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How to interface A line level to a Vintage console with mic Inputs?
Old 16th May 2016
  #1
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Rea's Avatar
 

How to interface A line level to a Vintage console with mic Inputs?

Im looking at this rebuilt custom made Vintage sphere Sidecar.

My goal is to hit the Mic Input Trafos with Line Level.

They way the builder did it is 16 mic inputs to the inputs trafos and 16 separate Line inputs that are going through THAT IC's, instead of a Trafo (in the old Sphere consoles there was no balanced Line input anyway).

I, However, want to take full advantage of the Input Trafo sound at mix down, utilizing the input Trafos instead of the THAT IC's.

What is the best way for me to achieve that?
Either out of the unit (pre entering it) or by modifying it internally?


Thanks!

Rea
Old 17th May 2016
  #2
Quote:
Originally Posted by Rea View Post
Im looking at this rebuilt custom made Vintage sphere Sidecar.

My goal is to hit the Mic Input Trafos with Line Level.

They way the builder did it is 16 mic inputs to the inputs trafos and 16 separate Line inputs that are going through THAT IC's, instead of a Trafo (in the old Sphere consoles there was no balanced Line input anyway).

I, However, want to take full advantage of the Input Trafo sound at mix down, utilizing the input Trafos instead of the THAT IC's.

What is the best way for me to achieve that?
Either out of the unit (pre entering it) or by modifying it internally?


Thanks!

Rea
To go into a mic input with a line level signal you are going to have to pad the signal significantly before it hits. Easiest way would be to use something like a little lands red cloud attenuator to do that.
Old 18th May 2016
  #3
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Hamburg58's Avatar
 

Quote:
Originally Posted by Rea View Post
Im looking at this rebuilt custom made Vintage sphere Sidecar.

My goal is to hit the Mic Input Trafos with Line Level.

They way the builder did it is 16 mic inputs to the inputs trafos and 16 separate Line inputs that are going through THAT IC's, instead of a Trafo (in the old Sphere consoles there was no balanced Line input anyway).

I, However, want to take full advantage of the Input Trafo sound at mix down, utilizing the input Trafos instead of the THAT IC's.

What is the best way for me to achieve that?
Either out of the unit (pre entering it) or by modifying it internally?


Thanks!

Rea
Josh Florian of JCF audio had a really cool converter I tried out a few years ago where you had to feed it into the mic inputs of the console.... Look him up.
Old 19th May 2016
  #4
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Capashitor's Avatar
You can make your own pads ! Use matched 7k5 resistors in series with hot and cold, and a 150 ohm shunt after the 7k5 ones in parallel between hot and cold and you have yourself a 40db mic/line pad.
Old 20th May 2016
  #5
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Use a DI...
Old 21st May 2016
  #6
Gear Nut
 

Quote:
Originally Posted by Samc View Post
Use a DI...
Not necessary, the DIY pad is sufficient, there is a transformer for galvanic isolation already and there should be no impedance problems just going with a pad...
Old 21st May 2016
  #7
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Quote:
Originally Posted by hop.sing View Post
Not necessary, the DIY pad is sufficient, there is a transformer for galvanic isolation already and there should be no impedance problems just going with a pad...
None of the options mentioned here are "necessary"...a DI is a relatively easy and inexpensive option...not absolutely necessary but very viable.
Old 21st May 2016
  #8
Gear Nut
 

Quote:
Originally Posted by Samc View Post
None of the options mentioned here are "necessary"...a DI is a relatively easy and inexpensive option...not absolutely necessary but very viable.
Well, i would say something like a pad is a good thing (necessary), otherwise you would have to turn down the volume at the source and than you make up all the noise from it...
Old 22nd May 2016
  #9
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emrr's Avatar
Resistive pads is how a lot of consoles did it. Much cheaper to make those than buy 16 DI's.
Old 22nd May 2016
  #10
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With pads you can have a very short / clean signal path and configure for the best pad value. You can make up multiple fixed value pads and use as needed or get fancy with a variable value pad. A few parts and simple soldering is all that is required. This web page will step you through it: http://www.uneeda-audio.com/pads/ It's worth a bookmark for all later readers of this thread.
Old 23rd May 2016
  #11
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****e....didn't realize the OP was talking about 16 channels, please excuse my mistake.
Old 23rd May 2016
  #12
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jjblair's Avatar
A U pad or an H pad is one way. Personally, I'd probably mod the channels with a transformer suitable for line level, and make it switchable, kinda like how most consoles did it, but I modified my Langevins AM16s to accept line level though padding. Maybe the easiest and least expensive way to do it.

The trick is to find the amount that balances between enough reduction to avoid over-modulation of the mic pre, but not too much, so that you have to use so much gain that you increase your noise floor.
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