stereo head unit watts plus amp watts per channel.....

[CliffA]

I am gong to use a small 2 channel amp to power a pair of 4 ohm 4" speakers.....the amp has a rating of 38 watts RMS per channel at 4 ohms....my stereo head unit has a built in amp with a rating of 14 watts RMS at 4 ohms per channel for 4 channels......

so if I use the speaker wires for the front speakers only from the head unit (not RCA pre outs) to connect to the 2 channel amp will i have a total rating of 52 watts (38 + 14) RMS per channel for the speakers?......

in other words would I add the RMS watts per channel from the head unit to the RMS watts from the amp together to get the total RMS watts per channel?....are RMS watts cumulative?.....

thanks....
cliff

 

[Sous]

So your "new" amp has high level (speaker) input that you will be connecting to your speaker ouput wires from your head unit. Am I understanding what you are doing correctly?

If so, then no (or very much not likely), this input for most amps I've seen is simply to give the amp its signal and is usually used for older head units without low level outputs or to put an amp at the speaker locations due to wiring constraints.

 

[CliffA]

So your "new" amp has high level (speaker) input that you will be connecting to your speaker ouput wires from your head unit. Am I understanding what you are doing correctly?

If so, then no (or very much not likely), this input for most amps I've seen is simply to give the amp its signal and is usually used for older head units without low level outputs or to put an amp at the speaker locations due to wiring constraints.

yes..sort of.....

I will be using the pre outs from the head unit to signal other amps that will be powering other speakers and a subwoofer.....I want to use an adapter for the speaker wires from the head unit that will convert them to RCA plugs.....then I can connect these adapted RCA plugs to the 2 channel amp to power the pair of 4" speakers.....

the reason I want to have the speakers setup on different amps is so I can use 'volume controllers' on each amp to balance the sound output from the speakers as needed.....each channel of speakers will be a 'zone' and the sub will be a separate 'zone' as well.....I would have independent 'zone volume control' with this set up.....

thanks.....

cliff

 

[Sous]

Ok I copy.

So 1) I assume that you will be using a line level converter correct? and 2) you will still be left with just the power from the amp to the speakers, the power from the head unit to the newly converted low level input would not be additive to the output power of the amp.

 

[CliffA]

Ok I copy.

So 1) I assume that you will be using a line level converter correct? and 2) you will still be left with just the power from the amp to the speakers, the power from the head unit to the newly converted low level input would not be additive to the output power of the amp.

OK....thanks.....the 38 watts RMS per cannel from the 2 channel amp will be sufficient to power the 4" speakers......they are rated at 45 watts RMS......

I will use a controller similar to this but it will be one i can flush mount with just the control knob sticking out of the dash....each unit will control the amp for one channel of speakers (3 channels total) and one will control the amp for the sub.......

http://www.parts-express.com/axxess...source=google&utm_medium=cpc&utm_campaign=pla

I will use an adapter like this to convert the speaker wires to RCA plugs....

http://www.onlinecarstereo.com/CarA...mYC_UsnU1zBBX_DL6T6l1v0fdRoI7tCXq0aAqaY8P8HAQ



cliff

 

[Joel_MD]

I am gong to use a small 2 channel amp to power a pair of 4 ohm 4" speakers.....the amp has a rating of 38 watts RMS per channel at 4 ohms....my stereo head unit has a built in amp with a rating of 14 watts RMS at 4 ohms per channel for 4 channels......

so if I use the speaker wires for the front speakers only from the head unit (not RCA pre outs) to connect to the 2 channel amp will i have a total rating of 52 watts (38 + 14) RMS per channel for the speakers?......

in other words would I add the RMS watts per channel from the head unit to the RMS watts from the amp together to get the total RMS watts per channel?....are RMS watts cumulative?.....

thanks....
cliff

Not cumulative, you cannot connect speaker-level signals to the RCA input on the amp. Some amps have speaker-level input connections, but it converts them to line-level voltage prior to amplification.

 

[Wylie_Tunes]

Sorry, no voltage stacking. Regardless of the signal level into the amp, the amps output potential would be it 38W rms x 2. You can use those speaker leads into the amp if the amp has a hi and low selection switch. If not, then the amp's input may be saturated by the speaker level input.

 

[CliffA]

OK...I may have a 'fly in the ointment' then.....the amp does not have an input selector switch.....it just has both hi and low level inputs....

so if I am understanding you guys correctly I cannot convert the speaker wires to RCA plugs to connect to the amp....right?.....so I am forced to use the speaker wire output from the head unit to connect to the hi level input on the amp since the RCA pre outs on the head unit are already being used by other speakers........correct?....

I might be able to find an amp controller that will work with speaker wires instead of RCA plugs......

cliff

 

[BillK2632]

Cliff -
I was talking recently with someone from Crutchfield about the amp I am buying. I have a Pioneer head unit that putts out 14w/channel but it only has two RCA outputs. I currently have 4 speakers in the cockpit and want to add two more in the bow area. The amp I am buy is a 4 channel 60w/channel amp (95w/channel @ 2ohms). Their recommendation was to connect it as follows.

Run the RCA outs from the head unit to the RCA rear inputs on the amp. This will drive the 4 cockpit speakers in parallel (approx 47watts each @ 2ohms).
Run the front channel speakers outputs from the head unit to the speaker level inputs on the amps front channel. This will drive the two new speakers, 4ohms 60w each.

So when it is done, the bow area will be the front channels / fader and the 4 in the cockpit will be the rear.

I specifically asked the same question as you, will the amp add to the 14w out of the head unit, he said no, the amp just sees a signal on the speaker input and drives that channel.

 

[CliffA]

that's a good thought Bill.....

thanks...

cliff

 

[CliffA]

Run the RCA outs from the head unit to the RCA rear inputs on the amp. This will drive the 4 cockpit speakers in parallel (approx 47watts each @ 2ohms).
Run the front channel speakers outputs from the head unit to the speaker level inputs on the amps front channel. This will drive the two new speakers, 4ohms 60w each.

So when it is done, the bow area will be the front channels / fader and the 4 in the cockpit will be the rear.

so a question......

how do you connect 4 RCA output plugs from the head unit to only two rear channel RCA input plugs on the amp?......do you use some type of 'Y' adapter cable?

cliff

 

[Sous]

OK...I may have a 'fly in the ointment' then.....the amp does not have an input selector switch.....it just has both hi and low level inputs....

so if I am understanding you guys correctly I cannot convert the speaker wires to RCA plugs to connect to the amp....right?.....so I am forced to use the speaker wire output from the head unit to connect to the hi level input on the amp since the RCA pre outs on the head unit are already being used by other speakers........correct?....

I might be able to find an amp controller that will work with speaker wires instead of RCA plugs......

cliff

Cliff you can do this you just can't solder the speker wires direct to the back of an RCA plug. You need to use a line level converter so that the unit provides the appropirate load to the head unit. You can easily get these at crutchfield or another mobile audio dealer.

You could use somethink like this with its own level control and "kill two birds" https://www.crutchfield.com/p_142LOC90/Scosche-LOC90-Speaker-to-RCA-Line-Output-Converter.html

 

[CliffA]

Cliff you can do this you just can't solder the speker wires direct to the back of an RCA plug. You need to use a line level converter so that the unit provides the appropirate load to the head unit. You can easily get these at crutchfield or another mobile audio dealer.

You could use somethink like this with its own level control and "kill two birds" https://www.crutchfield.com/p_142LOC90/Scosche-LOC90-Speaker-to-RCA-Line-Output-Converter.html

ah ha!!!!!!.......so as the comedian John Lovitz used to say 'that's the ticket'......didn't know this existed.....

thanks for the link.....

cliff

 

[Wylie_Tunes]

it just has both hi and low level inputs..

If the amp dedicates hi-level inputs then you will not need the speaker wire to RCA converters, just wire right to the amps hi-level inputs. The amp will compensate internally for that higher level speaker input.

how do you connect 4 RCA output plugs from the head unit to only two rear channel RCA input plugs on the amp?

If the amp only has a single left and right (2 plugs) input, then you only need to use two from the head unit.

 

[CliffA]

deleted

 

[CliffA]

If the amp dedicates hi-level inputs then you will not need the speaker wire to RCA converters, just wire right to the amps hi-level inputs. The amp will compensate internally for that higher level speaker input.

thanks Michael but that would take the amp volume controller out of this speaker channel/zone.....I want to be able to control the volume of all of the different amps (3 total) to maintain volume control in each speaker zone.....

all of this is your fault for getting me thinking about using 'zone volume controls' for the various speakers.....:grin:...

cliff

 

[Wylie_Tunes]

convert the head unit leads into a stereo RCA pair, then into a zone control POT and then out of the POT convert them back to speaker leads into wires for the amp's hi-level terminals. Effectively doing the same is of there was an RCA run direct from the head unit to amp.

Or, depending on the zone control options, a dual zone controller only requires a single RCA output from the amp in, to supply two zones out.

 

[TotallyGross]

Are you going to run a subwoofer? I have pretty much the same boat but a 2000 year. If so where are you placing it?
Sorry for the diversion but I am currently right with you in the planning out process.

 

[CliffA]

Are you going to run a subwoofer? I have pretty much the same boat but a 2000 year. If so where are you placing it?
Sorry for the diversion but I am currently right with you in the planning out process.

yes, i'll be installing a 10" sub (12" won't fit)......it will be located to the port side of the front passenger seat beside the fire extinguisher in the seat base....this is where the factory installed sub would be if the upgraded stereo system was ordered with the boat.....

I spoke with Wylie_Tunes (nice meeting you Michael) this WE at the local boat show....Michael owns his own sound system business and was a vendor at the show....we covered the things I want to do and he said it was very doable....he agreed with the approach i am taking on the layout and controls....he also showed me some equipment that I could use.....

I would be glad to discuss this upgrade with you...just send me a PM with either an email address or a phone/text number....

cliff