[1] Are there any sound engineers, or people with experience EQing pianos and have a good EQ chart with measurements that I could use as a rough guide?
[2] I tried first tuning the piano to the Harman Target Curve, but I don't think that is precisely best.
[3] I like a really bright, non-warm sound, but the keys in the bass clef need to have weight and impact otherwise the 'soul' of the piece is a bit lost.
1. I'm a sound engineer and I have experience EQ'ing pianos. Unfortunately, there's no simple answer to achieve what you're after. I've never seen or heard of a piano "EQ chart with measurements" and even if there were such a thing it wouldn't be "good", because there's two linked problems/variables here that make such a thing impossible: The sound you have to start with and the sound you want to end up with. The sound you want to end up with is a personal subjective preference and obviously there are no charts for your personal preference, although it's certainly possible that such a chart could provide "a rough guide". However, the only thing such a chart could tell you is the final output frequency response you should aim for, not what EQ you would need to apply to achieve that response, because the EQ you would need to apply depends on the sound you have to start with. Let's take an over simplified situation for illustrative purposes:
Let's say we could quantify your personal piano sound preference as a simple, single band EQ boost of +3dB at 3kHz. So, if you have a piano sound, what EQ do you need to apply to achieve your preference? It's tempting to say the obvious, +3db at 3kHz, but that most likely would be incorrect because it depends on the piano sound you have to start with. For example, if the piano sound you had to start with was already a bit low (say by 3dB) at 3kHz, then you'd need to set your EQ to +6dB at 3kHz to achieve your preference but if if it were say +5dB at 3kHz to start with, then you'd need to set your EQ to -2dB at 3kHz. So, we have two very different EQ settings to achieve exactly the same final result! Bare in mind that what we have "to start with" is ALWAYS a variable, different pianos have different frequency responses and even the same piano will have a different frequency response depending of course on how it's played but also depending on how it's been recorded (which/how many mics were used and exactly where they were positioned). This is for a real piano rather than a digital one but the principle is the same because the digital piano is based on "samples", recorded real pianos.
So, a useful EQ chart would need to know the frequency response of your personal preference AND the frequency response of the piano recording (or piano preset) AND in the case of a digital piano, the frequency response of the piano's speakers (in your listening environment). Such a chart is pretty much impossible unless you make it yourself.
2. How did you tune the piano to the Harmon target curve? To achieve the target curve you again run into the problem above, you would have to measure the response of the piano's speakers (at your listening position) to start with and only then could you apply the correct EQ to achieve the curve. So to start with you'd need an appropriate test signal (say pink noise or a sine sweep) and a measurement mic + analysis software.
3. The difficulty here is that a "non-warm sound" implies less high bass freqs but "weight" implies more high bass freqs. I can make some suggestions on what to try but without knowing exactly what you have to start with or exactly what you're after, I would have to guess and therefore, my suggestions would only have a small chance of success.
G
