Thanks for the comments, much appreciated. I’ll file that idea in the round filing cabinet in the corner of the room then.
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I agree that the PTT6.5 is one of the best midrange drivers, period. It may not be as sensitive as some, but it’s low distortion clarity is like magic up to 3kHz.
Because if the dome mid is anything like the mdm55 it'll be a step backwards in non linear performance Vs what the purifi can do.
I can understand the attraction of wanting to use the PTT as just a bass driver. But if you want to do this, and actually gain something from going to a three way, then the mid needs to be of stellar performance. Or you could go another route and use it with a coax, like the C18 from SEAS. You'll lose a little in terms of non linear performance but gain in terms of off axis performance.
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The dilemma, as I see it, is trading off a good directivity match vs. a good distortion match. I completely agree that there currently aren't midranges that can compete with the PTT6.5, but I'd rather not use the PTT6.5 up to 2k, much less 3k due to directivity mismatch. Also, few tweeters are comparably distortion free at 3k and below. Even the Bliesma T34 would have trouble matching it, in my opinion. The large ESS probably would, but it has frequency response issues. The SS 9900 appears to and seems a good option.
This is why I'm very anxious to see what the PTT4.0 can do. Have we heard anything about its projected cost?
This is why I'm very anxious to see what the PTT4.0 can do. Have we heard anything about its projected cost?
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A bit off topic, but the frequency response issues of ESS AMT can be fixed with EQ. I also heard that by covering part of the front magnets, response can be improved. On the Klipsch forum are people that use two stacked AMTs with waveguides. Reports are that 600 Hz crossover is possible and at high SPL this way, but EQ is required.
Fedde
Fedde
I paired the PTT6.5 with an RS28F dome in waveguide and crossed at 3.5kHz. The polars looks very nice and the distortion is very low.
Distortion at about 80dB 1m:
Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
Distortion at about 80dB 1m:
Simple Passive Harsch XO Using PTT6.5 and RS28F in a Waveguide
I agree with you, but like xrk post I too don’t see a massive directivity mismatch at least on the horizontals with my setup. But I’m yet to see verticals which I suspect are a mess and making the ceiling reflections a problem.
I’m very keen to see what the 4 can do, if the technology from the 6.5 translates to the 4 it should be one of the best mids in the world. I have the ATC mids here to compare.
Well verticals always tend to be a bit of a mess with most non coincident designs. Still, horizontally, you can have fantastic results using a 6.5" driver if you partner it with a waveguide like xrk has. I would expect a better directivity match by lowering the xover to 2-2.5kHz and then improving the vertical off axis too.
Still it highlights the true power of a waveguide design.
Still it highlights the true power of a waveguide design.
I’ve got a set of VM752’s on the way to compare with too. I have a feeling they have their work cut out for them when going up against the PTT6.5.
My last design was the Dayton ES180 matched to the RS28F in the SEOS waveguide. It was a superb 2-way, if I do say so myself. So I know what a waveguide can do. The RS28F was a very good tweeter, but I'm hoping for something even better with the Purifi. If I could somehow put the Bleisma T25B in a waveguide either with its grill still on or with some sort of grill incorporated into the waveguide and a crossover somewhere around 2k to 2.5k, I'd be quite happy. A tweeter without a grill is a nonstarter for me.
Regarding the ESS, yes, it can be EQed into shape, but I only want digital processing on my subwoofers, if possible.
I really look forward to the midrange comparisons.
Regarding the ESS, yes, it can be EQed into shape, but I only want digital processing on my subwoofers, if possible.
I really look forward to the midrange comparisons.
Too bad about the grille limitation. I've been thinking that stealing Jeff B's Helios idea and pairing the PTT6.5 with the Satori BE WG tweeter is pretty much as easy as 'world class speaker' is likely to get. Maybe augment below 50Hz if you're in a big room, but otherwise hard to see how much improvement is possible over that pairing.