A mono Speaker is not able to play a stereo source. Of course you can sum to Mono if Amp allows. This is not the same as a true mono sound but at least you won’t have big chunks of music missing from the performance.
Oh, I dunno….
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I like them all, but my favourite design would be like the second one, but using the corner of the room as the mouth of the horn. With a back loaded horn full range driver system you need corner loading, so make it part of the design.
The big fun horn is 4 feet high and 3 deep; I think my ideal would be much higher and less deep. It would disappear in room, I’m sure…
There’s a new helmet in town…
Armed with the new and improved Helmet hopes were high the Shouty could be tamed and bass much improved. After a little faff with screws, new rubber gaskets etc - here’s a clip of the new helment on the TP1 NOT IN CORNER
https://youtube.com/shorts/ZUImMlhopeE?si=OptbBPax8127UrzD
OK the shouty is improved but bass is thin, body is anorexic.
Tearing appart the floor to ceiling bass trap and shifting a 60 off Kg Westrex to get to the corner was enough for a man to need a nap - But Bass must be found or conniption may tear the world in two.
https://youtube.com/shorts/h0MRgMqddCg?si=iPrMfnBQhILuYvBE
OK, fuller sound, more bass and a shit load of damp on the wall revealed - Bingo!
No sure why links no worky ?
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Nope, me neither 
Did the damp hit the back of the westrex cab
No, there was half a foot of rockwool in that corner
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Lol-ther update.
Having torn out the floor-to-ceiling sound treatment, the TP1 & AER finally managed to get into the corner. The bass immediately filled out far more than I thought possible. The shouting stopped due to the improved helmet and corner position. These were large leaps in the right direction, but what then became apparent was an overall strange presentation: the sound (fairly well formed) didn’t seem to flow into the room — it felt very close to the speaker.
After much communication with Lowther horn folk, one guy asked what material I was using between the rectangular chamber exit and the throat of the LF horn mouth…? Up-thread you’ll note the original Lowther PM3 metal chamber has what I assumed was a bug screen over the chamber exit. Surely this little slice of linen couldn’t help reject some of the HF going down the LF labyrinth? More unscrewing, faffing, and replacement later, the screen was installed — again this brought an improvement in sound.
Performing all this in mono, I’m able to use my Westrex speaker on the right as a reference and A/B the sound (L&R pots on the AMP help). Stu came over this week as I was in need of some 500,000-year-old ears. His feeling was the same as mine: the sound still misses some body, and somehow it isn’t flowing outward as it might.
More faffing, this time with a very little amount of teased-out wool to see if there was still too much HF/mid going internally rather than coming out the front flare as it should.
Results were disappointing. The more I listen, the more there’s a kind of a sucked inwardness /echo happening.
List of hateful reasons:
- Corner placement next to record shelves / radiator makes first reflections annoying
- The helmet may be slightly too large???
- The cob wall the speaker backs onto is not a tight enough fit (loss)
- The AER driver is simply just not suited to the labyrinth of the TP1
- The downward-firing driver into the semi-scoop-type front flare is weirdly wrong
Using great cunning and intelligence I have also changed valves recently, so I thought I’d swap back to the WEs to see what effect this might have?. The rectifier performed a firework display and the fuse blew. I think I put one of the 300Bs in round the wrong way…?
In summary:
I have pulled apart the room, damaged the sound-damping floor-to-ceiling frames, revealed a damp patch on the corner wall, slightly nicked the foam on one of the BD5 drivers, torn the material off the PM3 helmets, and blown up my amp.
Your thoughts, gentlemen, please.
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Gone too far to turn back. 
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I know it’s against your rules - Plug in a mini dsp and adjust the FR curve on the fly - muting when needed.
Oh can you get a 3d model of the large horn? maybe a 3d print is feasable long term project?
Excellent vintage hifi fuckery!
Getting it actually working is a great step. The next steps, though, are much harder.
I would strongly advise to get measuring. I find that a lot of complicated hifi feelings, like expansiveness, shoutiness, inwardness and fullness are actually just frequency range issues. This is the first thing to understand. Indeed you can try in the short term using a graphic/parametric equaliser to see if it is indeed part of the issue.
Once you have identified the gross eq issues then you can work towards solutions. The size of the helmet will only affect the range around 100Hz, within an octave. Stuffing it will reduce the effective volume, which is easier than creating a dozen in a range of sizes!
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The Grand Pooh-bar of the moors is coming next week to measurebate. I’m not sure how easy that will be, due to the TP1 being a corner, downward-firing LF affair, but I’m hoping it will at least show a little of what’s going on. From there, potentially, we can start looking intelligently at the why scenarios.
I’m currently limited (insert completely) by my experiences with the BD5 drivers, which I have heard in the Pnoe horns many times — they can be ridiculously good. In their current placement they are not even coming up to the Westrex in terms of sound, so there is something most fishy and foul in Devon today.
One of the great things I love about these speakers is no crossover, the downside being less oportunity to signal meddle
Honestly I’ve never liked the idea of bouncing the mid and high frequencies around. Apart from bass, where there’s no real alternative, I think that horns should be straight. I don’t like the TP1, I didn’t like the Lowther Voigt when they were at a show, and there are very few times I’ve genuinely liked a system with a non straight horn.
Personally if I wanted to make those drivers work, I would fire then straight at the listener, with a huge back loaded horn into a corner. My favourite design for this is similar to what Pete talked about a while back - just a large square horn mouth pointing downwards, lifted about a foot off the floor or whatever height is suitable to give the right aperture. From the driver you’d have to go up then down to get the length.
Build it using a 3d printed interface at the driver, that has the compression chamber and square exit, and wood from there. Easy DIY job; hard to make it look great, of course!
AER make the Aerofon which looks like this
I’m being offered a loan of some of these (AER Excenter)
They are massive which poses some real world fit the bastards in the room probablms but as open baffle the larger issue is they only go down to 100Hz which of course means the purchase of x2 suitable subs. I’m semi prepared to entertain this fresh batshittedness.
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Why do they make them all so ugly?
I don’t understand why the white ones vent the horn to the front. Use the corner!
The black ones are just open baffle, I think? When I made the Lampizator P17s, I used Eminence 15a bass drivers (about £50 each then) with an open back box about 50cm deep. There was plenty of bass, and it was fast. There’s a lot to be said for nailing drivers to a plank.
There’s a guy called Jim Carfrae who lives in Totnes. About 20 years ago he was making an elegant looking version of the Big Fun horns. They sounded pretty good. Tall though, 7ft?
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Yes I went and met him quite a few years back - His solution was to have a bass driver in the back side of his standards and a stand alone sub for the big one. Nice guy but also the man behind some rather challenging footwear.
I’m not interested in your speaker because you have the wrong shoes. 
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Reminds me of my first business trip to the US when I was in my mid 20s - the guy who picked me at the airport said ‘You’ll never sell a thing over here in those shoes…’!