I'm playing DIY active crossover with a pair of PMC DB1+'s. (These are foot tall bookshelf sized speakers).
A quick estimate based on a few measurements of relative voice coil positions suggests that the in phase lobe at crossover points down at an angle of 8.5 degrees.
Since my listening position is slightly higher than the speakers, the solution is to turn the speakers upside down so that the tweeter is at the bottom and the in phase lobe then points up towards my head!
So, this has me wondering why speakers are almost universally made the wrong way up, with the tweeter at the top?
Discuss...
A quick estimate based on a few measurements of relative voice coil positions suggests that the in phase lobe at crossover points down at an angle of 8.5 degrees.
Since my listening position is slightly higher than the speakers, the solution is to turn the speakers upside down so that the tweeter is at the bottom and the in phase lobe then points up towards my head!
So, this has me wondering why speakers are almost universally made the wrong way up, with the tweeter at the top?
Discuss...
You can change the main acoustical lobe by modifying the crossover slopes, e.g. by using asymmetrical slopes.
But yeah, with symmetrical slopes, the main lobe are tilted downward with the typical cone (woofer) + dome (tweeter) combination, if tthe tweeter is on the top, the baffle is flat and no additional time alignment (e.g. DSP) are applied.
Why so many commercial manufacturer create speakers like this? Because it's cheap and simple to produce and they think it's good enough. But there may be other reasons.
But yeah, with symmetrical slopes, the main lobe are tilted downward with the typical cone (woofer) + dome (tweeter) combination, if tthe tweeter is on the top, the baffle is flat and no additional time alignment (e.g. DSP) are applied.
Why so many commercial manufacturer create speakers like this? Because it's cheap and simple to produce and they think it's good enough. But there may be other reasons.
The only thing that comes out of a product is the designer's balance of priorities/compromises vs. economics. Ask 10 designers, get 13 opinions.
For "normal" (ie not synergy or plasma or panels or ???) 2-way stuff, I like Wayne Parham's basic approach that you treat the forward lobe right (what you're actually saying, too, I believe) and aim the nulls at the floor-bounce and the ceiling reflection where you can. The rest is fighting the rooms or just swallowing it or brute-forcing with processing and sources...depending on your own balance of priorities/compromises vs. economics...
For "normal" (ie not synergy or plasma or panels or ???) 2-way stuff, I like Wayne Parham's basic approach that you treat the forward lobe right (what you're actually saying, too, I believe) and aim the nulls at the floor-bounce and the ceiling reflection where you can. The rest is fighting the rooms or just swallowing it or brute-forcing with processing and sources...depending on your own balance of priorities/compromises vs. economics...
Might want to try tilting the speakers back if there's room.........
Otherwise....... in the beginning, cinema sound 'drove' [multi-way] speaker system development and the tweeter horns were placed such that the dialog appeared to emanate from the screen's facial images [2/3 screen height] with the lower frequencies below it since these are less easy to be localized with decreasing frequency, hence the TMW of most multi-way systems and the others have already ~ filled in the rest of this 'puzzle'.
Otherwise....... in the beginning, cinema sound 'drove' [multi-way] speaker system development and the tweeter horns were placed such that the dialog appeared to emanate from the screen's facial images [2/3 screen height] with the lower frequencies below it since these are less easy to be localized with decreasing frequency, hence the TMW of most multi-way systems and the others have already ~ filled in the rest of this 'puzzle'.
You're quite right that the lobe of most commercial 2-way speakers is angled downwards, which isn't ideal, but there are other problems other than lobes.
Positioning the treble unit below the bass unit has two other acoustic problems:
1. The treble unit is no longer radiating into free space over the top of the baffle, which tends to reduce the power level of HF in the room.
2. The treble unit is radiating a proportion of its output upwards into the bass cone and downwards into the carpet.
Of course, 2) is also occurring with the treble unit at the top, but I have found that the ear is relatively sensitive to having a flat baffle area above the treble unit compared to being aware of the diffraction effects due to the bass driver surround and cone. In reality, the acoustic effects are a combination of 1) and 2).
Generally, you can compensate for these aspects by adjusting the crossover slightly. I have found that having the treble unit below the bass unit requires a higher level of power fed to the treble, for example.