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Old 03-08-2008, 11:52 PM   #1
hans030390
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Default Looking to add a second amp to my car...

I'm planning on eventually adding a second amp (4-channel) to my car audio setup (I only have one for my sub, the HU is doing the rest of the work with the speakers). However, there are a couple of questions I had:

1. I only have one RCA output on my HU...so I only have one RCA cable available. How am I supposed to hook up a second amp? I REALLY don't have the money for an extra HU. I was wondering if there was some way to split the RCA cable to hook up to both amps (hopefully without degrading sound quality)?

EDIT: I think I got #1 figured out. Thanks

2. I have an 8-gauge power cable running to my current amp. I'd also not like to have to replace that. If I were to get a new fuse holder and fuse (maybe 80-amps, which my 8-gauge SHOULD be able to handle with its length), and then get a power distributor, would that be sufficient for both amps? I doubt my new amp will be over 300-400 Watts RMS (my sub amp is 200 Watts RMS).

Here's the problem with 2, though...I can't find a power distrubutor that has an 8-gauge input (either that or I'm really bad at look or reading details)...generally it's 4-gauge or bigger. Is there a power distributor that has an 8-gauge input?
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Old 03-09-2008, 02:21 PM   #2
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Default Looking to add a second amp to my car...

8 guage might be a little small for 600 watts. As far as RCAs...you can get a splitter or just find an amp that has an RCA output...so the RCA's from your hu will go to the amp...then another set will go from that amps RCA out to the sub amps input.
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Old 03-09-2008, 10:16 PM   #3
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: Doodoo
8 guage might be a little small for 600 watts. As far as RCAs...you can get a splitter or just find an amp that has an RCA output...so the RCA's from your hu will go to the amp...then another set will go from that amps RCA out to the sub amps input.
Well, I don't think I'll need more than 80 amps, and for the length of my power cable, the 8 gauge is listed to be able to handle that (got that from Crutchfield). If possible, I'm only going to have 500 Watts RMS total.

I totally spaced that my amp should have an RCA output. I feel like a total n00b now.

But now, say I do keep the 8-gauge wire (which I want to), are there any power distrubutors that have 8-gauge inputs?

Thanks for your help.
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Old 03-10-2008, 08:31 AM   #4
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Default Looking to add a second amp to my car...

Maybe this will work.

Text
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Old 03-10-2008, 01:29 PM   #5
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Default Looking to add a second amp to my car...

While a splitter of some sort or an in-line speaker to RCA converter will give you the RCA connections you are looking for, the sound quality will likely not be where you want it. I have done one install where I had to use such methods above and the SQ was HORRIBLE. The setup made it very difficult to tune the system and get the accuracy where it should be. I'd seriously suggest you to step up to a quality head unit with 3 sets of pre-outs with at least 4V running them. (front, rear, non-fader/sub)

8 guage seems to be a little small and I've never found it to be a bad thing to run a little thicker wire when possible. Hell, I use 8 guage to my subwoofer from the amp! I'd say upgrade that to 4 guage between the battery and your distribution block. From there, short runs of 8 guage to the amps will be acceptable, so your wire won't necessarily go to waste.

Which amps/HU are you currently running?
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Old 03-10-2008, 04:27 PM   #6
hans030390
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: Doodoo
Maybe this will work.

Text
Ah, that may work. I'll look into it. Thanks

Quote:
Originally posted by: jamesbond007
While a splitter of some sort or an in-line speaker to RCA converter will give you the RCA connections you are looking for, the sound quality will likely not be where you want it. I have done one install where I had to use such methods above and the SQ was HORRIBLE. The setup made it very difficult to tune the system and get the accuracy where it should be. I'd seriously suggest you to step up to a quality head unit with 3 sets of pre-outs with at least 4V running them. (front, rear, non-fader/sub)

8 guage seems to be a little small and I've never found it to be a bad thing to run a little thicker wire when possible. Hell, I use 8 guage to my subwoofer from the amp! I'd say upgrade that to 4 guage between the battery and your distribution block. From there, short runs of 8 guage to the amps will be acceptable, so your wire won't necessarily go to waste.

Which amps/HU are you currently running?
I'm pretty sure my amp has an RCA output, so I should be able to run another amp from that. I think that solved my problem, and should sound fine. I'm really tight on a budget...I already plan on getting a new amp, new speakers, sound deadening stuff for my car, and extra wires/accessories to set it all up...a new HU is really adding too much.

I'm not saying it's a BAD thing to run extra wire, but if I don't HAVE to, I'm not going to. It was a big pain doing it the first time in my car. If I keep the 8-gauge, I'll only have a bit of work to do in the trunk (easy).

According to this chart, (and I think I'm close to the 13ft length, maybe slightly over) I should be able to run an 80 amp fuse with my 8 gauge...with that, and other information I've read, my 8-gauge SHOULD be able to handle a second amplifier if I get a power distributor and a better fuse/fuse holder. If I have to run a 4-gauge wire, I will...but if 8-gauge will do, I'm keeping it to save time, energy, and money.

My head unit is this, but likely a slightly older model (specs and looks seem to be the exact same, minus very minor things). I use this amp to power my sub (the amp and sub are both only 200 Watts RMS, so it works perfectly).

EDIT: The HU is actually a CDX-GT100, not GT120. I just found the model. They are still very similar.

That's all I currently have installed. The amp I have has an aux-out (next to the line in), so I'm assuming I can plug that into a second amp...

I was planning on getting something similar to this for my speaker amp (though maybe not this exact amp, just something with similar power ratings and such). However, it has line-ins for both the front and rear...but I'd only have one coming off the other amp. So, once again, I'm sorta back in the original situation.

Another thing I noticed is that the amp I listed above (a possible option for my speaker amp) has a fuse rating of 25 x3. Does that mean I'll need a fuse of 25 amps to run it, or one with 75 amps (neglecting that I'll need more for my sub amp)?
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Old 03-11-2008, 02:01 AM   #7
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Default Looking to add a second amp to my car...

I run a little over 1,000W RMS on my system with my amps rated to hit around 1,800W at peak, which I never hit since this is my daily driver. I wouldn't bother using more than a 30 or 40 amp fuse on your power line to the trunk. (I think I am using a 40A) You don't tabulate the amps based on the fuses in your amplifiers.

I typically recommend having an amplifier that will supply more than the RMS wattage of a subwoofer and speakers. The speaker will likely get very loud, but you will not always reach the full capabilities of a speaker unless you can supply a bit of clean read: QUALITY power. Amps are not always 100% efficient and having a good amp will allow you to keep your gains low, which can improve your sound quality if your amp starts sending out an imperfect sine wave to your driver when you increase the gains too much.

I hope I typed that properly. It's late and I'm tired.
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Old 03-11-2008, 07:51 AM   #8
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: jamesbond007
I run a little over 1,000W RMS on my system with my amps rated to hit around 1,800W at peak, which I never hit since this is my daily driver. I wouldn't bother using more than a 30 or 40 amp fuse on your power line to the trunk. (I think I am using a 40A) You don't tabulate the amps based on the fuses in your amplifiers.

I typically recommend having an amplifier that will supply more than the RMS wattage of a subwoofer and speakers. The speaker will likely get very loud, but you will not always reach the full capabilities of a speaker unless you can supply a bit of clean read: QUALITY power. Amps are not always 100% efficient and having a good amp will allow you to keep your gains low, which can improve your sound quality if your amp starts sending out an imperfect sine wave to your driver when you increase the gains too much.

I hope I typed that properly. It's late and I'm tired.
Ok, speaking of which...what are some amps that will give this "quality" power you speak of?
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Old 03-11-2008, 11:54 AM   #9
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Default Looking to add a second amp to my car...

1. 8 gauge will be fine for your power range.
2. You'll need 3 pairs of RCA for 2 amps. Here's some ways to solve your problem:
  • a. RCA splitters (cheap but SQ might suffer from all the splitting)
    b. buy an equalizer (many will take a pair of inputs and split it to 3 electronically so there won't be much signal loss and allow you to shape the sound to your likings too
    c. buy a new headunit with 3 pairs of outputs. 4volt outputs not necessary unless you have a noise issue. I had 2v and 4v headunits and I couldn't tell the difference especially in a car environment.
3. distribution blocks with 4g inputs will work fine.
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Old 03-11-2008, 12:28 PM   #10
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Default Looking to add a second amp to my car...

I don't know about Blaupunkt amplifiers, so I can't comment on them specifically. I typically recommend a single-channel monoblock class D amps for subwoofers as they are more efficient and the distortion from Class D isn't noticable in low frequencies. (Class A and B are preferred for running tweeters and midrange speakers)

I like Alpine and JL Audio for entry-level quality. (I use Alpines currently) If you're really serious, you can look at Zapco or Soundstream Reference series amps for the goods. There's a guy here on AT selling some Soundstream Reference series amps in FS/FT. These are typically heavily under-rated and will handle half-ohm loads without problems.

jtvang125, in my experience, a deck that puts out 4V on the preouts has always sounded better and obviously can get music louder faster without turning up the gains on the amplifiers. I had an Alpine CDA-9827 that put out 4V and I had to keep my gains a little up from nominal (zero) to get good play with the volume knob. With my Eclipse CD5435, the gains are at zero with 5V preouts and with the CD8445 that puts out 8V, the gains on all my amps have to be reduced as far back as they go. By having the strong signals go to your amplifiers, the noise picked up from internals is reduced as they are FAR weaker than the beefy preout signals. Most decks that have 3 sets of preouts these days supply the lines with 4V anyways.
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Old 03-11-2008, 01:48 PM   #11
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Default Looking to add a second amp to my car...

JL 5 channel and matching price tag
http://www.onlinecarstereo.com...l.aspx?ProductID=11727
or a bit more budget conscious
Alphasonic
http://www.onlinecarstereo.com...l.aspx?ProductID=14181
MB Quart
http://www.onlinecarstereo.com...l.aspx?ProductID=17701
Hifonics (been Making amps FOREVER)
http://www.onlinecarstereo.com...l.aspx?ProductID=16362

5 Channel Amp... might do what you want might not.... Depends
Dont know what your pushing and if you can offload that Sub amp you have now... also invest in a good head unit...
Just some Basics..

Wow I havent messed with car audio for so long.... Last Comp amp was a cheater MTX 225H.O. On three 10" Eclipse DVC's
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Old 03-11-2008, 04:01 PM   #12
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: jtvang125
1. 8 gauge will be fine for your power range.
2. You'll need 3 pairs of RCA for 2 amps. Here's some ways to solve your problem:
  • a. RCA splitters (cheap but SQ might suffer from all the splitting)
    b. buy an equalizer (many will take a pair of inputs and split it to 3 electronically so there won't be much signal loss and allow you to shape the sound to your likings too
    c. buy a new headunit with 3 pairs of outputs. 4volt outputs not necessary unless you have a noise issue. I had 2v and 4v headunits and I couldn't tell the difference especially in a car environment.
3. distribution blocks with 4g inputs will work fine.
I'll likely want to get a better fuse, though...right?

Say I split the RCA cable to my speaker amp, but then run the output to my sub amp (which only requires one input), the sound should be the same for the sub as if I had just ran the RCA cable straight to the sub amp, right?

I also wonder...is it possible to plug the cables into just, say, the front inputs and still get sound out of all four speakers? I thought I read somewhere that some amps will do that...maybe not, I'm not sure.

After looking around, I can get a full 4-gauge dual amp wiring kit for around $40 on eBay. Perhaps it wouldn't be so bad to rewire? And I'm not too worried about quality...it was a Kicker kit that sells for a lot more on other websites, and the sellers had very good ratings.
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Old 03-11-2008, 06:00 PM   #13
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Default Looking to add a second amp to my car...

Quote:
the sound should be the same for the sub as if I had just ran the RCA cable straight to the sub amp, right?
As long as it is labeled "pass-through" you should be good to go. I actually don't know if the voltage of the output is changed versus what the HU will put out...I guess you'll find out!

To get sound out of all 4 speakers, you'd want to get some RCA splitters and wire it up that way. I don't think there's an alternate way unless you spliced the speakers together, but that would change the nominal impedance of the speakers in series.

8 guage will likely be OK for 600W RMS. I think I freaked out at the beginning of my posts because I'm use to putting in 4 or 0/1 for installs. Whatever you do, be sure your fuse is a good one. (Stinger and KnuKonceptz brands are great) Afterall, the fuse can determine if your car may go up in flames!
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Old 03-11-2008, 08:01 PM   #14
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: jamesbond007
Quote:
the sound should be the same for the sub as if I had just ran the RCA cable straight to the sub amp, right?
As long as it is labeled "pass-through" you should be good to go. I actually don't know if the voltage of the output is changed versus what the HU will put out...I guess you'll find out!

To get sound out of all 4 speakers, you'd want to get some RCA splitters and wire it up that way. I don't think there's an alternate way unless you spliced the speakers together, but that would change the nominal impedance of the speakers in series.

8 guage will likely be OK for 600W RMS. I think I freaked out at the beginning of my posts because I'm use to putting in 4 or 0/1 for installs. Whatever you do, be sure your fuse is a good one. (Stinger and KnuKonceptz brands are great) Afterall, the fuse can determine if your car may go up in flames!
Alright, thanks. I suppose I'll just see what ends up happening, but it's good to know my 8-gauge should work with a better fuse.

For some reason, I don't necessarily mind the thought of installing a new wire...maybe it's because I found a good deal on it, and it's getting warmer (installing in a cold garage sucks).

I actually think I may end up getting that Blaupunkt THA475 (4x75 watts RMS). I can get it for $100 on eBay (normally $250 on Crutchfield, $150 after their price drop). They've been around for a long time, and I guess they're a fairly respectable brand. I'm very satisfied with their speakers, sub, and amp (that I used for my sub). I think that would be a good buy for me. I just hope it really is 4x75 watts RMS, but I'm trusting them that it is.
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Old 03-11-2008, 08:18 PM   #15
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Default Looking to add a second amp to my car...

I'd suggest a Kicker ZX350.4 Ebay for about $125 and very clean sounding. Kicker is an excellent brand, Blaupunkt amps are ok from what I've heard, but I can speak from experience that Kicker makes very solid amps. Kickers almost always put out more than they're rated, my old Kicker Mono amp was rated at 500 watts but the birth sheet showed it at I believe 528, more is better

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Old 03-11-2008, 08:29 PM   #16
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Default Looking to add a second amp to my car...

Quote:
Originally posted by: QueBert
I'd suggest a Kicker ZX350.4 Ebay for about $125 and very clean sounding. Kicker is an excellent brand, Blaupunkt amps are ok from what I've heard, but I can speak from experience that Kicker makes very solid amps. Kickers almost always put out more than they're rated, my old Kicker Mono amp was rated at 500 watts but the birth sheet showed it at I believe 528, more is better
Ok, thanks. I'll look into that amp.
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Old 03-11-2008, 09:20 PM   #17
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Default Looking to add a second amp to my car...

Since I just ordered my Boston Acoustic SX65 speakers (50 watts RMS at 4 ohms, I believe), I'm trying to figure out what multi-channel amps would work well with those speakers. I'm still trying to spend as little as possible, and I don't need anything crazy to power 50 watts RMS x4.
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Old 03-11-2008, 10:48 PM   #18
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Default Looking to add a second amp to my car...

My Setup can be added to pretty easily...I ran 0/1 back to a power/ground block. I can fuse at the block and then just upgrade the under hood fuse accordingly. I may eventually move my battery to the rear.

You can do something similar for cheaper through Parts Express.
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