So got around to testing the driver backwards pretty neat the magnet just funnels the sound 0-60 degrees are all fine and dandy then at 90 your -15db also that huge bump is definitely just the back of the drivers response being funneled down the magnet its acting like a waveguide. There is a peak out at 3.3khz that is some sort distortion much higher then anyway where else I'm guessing it's the gap between magnet and basket that I didn't fill with anything. Cardioid is much more interesting but that will have to wait a few weeks getting +3db at 250-400hz ?
Please post it if you have it available. I'm not about to spend $3.5K, but I'm curious to see what they offer for that price difference
If it is really good it might just justify the price. I have seen countless speakers thrown in the trash that were trash dumpster worthy, If it is really good, just buy it once.
Of course, the driver needs to be really good and not just expensive.
I still have and use drivers I bought around 1990. Also looking for a mate for a EV 15W my grandparents bought about 1965. The 1965 15W, T250 and T350 certainly are above many things you might buy today.
Goal for EQing is +-0,5dB, measured reliable on the same spot. Sensitivity is also different, so 2 complete different setups. Takes some time, and that's the reason why I still couldn't make it
even if you can match the SPL on axis to a tight window of +/- 0.2dB; for example, the polar response doesn’t follow.
What one needs is to match +/- 0.2dB over +/- 90 degrees.
And that’s a challenge I haven’t been able to overcome- to properly compare a poly cone to paper cone to aluminum cone to beryllium cone.
And that’s probably one big reason why they all sound slightly different.
What one needs is to match +/- 0.2dB over +/- 90 degrees.
And that’s a challenge I haven’t been able to overcome- to properly compare a poly cone to paper cone to aluminum cone to beryllium cone.
And that’s probably one big reason why they all sound slightly different.
Polar response from 2 3" mid domes, crossed at 2kHz ... will be pretty similar ;-)
Also my test room is extremely well dampened - no reflections from 3 walls and ceiling. It would be very hard to have better test conditions.
+-0,5dB is pretty far, of course I try to get better (and that normally works).
And in fact - the polar response is part of the driver. When comparing drivers (and not purely membrane materials) its ok to have it in the equation.
When I record the response of T25A and T25B it's very hard to tell any difference. But in real one next to each other I hear a difference. So even in my highly dampened room there seem to be some influence of off axis response. But I still prefer the T25B, no matter what's the reason ;-)
Also my test room is extremely well dampened - no reflections from 3 walls and ceiling. It would be very hard to have better test conditions.
+-0,5dB is pretty far, of course I try to get better (and that normally works).
And in fact - the polar response is part of the driver. When comparing drivers (and not purely membrane materials) its ok to have it in the equation.
When I record the response of T25A and T25B it's very hard to tell any difference. But in real one next to each other I hear a difference. So even in my highly dampened room there seem to be some influence of off axis response. But I still prefer the T25B, no matter what's the reason ;-)
What stimulus/signal do you use? And I sincerely hope you are not listening with your eyes because -t.b.h.- I doubt whether any differences could be determined at all unsighted in case a -say- 400-2500 Hz bandwith is used.
I'm also VERY skeptical that you can hear any difference between the M74A and M74B. But I could between M74A and M74S - but the S version is made for a smooth sound with a pretty thin membrane.
After all the B version has better sensitivity and smoother frequency response - so for a "lonly island" speaker I still would chose the B version.
After all the B version has better sensitivity and smoother frequency response - so for a "lonly island" speaker I still would chose the B version.
I'm planning on building very dynamic LCR speakers for my living room home theater and especially for a center speaker under the screen this dome seems to be a godsend as it allows a very compact low mid-tweeter combination that avoids directivity problems that many WTW center speaker designs suffer from.
The original plan was building MTM units with the Purifi PTT6.5M08 (already bought) and a still undecided tweeter but that would make the center speaker at least 60cm high.
The original plan was building MTM units with the Purifi PTT6.5M08 (already bought) and a still undecided tweeter but that would make the center speaker at least 60cm high.
You would need a 3rd way for the M142, they don't get to 80-100Hz. But it's a complete different animal as the Purify driver.
You can have a look after PHL drivers - they have very high efficiency drivers which behave very well. Maybe even an 8"? combined with a big tweeter like T34, probably even in a WG, these is probably the best choice between PA and HiFi.
You can have a look after PHL drivers - they have very high efficiency drivers which behave very well. Maybe even an 8"? combined with a big tweeter like T34, probably even in a WG, these is probably the best choice between PA and HiFi.