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Old 7th October 2003, 04:40 PM   #21
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Do I understand correctly, The Adcom has balanced out and the Marchland has balanced in?

It sounds like thatís your interconnect path if thatís how the devices are configured.

I understand that you are considering building the gain clones and the crossover into single chassis that would be located with each speaker. That also sounds like a good thing.

You could place the crossovers and the preamp at the listening position and run two balanced lines to gain clones located at the speakers. This would allow you to make adjustments to the crossovers while listening to them but you would have to add the expense and complexity of adding balanced outs to the crossovers and balanced in to the gain clones.

I think your idea works better.

-Dave
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Old 7th October 2003, 04:52 PM   #22
usekgb is offline usekgb  United States
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Default Getting back to the original question.........

The main reason for putting the amps near the speakers is to reduce the effect of the impedence and the resistance of the speaker cable on the interaction between the amplifier and the speakers. If you run long lines of speaker cable, the impedence and resistance that builds up in the speaker cable can change the x-over frequency and phase response of your speakers. This is the ONLY reason for doing this.
As far as running long interconnects, you can run an unbalanced interconnect up to about 20 feet before losing significant HF response to to the capacitance of the unbalanced cable. This is one of the reasons why the consumer world has stuck to RCA connections for all these years. At distances of 3 feet or so (the typical distance between source and amplifier) the negative effects of an unbalanced cable are negligible. If you want to run longer runs, definately go balanced. The advantages to running balanced cable are as follows:

1: You get a hotter signal

due to the fact that you are running two signals side by side, and summing them at the input of your amp.

2: Any noise that is picked up in the twisted pair will be eliminated at the terminus. This is done by reversing the polarity of pin 3 at the terminus. Any noise on pin three will now have a reversed polarity to that of the noise on pin 2. These two noise signals are summed and cancel each other out, leaving only the origianal signal that was transmitted along the balanced line in the first place.

3: It's just a lot cooler to run everything balanced. You'll make all your friends green with envy

As far as the signal being 14dB hotter, this is not quite true. I thing you are looking at the -10/+4 consumer/pro levels. These are just two different standards. You can run -10 balanced or unbalanced. When you run balanced, you only gain about 3dB of signal when you sum the two signals.
If you are looking to balance the input of your amps, you can do this a couple of different ways. One, you can get a high quality balancing transformer from Jensen, or you can build a small balancing circuit from a couple of op-amps. either way will work just fine.

I hope this helps.

Cheers,
Zach
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Old 7th October 2003, 06:12 PM   #23
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Default Re: Getting back to the original question.........

Quote:
Originally posted by usekgb
due to the fact that you are running two signals side by side, and summing them at the input of your amp.
Just to pick a nit, they're subtracted, not summed. If they were summed, the signal would be rejected and the noise would be amplified.

se
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Old 7th October 2003, 06:17 PM   #24
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CMNA
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Old 7th October 2003, 06:30 PM   #25
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Quote:
Originally posted by Da5id4Vz
CMNA
WTFDTM?

se
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Old 7th October 2003, 06:32 PM   #26
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Common Mode Noise Addition
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Old 7th October 2003, 06:40 PM   #27
jam is offline jam  United States
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Steve,

Been away for a few days.......................
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Old 7th October 2003, 06:42 PM   #28
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Hi,

Quote:
Been away for a few days.......................
You noticed??

Cheers,
__________________
Frank
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Old 7th October 2003, 06:54 PM   #29
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Quote:
Originally posted by Da5id4Vz
Common Mode Noise Addition
TY.

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Old 7th October 2003, 06:55 PM   #30
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Quote:
Originally posted by jam
Steve,

Been away for a few days.......................
Steve? No, I'm Stuart.

se
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