Switching arrangement?

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Bequerel

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Switching arrangement?
« on: 11 Feb 2003, 07:46 am »
Questions from a rookie...

I suppose that everyone want the cleanest and simplest signal path possible.

1) If I choose a solution with only one XLR input and one XLR output, is it OK to use a balanced-to-SE-adapter if I need to use equipment without balanced outputs or inputs from time to time?

2) If I choose a solution with one XLR and one SE* connection pr channel, do I need a switch for selection as long as I disconnect  the equipment I dont use? (Only one input and one output active and connected at the time.)

*SE = Single ended

Thank you!

John Chapman

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    • http://www.bentaudio.com
Switching arrangement?
« Reply #1 on: 11 Feb 2003, 12:53 pm »
Hello!


I'm a simple signal path guy too so good questions!

>1) If I choose a solution with only one XLR input and one XLR output, is >it OK to use a balanced-to-SE-adapter if I need to use equipment >without balanced outputs or inputs from time to time?

On the output side in the kits there is an XLR/RCA switch but it is NOT in the signal path 'propper'. Pin 2 of the XLR is wired directly to the hot of the RCA and pin 3 is wired directly to the body of the RCA (RCA ground). The RCA/XLR switch  only selects which pin grounds to the central case ground. In RCA mode the body of the output RCA is connected to ground and in XLR mode pin 1 of the XLR is connected to the ground point.
The schematics on the downloads section of my site show this if you can read schematics ok.

>2) If I choose a solution with one XLR and one SE* connection pr >channel, do I need a switch for selection as long as I disconnect the >equipment I dont use? (Only one input and one output active and >connected at the time.)

This is a 'maybe can do'. First I need to run through the input grounding options as it is a factor in this question. In the standard wiring of the kits there is an input ground switch that can be used to connect the input ground to the output ground. If your system has all your sources and your amp grounded via power connections then you'd want to float this connection to avoid ground loops and the switch is set to float the grounds. If you have a source that is not grounded (floating in the breeze) it is normally grounded to the amps ground through the interconnect so with this switch in the float position you'll likely get a humm/buzz with that source not connected to any ground reference. This is when the hard ground is used. Most pre-amps do not have the option to float the input ground to output ground (needing a transformer to do it) so any typical pre-amp is basically 'hard grounded'.

That's quite a lot of info - sorry to be long winded! Usually the input ground switch setting is easy - just try both positions in your system and use the one that is quietest. Now finally to your question. If you want to just wire both an RCA and an XLR to the primary of the TX102 you can do it as long as your system is happy in the 'float' position where you do not need to connect 'input ground' to 'output ground'. If you need to connect these grounds then you'll need an input switch because in the RCA case the body of the RCA would be the ground point and in the XLR case pin 1 would be ground. If you just do a straight hardwire then the XLR pin3 would end up grounded - not an idea hookup! This switch does not have to be in the 'signal path propper'. This input select switch could be wired like the output ground switch and just select which wire ('RCA gnd' or 'XLR pin1') would feed the ground select switch. That way you could have the primary of the TX102 connected directly to both the RCA and the XLR connector like the output connectors are.

I hope this is not too confusing!

Many Thanks!

John Chapman
www.bentaudio.com

Bequerel

  • Jr. Member
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Switching arrangement?
« Reply #2 on: 11 Feb 2003, 02:53 pm »
Thanks, John, for a lot of VERY informative "input"!

 :wink:

Bequerel

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Switching arrangement?
« Reply #3 on: 11 Feb 2003, 03:17 pm »
Having read the reply, John, I am a little bit confused about question 1) since your reply only covers the outputs:
Is it OK to have one XLR-input and hardwire a litte SE-to-XLR-adapter if I need to use single ended equipment? (I understand that a output select switch is OK, since it is not in the signal path.)

John Chapman

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    • http://www.bentaudio.com
Switching arrangement?
« Reply #4 on: 11 Feb 2003, 03:38 pm »
Hello!

All that typing and I missed question #1! Sorry about that. You can wire just an XLR input and then use an RCA to XLR adapter when you use that input for RCA. It's a few extra connections in RCA mode (the min path guy in me does not like that!) but it'll work. The Hot of the RCA goes to Pin 2 and the GND of the RCA goes to  both Pin3 (connected to the bottom of the TX102 primary) and PIN1 (connected to the input ground node).

Thanks!

John Chapman
www.bentaudio.com

Bequerel

  • Jr. Member
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Switching arrangement?
« Reply #5 on: 11 Feb 2003, 04:13 pm »
Thank you, just what I hoped!