Measuring bypass systems

So I always write about true bypass systems and how the idea of zero insertion loss is usually beneficial to a guitarist. In this example I had a DOD Vibrothang sent in because the pedal killed the tone when in the signal chain. Using TrueRTA as shown on I made a quick comparison of the signal loss from a true bypass pedal versus the Vibrothang (before and after modifications). In the stock form the signal starts rolling off around 1KHz and dramatically drops blow 200Hz. Keep in mind that this is when the pedal is bypassed which means if you have this pedal plugged in, you’re always sacrificing part of your signal. This loss in midrange will thin out your guitar’s signal and may become a larger problem when combined with other pedals. After modifying the input and output buffer the insertion loss is significantly less overall and the low end roll off only starts around 100Hz which is perfectly acceptable.

I think a project for the future will be taking a variety of pedals and comparing their bypass systems. Also, note that DOD has used a variety of bypass designs in their history so your model may not have the same problems as the DOD Vibrothang..

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