Question about car sub wiring

[Enderman]

Hi, if you are reading this hopefully you know something about car amps and subwoofers

 

Two things I have determined from research are:

1) AV/stereo receiver channels should not be bridged

2) Subwoofer voice coils should be getting a mono signal (not stereo) because otherwise they will be out of phase

 

So based on these two facts, would it be safe for me to wire one voice coil to the left channel, and the second voice coil to the right channel, if the receiver is getting a mono audio signal?

If the input to the receiver is mono, both left and right outputs will be exactly the same, correct?

 

From my understanding, using one voice coil per channel will not bridge the L+R channels, but will still give the sub the power of L+R combined.

Thanks in advance!

 

@Lutkeveld @mr moose I know you guys might be able to answer this...

[Guest]

1. true

2. "stereo" subwoofers should get only mono signal. You dont wont to wire it to two channels. Reasons for multiple coils are because there are mono amps that output more power on example 2 ohms instead of 8 in case that coils are 4 ohms each. That way manufacturer leaves you space to chose more amp options.

 

sry if I wasn't clear english is not my native language

[mr moose]

Hi, if you are reading this hopefully you know something about car amps and subwoofers

 

Two things I have determined from research are:

1) AV/stereo receiver channels should not be bridged

2) Subwoofer voice coils should be getting a mono signal (not stereo) because otherwise they will be out of phase

 

So based on these two facts, would it be safe for me to wire one voice coil to the left channel, and the second voice coil to the right channel, if the receiver is getting a mono audio signal?

If the input to the receiver is mono, both left and right outputs will be exactly the same, correct?

 

From my understanding, using one voice coil per channel will not bridge the L+R channels, but will still give the sub the power of L+R combined.

Thanks in advance!

 

@Lutkeveld @mr moose I know you guys might be able to answer this...

 

That depends on the amp and the impedance of each coil.  The reason car subs have two coils is to allow you to connect them to get  any combination of 2 ohm, 4 ohm and 8 ohm loads.  This way you can match it to your amp.  You can only wire each voice coil to a different channel if each channel is providing exactly the same signal (ergo both channels fed the same signal).  If you wire one coil to the left and the other to the right you will end up with a distorted output as there a subtle differences between the two. 

[Lutkeveld]

1) Depends. Often: no. Sometimes: yes.

2) You can power it with a stereo amp, as long as it's not given a different signal on each coil. Most MP3 files are joint stereo in the <200hz anyway, so often it's not a problem. But better be safe than sorry.

 

You have 3 options with a dual, let's say 4 ohm, voice coil sub: 

-Stereo: double 4 ohm

-Series: single 8 ohm

-Parallel: single 2 ohm

 

Aleksa: In fact, all amplifiers can put out more power in 2 ohm than in 4/8 ohm. It's just the question if they can cope with the increased thermal/current load.

 

Paralleled voice coils on a mono amp would be my recommendation

[Aniallation]

So based on these two facts, would it be safe for me to wire one voice coil to the left channel, and the second voice coil to the right channel, if the receiver is getting a mono audio signal?

If the input to the receiver is mono, both left and right outputs will be exactly the same, correct?

 

From my understanding, using one voice coil per channel will not bridge the L+R channels, but will still give the sub the power of L+R combined.

Thanks in advance!

 

@Lutkeveld @mr moose I know you guys might be able to answer this...

Both voice coils should be wired to one channel, not two. The reason there's dual voice coils is so you can choose between two different impedances for the woofer. Instead of having to choose between buying a 2 or 4 ohm woofer, you can now have either one on demand with the same woofer.

 

It's always best to use a dedicated mono amp, connected to one voice coil of the desired impedance for the amplifier, if you have a 2/4 ohm dual voice coil subwoofer, using the 2 ohm option would allow the amplifier to push out more power since there's less resistance.

 

Where's me and @EcoBoost in the list???

[Guest]

1) Depends. Often: no. Sometimes: yes.

2) You can power it with a stereo amp, as long as it's not given a different signal on each coil. Most MP3 files are joint stereo in the <200hz anyway, so often it's not a problem.

 

You have 3 options with a dual, let's say 4 ohm, voice coil sub:

-Stereo: double 4 ohm

-Series: single 8 ohm

-Parallel: single 2 ohm

 

Aleksa: In fact, all amplifiers can put out more power in 2 ohm than in 4/8 ohm. It's just the question if they can cope with the increased thermal/current load.

 

Paralleled voice coils on a mono amp would be my recommendation

I know but with my poor english this was easier to explain

I still think he shouldn't use stereo amp because channels cant have perfectly same amplifications so its a risk.

[Aniallation]

I know but with my poor english this was easier to explain

I still think he shouldn't use stereo amp because channels cant have perfectly same amplifications so its a risk.

Stereo amps weren't really meant to power a subwoofer unless they at least have a low-pass filter.

[Guest]

Stereo amps weren't really meant to power a subwoofer unless they at least have a low-pass filter.

Almost all car amps have low pass filter. Even most quad channel.

[Lutkeveld]

I don't recommend a stereo amplifier too but it's possible. Ensuring mono signal and same LPF is pretty important.

[Enderman]

Both voice coils should be wired to one channel, not two. The reason there's dual voice coils is so you can choose between two different impedances for the woofer. Instead of having to choose between buying a 2 or 4 ohm woofer, you can now have either one on demand with the same woofer.

 

It's always best to use a dedicated mono amp, connected to one voice coil of the desired impedance for the amplifier, if you have a 2/4 ohm dual voice coil subwoofer, using the 2 ohm option would allow the amplifier to push out more power since there's less resistance.

 

Where's me and @EcoBoost in the list???

I dont have a good memory of all the people who reply to my posts

The reason I wanted to do one voice coil per channel is because each coil is 4 ohms. If I used parallel I would only be able to use one L or R channel (which would be half the power of my receiver) and I would only be able to choose between 2 ohm (too low inpedance) and 8 ohm (which would be too quiet with only 50% power)

 

1) Depends. Often: no. Sometimes: yes.

2) You can power it with a stereo amp, as long as it's not given a different signal on each coil. Most MP3 files are joint stereo in the <200hz anyway, so often it's not a problem. But better be safe than sorry.

 

You have 3 options with a dual, let's say 4 ohm, voice coil sub: 

-Stereo: double 4 ohm

-Series: single 8 ohm

-Parallel: single 2 ohm

 

Aleksa: In fact, all amplifiers can put out more power in 2 ohm than in 4/8 ohm. It's just the question if they can cope with the increased thermal/current load.

 

Paralleled voice coils on a mono amp would be my recommendation

Yeah as I said above ^^^ I would have to choose between 2 or 8 ohm on a single channel, which would only give me 135W instead of 270W max.

 

That depends on the amp and the impedance of each coil.  The reason car subs have two coils is to allow you to connect them to get  any combination of 2 ohm, 4 ohm and 8 ohm loads.  This way you can match it to your amp.  You can only wire each voice coil to a different channel if each channel is providing exactly the same signal (ergo both channels fed the same signal).  If you wire one coil to the left and the other to the right you will end up with a distorted output as there a subtle differences between the two. 

So mono input to the stereo would output the same on L and R right?

 

1. true

2. "stereo" subwoofers should get only mono signal. You dont wont to wire it to two channels. Reasons for multiple coils are because there are mono amps that output more power on example 2 ohms instead of 8 in case that coils are 4 ohms each. That way manufacturer leaves you space to chose more amp options.

 

sry if I wasn't clear english is not my native language

As I said above, 2 ohms is too low and 8 ohm wount be loud enough with a single 135W channel

[Aniallation]

Almost all car amps have low pass filter. Even most quad channel.

I have used many older ones that don't have a LPF, and if OP is looking for a brand new one, might as well get a proper mono amplifier. 

[Enderman]

Stereo amps weren't really meant to power a subwoofer unless they at least have a low-pass filter.

I have been using a stereo amp to power multiple subs for the past year. I notice that if the sub has a limited frequency response I dont need a low pass filter because it will only output (for example) 30-150Hz and nothing else.

[Guest]

I dont have a good memory of all the people who reply to my posts

The reason I wanted to do one voice coil per channel is because each coil is 4 ohms. If I used parallel I would only be able to use one L or R channel (which would be half the power of my receiver) and I would only be able to choose between 2 ohm (too low inpedance) and 8 ohm (which would be too quiet with only 50% power)

 

Yeah as I said above ^^^ I would have to choose between 2 or 8 ohm on a single channel, which would only give me 135W instead of 270W max.

 

So mono input to the stereo would output the same on L and R right?

 

As I said above, 2 ohms is too low and 8 ohm wount be loud enough with a single 135W channel

I have to ask you did you tried it at 8 ohm? If its real 135W it should be loud as ****.

[mr moose]

 

So mono input to the stereo would output the same on L and R right?

 

So long as the amp sends that mono signal to each channel and doesn't invert one. If necessary you can use a y cable and send the same mono signal to each channel then use one channel for each coil.

 

The other thing you can do is bridge the amp and put the voice coils in series, this will give the sub 8 ohms, but the combined power of each channel in the amp will make up for it and give you the same result as using each channel individually. (each amp channel will see 4 ohms even though the sub is 8)

[Aniallation]

The reason I wanted to do one voice coil per channel is because each coil is 4 ohms. If I used parallel I would only be able to use one L or R channel (which would be half the power of my receiver) and I would only be able to choose between 2 ohm (too low inpedance) and 8 ohm (which would be too quiet with only 50% power)

What specific sub do you have? 

 

If it's a sub with a 2 ohm coil + an 8 ohm coil, running them in L and R off a stereo amp would have one coil getting much more power then the other since it'd have less resistance, which would be..... less then optimal.

[Guest]

What amp are you using?

[Guest]

So long as the amp sends that mono signal to each channel and doesn't invert one. If necessary you can use a y cable and send the same mono signal to each channel then use one channel for each coil.

 

The other thing you can do is bridge the amp and put the voice coils in series, this will give the sub 8 ohms, but the combined power of each channel in the amp will make up for it and give you the same result as using each channel individually. (each amp channel will see 4 ohms even though the sub is 8)

By bridging amp its output impedance is lowered and it becomes less effective at 8 ohms.

btw 95% "home" amps cant be bridged if he uses one.

[Aniallation]

I have to ask you did you tried it at 8 ohm? If its real 135W it should be loud as ****.

I have two 4 ohm subs running off a CX600 (Kicker, not Corsair) which can do 4 ohms at 300W RMS, and it's not loud enough for me

[Guest]

What specific sub do you have? 

 

If it's a sub with a 2 ohm coil + an 8 ohm coil, running them in L and R off a stereo amp would have one coil getting much more power then the other since it'd have less resistance, which would be..... less then optimal.

never saw 2+8 sub does that really exist?

[Lutkeveld]

I have two 4 ohm subs running off a CX600 (Kicker, not Corsair) which can do 4 ohms at 300W RMS, and it's not loud enough for me

 

That's why you weren't on the list. You judge loudness by the amounts of watts 

[Aniallation]

That's why you weren't on the list. You judge loudness by the amounts of watts 

I don't. That's why I was quoting the guy who was saying that 135W would be loud cause he was the one saying that watts = loudness.

 

I won't get good SPL at all in my car, cause I have a minivan.

[Guest]

I don't. That's why I was quoting the guy who was saying that 135W would be loud cause he was the one saying that watts = loudness.

 

I won't get good SPL at all in my car, cause I have a minivan.

I said if that is "real" 135 W  it should be loud.

By that I asked him did he actually tried it, maybe its loud enough for him.

[Lutkeveld]

135 watt is around a 21db gain over 1 watt. 

WIth a low efficiency car sub it may dissappoint in a normal room.

A reasonable efficient car sub (~90db/w/m) should do 100+ easily in normal listening scenarios.

 

Normally comparing watts doesn't make any sense, but with 100+ watt and a proper sub (in a proper enclosure) should bump pretty hard regardlessly.

Difference between 135 and 600 watt for example is a lot less than people think. It won't even be perceived as a doubling of power by most people.

[Enderman]

What specific sub do you have? 

 

If it's a sub with a 2 ohm coil + an 8 ohm coil, running them in L and R off a stereo amp would have one coil getting much more power then the other since it'd have less resistance, which would be..... less then optimal.

Its a 4+4 ohm, so each voice coil is identical, so ti should work out ok.

 

What amp are you using?

Its a 135W x2 stereo receiver, not a car amp.

 

So long as the amp sends that mono signal to each channel and doesn't invert one. If necessary you can use a y cable and send the same mono signal to each channel then use one channel for each coil.

 

The other thing you can do is bridge the amp and put the voice coils in series, this will give the sub 8 ohms, but the combined power of each channel in the amp will make up for it and give you the same result as using each channel individually. (each amp channel will see 4 ohms even though the sub is 8)

1) yes that is what I plan to do

2) that is what I thought, but I would rather not bridge a HT receiver because from all my google research it can be bad for the receiver since its not made to be bridged (that is why I will try the mono thing instead)

[Lutkeveld]

You can however parallel most HT amps. That means taking the L+ and R+ together and taking the L- and R- together.

This way the amp is capable of driving half the impedance it normally can. So now it can take 2 ohms.

BTW, even if the subs natural rolloff serves as kind of a low pass filter, it's better to use one anyway.

It can be as simple as an inductor in series at input or output level.

 

This can be a really fun low cost DIY project