What can I use instead of k170/j74?

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Official Court Jester
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The Front End


Initially we designed a new front end that could be tweaked to produce arbitrary ratios of low order harmonics, and while this worked fine, after we finished working with the output stage portion of the design we found that it worked better to have the front end simply complement the output stage in a largely neutral manner.
The new front end is not more complex than the previous design. It still uses cascoded matched Toshiba Jfets (NOS from our large cache) for the input devices which drive complementary Mosfets.
However we have increased the heat sinking so that this stage can be biased with 2.5 times more current and brought in higher quality Toshiba Mosfets (also NOS).
This dramatically increases the linearity and bandwidth of the front end, and with the proper adjustment of each part of each stage and balancing degeneration with loading gives us an amplifier front end which by itself has low distortion, a 100 Khz bandwidth and a fairly low output impedance – all without a feedback loop.
Also, the new front end has a 200 Kohm input impedance (balanced) with very small capacitance. Anything will drive it.
Feedback is not essential for this front end, but we have left it with enough open loop gain to allow some feedback around the output stage. This is strictly in service of the sound of the output stage – it already has decent specs.


entire chapter is about FE , and nothing else


in any case , I already wrote more than I wanted
 
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