Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Other Topics => Topic started by: Bassmanster on September 15, 2010, 01:19:27 pm
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Anyone built? I like my sensitive mic pre for spoken word, but I have to turn it down too much for a screaming amp, especially if I use a condenser. It gets dull.
There are the XLR inline ones, but it would be nice to make a box with several dB reductions.
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http://hairballaudio.com/shop/index.php?cPath=27&osCsid=737912ebe94558a04c0306b00ce1b3cd
(http://hairballaudio.com/shop/images/388_Att.jpg)
35 clams
Seems expensive, but you can hardly source parts for a stepped T pad for less. Plus it would take quite a while to build. Schematic attached.
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Those are both 600:600 pads.
Microphone pads should be different.
In fact you can't make a good mike pad less than 20dB, so-so 15dB. You shouldn't often need over 20dB pad... else you may be using poor-choice tools.
Hot condensers should have a -10dB capsule shunt. Use it.
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Thanks guys. If I did I would emulate the in/out impedance of Shure's pads, which are published.
Cheap condensers, no pad.
I think I'll try using a buzz box for the time being and turning the amp down. I can also hack the built-in -14 pad in my mic pre (Hamptone) to something higher (er, lower).
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Sometimes I think I'll never figure this stuff out. Here's a good link:
http://www.uneeda-audio.com/pads/
Looks like the standard is a -20dB "U" pad using 2 - 680 ohm and 1 - 150 ohm resistor. Meanwhile my project is completely backasswards. :BangHead:
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I found some online java applet calculators for H pads. You input the attenuation, input and output Z and it gives you the five resistors. So that will come in handy if I decide to do it.
I should have just got the resistor-based step gain controls on my pre, but it was more money.