Hifisonix Micro Ripple Eater

You can buy Micro Ripple Eater boards in the Shop

This simple ripple eater (aka MRE) can deliver up to 10A per supply rail (provided it is suitably heatsinked!) and will reduce mains related ripple on amplifier supply rails by up to 40 dB and as much as 50 dB at HF.

The board is small, compact and easy to mount virtually anywhere within the amplifier chassis. You can use a single ripple eater to comfortably power stereo amplifiers of up to 100W per channel, or you can use two to individually clean up the supply rails on higher power amplifiers. The series pass transistors are not critical and any 15A TO3-P or TO247 type packaged devices will work.

The hifisonix MRE makes a perfect upgrade to class A amplifiers where the usually heavy load current can cause excessive supply rail ripple. At 2.5A load current, the MRE 100/120 Hz supply rail ripple is under 20mV vs 1~2V pk to pk using a standard rectifier + reservoir capacitor setup. At higher frequencies in the audio band, it is even better and with good amplifier construction and cable dressing, can be well below 10mV pk~pk. Further, the slow start-up of the MRE helps to reduce switch-on thumps from the speakers.

Download the PDF build doc below (updated 4th December 2022)

Can the MRE be used with amplifiers that have supply rails > 50V?

The MRE is designed to work with amplifiers with supply rails of up to +-50V. If you want to use it with higher supply rails, the voltage rating of the capacitors has to be increased. The maximum diameter on C1 and C2 is 16mm and on C3 and C4 10mm. The transistors specified in the BOM are good for up to +-80V supply rails.


16 responses to “Hifisonix Micro Ripple Eater”

  1. Vladimir says:

    What is voltage drop on ripple eater


    • Bonsai says:

      Hello Vladimir – it’s between 1-2 volts depending upon load. At full load it will be about 2 volts.

  2. Tony says:

    What is the value for R1 & R2 – 1k or 10k .
    PCB=1k & Bom=10k?

    • Bonsai says:

      Tony R1 and R2 should be 10K

      Thanks for highlighting this – I will put a not on the build doc and update the PCB’s on the next batch.

  3. Nickson says:

    Hi Andrew,

    Are load resistors R1 R2 really needed? After all, R5 R6 quite cope with their role.

    Best regards,

  4. Ricardo says:

    Hi, can this ripple eater be used with 78 Volt supplies by increasing capacitor voltages and using something like MJL 4281s?
    I’m thinking about using them for an Adcom GFA 555 Mk2

  5. Simon says:

    hi there:
    I was wondering if I could use MOSFET(or IGBT) instead of general purpose transistor? Do I have to modify schematic?

    • admin says:

      Jose, you will lose 1.5 to 2 volts across the MRE. With +-12 V secondaries you will get about 16 V out and after the MRE about 14 V. Ideally, you want 13-0-13 V secondaries.

  6. José C R Fardo says:

    Yes got It. Thanks

  7. Anand says:

    Hi! Is there a requirement/recommendation to use a cap bank after this MRE in a **Class AB** 100 watt amplifier designs (i.e. assuming a quiescent bias 93dB efficient?

    Thanks again for all you do!

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