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Old 16th October 2006, 18:44   #1
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Default Mono Rear Channel!

Hi Guys,
Have anyone tried bridging the rear channel (i am not talking about "sub woofer" bridging) and using the rear channels as a single channel? (Bridging is not done for increasing the power... but to get a mono output!)

Reason for my question:
You are using ur rear channels just for fills!... (This is for people who have components in front and small speakers at rear... so that you get a good front stage!)...
so you may not want a left channel and right channel seperatly sounding from back of ur car!...

This is just an idea!!....

Now Question to you gurus!....
What would sound better?... A stereo set up at rear or a mono setup at rear....

Last edited by anToNIcHeN : 16th October 2006 at 18:47.
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Old 16th October 2006, 20:48   #2
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ummm

I'm a little surprised because anotnichen, your queries and posts generally indicate an above average level of audio.

Let me get this straight. You have a stereo channel for the rear and you would want to bridge it. Apparently not for increasing the power, but to get a mono output.
1. The power will increase, if you like it or not. Your speakers will recieve significantly more power.
2. By bridging a channel, you effectively halve the impedance the amplifier "sees"

Further elaborating point number 2 - you have 2 rear speakers, 4 ohms each. Obviously by bridging your channels, you effectively have a single mono channel for the rear that sees half the impedance presented to it.
Now 4 ohms parallel 4 phms is 2 ohms. Effectively the amplifier will see 1 ohm and that isn't very good for the amplifier. So how would you connect 2 speakers to the bridged channel? Unless you plan to use a single centre channel in the rear!

Secondly, i see a complete chaotic soundstage with a mono rear. Here (2 Subs - Dual Mono or Stereo - "Kb ka dB") we have had a long argument about if subwoofers in the boot should be in stereo or mono. That should give you some idea about the (generally) mono sub channel.

TO answer your question, please dont.
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Old 17th October 2006, 07:28   #3
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Default Alas!

It wont be sensible to do a bridging for rear channels.
First of all, the rear speakers are not meant to be played mono. And going mono in the rear will spoil the soundstage of the whole setup. I am of the opinion that even Subs should be played in Stereo. Even if an amp is able to handle the output in the specified way, it'd be a spoilsport.
I think the rear speakers can be put to good use rather than being just a fill. Imagine if there're rear seat passengers, they'll be more close to the rear speakers. So, they'll be having a soundstage in their backs which is not very desirable. So, I think the rear speakers should be mounted in such a place so that even the rear passengers will have a front soundstage. And this can be achieved beautifully by keeping the speakers on the rear doors. This will not cause much hindrances to the front seat passenger's soundstage. I've experienced this in different cars of different sizes. The stereo setup can be well enjoyed this way.
Then, if it's more important for a person to have a very strong front soundstage with hardly any sound from the rear, then he should rather avoid buying the rear speakers. It'll be far better than having a mono setup in the rear. In this case, he can even go active with a 4 channel amp and avoid the crossovers. He can feed 2channels from the amp directly to the tweeters and the other 2 can be fed to the woofers. This way, one can have more freedom in the front soundstage. It'll be able to adjust the tweeter levels, woofer levels etc from the HU itself. This type of setup will be far better than having an extra pair of speakers being fed with a bridged mono output.
Then, there's also the problem of rears overpowering the fronts in the said mono setup. Yes, as Sam said; the power increase is inevitable once you bridge 2channels. So as a result, it may play louder than it's supposed to be unless gains are tuned well. Even if so, the amp will have trouble with the way it's connected to the speakers.
All in all, I think it's very much not right to have a mono setup in the back.

Has anybody tried it and found better? I'll withdraw all my above theories.

@Sam. After some very very dull'n dry days, your above post has brought some fresh cool winds into our beloved ICE section. I still cherish those lovely days when we had similar informative discussions everyday. Maybe, due to our own baddoings, irresponsibility and lack of self respect, those happy ICEy days are almost on the verge of getting lost.
A humble request to all ICE gurus; Cant we have it back? Please:
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Old 17th October 2006, 11:25   #4
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Quote:
Originally Posted by anToNIcHeN
so you may not want a left channel and right channel seperatly sounding from back of ur car!...


This is just an idea!!....


why do you think anyone wouldn't want stereo sound from the rear ? music is meant to be listened to in stereo, unless ...... forget it. not a great idea anto. sorry pal.
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Old 19th October 2006, 01:51   #5
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This topic needs to be discussed more in depth I think. Or is it too much a stupid thing to be discussed at all??

Gurus, Please do the needful.
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Old 19th October 2006, 09:01   #6
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Zak baba,

No question is too stupid. But as a discussion, this is pointless. Subwoofer frequencies are mostly mono, hence it was a point worth discussing in kb's thread.

Rear channel is a stereo recorded channel and very musch part of the internal soundstage in the car. Playing the rear in Mono will ruin it. And as you can see from the discussion, even the connection is difficult. It is trult a pointless discussion.

And my dear sentimental Zak, all is good in our beloved ICE section, I am glad I brought you some cool breeze lol, now sshhh or people will think we're in love.
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Old 19th October 2006, 10:13   #7
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Quote:
Originally Posted by Sam Kapasi
Subwoofer frequencies are mostly mono.
huh?
Bass is recorded in stereo on most CDs. in the days of LPs we used to record in mono to reduce stylus wear. In Home theater (5.1, 6.1, 7.1 ...) bass has it's own dedicated channel and there still might be other bass information on the 5/6/7 channels.

However bass frequenices have long wavelengths and hence to some extent one can sum the 2 channels without loosing the soundstage.
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Old 19th October 2006, 17:29   #8
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Arrey baba Navin, I meant to say that sub-bass is onmi directional and hence these frequencies can be played in a mono summed channel, but NOT the frequencies that need to be played through the rear channel.
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Old 20th October 2006, 09:57   #9
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Quote:
Originally Posted by Sam Kapasi
Arrey baba Navin, I meant to say that sub-bass is onmi directional and hence these frequencies can be played in a mono summed channel, but NOT the frequencies that need to be played through the rear channel.
Ok I misunderstood you earlier. Sorry. Yes in a car one can be very happy with a mono bass channel (below 80Hz, more preferably 60Hz). It saves valuable space.

On a personal note, I am considering stereo bass and mono "sub-bass". 2 x 12" mono for 30-60Hz(push-pull), 2 x 6" aperiodic for 60-120Hz, regular components in the front and rear. This will need atleast 3 amps 1 4 ch. for the components, 1 stereo amp for the stereo bass, and 1 mono amp for the sub bass.

Last edited by navin : 20th October 2006 at 10:00.
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Old 23rd October 2006, 14:46   #10
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Quote:
Originally Posted by Sam Kapasi
2. By bridging a channel, you effectively halve the impedance the amplifier "sees"

Further elaborating point number 2 - you have 2 rear speakers, 4 ohms each. Obviously by bridging your channels, you effectively have a single mono channel for the rear that sees half the impedance presented to it.
Now 4 ohms parallel 4 phms is 2 ohms. Effectively the amplifier will see 1 ohm and that isn't very good for the amplifier. So how would you connect 2 speakers to the bridged channel?

TO answer your question, please dont.
Sam.. I didnt understand this?... or did you mean doubling?.... say for eg. an amp which is 2 ohms stable in stereo mode would be 4 ohm stable in bridged mode. Likewise an amp which is 1 ohm stable in stereo mode would be 2 ohm stable in bridged mode.

@Zak: we can go about discussing about this without any results for months all together (all theory... but when it comes to practical aspect of it... things might be different)... (can you believe it... i went thru all the post of KB ka DB... )... What i was asking was that, in practise, have anyone compared side by side, a stereo and mono set up?... (I have someone PM me, saying that... they have tried it and produced a good soundstage at front in "mixed mono rear fill")

regards,
ant.
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Old 23rd October 2006, 15:59   #11
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Quote:
Originally Posted by anToNIcHeN
Sam.. I didnt understand this?... or did you mean doubling?.... say for eg. an amp which is 2 ohms stable in stereo mode would be 4 ohm stable in bridged mode. Likewise an amp which is 1 ohm stable in stereo mode would be 2 ohm stable in bridged mode.
That's what Sam meant, he was just putting into perspective what load each individual unbridged channel of the amp sees. So he's trying to say that most amps will be stable down to 2 ohm only in stereo, so if you present a 2 ohm load in bridged, the unbridged channel is seeing 1 ohms, and that's not good.
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Old 25th October 2006, 09:52   #12
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Quote:
Originally Posted by anToNIcHeN
What i was asking was that, in practise, have anyone compared side by side, a stereo and mono set up?... (I have someone PM me, saying that... they have tried it and produced a good soundstage at front in "mixed mono rear fill")
if the mixed mono was at a low level it would not affect the front soundstage much.

1. why use mono when most cars have pods for 2 rear speakers and most HUs have stereo pre outs/speaker outs.

2. Mono is used for bass solely to reduce the space requirements. Ideallly it would ncie to have stereo bass but becuase bass wavelengths are long one can "get away" with a mono bass channel. More so in the car than at home.

3. did whoever produced the good soundstage in the front using mono rear compare the result with a stereo rear?
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Old 26th October 2006, 15:23   #13
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Quote:
Originally Posted by navin
if the mixed mono was at a low level it would not affect the front soundstage much.

1. why use mono when most cars have pods for 2 rear speakers and most HUs have stereo pre outs/speaker outs.
navin, this is just an idea that i read somewhere... again why it made sense when i thot about it..
your rear speakers act as fills... hence having a seperate channels (unless ofcourse you are watching a dolby encoded movie where you want 5.1 surround sound) may not be an absolute requirement...
so i was asking --> anyone fiddled around and asked how different it sounded?....
Quote:
Originally Posted by navin
2. Mono is used for bass solely to reduce the space requirements. Ideallly it would ncie to have stereo bass but becuase bass wavelengths are long one can "get away" with a mono bass channel. More so in the car than at home.
true... i do agree... and also someone has said, mono signal (bridged mono) would be "stronger" than seperate channels.. one more reason to go mono....
Quote:
Originally Posted by navin
3. did whoever produced the good soundstage in the front using mono rear compare the result with a stereo rear?
he didnt tell me that... hence the question open in the front...
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