Bob, Yes, I don't need a filter- the electronics are flat to 2 Hz from the phono input and the speakers begin to roll at about 23 Hz and are 3 db down at 20Hz.
Anytime you have a cutoff frequency, such as one introduced by a filter, phase anomalies will be seen in the signal usually to about 10X or 1/10th the f3, depending on what type of filter, high or low pass. This is how a filter can make itself audible, even when it is operating out-of band.
In fact, this is why you want your electronics to go down to at least 2 Hz, so that there will be no artifact at 20Hz. The old MFA Magus had an error in the RIAA curve (I know, the RIAA does not spec that high) that made the preamp go from -6db per octave to flat at 50KHz. It manifested as a brightness in the phono. Once fixed, the phono got very relaxed.
I've used pink noise systems to analyze the room. I have a peak at 26 Hz that some speakers exacerbate, and I have found that certain designs minimize that node. My current speakers have one woofer down-firing, and are pretty successful at that.
Anytime you have a cutoff frequency, such as one introduced by a filter, phase anomalies will be seen in the signal usually to about 10X or 1/10th the f3, depending on what type of filter, high or low pass. This is how a filter can make itself audible, even when it is operating out-of band.
In fact, this is why you want your electronics to go down to at least 2 Hz, so that there will be no artifact at 20Hz. The old MFA Magus had an error in the RIAA curve (I know, the RIAA does not spec that high) that made the preamp go from -6db per octave to flat at 50KHz. It manifested as a brightness in the phono. Once fixed, the phono got very relaxed.
I've used pink noise systems to analyze the room. I have a peak at 26 Hz that some speakers exacerbate, and I have found that certain designs minimize that node. My current speakers have one woofer down-firing, and are pretty successful at that.