My car has 2 ohm speakers (I assume amp is equivalent stable) - if I replace the rears with 4 ohm speakers, then bridge a 4 ohm sub to them, will that trio have a net of 2 ohms each presented to the amp? Or...?
Thanks.
Thanks.
So if I understand you, you will run both channels to the single coil woofer and then split it back to two speakers? I see two things but maybe others can chime in here.
If your amp is 2Ω stable in stereo then the woofer must be 4Ω or greater if you wish to bridge it. So if you add the extra speakers, you are dropping it below that and even if you could do that, haven't you lost stereo?
If your amp is 2Ω stable in stereo then the woofer must be 4Ω or greater if you wish to bridge it. So if you add the extra speakers, you are dropping it below that and even if you could do that, haven't you lost stereo?
The two main speakers will remain with the factory wiring - they will receive the same signals as before. I'm not planning on running the wires to the sub fist and then off to the main - I'm planning in tapping into the main wires to run the sub - it would be (example) sub positive to right main positive, and sub negative to left main negative.
P.S. sub will get a filter.
Hi sdclc'
I think you want to use the right and left channels of an existing stereo amp/ HU, using the pos(+) speaker wire from the right ch, and the neg(-) speaker wire from the left, and drive the sub woofer that way... is that it? Sorry, it won't work that way. You see, the R&L channels are completely independent of each other, so you won't have a complete electrical circuit using only the (+) R ch and the (-) L ch.
The sub-woofer will need to have it's own (independent) power amplifier to drive it. That sub's amplifier will get it's input signal from both the left and right channels (summed) of the head unit. This is why you'll see some full range amplifiers will offer "five channels"; L&R front, L&R rear and a single channel for the sub output. So in your case, you just need a "mono-block": a designated sub-woofer amplifier. Hope this helps...
rigtec, best to you
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Oh I see what you mean. Hmm I thought I did this before in my other car and it woked, but maybe I was only getting one channel to the sub - they show doing it that way in the amp wiring diagram (4 channel). Yes I see that couldn't work that way.
Well, I'll think about it and see - maybe I'll just replace the rears with small subs anyway. Thanks.
Hi,
To bridge a sub you need to :
Invert one channel and invert one speaker connection.
Connect the sub across R+ and L+.
This is assuming R+L have a common R- and L-
which is not a good assumption to make, you
can't bridge already bridged, most car amps are.
rgds, sreten.
FWIW for a common negative amplifier wired
as above for 4 ohm L+R the sub should be
8 ohms for a 2 ohms per channel load.
To bridge a sub you need to :
Invert one channel and invert one speaker connection.
Connect the sub across R+ and L+.
This is assuming R+L have a common R- and L-
which is not a good assumption to make, you
can't bridge already bridged, most car amps are.
rgds, sreten.
FWIW for a common negative amplifier wired
as above for 4 ohm L+R the sub should be
8 ohms for a 2 ohms per channel load.
Unfortunately, no, hahaha! Bridging an amp is not just tying the left and right channels together and feeding a common speaker; that'd be a good way to "Incinerate" the output devices to a firey grave, 😱 lil' more to it than that.
There's a bunch of great 'car sub builds' on this website that I've benefited from over the years. If you don't find one that's helpful, here's a write-up that I did a few months ago on another forum that may be helpful: Thanks Gurus, for all your "Low-end" help!! ...hope so!
rigtec
Here's a Diagram
This is what I'm talking about - bridge the subwoofer to right +ve and left -ve. It may give a single channel to the sub, but that's fine - and yes this is what I did in my other car - bridged the sub to the two rear channels, and ran satellites out of them too. Worked fine with 4 ohm satellites and an 8 ohm sub - the amp is 2 ohm stable.
So my question was, with a 2 ohm stable amp, if I run 4 ohm satellites out of stereo rear channels, and bridge a 4 ohm sub to those same channels, will the amp see 2 ohms at those three points, or something else? Or just 2 ohms at the sub? I can use 8 ohm speakers all around if necessary - the ones I like come in both. I'm flexible.
I will be bridging by tapping into the wires, not the amp itself, but I don't see how this could make a difference.
I apologize - it now looks like my original post wasn't very complete or clear.
This is what I'm talking about - bridge the subwoofer to right +ve and left -ve. It may give a single channel to the sub, but that's fine - and yes this is what I did in my other car - bridged the sub to the two rear channels, and ran satellites out of them too. Worked fine with 4 ohm satellites and an 8 ohm sub - the amp is 2 ohm stable.
So my question was, with a 2 ohm stable amp, if I run 4 ohm satellites out of stereo rear channels, and bridge a 4 ohm sub to those same channels, will the amp see 2 ohms at those three points, or something else? Or just 2 ohms at the sub? I can use 8 ohm speakers all around if necessary - the ones I like come in both. I'm flexible.
I will be bridging by tapping into the wires, not the amp itself, but I don't see how this could make a difference.
I apologize - it now looks like my original post wasn't very complete or clear.
Attachments
Okay sdclc'
Starting at the beginning. In your diagram above it shows a two channel amp in bridged "MONO" mode; some amps have this feature, some don't, but let's assume that your amp does. If you are in bridged mono mode, an amp that is rated for 2 ohms/channel 'in stereo' mode, will only be capable of 4ohms 'bridged'. That's because each individual amp (L & R) is only seeing "Half" of the 4ohm load (2ohms) when bridged.
In your question, you said:
You can run the 4ohm sub w/that 'bridged' amp, and the amp will see a 2ohm load. But if you add two more 4ohm satellite speakers to that load (in parallel), the amp could potentially see 1 ohm; which is almost like driving a nail across the (+) and (-) speaker terms of the amp. Wiring these satellite speakers together in series wouldn't be much better; don't know why anyone would want to run a sub-woofer and two full range drivers together in a circuit anyway 😕
Still not sure if you're trying to run the amp in stereo or bridged mode because you proposed to
and then you said
Please tell me what I'm missing... rig
sdclc'
A few of us are really just trying to help you but maybe have misunderstood exactly what you are trying to do. I think sreten did a excellent job trying to explain how to "bridge" two channels together. Cal Weldon is a true expert; I've seen some of his work and posts here over the last few years.
Me... I'm just a "hobbist" and really love audio systems, particularly subs, but would still like to help. It would be nice if you could try (again), to explain how I have missed what you are (were) trying to get done. This way, if I don't know the answer(s), I'll at least know that I've understood the question(s)... fair enough?
Best to you
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