I think that we are talking past each other. I was referring to the midrange (I thought that is what you meant when you talked about reproducing human voices), while you are referring to high frequencies.
I believe that I have heard that the most important cause of the ragged response in the higher frequencies (7K hz) is break-up modes, although I have heard some, like yourself, attribute the ragged response to the interference between the whizzer and main cone (maybe both play a role). One way to verify this would be to remove the whizzer and then measure again. Paul Butterfield or Jon ver Halen would be good people to ask.
I think, though, that most who have heard Lowthers and complained about their "shout" are listening to the peakiness in the upper midrange, around 2000 hz. Dick Olsher showed that this problem can be readily remedied with a trap filter. By the way, the 15 ohm Lowthers don't have the Lowther shout (2khz peak). Once that is fixed, the raggedness (breakup modes) in the 7000 hz range are much less of an issue. But, I certainly would not challenge anyone who said that a RAAL tweeter would be better in this frequency range. Although, again, the EnABLe treatment really does improve the high frequencies of Lowther drivers (interestingly, waterfall plots do not show much, if any, improvement in the breakup modes, so what EnABLe does is still a mystery).
It really is pure joy to hear a well set up Lowther system with all the Lowther weaknesses addressed.
Retsel
Can I suggest that you try a pair of Graetz BV8070 field coil driver for comparison. Married to a suitable super tweeter i would say they would match a Lowther at a fraction of the price without the ragged top end response coming off the whizzer.
Thats the sort of ragged top end response you get from almost all the Lowthers and it clearly shows the comb effect I was talking about. That for me is why they are almost universally described as shoutey - that dip at 3k and a peak like that at 10K will stand out like a sore thumb.
Its literally a matter of simple physics that a whizzer speaker will always have that comb effect, it cannot be avoided when two resonating bodies are in such close proximity. The best that could happen is if the comb effect is somewhat canceled by fortuitous coincident break up modes that cancel them - but that will definitely sound muddy. The Lowther is going to be particularly bad because the whizzer is so damn big in relation to the main cone.
The only way to at least minimize such effects is to forgo the whizzer and add a phase plug.
If thats what you want to spend your hard earned money on then your welcome.
Shoog
An externally hosted image should be here but it was not working when we last tested it.
Thats the sort of ragged top end response you get from almost all the Lowthers and it clearly shows the comb effect I was talking about. That for me is why they are almost universally described as shoutey - that dip at 3k and a peak like that at 10K will stand out like a sore thumb.
Its literally a matter of simple physics that a whizzer speaker will always have that comb effect, it cannot be avoided when two resonating bodies are in such close proximity. The best that could happen is if the comb effect is somewhat canceled by fortuitous coincident break up modes that cancel them - but that will definitely sound muddy. The Lowther is going to be particularly bad because the whizzer is so damn big in relation to the main cone.
The only way to at least minimize such effects is to forgo the whizzer and add a phase plug.
If thats what you want to spend your hard earned money on then your welcome.
Shoog
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