Are you sure or is this a knee jerk reaction?
As Purifi have already done a midrange version of their 6.5" unit I anticipate a 4" midrange coming along in the next 12 months. Still won't be a dome mind...
ATC's maximum SPL seems to be 7 to 12dB higher, but how about distortion at very high level?
http://nedlab.com/wp/wp-content/uploads/2014/06/ATC-SM75-150.pdf
http://nedlab.com/wp/wp-content/uploads/2014/06/ATC-SM75-150.pdf
I fully realize I am on very shaky ground here, but my hunch is the dome will fall apart at lower signal levels because of its intrinsically floppy structure. That being said in general, the very low sensitivity of the Purify may spoil its performance somewhat at higher (94dB<) signal levels, so the ATC may outperform the Purify 4" @ say 96 dB/m or so.
Has Compass measured the ATC dome yet?
Has Compass measured the ATC dome yet?
Let me be clear I do think the ATC SM75-150 in normal and SL guise is an amazing midrange. Doing duty in studios all around the world where scary headroom is needed for dealing with raw mic feeds. If building a 3-way I'd probably not be able to stop myself chosing that (or realistically the volt as you can't buy the ATC) but I know I don't need a midrange with anywhere near that headroom. For anything up to THX ultra requirements I think the Purifi, despite its ineffeciency might do the job. It's a fair question to discuss anyway (IMO)
I feel instead of just comparing the sensitivities its better to compare the sonic differences and what yet it takes to make a better driver than ATC is the thread all about.
Firstly Is it possible secondly there are volts and scanspeak domes but volt being on higher magnetic force and scanspeak being with simpler and higher qts version. Now looking towards atc they have dual suspension. It looks good on the concept that it reduced the rocking modes but I suspect strongly that it will not have as much transparent sound if its single suspension. Any more stiffness will addup the resistance to free movement. Then the whole point of looking towards dome in mid doesnt make sense I would rather prefer a small cone with suspension than just going with dome. Now what can be made better in the dome midrange is something would love to listen.
I was lucky enough to have a pair of Volt 3in mids to play with for a while. I feel that they are trying to solve a problem with brute force and in doing so, are way too big, heavy and expensive. I am not so sure there is much to be gained vs using a well behaved pro audio midrange that will get you 400Hz to 4kHz coverage just as well, for 1/7th the cost and 1/10th the weight. I personally could not justify using it as the magnet diameter was so big it prevents the tweeter from being mounted closer.
What are sonic differences and by what metric are they expressed? I do not think "sonics " is a fundamental design parameter of a transducer: we can optimize diaphragm behaviour, we can improve its suspension, the motor in order to decrease IMD end THD, etc. but the sonics? Would you care to tell me how you do that and what desgin parameter you target?
@audiothings and I designed a soffit-mounted studio monitor using the Volt midrange. Yes, it was a challenge getting the tweeter mounted close. The magnet is about as large as what is typically used on a 12" woofer. The Volt has to be rear mounted, which for us meant a removable mid-tweeter sub-baffle that is recessed into the main baffle.
@audiothings reports that the finished product is in service and the studio owner / client is very happy with the result. I wish I could give them a listen, but Mumbai is 13,000 km from me, so it is not happening anytime soon
j.
sound which comes with material science as different materials will be different damping behavior and natural timber that is usually not be able to measure with the IMD and FFT tools. The structural engineering can be done in any FEA design software with optimized results but the whole concept of the dome shape itself and voice coil former types. Many things to consider if you ask me.
Now in the earlier posts there were some measurements done on the frequency response of the atc dome mid in which you can see a considerable dip at 5Khz now that is happening because of the back wave reflection which seems not absorbed but imagine much of the back portion of the dome is open and ready to have decent absorption material that will be on whole new level of coherency. Also imagine if there is a dome breakup absorption material behind the dome then you also get a sense of alot of silence. So there are many things that can be done in a dome midrange. In fact the motor itself. A unmodulated motor design.
A new dome by Tang Band reviewed in voicecoil https://audioxpress.com/article/test-bench-tb-speaker-75-1558sh-high-end-home-audio-3-dome-midrange
Has a listing on PE but no stock https://www.parts-express.com/Tang-Band-75-1558SH-3-Fabric-Dome-Midrange-264-856
Has a listing on PE but no stock https://www.parts-express.com/Tang-Band-75-1558SH-3-Fabric-Dome-Midrange-264-856