficient than class D amps commonly used on subs, so that amp could draw the same current as a class D with say 1200W.

Also something to note, alternators don't put out near the amps at idle as they do when running. For example, these 150amp rated alty's don't put out 150amps at idle. You said you were in traffic (I assume stopped or stop and go) so I would expect your alternator to not be able to keep up and therefore you would fall back on the battery (which should read dead on 12V until you start to wear it down, which would take more time than a couple of mins stopped in traffic.) The fact that it came back up after you turned some accessories off makes me think that your alty is fine considering you have a system and were stopped. Check it when you're actually driving. Of course if you over strain the elec. system with a big stereo you can decrease the life of your alty, but I wouldn't worry about it until you have symptoms that are affecting something.

[complacentsee]

Thats a good point. The class A/B is probably at best 50% (probably more like 20) efficient at lower levels and *maybe* 75-80% at peak levels.

But jib, who doesn't want 700 watts of of full range power. Digital amps are only good for 500 Hz.. Weak sauce

[jibberjive]

Thats a good point. The class A/B is probably at best 50% (probably more like 20) efficient at lower levels and *maybe* 75-80% at peak levels.

But jib, who doesn't want 700 watts of of full range power. Digital amps are only good for 500 Hz.. Weak sauce

If the amp is only going to be used on subs crossed over at 120hz, then I could care less if it's full range and would prefer 500 watts of more headroom.

Also, there's been some full range class d amps that people are super impressed with, one of them being the Alpine PDX-4.150 that I'm going with. It's tiny and super efficient (as well as sounding good), all of which are important to my specific system because I want it as light as possible for performance. Also with my other amp pulling over 200amps itself, the efficiency is key. Check it out, you might be surprised

http://www.caraudiomag.com/0607_cae_...ier/index.html

Cadence also used to have a full range "class T" (read full range class D) amp as well.

[complacentsee]

I was being sarcastic on the full range.

Digital Amps have come leaps and bounds since there first commercial releases. I only own one of them. And that's my home theater sub. I'm super impressed with them, especially their efficiency. Compared to my 6 channel HT amp which probably uses about 10x the power of my sub amp which is rated at twice the rms wattage...

A few years back I read all about the "class T" ones. Nice little full package chip. I only read about the actual hardware not the devices they were being packaged into. Thats a nice alpine amp. I love how they have gone from most the amp being heat sink to just having the actual enclousure being a heat sink.

[shorterthanrich]

Yeah it might be 600 RMS. It was one of those RF 4 channel amps, so 75x4, 150x2, 300x2 4ohm.. yep checks out. I was going for quality over volume. I guess that would make since on why in installed 4 gauge wire. Jesus, you can forget alot of shit over 5 years.

Even at this the trunk really shakes and the rear deck can move over an inch. I added deadening to both of them.

Although I love having the subs, and finally have them working just the way I like it. I hate the amount of trunk space they take up and kind of wish I would have cut up the rear deck and done custom boxes mounted thier.

Unless you really really really just want it loud.. I wouldn't go to nuts. These cars are pretty small on the inside. If I ever do pull my engine to the the 6pd conversion and turbos, I'll pull a jibberjive and do an Ultranator.

The aftermarket deck worked fine for me. Just get a good one with a decent power rating. Mosfets usually don't have trouble driving lower impedence speakers. If it were old school BJT forget about it thermal overload and all that. Just understand that your whatever watt deck will be cut in half on the power output based on the current output. And the bose ones are like some miniscule wattage handling anyway. I would sugest hunting for some ebay deals for speakers.

I mixed and matched wierd speaker combos to do mine. 1 set of MB quart 2 ways (could have been 3 way but I usually don't go for that kinda think so I doubt it) for the rear speakers. And then a set of expansion speakers for the rear. These are like the add on to convert 2 way component to a 3 way. Then I used the factory bose tweeter, and the midbase. Sound is way better than stock. My guess is the bose speakers will start to go pretty quick once you start driving them hard.

Alright WHOA this thread has had a lot of responses while I was traveling today. I'll respond to each of these things as I can!

So, 600 Watts with the right subs in the right box can definitely shake a car, no problem. Not meaning to offend, but I wouldn't ever mix speakers. All speakers have a different timber, etc, so you really can make some odd things happen with different brands in there. I'm sure it still sounds good, though. I'm not going to go tooo crazy with the subs. Like I said, roughly 1500 Watts will be given to the subs...that's really not that crazy, especially in a sealed box. The subs are happy in .7cf, so a 1.5 cf box will be tiny, especially if I build it tall. They only have 6.6" or so mounting depth...wont take up much space at all.

I'm not sure what you meant by "ust understand that your whatever watt deck will be cut in half on the power output based on the current output." From the way I read it, you're saying that I'll output less power with the 2 ohm speakers? That's the backwards of the case...If I got a 22 Watt RMS, which usually now with CEA 2003 compliance is really 14 Watts RMS, if I was running 2 ohm speakers it would be more like 28 Watts, but with a higher THD.

I don't think that's what you meant, though. Regardless, the more I think about it, the more I think I'll go with a LOC and ipod adapter or tap into the low level bose output etc. simple, effective, and if I ever want to upgrade the HU and speakers I still have the option....

[complacentsee]

Alright WHOA this thread has had a lot of responses while I was traveling today. I'll respond to each of these things as I can!

So, 600 Watts with the right subs in the right box can definitely shake a car, no problem. Not meaning to offend, but I wouldn't ever mix speakers. All speakers have a different timber, etc, so you really can make some odd things happen with different brands in there. I'm sure it still sounds good, though. I'm not going to go tooo crazy with the subs. Like I said, roughly 1500 Watts will be given to the subs...that's really not that crazy, especially in a sealed box. The subs are happy in .7cf, so a 1.5 cf box will be tiny, especially if I build it tall. They only have 6.6" or so mounting depth...wont take up much space at all.

I'm not sure what you meant by "ust understand that your whatever watt deck will be cut in half on the power output based on the current output." From the way I read it, you're saying that I'll output less power with the 2 ohm speakers? That's the backwards of the case...If I got a 22 Watt RMS, which usually now with CEA 2003 compliance is really 14 Watts RMS, if I was running 2 ohm speakers it would be more like 28 Watts, but with a higher THD.

I don't think that's what you meant, though. Regardless, the more I think about it, the more I think I'll go with a LOC and ipod adapter or tap into the low level bose output etc. simple, effective, and if I ever want to upgrade the HU and speakers I still have the option....

The wierd mix was all the same same brand and series. Just used a set of coaxial speakers , in combination with a add on speaker for a full component set of the same brand and series. The mix is great actually as the stocks are only midrange all around besides the 2 factory tweeters.

The limiting factor of these decks is the current output. The transistors in the output stage can only flow so much current. The peak voltages availible remain the same for any ohm speaker you use. So if you have a 4 ohm rated deck at 20watts RMS @ lets just make up 50WPeak. Your deck will have a peak to peak voltage of (p=V^2/R) V=sqrt(50*4) = 14v. Using this equation alone, you are correct that you could provide twice the peak power. However you must also assume that the deak was designed to only flow @ RMS power for any real length of time. So, you also use the equation P=R*I^2. Using this, 20Wrms yeilds I"rms"=sqrt(20/4) = 2.23A. If you use a 2ohm speaker this give you P=2.23^2*2=10Wrms.


This means that when you reduce the ohms by a factor of 2, you double the peak power. However, since the transistors can only flow above there design current for limited time period you must cut the power you should be running the amp at in half.

[shorterthanrich]

The wierd mix was all the same same brand and series. Just used a set of coaxial speakers , in combination with a add on speaker for a full component set of the same brand and series. The mix is great actually as the stocks are only midrange all around besides the 2 factory tweeters.

The limiting factor of these decks is the current output. The transistors in the output stage can only flow so much current. The peak voltages availible remain the same for any ohm speaker you use. So if you have a 4 ohm rated deck at 20watts RMS @ lets just make up 50WPeak. Your deck will have a peak to peak voltage of (p=V^2/R) V=sqrt(50*4) = 14v. Using this equation alone, you are correct that you could provide twice the peak power. However you must also assume that the deak was designed to only flow @ RMS power for any real length of time. So, you also use the equation P=R*I^2. Using this, 20Wrms yeilds I"rms"=sqrt(20/4) = 2.23A. If you use a 2ohm speaker this give you P=2.23^2*2=10Wrms.


This means that when you reduce the ohms by a factor of 2, you double the peak power. However, since the transistors can only flow above there design current for limited time period you must cut the power you should be running the amp at in half.

Ohhhh I see - mixing the same brand/series with comps and coax is a different story. no problems there :-D

In a practical application, you'll find that overall your output will be higher. Lets disregard peak for everything, since it really is 99% a marketing tactic, and the only thing you ever really can measure by is RMS. It'll come down to the thermal handling of your transistors, etc. For sub amps, they're typically designed to run lower impedences, but I don't know much about HU handling.

[complacentsee]

Ohhhh I see - mixing the same brand/series with comps and coax is a different story. no problems there :-D

In a practical application, you'll find that overall your output will be higher. Lets disregard peak for everything, since it really is 99% a marketing tactic, and the only thing you ever really can measure by is RMS. It'll come down to the thermal handling of your transistors, etc. For sub amps, they're typically designed to run lower impedences, but I don't know much about HU handling.

Yep, the peak just tells you what the voltage rails run at. For example head units can run find on just the 14v rail from the alternator. Sub amps however have DC to DC converters built in which raise the rail voltage. This is also the reason why low impedence amplifiers (atleast used to, I havent been in the market since digitial amps became the rage, the are usually cheaper due to the fact that they can run power transistors capible of high currents and are usually cheaper than signal transistors) cost alot more. They required twice the output transistors to to achieve the same power output at the same voltage. However, it allow allowed them to double the power output without having to increase the rail voltage just the rail supply current.

[shorterthanrich]

Sounds like you're going to have a sick system! I'm still working on my system for my B5 S4, but I'm going to be putting in a Pioneer AVIC f90-bt, 2 Critical Mass UL12's, Powerbass XA-3000D, Alpine PDX-4.150 for the speakers, and I haven't decided which components to run up from yet. I haven't bought the PDX amp nor front speakers yet, so that'll prob come with time as I'm out of money because of my performance build. And BTW, nice on the Audioque. I was going to be running two of their HDC3 12's, but I found these crazy light UL12's.

I'm also going to be doing the big 3 and relocating my battery to the trunk. If you haven't already bought your 0ga wire yet, the cheapest (and excellent quality) kit you can buy is the Kicker PKD1.

http://cgi.ebay.com/KICKER-PKD1-0-1-...lenotsupported

It comes with 20+ feet of 0 ga and a good amount of 4 ga as well as a battery fuse and some distro blocks (non-fused) if you are going to run two amps. I got it for like $100 shipped on ebay from Sonicelectronix's or whatever IIRC. Or if you want to go as budget as possible, find a local welding supply shop and get flex-a-prene. I hear it's the most flexible welding cable and is actually quite manageable. You'll also want to get your ring terminals from the welding supply shop as well because the car audio ones are pretty expensive. You'll also want this to crimp the ring terminals on wires that big (or a big table vice or something). I'm actually going to buy that right now ha.

http://cgi.ebay.com/ws/eBayISAPI.dll...lenotsupported

As for the big 3, I'll let you know how hard it is when I tackle it in a couple of weeks. To take out the alternator the general consensus is that you have to take off the front clip to take off one of the bolts, though a couple of people have said that they were able to get it off without taking the nose off. Others say they tried with the front on and it's impossible. However, once the front is off and the accessory belt is off it's really easy to get off, just a couple of bolts.

I'm going the upgraded alternator route because of the current draw of my amps (3000W RMS + 600W RMS.) I'm going the Ultranator route and he rewinds it to 150 amp and replaces the voltage regulator with a slightly higher Bosch one (14.8 vs 14.) I'll still be quite underpowered with that alternator, but it's not like I'm going to be having it at competition volume levels all day, so I should be fine daily driving. You can't really go that much higher than that with just a rewind of the alternator that will go back in to the stock place because cooling/reliability would be compromised. If you or anyone else is interested in the Ultranator that will bolt right back in, contact Avi at [email protected] and tell him Mike Romney (jibberjive) sent you. Good prices and one of the only ones around to do these Audi alternators. I think the email address on their website is wrong though, so use the one I posted above.

Ultranator Website

If I were you though with your setup I'd just do the big 3 and see how it fares. If it dims too much or just straight pulls too many amps, then go for the upgraded alty. I've got a B6 A4 that I'm currently running 1600W RMS to a RE SX15 daily and my car handles it surprisingly well.



If I'm bumping it super hard and have the map lights on they do dim a little, but normally I don't notice any dimming on my dash board and whatnot like I did with my jeep. I haven't even done the big 3 in my A4 yet either, so I bet you'll be fine. Also, for the ipod in my A4 I'm running a dension ice adaptor that is hardwired and I've custom run to the folddown center console. Sound quality is awesome and I'd do that if I were you (assuming you can find one, because they went out of business a little bit ago.) The placement in the center console is awesome too (I can grab some pics and details if you want.)

As far as using the stock deck with your subs, I wouldn't run a line output converter because the stock bose HU already sends a low level signal to the rear where the bose amp is. You can just straight up splice your RCA's into that line before it reaches the amp and get a really good, clean signal before it's processed at the amp. This is exactly what I did in my A4 (I'm running the stock HU.) Though if you just want to make the install easier you can tap into the leads to the sub just below the rear deck and run a LOC. Fact of the matter, if you decide to go that route I've got one of the highest quality LOC's made (Richard Navone LOC) that I'll sell you. I bought it to use in my A4 but figured out how to get that low level signal, so I've just had it sitting around.

And just so people know that my advice is somewhat legit, I used to be a sponsored car audio competitor.



I thought most people worry about having their speakers keep up with the big bass they install, not vice versa

You have to let me know how the big 3 goes. I've made up my mind against the H O Alt, since really 120 will be plenty for me. I'm going for high SQ in that sealed box, with enough output to make me mildly uncomfortable. The 13Ov.2s will have nooo problem doing that with 1500 watts.

Thanks for the suggestion on the wires, though I would verrry strongly recommend KnuKonceptz over kicker, stinger, etc. I've used their wires on a lot of separate occasions and they never fail to disappoint. Literally 1/2 of the price of other quality brands. Have you seen their stuff before? www.knukonceptz.com . They also have ridiculous fast shipping. You're spot on with the welding supply cable/ring terminals. I might go welding supply...but it depends on what you say about the big 3. If I cant do the big three without taking apart my whole front end...I might not do it. I don't have a garage or a lift or any more time than a weekend ever (due to traveling for work constantly) so it could be a problem. I do anxiously await your report on that.

If I get a lot of dimming, I'll more than likely just lower my gain or build a slightly larger box. Box building isn't too hard and is like $25. So, that should help out.

Also, yeahhh I'm super pumped about that AudioQue amp. What amp are you running right now with 3,000 Watts RMS?

Ok, so about the line level signal to the bose amp. I was looking for a bose amp in the back because my maxima had that situation, and I couldn't find one. So I assumed that all of the amping was happening at the HU. Is that wrong? It does actually send a line level voltage and each speaker has a mini amp? I'd be curious to just splice into that.... but if it becomes irritatingly complex I'd be happy with a standard LOC.

I'd like some pictures of your ipod situation. I got some info on ipod adapters that run from the hookups for the 6 CD changer. They're like $60, high quality since it runs through the ipod port rather than the aux. Should be fine.

PM me about that LOC. IF for some reason its not much more than a standard LOC I might buy it off you. Though like I said I'm interested in tapping into the line level.

I know when someone knows what they're talking about or not. So no street cred required. ;)


And yeah, with the way I tend to overdo subs....i've never been worried that the subs can't keep up.

Also NICE call on the RE 15". Killer.

[complacentsee]

Also, sorry if I come off strange about this stuff. Audio amplifiers were the main reason I chose to go into electrical engineering and I'm just into the design stuff.

[shorterthanrich]

It was a limitation of the gain on my amp, not the wattage. Using the "super high efficency" bose speakers my subs would sound rather pethedic. My subs would just chill there not being driven and the bose would be screaming loud. They were simply too high of efficiency drivers and worse, had a very low power rating.

I doub't you will have an issue like mine running that kind of wattage. But if your going to try and get the stocks to keep up with that much sub... you'll blow them out pretty quick

Once I finally got those bose speakers out, I ended up destroying one one night while I was bombed and had some one drive me in my car to get some taco bell. I was finally able to bring that +15 back to zero. Just one of those issues that arrieses when trying to integrate POS stock equipment with a decent deck. Even with some low cost drivers the sound will be improved alot over the bose stocks.


Just figure $100 extra for new drivers in the doors and do it right. No point in going half ass with that much sub.

You definitely have a good point. You're right I'll NEVER have a problem getting my subs to keep up, I'll have the reverse. I know the woes of integrating POS Blose speakers with better stuff. It's a nightmare. I'm trying not to spend too much money on my audio, hence my aversion to replacing it. IF I do end up replacing the HU, I know I'll almost definitely break down and replace the comps, too. I wouldn't be happy with cheap speakers, though. I'd almost definitely go with c/d/t comps. What size are the front speakers and the speakers in the rear doors?

[complacentsee]

Ok, so about the line level signal to the bose amp. I was looking for a bose amp in the back because my maxima had that situation, and I couldn't find one. So I assumed that all of the amping was happening at the HU. Is that wrong? It does actually send a line level voltage and each speaker has a mini amp? I'd be curious to just splice into that.... but if it becomes irritatingly complex I'd be happy with a standard LOC.

Bose amp is located in the drivers side of the trunk behind the trunk liner. The line output from the bose amp is 4 signal wires with a common ground. There is also a remote turn on lead. Then the amp amp has 6 outputs, 2 front doors, 2 rear doors, 2 rear deck. Wiring and pinouts are available in a tech at audiworld.

[shorterthanrich]

Edit: Now that I see that you may go with a smaller amp, I'd for sure do the big 3 and try it before you go nuts with the alty.

Also, if you haven't bought your amp yet and are considering going slightly smaller, I've got an amp that I'm going to be taking out of my A4 because I'm selling the car that I'll sell you for a killer deal. It's a Cadence Daytona DCA1600, true 1600W RMS and one of the smallest footprints for that powerful of an amp. It's also really efficient, so maybe that's why I don't have any dimming issues with it in my A4. I'll give you a really good deal, so shoot me a PM if you're interested.



(Forgive the sloppy install, I wanted it easily removable as well so I mounted it on that piece of MDF that I covered with carpet and put velcro hooks on the back, which sticks to the rear of the seat.)

I'm quite familiar with the Daytona series. VERY solid amps, underrated, AND rated at 13.8 volts. PM me about your price on that. 1,600 Watts is probably perfect. I plan on buying a Porsche 911 in about two years, in which I'm going to do a very complex install with two shallow mount subs above the rear engine bay, and its VERY unlikely I'd need 2200 watts in that car. I could ONLY imagine the cost of replacing an alt in a 911. yeesh.

Tell me more about your install. That's actually not a bad idea. I was planing on mounting it upside down under the rear deck. so it's always out of the way.

[shorterthanrich]

Yeah, I see how you could have issues like that with running the stock speakers with an aftermarket deck. With my stock HU and stock speakers though I'm able to get it to blend rather nicely with my crazy sub setup. Also, since I tapped the low level output for the rear, I can control the volume of my sub with the stock fade control. I'm surprisingly pleased with the mids/highs of the stock bose in my B6 A4. Can't necessarily say the same about my B5 though, and if I were him and were to spend that much on my sub stage, I'd definitely at least get those cheaper Infinity stock replacements that everybody bolts in for less than $100 (like you said.)

Can I get a link to the 2 ohm infinity speakers? THAT I might be interested in for sheer simplicity.

My problem is that if I go with nice new comps, I'll get $150 c/d/t in front AND rear and then I'll need to amp them and blah blah and I'll get all crazy about it and spend a ton of money haha.

[shorterthanrich]

Jib, do you recomment Caps or not. My math tells me it would probably be approximately usless I had a really big one. But you see enough people swear by them and enough other people do the math and say nope.

I should just start designing amps and effects again instead of reading yours and gurus build every day... You guys make me want to spend wayy to much money.

Jib already covered this, but nooooooo no caps, never, for no reason, no matter what. Waste of time, money, and space.

[shorterthanrich]

What Rockford amp do you have? I ask because the class A/B amps are way less efficient than class D amps commonly used on subs, so that amp could draw the same current as a class D with say 1200W.

Also something to note, alternators don't put out near the amps at idle as they do when running. For example, these 150amp rated alty's don't put out 150amps at idle. You said you were in traffic (I assume stopped or stop and go) so I would expect your alternator to not be able to keep up and therefore you would fall back on the battery (which should read dead on 12V until you start to wear it down, which would take more time than a couple of mins stopped in traffic.) The fact that it came back up after you turned some accessories off makes me think that your alty is fine considering you have a system and were stopped. Check it when you're actually driving. Of course if you over strain the elec. system with a big stereo you can decrease the life of your alty, but I wouldn't worry about it until you have symptoms that are affecting something.

I was going to say exactly this. You don't get full output at or near idle, so in traffic with the fan on and the subs going hard you could easily see voltage drops. Nothing to really worry about unless it starts acting up under normal use. Amps are also less efficient at higher temperatures.

[complacentsee]

Can I get a link to the 2 ohm infinity speakers? THAT I might be interested in for sheer simplicity.

My problem is that if I go with nice new comps, I'll get $150 c/d/t in front AND rear and then I'll need to amp them and blah blah and I'll get all crazy about it and spend a ton of money haha.

http://www.audizine.com/forum/showth...infinity+4022i

The biggest issue with using the low level outputs from the bose head unit to feed an aftermarket head unit is the signal processing that happens in the bose amp. I haven't experianced this myself but you might want to read up on the tech article that covers it at AW. The guy never tried using line level converters or line levels IIRC, so that might be a different path to try...

[shorterthanrich]

On the Class D/ Class A/B amps subject, AB is way less efficient which has already been commented on. There's definitely been leaps and bounds in Class D tech, but hardcore audiophiles will never stray from the A/B. But, you really have to be just that to really even notice - an audiophile.

Alright, my girlfriend just made me a surprisingly strong drink, and my spelling errors have been getting increasingly high as I've typed things out in the last hour. Thanks a ton for all of the responses. Jib, I'll be PMing you on that daytona amp. It sounds perfect for my application. I think it's time for me to give up on the idea of making a super audio car. I had been thinking I'd eventually make a 2200+ watt sub, 600 watt + components car with a big ported box and all of that...but now with the S4, followed by the eventually to be purchased 911, performance will be so much more important than booming audio. I cared about it in my Maxima...because it wasn't a performance car. I'm a driving enthusiast and I was compensating for what my car lacked with sound. So from now on I think it'll be much more reasonable aspirations. Loud but with a primary focus on beautiful SQ.

I'll be waiting to hear about the big 3 upgrade...

[shorterthanrich]

Also, sorry if I come off strange about this stuff. Audio amplifiers were the main reason I chose to go into electrical engineering and I'm just into the design stuff.

No worries at all, mate. +5 for serious knowledge. I run into far too many car audio folks who really don't understand the science...