4 Channel Amp from 2 RCAs?

[BigJoe]

Just a quick question, I have a pair of RCA's on the back of my HU and i plan on adding a 4 channel amp (Vibe Slick A1) to drive my door comps....

Will i have to use a couple of Y splitters into the amp to get all four channels working??
Is there any significant disadvantage with doing this?
Are there any other ways round it?

Here is a pick of the business end of the amp if it helps.

Thanks.

 

[corsacj]

You could wire in rca adapters to the speaker outputs at the back of your headunit instead, so you maintain separate channels.

Or if having front and rear fade isn't a priority I would just run the splitters, have done so myself in the past but was only for low range.

I'm assuming you are wanting to amp one comp per channel?

 

[BigJoe]

Yep, 4 channels, one speaker in each door.

Not really worried about fader front and rear as i always leave it in the middle.

I'm not really up for using the speaker level input as the signal will not be a clean as the RCA's will put out.

So Y splitters are the way to go then?

 

[Cartunes]

Just split the RCA leads and set the gain lower to the rear.

There is no great disadvantage in splitting the RCA voltage, though nay-sayers and the ignorant will say otherwise!

 

[BigJoe]

@Cartunes thanks for that, if anyone knows I'm sure that its you!

 

[pablo]

is the 4CH 2CH switch not to set inputs from 2 or 4 channels?

 

[Cartunes]

is the 4CH 2CH switch not to set inputs from 2 or 4 channels?

I'd read the manual if you have it. If not, you can download it from Vibe's website. It is not clear from the legend but I would suggest trying it at 4-channel first, then there will be no need for the"Y" leads. On some Amplifiers it can mean that a 2-channel input is split to 4 indeed @pablo ........

 

[BigJoe]

I have the manual downloaded and its no clearer. In fact here is also a switch position for running 3 channels I think. 2 fons and a bridged sub sor of thing

 

[pablo]

2/3/4 channel output is usually just dictated by what you connect up. I think that switch is what you want.

post the link for the manual

 

[BigJoe]

http://www.manualslib.com/products/Vibe-Slick-A1-3509410.html

Theres the manual for your perusal

 

[pablo]

" In order to obtain a four channel output from a two channel input please set the switch to 4 channel and plug the RCA's into channel 3 and channel 4"

 

[BigJoe]

AH! @pablo what page did you get that from???

so i just plug my 2 RCA's into channel 3+4 and flick the switch to 4 channel....winner winner chicken dinner!

 

[Cartunes]

RTFM SAVES FORUM POSTING......... Lessons learned!

Thanks @pablo - one is too busy cramming loads of toys and other gear into the next Generation Conti to have the time to read manuals, or post on RMS..........

 

[pablo]

http://www.manualslib.com/manual/778285/Vibe-Slick-A0.html?page=7#manual

section 1

 

[BigJoe]

So.....i have wired all the components, all the tweeters, new cabling back to the boot. Wired the amp with 4awg wire and earthed it.

Wired the front first as i didn't have any MDF to make rings for the back doors. Front sound good... wired the rears tonight and....

Cant get all four doors to bump together. Stranger than that is if i have it on 4ch and move the RCA's to each channel I can hear each door, but cant get 4 to work from 2 RCA's...looks like i need a pair of y splits after all......crap!

 

[Cartunes]

Strange indeed..... can you throw up a photo of all the connections and switches as it's fitted?

 

[BigJoe]

Will do...strange thing is if i flick the switch to 4ch and move the RCA's it will play any channel that the RCA is plugged into...I also now have a whine with the engine on, however the only change I have made is adding the two rear speakers...

 

[Pumesta]

Are you trying to run 4 speakers from the amp when it's in 2 CH mode? If it like my kenwood when you put it in 2 ch mode the front and rear channel just become one channel. So when connecting up your left channel you would connect one wire to the front + and the other to the rear -. Thus in effect doubling the power each channel, say you amp was 200 watts. In 4 channel mode 50 watts per speaker in 2 channel mode 100 watts per speaker

 

[BigJoe]

Are you trying to run 4 speakers from the amp when it's in 2 CH mode? If it like my kenwood when you put it in 2 ch mode the front and rear channel just become one channel. So when connecting up your left channel you would connect one wire to the front + and the other to the rear -. Thus in effect doubling the power each channel, say you amp was 200 watts. In 4 channel mode 50 watts per speaker in 2 channel mode 100 watts per speaker

I have tried.....
2xRCA's in channel 1&2 with the switch in both 2 and 4 channel mode
and
2xRCA's in channel 3&4 with the switch in both 2 and 4 channel mode

how ever i do it, i only get one pair of speakers working...

Here are a couple of pictures from the amp as it stands (dont worry about the gains)

 

[Pumesta]

I have tried.....
2xRCA's in channel 1&2 with the switch in both 2 and 4 channel mode
and
2xRCA's in channel 3&4 with the switch in both 2 and 4 channel mode

how ever i do it, i only get one pair of speakers working...

Here are a couple of pictures from the amp as it stands (dont worry about the gains)

Strange going by the instructions RCA into 3 & 4 and amp set to 4 channel should work. You also say that you can get all channels working just not at the sametime. If it was me by now I would have either ran another RCA from the H/U if it allows or fitted a Y splitter

 

[BigJoe]

I would have run another RCA but the HU only has one pre out. Y splits won't kill me so might go for that. The whine when the engine is running is killing me at the moment. I have checked the earth and it looks OK....any other ideas?

 

[Pumesta]

I would have run another RCA but the HU only has one pre out. Y splits won't kill me so might go for that. The whine when the engine is running is killing me at the moment. I have checked the earth and it looks OK....any other ideas?

speaker wires or RCA run to close to the power wire or other power cables in the car. Have you earthed it to an existing earth point in the car? If so drill a hole and make one only for the amp. Have you bolted the amp to something metal like the back of the rear seat? If so fit some MDF to the seat back and screw the amp to the MDF

 

[BigJoe]

The amp is screwed to the underside of the metal parcel shelf bracket, the earth point is also on this panel....I'll have a go at the MDF jobby.
Strange thing is that I wasnt whining before i added the rears....ho hum.

 

[Pumesta]

Is the amp mounted upside down? While it wont cause any off the problems you are having it's not good for them as heat rises and you run the risk of cooking the internals of the amp. Are you rear speakers in the rear shelf too? If so this could be the cause of the whinning as you are earthing the amp to the same panel the speakers are screwed too. @Cartunes would know better than me on sorting whinning noises

 

[Cartunes]

The whine is probably happening because the amp is screwed to the parcel shelf and/ or it has a bad earth. As Stephen said before, Screw wood to the shelf first, the use short screws to secure the amp to the wood making sure that the amp does not touch the screws that secure the wood to the parcel shelf. You won't hear a whine through a subwoofer if the low pass filter is on as the frequencies of the whine are not being allowed to pass to the sub........ While it isn't great to have an amp upside down, it shouldn't cook itself unless you are driving it hard. An amplifier's heat sink should indeed be "skyward" for proper heat dissipation.

You now have enough knowledge to be dangerous..... Go for it....