First, let me say I have this site to thank for highlighting the importance of room acoustics in getting the best out of any given hardware setup. When I hit upon this little scheme, therefore, I thought I ought to give what little I could in return. Hopefully you'll find it novel!
So here goes.
Those of you familiar with hardware parametric equalisers already know what they typically aim to do: flatten the low frequency response of your hi-fi/room combo. You probably also know they don't exactly come free with cereal.
It occurred to me recently that there might be a cost-effective way to - if not exactly replace such pieces of kit, at least get (and more importantly convey) an idea of what benefit they might yield: equalize the music at source.
So, with the aim of improved sound and a budget of exactly zero, I set about my task.
First, I wired my PC to my amplifier, and downloaded a free tone generator; a fairly basic one: google "NCH Tone Generator" for links. I also googled 'Frequency of notes" for a reference table of values.
I then used the tone generator to get a feel for the response of my room. It was immediately apparent that there was a broad dip centered around 55hz and a narrower one around 87hz, plus a bit of resonance 'boom' at 110hz. If you haven't performed this kind of test before, prepare to be surprised just how distinct these effects can be!
Armed with this rough and ready info I googled another piece of software: "Parametric Equalizer Pro 3" from ANWIDASOFT. This little gizmo gives you four parametric filters (each with gain, frequency and width) plus high and low pass filters (adjustable gain and baseline) for overall balance.
Back to the tone generator, and I set up a ramped waveform from 30 to 120hz over 8 seconds, and saved it do disk. Listening to it, the dips and peaks were clearly audible.
I loaded the test sound into PEP3 and set about adjusting the values. The discovery that double-clicking the otherwise fiddly and oversensitive dials allows you to enter an accurate value saved a lot of time. It took a minute or two to enter the frequencies and adjust the bandwidth and gain, but afterwards the ramped test tone sounded a lot more consistent. Some variation in volume was audible, but it was still a tremendous improvement.
Time to test it out on some real music. I trawled my MP3 collection for good test cases and selected White Stripes: Seven Nation Army, Gorillaz: Dare and a classical track, the Pastoral Symphony, all of which had previously failed to inspire during attentive listening sessions. I'm going to assume for all our sakes that - like me, naturally - you'll obtain the copyright holder's permission for this next bit.
Google a 'CDA to WAV' converter and grab your legal choice of test music. Now, unless PEP3 has already convinced you to shell out for the full version, you can only actually 'mix down' thirty seconds of music, so you'll need to use something like the windows audio recorder to chop out a few representative thirty second chunks. You can play the full tracks through PEP3, but it'll beep at you from time to time and in any case, the real test can only be done via your CD player. Go ahead and 'Mix Down' your test chunks.
Now open Windows Media Player (or your choice of CD burning software) and burn your test chunks to a CD, alternating before and after versions. Plonk the CD in your transport, sit back, and listen...
What I heard:
Essentially, a big improvement. Previously reticent bass notes held their ground, whilst their pushy, obnoxious neighbours restrained themselves admirably. 'Dare' and 'Seven Nation Army' were constructed on an altogether more solid and confident foundation, and really engaged the attention. The most satisfying improvement, however, came from the Pastoral Symphony, where a whole extra third of the orchestra decided to come out of the changing rooms and join everyone else on-stage. At a few points the violins and double-bases execute a brief 'duelling banjo' style pair of solo riffs, which the big guns previously lost hands down. In the tweaked version they gave every bit as good as they got.
Bear in mind that this exercise was carried out entirely subjectively, with no SPL metering or mode calculation. It took a couple of hours to complete, and cost me nothing at all (I nicked the blank CD from my wife's home office), yet the improvement to the listening experience was approaching what I'd expect from a component upgrade. As I said, it doesn't replace hardware parametric equalizers, but it sure gives a taste of what they can do for you. Why not give it a try?
