JA Perspectives VS Tyler Acoustics Linbrook Sig System

I wouldn’t downplay the significance of the proprietary JA Infinite Slope crossover.  To my ears it gives the speakers a special sound that sets them apart, so I’d buy used Perspectives but that’s me.  The JA Profiles would also be high on my radar if buying new. 

I’d actually guess — and it’s just a guess — that the new LSA-20 (from Underwood Hifi) may sound more like the Perspectives than the Tylers as they seem to be doing some similar variable-slope type things with the crossover.  Since they’re sold direct they’ll be very price competitive as well.  Hope this helps, and best of luck. 

I have to say that looking at the latest measurements from the JA perspectives I am not sure if JA is applying his trademarked crossovers here. The measured impedance and slopes seem rather conventional.

This paragraph from Stereophile is curious:

Speakers from Joseph Audio's early days used crossovers featuring Richard Modaferri's patented Infinite Slope topology, in which a modest network (in terms of number of components used) produces high- and low-pass filter slopes in excess of 100dB/octave. The Perspective and the Pulsar, however, use what Jeff Joseph calls an Asymmetrical Infinite Slope Crossover set at 2kHz, which attenuates the woofers by about 41dB.

This does not of course negate the quality of the sound, or the value of the finished product.  I'd just be cautious about ascribing the end result to the Infinite Slope crossovers.

The Perspective’s crossover still operates on the basic principles of the patented Infinite Slope design — common to all JA speakers — with tweaks to the slopes for more optimized performance (this is paraphrased from what Jeff Joseph told me in person).  The crossover remains the key to the JA sound as the cabinets and drivers, while very good, aren’t anything unique or special.