Everything I've read from others about modeling amps with built in boost like that is to use the peaking 2nd order high pass, or use SOS highpass with user specified Fc and Q.... because the boost is created by using a high Q high pass filter (which is different than PEQ). Your PEQ curves look better below the boost frequency than the peaking 2nd order high pass curves because with PEQ you are not adding in the high pass filter. For the boost models, the Fc of the high pass seems to be around 30Hz, based on reports from users who have traced out the preamp board resistors and calculated the filter based on those values.
Note, in the graphs with +6dB boost, you need to cut the input power to 75W if modeling the 300w amp (ie. divide by 4) to get an idea of the true excursion and SPL with boost (as pointed out in the WinISD link). The SPL at the boost frequency (30Hz) hould be the same as the SPL at that frequency for the the non-boost with a full 300W input power. The 125W input is for modeling a 500W amp with 6dB boost.
Also note, as I already mentioned, the Yung amps don't appear to have a full 6dB of boost... actually don't even appear to have half that much.
And final note - the non-boost models still have a high pass filter, which you are omitting in your WinISD models. Yes non-boost looks smoother, but that's because the high pass is missing. According to a Parts Express rep, the filter roll-off begins at 30Hz, and is -3dB at 21Hz. So it seems the high pass for the non-boost models
could be modeled as a SOS high pass with Fc=21Hz and Q=0.707 (a Q of 0.707 means no boost at the filter's corner frequency).
There is more info about these amps here:
There still seems to be some confusion surrounding where the filter actually is on the non-boost models, and what the boost/frequency actually is on the boost models... but some members have taken the time to trace out the resistors in the preamp board to figured this information out for the boost models (and it's in those threads)... and the best info we have on the non-boost versions is from the PE rep.Edited by alphaiii - 12/4/12 at 11:00am