You need to contact Dave (Planet10). Like FHXL it is available in exchange for a donation to this forum.
+1 for the F4, I'm using one with a tube preamp to drive some not very sensitive 3 ways. Really nice sounding amp if you properly feed it.Rob7,
The F4 is not just another "more powerful amplifier"... it has zero voltage gain, making it different from most of the other amplifiers that are out there.In theory using the 45 tube amp as a preamp driving the F4 you should be able to preserve a lot of the 45 amp "sound", but gain more headroom.
To be honest, I don't think any MA driver is ideal with a 45 SET as-is since however those valves are implemented, the amplifier isn't going to be a power-house. The F4 suggestion could be an interesting direction & may make the most of it.
That said, 12P / 200M is an interesting question. Some comparative data is useful: 12P / 200M format:
Sd = 147.41 / 206 cm^2
Re = 7 / 6.8 ohms
η0 (percent) 0.943 / 0.567%
SPL 91.76 / 89.56 dB 1m/w
SPL 92.343 / 90.26 dB 1m/2.83v
Peak force 15.61 / 23.17 N
Max diaphragm acceleration 1527.77 / 1094.9 m/s^2
Motor strength ratio 8.122 / 10.74 N^2/W
Assuming a 2.5m listening distance & a 95dB peak / crest value, then
Nominal rating distance = 102.96dB peak
For -3dB headroom 98.98dB peak
Peak voltage requirement 10.27 / 13.24v
Peak watt requirement per channel 7.54 / 12.89w
For -3dB Voltage requirement 6.5 / 8.374v
Wattage requirement per channel 3.015 / 5.16w
So setting other factors aside: although the 12P is the smaller driver & in outright terms doesn't have as much dynamic range / headroom as the 200M (which is far from inefficient given its size & general characteristics), you'd probably need more power than a 45 SET can put out to actually benefit from them, and with what you have, the smaller unit with its greater conversion efficiency may end up being the better choice.
Should not be an issue provided your 45 does not put out any voltage spikes at power on or off or output DC voltage which is unlikely but can sometimes happen in tube amps with feedback taken from the output transformer secondary. If you want to use the 8 ohm tap you would connect an 8 ohm resistor across it and use the speaker terminals as input to your amplifier or preamp. 45 output voltage is so low that it’s more like a source component voltage wise. If you really want to be careful put a 100-1k ohm resistor between the + output of the 45 and the amplifier input. You could connect the 45 to any typical integrated amp that way. You could connect to a conventional high gain power amp using a low impedance volume control between the 45 and the power amp input. Lots of possibilities.
That is the extents document. To get the entire planset requires a donation. to diyAudio. email me your receipt.
dave
Sorry! Misunderstood your prior post. That’s what I get for skimming over your answer. Very intriguing. I’m definitely going to look into this Thanks!
Thanks for the detailed answer! Exactly what I was looking for. Likely go ahead with a Joan 12p. maybe see what else you come up with for the 200 down the road— something to try with my EL34 or future SS. meanwhile, my quest for a good DIY speaker for my 45s continues! Not to thread Jack, but a short mention of a diy driver and enclosure for a 45 would be appretiated. Thanks, Scott.
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Apologies, I missed this before. Depends on the corner of course
but yes, these Keele EBS alignments (when they aren't being used for subwoofers -slightly different scenario there) are optimal for use near at least a front boundary wall, and in this case a corner will work also. Power-handling isn't high, as you'd expect: that's the tradeoff. Makes an interesting alternative to the usual run though if you don't need high SPLs, and of course, it doesn't unload as such until (in relative terms) very low compared to most, so it does help keep excursion in check better than a bald graph might suggest: especially when you remember that (ignoring the unloading < Fb) the point of maximum excursion in a vented box is roughly an octave above tuning. In most boxes with an Fb around 40Hz or so, that puts it slap-bang in the middle of the main 'power band' for LF in rock, most contemporary material (if it isn't compressed to death), even a goodly bit of orchestral. So the low tuning, notwithstanding the other tradeoffs, can have some advantages there, even though excursion is higher than usual given the Vas-swampting Vb. YMMV as always of course. 
The japanese distributor's blog has a test report on the MA200M and new tweeter.
The MA200M has a wide range that is perfect, but with the addition of a tweeter, the sound quality will be even higher.
http://blog.fidelitatem-sound.jp/2024/09/03/ma200multitw6今冬発売！mjオーディオラボ出展決定/
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Typically you have to account for any shift in position on the Z-axis (relative to the reference plane) whatever filter order you're using. In some senses higher order filters are less sensitive to variation -in others they're arguably more so, since the higher the order, the more precise you typically need to be. That's why most of the time with passive filters we have some asymmetry in the slopes in order to line the phase up, or some kind of mechanical offset. You can also (although many don't want to go there) use a delay network. Digital active gives the opportunity of lining phase up with symmetrical circuits that way if its felt important.
Troels has spent the last few years promoting LR2, or at least 2nd order slopes, with physical offsets to the HF (& if relevant midrange) drivers, although he's backed off on some of the measurements, and, presumably, consistency of phase alignment since he first started down that road about a decade ago. He also did one, now discontinued, design with physcially offset HF driver, with the option of symmetric LR2 or symmetric LR4 slopes. I've never been convinced by the phase argument myself (within reason) -there's a boat-load of evidence from properly conducted trials by Toole & others that within very broad limits its inaudible with loudspeakers in ordinary rooms on ordinary music. The differences in the power-response, distortion behaviour etc. OTOH, are another matter.
Troels has spent the last few years promoting LR2, or at least 2nd order slopes, with physical offsets to the HF (& if relevant midrange) drivers, although he's backed off on some of the measurements, and, presumably, consistency of phase alignment since he first started down that road about a decade ago. He also did one, now discontinued, design with physcially offset HF driver, with the option of symmetric LR2 or symmetric LR4 slopes. I've never been convinced by the phase argument myself (within reason) -there's a boat-load of evidence from properly conducted trials by Toole & others that within very broad limits its inaudible with loudspeakers in ordinary rooms on ordinary music. The differences in the power-response, distortion behaviour etc. OTOH, are another matter.
No problem, and thanks for the answer! As a user of the Woden design Poplar (Alpair 10.3), which benefits from near-wall placement for bass enhancement, I find this type of designs quite tempting. The Poplar really opened my eyes to what a modest full-range driver can achieve. However, with the EBS alignment for the MA200 being quite large (around 170 liters), I assume it can't be adapted to a more flat, wall-mounted design like the Poplar, even with higher tuning?Apologies, I missed this before. Depends on the corner of course