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John Hardy 500 series preamp
Old 22nd October 2019
Gear Maniac
chumusic's Avatar

John Hardy 500 series preamp

Had a brief email contact with John Hardy.
It seems like his 500 series Twin Servo 990 preamp is still in development.
I honestly never tried the Radial Twin Servo.
Can't wait to get my hands on John's 500 series preamp.

John shared his thoughts and here is some issues he came across while developing the 500 series.

John in his own words:

Thank you very much for the compliments.

I am revising my first 500-series mic preamp, which is a version of the Jensen Twin Servo 990 Mic Preamp. I had board #1 finished and many others mostly assembled, when I learned that a critical component was discontinued. It was the LM3915 LED bar-graph driver chip. So I decided to redesign the meter circuitry and develop a much nicer meter. I also decided to convert as much of the circuitry as possible to surface-mount assembly because tighter-tolerance resistors and capacitors are readily available in surface mount.

I don't have a specific timetable for the revised version. It will be at least a few months.

You can always buy the regular versions of my preamps in the 19" wide 1.75" high chassis. The regular versions run on higher power supply voltages than the 500 series (+/-24VDC vs. +/-15VDC) and probably have better power supplies than most of the 500 series frames.

In early 2018 I revised the power supplies for my M-1, M-2 and Jensen Twin Servo 990 mic preamps. The new design automatically adjusts to any AC line voltage from 100VAC to 240VAC. Weight is reduced by two pounds and there is less heat generated. The new design uses a series of switchmode AC/DC modules in place of the original toroidal power transformer to pre-regulate all of the DC voltages. The original linear regulators are retained to perform the final regulation to achieve the lowest noise.


Old 1 week ago
Lives for gear
elambo's Avatar
I hope it's for real this time. I don't know exactly when this was first mentioned but it seems like a decade ago and threads which discuss it tend to stall awkardly. A Twin-Servo 990 has been on my wishlist since we got our rackmount version ~15 years ago.
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