The XT is a variation of the original Mockington-TN. This is for the benefit of builders that already have the Peerless XT25TG30-04 tweeter. For those that do not have this tweeter, I suggest building the Mockingbird-TN.
Mockingbird-XT Frequency Response
Fig 1 – Mockingbird-XT Frequency Response
Disregard the deep notch at 150Hz. It’s caused by a “floor bounce”
In replacing the HiVi TN28 with the XT25TG30-04, I paid particular attention in retaining the sonic signature of the FW168. Both versions sound exactly the same up to 4kHz. The difference is in the treble. The two tweeters sound good in the higher region. There are no harshness. HiVi TN28 produces a smoother response because it suffers less baffle edge diffraction than the XT25TG30.
Fig 2 – Mockingbird-XT Frequency Response with the XT25TG30 tweeter wired in Reversed Phase.