How best to use a Lowther A45? for a mono speaker

I'm looking for advice on a mono speaker design for a small room.

A couple of years ago I had an idea of building a big Tractrix front loaded horn (FLH) and large mid-bass horn to go with - for a single mono speaker, i.e. a large 2-way (at the time inspired by Tune Audio). The mids driver used by Tune Audio is a modified Fostex 126 but I decided for some reason now lost in the mist of time to buy a Lowther A45 driver. I didn't proceed very far with this idea once I realized that I don't have a large enough room for such a beast and that the work effort involved was just too much for me to take on when I have other demands on my time. So I have this Lowther A45 just sitting around and I'm not sure what is the best way to put it to use. I'm interested in some suggestions from the forum members ?

To keep this simple I'm OK accepting some compromises in terms of the performance in order to limit the size and complexity so that I can build something without it taking months of effort. I'd also like to be able to deploy the speaker in a smaller room where it can provide a more intimate listening experience, partnered up with a tube amplifier.

1/ The driver is not really suitable for baffle mounted use due to the rising treble response (see attached datasheet). So, right off the bat I expect I'll need to address that limitation. One option is to shape the frequency response of the driving signal, either a filter network at the driver, or at line-level. The other option is to shape it physically by employing a small front horn, something designed to help flatten the frequency response rather than provide directional control - I'd actually like wide dispersion if possible.

2/ The driver is not really suitable for generating bass, it's got limited cone area and limited x-max. I guess it's good down to 200Hz to 300Hz at moderate listening levels suitable for a small room. Other than accepting limited low frequency output the only option would be to add a supporting woofer.

So with my limited experience I have been thinking about
a) Open Baffle with small front-horn on the Lowther and with the woofer needing real power it would have to be a bi-amp set-up,
b) A modest compound horn, i.e. a back loaded horn (e.g. Lowther Alerion for which I do have the plans) perhaps with a small front-horn on the Lowther. A separate sub is possible. What about a double mouthed horn - worth the extra wood ?

So as you can see, I've given this some thought already but I've so little experience of these things.

Your thoughts ?


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Bigun, you will never get any serious bass out of that midtweeter, no matter the enclosure. Even jlow, kleinhorn or jericho horn, no real bass. Not to mention complicated construction.
If you accept this fact, and go for simple 2way, woofer plus extended range, crossed at say 150Hz, all can be pretty simple. Lowther in small closed bookshelf box, woofer whatever you stomach.
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