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Category: Projects
Hifisonix Speaker Protection Board
This simple, low cost speaker protection board measuring just 82mm x 50mm uses the ubiquitous UPC1237 from Unisonic, a Taiwan based semiconductor manufacturer. The circuit will work from 25V through to 75V and uses mosfets to switch the speaker load rather than relays which are problematic and unreliable. A current overload input is also provided,…
Hifisonix Standard PSU
Click here to buy a PCB for the Standard PSU Click here for the build documentation Click here for the BOM The Hifisonix Standard PSU features low noise, up to 400mA per rail output current, a MUTE relay driver to ensure when the load powers up or down there are no clicks or thumps, a…
Hifisonix HPA-1 Class A Headphone Amplifier
The circuit combines a dual ultra-low distortion opamp, the LM4562 or OPA1642, with a class A discrete power output stage to deliver outstanding performance both measured, and sonically. The complete amplifier, including the opamps, runs in class A. Into 60 Ohm headphones and above, the HPA-1 remains fully in class A up to the rated…
Hifisonix Accurate Inverse RIAA Network
The diagram above summarizes the interaction of the cutting head response (purple) and the playback EQ (red) which produces the final flat response (green). Note that the cutting head and the phono pickup (cartridge) are velocity transducers and therefore the cartridge output rises at 20 dB/decade if the record groove is cut at constant amplitude.…
Hifisonix Ripple Eater PSU for the sx and kx-Amplifiers
The PCB’s are through hole plated and silk screened and are available from Jim’s Audio here: Ripple Eater PSU for kx and sx Amplifiers (please note these PCB’s are not available from the Hifisonix Shop) Here is an Excel file with the BOM: Ripple Eater PSU BOM The BOM is provided for assistance – always…
Very Simple, Accurate RIAA Phono EQ Amp
Very High Quality Silk Screened PCB’s for this project are available from Jim’s Audio here:- Hifisonix RIAA Amplifier Here is a simple no-nonsense, accurate RIAA equalizer amp you can easily build. The design uses an all-active topology and is based around an NE5534A low noise opamp. I make no claims for originality but you wont…