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DIY attenuators
Old 5th February 2009
  #1
Gear Addict
 
🎧 10 years
DIY attenuators

hey all,

I'm looking to build a pair of simple -10dB or -12dB pads to use between the output of my API 512s and my converters. I want to build them using spare neutrik connectors which I already have. I've read a couple of articles on this and I'm still a bit boggled by the math.

Can any of you guys help me through this? I've got basic soldering skills, so I basically just need to know what resistor values I need, and where to connect them.

Thanks in advance,

C
Old 5th February 2009
  #2
Lives for gear
 
AdamJay's Avatar
 
🎧 15 years
i think this is what you are looking for:
Uneeda Audio - Build your own attenuator pads

scroll down to the DIY section, although the whole page is a great read.
good luck!
Old 5th February 2009 | Show parent
  #3
Gear Addict
 
🎧 10 years
great, thanks!

C
Old 6th February 2009 | Show parent
  #4
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Fishmed's Avatar
 
1 Review written
🎧 10 years
Here is another good site:

Passive Audio Attenuators

They have a online script to help you find the right values (doing the math for you).
Old 6th February 2009 | Show parent
  #5
Lives for gear
 
🎧 10 years
Make sure you mount the attenuator on the receiving/load end of the cable.


/Peter
Old 6th February 2009 | Show parent
  #6
Gear Addict
 
🎧 10 years
Quote:
Originally Posted by Audiop ➑️
Make sure you mount the attenuator on the receiving/load end of the cable.


/Peter
Hi Peter,

Not sure exactly what you mean. The photos on the Uneeda Audio page show the resistors wired to the male xlr end, which would be the output, no?

C
Old 6th February 2009 | Show parent
  #7
Lives for gear
 
🎧 15 years
Hi
The male end would usually be the receiving end as it plugs into your mic preamp or whatever.
The general plan is that the majority of the cable length will be carrying signal at maximum level and the attenuator goes at the far end or this, where it is connected to the 'input' of your gear.
This method is used to ensure the signal is 'interfered with' as little as possible, as the attenuator you fit will reduce the signal AND the interference.
Matt S
Old 6th February 2009 | Show parent
  #8
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Fishmed's Avatar
 
1 Review written
🎧 10 years
Since we are on the subject...

What is the best way to build one using a pot (say 2.5K)?
Old 6th February 2009 | Show parent
  #9
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Fishmed ➑️
Since we are on the subject...

What is the best way to build one using a pot (say 2.5K)?

DIY attenuators-potschem.jpg


/Peter
Old 6th February 2009 | Show parent
  #10
Gear Addict
 
🎧 10 years
Quote:
Originally Posted by Matt Syson ➑️
Hi
The male end would usually be the receiving end as it plugs into your mic preamp or whatever.
The general plan is that the majority of the cable length will be carrying signal at maximum level and the attenuator goes at the far end or this, where it is connected to the 'input' of your gear.
This method is used to ensure the signal is 'interfered with' as little as possible, as the attenuator you fit will reduce the signal AND the interference.
Matt S

ok. I'm pretty sure the outputs on my API's are xlr male, meaning it would need an xlr female. I think I'm confused now.

C
Old 6th February 2009 | Show parent
  #11
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nosebleedaudio's Avatar
 
🎧 15 years
Also if you roll your own Pad make sure the in/out is correct, a pad has an input, otherwise it will not work correctly.
Old 6th February 2009 | Show parent
  #12
Lives for gear
 
🎧 15 years
Hi
Most equipment has a Male connector for the output, like a microphone which also has a male output connector.
You would not put the attenuator at this end but at the INPUT of the following gear.
If you had a particularly 'hot' mic signal for example you would have standard cables at the mic and then where it goes into the preamp you would attach your attenuator.
Old school attenuators would be built as 'constant impedance' which would be bidirectional but this is rarely done now although in reality if you are using gear with a transformer output you really should be maintaining the correct load impedance (typically 600 Ohms for 'usual' connections). Inpedance matching as this is known is necessary when using transformers to maintain the 'flat' response it was designed for. Granted many circuits now use a lot of feedback and high quakity transformers whose response varies by only a small amount if incorrectly loaded.
Matt S
Old 14th February 2009 | Show parent
  #13
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ulysses's Avatar
 
🎧 15 years
Quote:
Originally Posted by Colorblind ➑️
ok. I'm pretty sure the outputs on my API's are xlr male, meaning it would need an xlr female. I think I'm confused now.

C
By "preamp or whatever" he actually meant your converters. Put the pad at the destination end of the cable, which is the end with the male XLR on it.

And do the math yourself. You'll learn a lot more that way - both about audio and about math. It's really a great feeling when everything starts to make sense. It's really not that complicated or difficult once you come to understand parallel resistor calculations, voltage dividers, Ohm's law, and logarithms (such as decibels).
Old 14th February 2009 | Show parent
  #14
Lives for gear
 
🎧 10 years
Agree, doing a little (or not so little :-) homework so you get pass the point where everything seems like latin or greek is very rewarding.

Understanding ohms law, log/dB and waveform/spectra is a good thing for anyone dealing with audio. A little acoustics doesn't hurt either. thumbsup


/Peter
Old 17th February 2009 | Show parent
  #15
Gear Addict
 
🎧 10 years
Cool, thanks for the advice, guys.

C
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