Bridging question
04-30-2007, 11:03 PM
#1
Registered User
Thread Starter
Join Date: Apr 2007
Location: Irvine/Orange
Posts: 1,172
Likes: 0
Received 0 Likes
on
0 Posts
Bridging question
Hopefully someone could verify my problem or lack thereof.
I am bridging a 4ch amp to 2ch (Alpine F250) to give 100watts rms to my alpine type r components.
My question is that alpine reccomends that I use a 2-ch interconnect to a y-cable and then to the amp. Is that really necessary?
In place of the above I used a 4-ch interconnect directly to the amp. Will I kill the amp or headunit eventually if I use the 4-ch interconnect?
The sound is awesome and I'm loving it so far but I need to know if its wired correctly.
TIA
I am bridging a 4ch amp to 2ch (Alpine F250) to give 100watts rms to my alpine type r components.
My question is that alpine reccomends that I use a 2-ch interconnect to a y-cable and then to the amp. Is that really necessary?
In place of the above I used a 4-ch interconnect directly to the amp. Will I kill the amp or headunit eventually if I use the 4-ch interconnect?
The sound is awesome and I'm loving it so far but I need to know if its wired correctly.
TIA
05-01-2007, 01:36 PM
#3
Interconnects shouldn't matter as long as you get the correct signal to the correct inputs.
Alpine probably recommends using a 2-ch cable and then a Y at the amp as a way to guarantee you drive each amplifier (of the bridge) equally. In a bridged configuration you use 2 independant amplifiers to drive one speaker. Each amplifier obviously needs an input signal and it's important that both amplifiers receive the EXACT SAME signal. Some manufacturers guarantee this by incorporating a switch (either manual or automatic) to internally connect the inputs of the 2 amplifiers when in bridged mode. In some cases (evidently like this one) the amp does not have a switch so you have to physically connect a signal cable to each amplifier input.
Why is it so important to drive the pair of amplifiers equally? Aha! I wondered when you would ask.
The output (volume) of the speaker is a combination of the outputs of both amplifiers. Let's say you have a 4x100W amp and in bridged mode you get 2x160W (typical). If both amplifiers are driven equally then you can raise the volume to 160W total (80W from each amplifier) and all is well. Both amplifiers are operatiing below their "clipping" level so there is no problem.
But if the amplifiers are not driven equally (let's say one is fed twice the signal that the other one gets*) as you turn up the volume the over-driven amplifier will start to clip at 80W while the other is only putting out 40W. You only have 120W total so you keep turning up the volume. Now the one amplifier is driven WAY into clipping and the music sounds like crap and your tweeters catch fire (or just stop working).
If you used a 4-ch cable and made the mistake of connecting one pair to the front outputs (on the HU) and the other pair to the rear outputs then it's possible you could adjust the fader control and end up with a lop-sided signal - driving one amplifier harder than the other. Overall volume will be lower (because it's the average of the 2 amplifier outputs) so you'll tend to turn it up louder to get the volume you want, causing premature clipping.
So by avoiding the possibility of unequal drive, Alpine receives fewer complaints about their amp sounding like crap or blowing up tweeters (when in fact the problem is how the interconnects are run).
*You might think that it would be hard to have one amp driven with twice the signal of the other; that you would have to really set the fader control way off to one side to get that out of balance. Not so. "Twice the power" is the same as a 3dB difference, and most head units have volume increments that are 2dB apart. Think about it - one "notch" on the volume control isn't that big a volume change is it? Sometimes you might not even notice if someone tweaked the volume up one notch when you weren't looking. So if the difference between front and rear is slightly more than one volume notch (which is what, maybe 5
Alpine probably recommends using a 2-ch cable and then a Y at the amp as a way to guarantee you drive each amplifier (of the bridge) equally. In a bridged configuration you use 2 independant amplifiers to drive one speaker. Each amplifier obviously needs an input signal and it's important that both amplifiers receive the EXACT SAME signal. Some manufacturers guarantee this by incorporating a switch (either manual or automatic) to internally connect the inputs of the 2 amplifiers when in bridged mode. In some cases (evidently like this one) the amp does not have a switch so you have to physically connect a signal cable to each amplifier input.
Why is it so important to drive the pair of amplifiers equally? Aha! I wondered when you would ask.
The output (volume) of the speaker is a combination of the outputs of both amplifiers. Let's say you have a 4x100W amp and in bridged mode you get 2x160W (typical). If both amplifiers are driven equally then you can raise the volume to 160W total (80W from each amplifier) and all is well. Both amplifiers are operatiing below their "clipping" level so there is no problem.
But if the amplifiers are not driven equally (let's say one is fed twice the signal that the other one gets*) as you turn up the volume the over-driven amplifier will start to clip at 80W while the other is only putting out 40W. You only have 120W total so you keep turning up the volume. Now the one amplifier is driven WAY into clipping and the music sounds like crap and your tweeters catch fire (or just stop working).
If you used a 4-ch cable and made the mistake of connecting one pair to the front outputs (on the HU) and the other pair to the rear outputs then it's possible you could adjust the fader control and end up with a lop-sided signal - driving one amplifier harder than the other. Overall volume will be lower (because it's the average of the 2 amplifier outputs) so you'll tend to turn it up louder to get the volume you want, causing premature clipping.
So by avoiding the possibility of unequal drive, Alpine receives fewer complaints about their amp sounding like crap or blowing up tweeters (when in fact the problem is how the interconnects are run).
*You might think that it would be hard to have one amp driven with twice the signal of the other; that you would have to really set the fader control way off to one side to get that out of balance. Not so. "Twice the power" is the same as a 3dB difference, and most head units have volume increments that are 2dB apart. Think about it - one "notch" on the volume control isn't that big a volume change is it? Sometimes you might not even notice if someone tweaked the volume up one notch when you weren't looking. So if the difference between front and rear is slightly more than one volume notch (which is what, maybe 5
05-01-2007, 02:26 PM
#6
Registered User
Thread Starter
Join Date: Apr 2007
Location: Irvine/Orange
Posts: 1,172
Likes: 0
Received 0 Likes
on
0 Posts
Whoa. Thanks Modifry! I had to read your post several times before I understood it. I actually set the balance on my headunit to send more juice to the passenger side but that seems to be a big NO-NO.
I guess I'll go out and buy some quality y-cable interconnects and do it right!
Cub2sk and darkknight1999, I read the manual last night but thought I could also use a 4-ch interconnect that I had laying around as an alternative.
Thank you all for your help!
Trending Topics
05-04-2007, 07:09 AM
#8
Originally Posted by kix,May 1 2007, 05:26 PM
Whoa. Thanks Modifry! I had to read your post several times before I understood it. I actually set the balance on my headunit to send more juice to the passenger side but that seems to be a big NO-NO.
I guess I'll go out and buy some quality y-cable interconnects and do it right!
Cub2sk and darkknight1999, I read the manual last night but thought I could also use a 4-ch interconnect that I had laying around as an alternative.
Thank you all for your help!
The only condition you have to avoid is where the 2 paired amplifiers receive different signals. This can occur if you use the front and rear outputs from the HU instead of only one of the outputs and installing Y connectors at the amp.
Thread
Thread Starter
Forum
Replies
Last Post