As mentioned in another post, I have started working with the ZOB, using BSC and treble enhancement. It is important that I clarify by saying the BSC and treble enhancement is being accomplished at the pre-amp signal level, allowing much less negative effect from this process than when using added components at the speaker/power amp level. It is also important that I say that I am doing this to help compensate for recent hearing loss. Treble has become less in my left ear, and has started to affect some of the ambient effect of stereo reproduction. Lastly, I find it important to give credit here to the inventor/developer of this circuit, who is Paul Joppa of Bottlehead Audio.  Simply moving this circuit to the pre-amp stage was, in itself one of the strongest reasons that I chose it to build it. The circuit only performs it's function by attenuating the midrange band of frequencies, and does not employ any amplification of it's own. Because the midrange has carefully lowered, the bass or treble(depending on which switches you have engaged) appears to be increased by comparison. Of course, there should be an adjustment of the overall volume to compensate for the attenuation in the first place. Whew! A little wordy for me, and there is more to say, but this short explanation  might give you the idea of what's happening. NOW, having said all of that, I will quickly state that I intend to build this circuit into one of my future projects. I intend to incorporate it into a pre-amp project. What I am hearing is exactly what I was looking for. Before I forget, there are 4 switches that allow you to choose the turnover frequency and control the cut as well. Because of this, I am able to play more music without the need for any sub woofer. That is not to sat the bass is now a thumping machine, but that it has been filled out to a greater degree without bloat. The treble adjustment is really what I was needing most, and I chose the 5K turnover frequency and 4db selection for this. Even though I have lost a bit of hearing, around 4k can be an annoying range for me. The filter starts it's cut just BELOW 4K(I am correcting this to avoid confusion), giving the effect that I desire for less splat at that frequency. Now let it be said that have NO reservations about the FRX2  and never had. I feel that it reproduces so much of what I was looking for many years. I love the reproduction that it has, and only wish that I were younger when I bought it. More on these experiments as time goes by.

It's a little premature, but since my 34I.3 came in today, I have an update. Right up front, I will tell you that the new amp with the ZOB does not need any help in the treble, so the circuit that I was intending on using which incorporated a treble enhancement, will most likely be tried with just BSC for the bass. Also, since this amp has dual mono controls, I don't feel that there is any more tweeking for the room response as far as the right channel being a little more absorbent than the left. It is apparent that with this combination that the Carver C9 upgraded unit that I occaisionally used on some recordings will be in circuit. More to follow.

As expected, some things change as experiments continue. Let me start with a concept that I learned in photography. Simply stated, 'do as much in the field for the photo as you can, and then the darkroom'. To transfer this thinking to audio, it might read  'do as much acoustically as you can, and then the electronics'. Following this trail, I removed the BSC circuit from the speakers, and instead, employed an acoustic measure. Pretty simple really. Take a memory foam pillow, and cut it in half long ways. cut the remaining half into two pieces, leaving a shape that will have a hump rolling off one side. I will add photos later that will make this much more clear. Remember, the pillow usually has a neck support shape to it, and it's this shape we are using to create the rounded hump. Ok, so going on, each one of these pieces will fit on the 'shelf' of the ZOB in the rear, close to the driver, but not blocking the slot. The idea here that a wave guide for the bass is being created to increase the amount of 'blow' across the throat of the slot. Secondly, it will attenuate those frequencies above 300hz(I am guessing here). The effect is reduction in midrange, and some air. Most of my CD's have a harder edge in the midrange due to the fact that this system has much more resolution now with the 34I.3.. Yes, I know, the FRX2 has a switch that helps compensate for this, but this approach is somewhere in between the switch position being selected for a more closed sound or open sound. And there is a definite bass increase. Keep in mind that this all revolves around my little world and ears/room/preferences. But folks, if you are going for the status quo, that's your business. I have particular goals in mind, for my system...shouldn't we all?