[1230] Bypass Systems Measured

Date: April 11th, 2012 | Comments : [7] | Categories: DIY.

jfet bypass response

I tested the signal level and frequency response of a short chain of true bypass pedals against the same number of buffered Boss pedals. See the full article in my Lab Notebook.


7 Responses to “Bypass Systems Measured”

[2830] admin Says: 10:26 pm, April 11th, 2012

If you want to jump straight to the article, it is here:


[2848] brenton Says: 4:51 pm, April 16th, 2012

I am curious what the frequency response of 4 well designed buffered bypass pedal would be. like 4 mini buffers from that AMZ newsletter or 4 klon style buffers.

[2857] admin Says: 1:43 pm, April 20th, 2012

Four well-designed opamp buffers in series would have very good response and unity gain. It would not be exactly like 4 switches in series but good enough that you certainly could not hear the difference. This is quite a bit different than the multiple transistor buffers put into many commercial pedals, which will have a significant impact on the sound as illustrated above.

[3008] Chris Says: 8:02 am, July 8th, 2012

I did a freq response test of 10 individual Boss pedals, then ran them all in series & repeated the test. Hilarious results!

[3009] Chris Says: 8:05 am, July 8th, 2012

FWIW, the buffered bypass used by Tech21 in their SansAmps is fantastic – barely deviates from the loopback response.

[3010] Chris Says: 6:32 pm, July 8th, 2012

[3016] admin Says: 4:28 am, July 21st, 2012

Thanks for posting the graph, Chris.

The 10 Boss pedal response is revealing and in line with what I found with 4 Boss pedals. The high end roll off is -3db at about 8.8k Hz, compared to the mid-range response, and I’m wondering if a particular one of the 10 pedals is contributing most of that loss.



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