PDA

View Full Version : Balanced or unbalanced, that is the question!



Jakob
11-18-2004, 03:01 AM
Hi!
Building a pair of 18"-subs for my 250 ti's put me in rather a big problem. Here's the background:
My pre-amp has both balanced and unbalanced outputs.
My active crossover has balanced in and outputs.
My 250 ti amp has unbalanced inputs.
My subs amp has balanced inputs.

My AC wall outlet has no ground connection.

Is there then any meaning in going balanced from the pre-amp to the crossover and then to the sub amp and unbalanced just from the network to the 250 ti amp, or should I just go unbalanced all the way, and is it really possible to go balanced at all when there is no ground wire in my wall outlet?

Please excuse my bad english and please help me out!

Thanks!

boputnam
11-18-2004, 06:31 AM
Whoa... Your english is fine, but the country's electric grid is nutters! :hyp:

Out of curiousity, what is the voltage? I can't imagine there isn't ground in the circuit. You guys are supposed to be progressive over there!! :rotfl:

If it were me, I'd run balanced all the way, but would be dropping Pin1 (shield) at the inputs to the power amp anyway. You could make a case for dropping Pin1 at EVERY input along the signal path.

Zilch
11-18-2004, 10:42 AM
You should run balanced wherever you can. If I'm reading correctly, that's everywhere except for the 250ti amp. With no ground, you want all the common-mode noise reduction you can achieve....

Jakob
11-19-2004, 02:43 AM
Well, I live in an old house and the outlets in the kitchen and toilets have ground connectors but the others just have hot and cold. Can't bring the stereo to the toilet or kitchen, not enough space ;) .
What does the dropping of the shield on the inputs do?

Thanks for your input!

B.R: Jakob

scott fitlin
11-19-2004, 09:47 AM
Technically Pin 1 is the ground, while 2 and 3 are the positive and negative sides of the signal! But in the real world sometimes ground loops develop when Pin 1 is connected, so we drop Pin 1 ground, and it solves noise problems. If you connect Pin 1 and hear a buzzing type noise through your system or hum, you know you have a ground loop. Dropping Pin 1 will not hurt anything and does solve noise problems!

You should listen to both the balanced and unbalanced connections of your equipment and see if there is a difference in sound, and whatever sounds best to you is what you use! In a home system its perfectly OK to run an unbalanced system. With pro gear usually the balanced outs of a preamp have more drive, but not always.

andresohc
11-23-2004, 11:17 PM
Scott, whats the easiest way to drop pin one on XLR connections especially when most off my cables are sealed. Buy amphenol solder cup XLR connectors, cut the molded ones off and solder on new minus pin one? TRS the same, if sealed cut and put on new solder cup connectors? Am I missing something obvious are is this about as easy as it gets?

John Nebel
11-24-2004, 05:14 AM
Another approach is to use a transformer such as

http://www.sescom.com/

scott fitlin
11-24-2004, 07:37 AM
Scott, whats the easiest way to drop pin one on XLR connections especially when most off my cables are sealed. Buy amphenol solder cup XLR connectors, cut the molded ones off and solder on new minus pin one? TRS the same, if sealed cut and put on new solder cup connectors? Am I missing something obvious are is this about as easy as it gets?Inside the XLR just dont attach the wire to pin 1, or if it already is, cut it, and make sure it isnt shorting to the outer casing, and you will drop pin1.