Since the cat is out of the bag on the new v4 subwoofers, I figured it would be a good idea to start an official v4 subwoofer thread where we can discuss these new products all in one place. I'll give a quick overview of what's new/changed/updated and then open the thread up to your questions/concerns/comments/etc.
So, what has changed?
ALL of the amplifiers are new. Although the amplifiers themselves appeared a few months ago in the v3 models, the full performance improvements and changes in analogue EQ (EP125/175/350) and DSP programming (EP500/600/800) have only now been implemented in the v4 models. All amplifiers now feature heavy-duty, panel mounted gold-plated input and output RCA jacks. No more 1/4" phono adapter or having to mix connections when daisy-chaining subs. The non-DSP models now only have RCA and speaker-level inputs, while full RCA and balanced XLR input and outputs, along with stereo speaker-level inputs can be found on the DSP models.
ALL of the woofers have been newly designed with higher linear excursion, higher power handling, and lower distortion. Higher power handling was required in order to make full use of the capability of the new amplifiers.
The non-DSP models now feature signature Axiom trapezoidal cabinets, revised bracing, and revised tuning/alignments. The EP125 and EP175 have grown somewhat in size and feature far greater low frequency headroom with longer ports for lower tuning. All of these models also utilize a newly designed pre-amp/EQ/limiter module that incorporates an "analogue biquad", essentially an extremely flexible parametric filter block that allows these models to now be nearly as linear as their DSP controlled big brothers. I would go so far as to say that, except in a head to head blind listening test, you would be hard pressed to tell the difference between an EP175v3 and an EP125v4! The EP350 has actually been reduced in size, and now features a triple vortex porting arrangement. I should also note that all of the non-DSP models utilize a unique bracing system that braces both the cabinet walls and the now much-longer port tubes.
For the DSP models, the EP500 has now also taken on the signature Axiom trapezoid cabinet shape and the EP600 has been reduced in height, falling between the heights of the EP500v4 and the EP800. The EP800 remains the same size (i.e. BIG!) but features revised bracing and a new, dual-chamber configuration. You can think of it as essentially two independent subwoofers in one cabinet. Now, the biggest change to the EP500 and EP600, that many of you have already noticed, is that all of the DSP subwoofers are now sealed, acoustic suspension designs. I'm sure that there will be many questions asking why we decided to go in this direction. The simple answer is distortion. At some point, ports have a tendency to make some noise, particularly with subsonic movie effects. There is also the issue that the woofer in a ported system becomes essentially unloaded below the tuning frequency of the ports. In order to EQ a ported subwoofer to be linear down to the lowest frequencies, we are asking a lot of the woofer in terms of excursion. With higher excursions, no matter how large the Xmax of the woofer, distortion increases. Sealed subwoofers have the benefit that they are constantly loaded by the pressure inside the cabinet. The required filtering is also more elegant and we are able to drive the woofer right up to the limits of the amplifier power available. The end result of all this technical talk is that, even though the EP500v4 has a smaller footprint and is a sealed box, it is capable of the same maximum output as the ported EP500v3 with less distortion.
To close, this project comprises an enormous R&D effort that took the better part of a year. We are very pleased with the results and hope that those of you that choose to buy or upgrade will be impressed by the results!