Very interesting post John, Thanks a lot for your contribution.
Inspired by your own listing of the fq rep. as a list of numbers in another thread, I put the numbers into Excel, and added the Lambda and Sigma fq rep. as well.
I was curious to see how the corrected Lambda compared to the Sigma, as the latter was design to include DF to some degree.
To some degree the ED'ed Lambda seems to simulate a moderate Sigma's fq response ...
My experience from trying to compensate the Sigma's was implementing a voicing that utilizes a simple shelf filter + a parametric filter for boos'ting the low bass. Compensating the roll off above 1kHz with 15dB to get flat response didn't sound right ... I ended up compensating approx +6dB in that region ...I guess that puts my correction somewhat a bit lower than the ED'ed Lambdas.
The Sigma seems to have some significant drops around 1,5-2,5kHz, again at 5-6kHz, or a boost of the 3kHz area that the ED corection seems to simulate. Is that where the added spatial experince stem from?
Makes me wonder if some ing. at Stax have balanced the fq response of Sigma with the Lambdas, balancing the amount of spatial experince with the tonal experience ...Anyways, I guess the ED box'es does a bit more than just making an Eq
