Equalizer APO


A system-wide parametric equalizer for Windows 7 / 8 / 8.1

4.7 Stars (23)
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Equalizer APO is a parametric equalizer for Windows. It is implemented
as an Audio Processing Object (APO) for the system effect infrastructure
introduced with Windows Vista.

- virtually unlimited number of filters (currently limited to 100 per channel for sanity)
- works on any number of channels
- very low latency, which makes it suited for interactive applications
- low cpu usage

- Windows Vista or later (currently only Windows 7, 8 and 8.1 have been tested)
- Sound card driver must support APOs (this includes most onboard sound drivers)
- The application must not bypass the system effect infrastructure
(possible by using special APIs like ASIO)

Equalizer APO is best used in conjunction with Room EQ Wizard (http://www.hometheatershack.com/roomeq/), because it can read its filter text file format.

Please have a look at the Wiki (http://sourceforge.net/p/equalizerapo/wiki/) for instructions on installation and configuration.

Equalizer APO Web Site

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User Ratings

ease 1 of 5 2 of 5 3 of 5 4 of 5 5 of 5 3 / 5
features 1 of 5 2 of 5 3 of 5 4 of 5 5 of 5 4 / 5
design 1 of 5 2 of 5 3 of 5 4 of 5 5 of 5 3 / 5
support 1 of 5 2 of 5 3 of 5 4 of 5 5 of 5 4 / 5
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User Reviews

  • deprisonne
    1 of 5 2 of 5 3 of 5 4 of 5 5 of 5

    EQ APO is a great tool to set an EQ globally and independent of playback/recording software. It does not matter if you use an integrated, discrete or external soundcard. It is much better than the manufacturer- and hardware-specific EQs of consumer grade soundcards. For basic EQ and amplification tasks the usage is very simple. EQ presets are changed by editing the config.txt file. Different Eqs for each playback „and“ recording device in the windows sound mixer are possible. It is possible to choose an individual ampification for each channel, too. When the playback device is changed via OS another EQ is applied. As I switch between speakers and headphones at the same jack, a GUI for switching presets or a automated script would be helpful. Editing a few lines of code every time is a little tiring. As decribed on the project page, together with REW stunning results are possible. I was able to linearize the frequency response of my microphone, headphones and speakers. But to achive that it takes a little knowledge in audio engineering and time for EQ-tweaking. So far EQ APO ran totally stable. It did not cause any additional problems.

    Posted 07/19/2014
  • miumau
    1 of 5 2 of 5 3 of 5 4 of 5 5 of 5

    I recently started to use this (0.8.1) on Win7/64bit and an external Motu Ultralite Mk3 audio interface connected via USB. The equalizer works perfectly for the Motu main outs, and I'm really happy how it allows to put different EQs on the left and right channels. Just what I had been looking for. I didn't try EQing other outputs. Many thanks to the developers for their great work.

    Posted 06/30/2014
  • zamiere
    1 of 5 2 of 5 3 of 5 4 of 5 5 of 5

    It's just works perfectly, a must-have for correcting small linearity errors in consumer hifi headphones and speakers.

    Posted 06/12/2014
  • makzmakz
    1 of 5 2 of 5 3 of 5 4 of 5 5 of 5

    Amazing, with a decent sound card I dont need to buy an expensive Audessey receiver, I can just let my HTPC do the DTS decoding and do the EQ I need on every channel - all in the digital domain!

    Posted 06/08/2014
  • jacemace
    1 of 5 2 of 5 3 of 5 4 of 5 5 of 5

    Too esoteric - i.e., time consuming and non-responsive. Tried many configurations, and they did not work. Tried a previous posters GUI equalizer, and it did not work. The pre-amp did work. Hopefully it continues to develop and becomes more (user) intuitive. Also requires Java, which I do not like. Uninstalling (for now) and will try again later. Thanks.

    Posted 06/03/2014
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Additional Project Details


English, German

Intended Audience

Advanced End Users, End Users/Desktop

User Interface

Non-interactive (Daemon)

Programming Language



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