House curve: some advice on its use or non-use

[tnargs]

I have about 8 years’ experience in equalisation of my home audio system, having owned and used both the current version and an earlier incarnation of Behringer’s digital equaliser, which has built-in pink noise RTA tools.

In my efforts to identify an appropriate target EQ curve for the in-room response to pink noise, I came across the X curve standard in pro audio, and have had discussions with local AES members, who have expertise in home audio, cinema and venue audio, and one fortunate member with crossover experience in both fields.

More recently I have had a look at the excellent efforts of this forum’s members to come to grips with the same question of the choice of target curve for use with REW. I particularly appreciated the efforts of Wayne A. Pflughaupt with the sticky note “House curve: What it is, why you need it, how to do it!”.

However, this is a topic that is rife with misunderstanding, because it is difficult to conceptualise (for me, at least, and I presume also for others like me), and some misunderstandings have crept into Wayne’s writings. I would not concern forum readers and fellow enthusiasts with a few minor points of correction, but if a misunderstanding leads to the wrong recommended course of action, i.e. the wrong choice of target curve, then I must speak my mind.

My experience in equalising to flat at the listening position with pink noise was exactly like Wayne’s early experience: searing treble and AWOL bass. Applying the X curve, or half or three quarters of the X curve, as a target brought things back to the realm of listenable, although more than half of X invariably meant loss of sparkle in the highest treble.

However, my bottom line is that the amount of HF cut you need will vary from recording to recording, and some correctly made recordings will produce correct sound in your room (and mine) with no treble attenuation – irrespective of the size of our respective rooms. I could not make that claim if Wayne’s statement were true, that “speakers sound brighter the closer you get to them. Therefore we must compensate with a tilted response curve that reduces the highs and emphasizes the lows” in the fifth paragraph under the heading “It’s all about the room”. I also cannot leave be the stated notion that the house curve is one where the listener hears all notes or tones at the same loudness, as stated by Wayne in his third paragraph under the heading “An easy way to determine the house curve you need”.

Rather than argue points, let me explain by way of an example.

Let us say an orchestra (or solo piano) is playing in a world class venue, and the recording mic is placed in the best seat in the house, say centre stage, 20 rows back. No EQ or compression is applied to the recording. When we play this back in our homes, what is the ideal target curve? It is flat, not X. Flat EQ will reproduce the same bass-to-treble balance in the listening seat as in the seat where the mic was placed. Playing the above recording through an X curved system will sound far too dead due to the attenuated treble. Our homes are not big enough to require an X curve on the basis of room size.

There are other reasons for the bass-shy sound in our homes with flat EQ. One is that the recording mic is usually very close to the instrument, which provides a completely different tonal balance to a mic in the audience seat. Another reason is the generic use of multibanded compression as part of the production process. I have heard side-by-side master edits of acoustic music with and without compression, and it isn’t the bass that gets boosted as a result of compression!

My conclusions? Yes, most recordings sound too sharp with flat EQ’d pink noise at the listener’s seat. No, it is not due to the X curve effect. Yes, applying the X curve helps with many (most) recordings, but only fortuitously and not with any accuracy; for example, the knee need not be at 2kHz and the slope need not be 3db/octave. After all, the sound errors are not being caused by the effect that the X curve correctly compensates. So feel free to experiment more freely with target curves, and recognise that different recordings need different EQ. So many recordings are badly done that a fixation on “one right setting” is only a means to bring suffering upon oneself.


Arg