Buffer with specific output impedance

Started by ugly_guitar_guy, February 06, 2012, 01:29:28 PM

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ugly_guitar_guy

Hey guys,

After building a new pedalboard to use with my Mesa Mark V I've run into an interesting issue that I didnt notice with my GT-10 I previously used.

Long story short, the FX send on the Mark V is 25k Ohms, and the return is 50k Ohms, so I need a buffer with a 50k Ohm output so that I can match the return (the DD-3 at the end of my fx chain is only 10k Ohm output and I can tell it's effecting the return tone).

Any direction to a buffer that can be dialed to that specific Ohm output?? Thanks!
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therecordingart

Quote from: ugly_guitar_guy on February 06, 2012, 01:29:28 PM
Hey guys,

After building a new pedalboard to use with my Mesa Mark V I've run into an interesting issue that I didnt notice with my GT-10 I previously used.

Long story short, the FX send on the Mark V is 25k Ohms, and the return is 50k Ohms, so I need a buffer with a 50k Ohm output so that I can match the return (the DD-3 at the end of my fx chain is only 10k Ohm output and I can tell it's effecting the return tone).

Any direction to a buffer that can be dialed to that specific Ohm output?? Thanks!

You don't want to match the 50k ohm impedance on the return. In situations like this you want your source impedance to be 1/10th (or smaller) of the load impedance. By matching the impedance you'll see a 6db reduction in signal level vs a .8db reduction in signal level if the output impedance of your pedal were 5k.

ugly_guitar_guy

Quote from: therecordingart on February 06, 2012, 02:57:05 PM

You don't want to match the 50k ohm impedance on the return. In situations like this you want your source impedance to be 1/10th (or smaller) of the load impedance. By matching the impedance you'll see a 6db reduction in signal level vs a .8db reduction in signal level if the output impedance of your pedal were 5k.

Ok, so if the DD-3 is a 10k Ohm output then it should be close enough? I suppose there might be another reason for the loss of highs then, this just seemed like something obvious, but apparently I don't understand the concept well enough. Back to the drawing board. Thanks
Check out my metal band here: www.facebook.com/hollowshell
or
my personal effects building page here: www.facebook.com/brotronics

DavenPaget

Quote from: ugly_guitar_guy on February 06, 2012, 03:14:39 PM
Quote from: therecordingart on February 06, 2012, 02:57:05 PM

You don't want to match the 50k ohm impedance on the return. In situations like this you want your source impedance to be 1/10th (or smaller) of the load impedance. By matching the impedance you'll see a 6db reduction in signal level vs a .8db reduction in signal level if the output impedance of your pedal were 5k.

Ok, so if the DD-3 is a 10k Ohm output then it should be close enough? I suppose there might be another reason for the loss of highs then, this just seemed like something obvious, but apparently I don't understand the concept well enough. Back to the drawing board. Thanks
You would be safer with a TL072 buffer . 1K impedance . that's 1/50 ratio .
Hiatus

ugly_guitar_guy

Quote from: DavenPaget on February 06, 2012, 03:34:26 PM

You would be safer with a TL072 buffer . 1K impedance . that's 1/50 ratio .

Cool, I'll try something like this then and see how it works out.
Check out my metal band here: www.facebook.com/hollowshell
or
my personal effects building page here: www.facebook.com/brotronics