![]() ![]() ![]() The bottom line: you need to make simple noise and headroom tests, whereby ONLY the FET becomes the variable under test. I am not an electronics engineer and not even the kind of layman who would dedicate enough time necessary to be reaching deeply into this matter, but I can speculate that the enormous input impedance the gate sees in a single-FET microphone (in excess of ten thousand million Ohms) throws off the usual lab specs of the device, similarly to the impossibility to predict tube noise in this type of high impedance environment, no matter what the tube tester (or tube salesman) says. I tried a few of these "superior" FETs (as per spec sheet) and found that their headroom was so grossly inadequate that I was scratching my head where that discrepancy may stem from. If I were to rely on that information, many a FET would be preferable to the good old 2N3819 or other stand-bys which Neumann used in more microphone models for more years than any other FET. I have found that the two most relevant parameters of J-FETs, noise and headroom, cannot be gleaned from 1/F, max voltage or other information provided by the manufacturer. The transistor is designed for low gain signal amplification with good noise filtration due to which it can be used in variety of small signal amplification purposes.I am afraid the answer is not as straight-forward as throwing you a simple part number or referring to spec sheet for a given FET. Having features like high gain, low noise, low power operation due to which it can be used in battery operated devices. Replacement and Equivalent: 2N4339, 2N4340, J201, 2N4338, 2N4341, 2N5458, 2N5459, NTE458 (Note: Pin configuration of some equivalent transistors may different from 2N5457, therefore check pin configuration before using in the place of 2N5457) 2N5457 Description:ĢN5457 is a famous TO-92 packaged JFET transistor that is designed for general purpose switching and amplification purposes. Max Storage & Operating temperature Should Be: -55 to +150 Centigrade. ![]() Minimum to Maximum Gate to Source Cutoff Voltage : – 5 to – 6.0.Max Reverse Gate to Source Voltage is: – 25.Max Drain to Gate Voltage Should Be: 25V.Max Voltage Applied From Drain to Source: 25V.These are used in many boutique builds including our XX Double-shot, Guitar/Bass Driver & many more. Hand Tested and all are in the proper range for guitar pedals. This is one of the most important parts of your build so be sure to get genuine transistors that are within specifications of the datasheets. Description (1) Genuine 2N5457 JFET Transistor from my own personal collection. ![]()
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