Why am I having GreenMountain time-coherency flashbacks?
Though I think the GM Europas do attempt to address some of the same beaming concerns that seem to be DS's obsession with their discussion of 1st-order crossovers and the use of heavy sound damping on the outside of the speaker (something I'm about to attempt on my WmAx customs to resolve what I think is an edge diffraction problem).
(DS's blog which shows this focus:
Serious Audio)
It is interesting to me that many people seem to have their personal windmill at which to tilt. For Chris (WmAx) it was (is?) cabinet resonance and off-axis FR (he was a big fan of dipole HF, which is becoming more popular now). For the GreenMountain fans it is shallow crossovers and phase coherency. For DS it's dispersion patterns at the crossover point for the midrange.
Of course: there are many, many speakers in general use which would not run into this problem. Many of even the least expensive 3-way speakers (infinity Primus 36x) use a 3" midrange driver covering the entire frequency range he's concerned about. Martin Logan, Magipan, Walsh Ohm speakers (which use a single driver with a mechanical crossover); as well as concentric speakers like Tannoy or Kef.
I've owned several of these. I've not noticed the clear superiority that I would expect given the implied severity of the issue.
I'm prone to thinking: there may indeed be an issue with midrange bloom caused by the reality of many speaker designs; but like cabinet resonance (caused by all cabinets) or off axis non-linearity (caused by all non-omni-polar emitters); it is something that can be and is mitigated in design.
As such: while some designs solve the issue intrinsically; they pay for that gain with the creation of other issues they must mitigate.
There is no perfect design; and though there are yet things to learn (such as we've seen with the proliferation of di-polar speakers): there is no one solvable problem which overshadows all others nor one solution which does.
I think it's a claim that is prefacia reasonable; and so worthy of considering what the real trade-offs are before deciding whether to factor or dismiss (look at the work under Toole on phase coherency and its lack of actual import: It was considered, studied, and then a determination was made)
You have gone to the nub of the issue.
All speaker designs, have lot of compromises. It's how you handle all those compromises within your overall design concepts and goals that counts.
If you just concentrate on one windmill, as you say, to the exclusion of others, I guarantee you will end up with a poor overall design.
So I'm not so keen on ribbon tweeters as Dennis Murphy, but that does not mean you can't make a good speaker with ribbon drivers.
I think most people who have done this a long time have a laundry list of speaker faults, they just can't tolerate. I know I do and it's lengthy. Further I think we do have a windmill or two we toss at. The trick is to not let that obsession spoil the cake.
I guess my windmill is crossovers and tying to do with as few as possible, and making them the best I can, where I have to insert one. Those of us who listen to "Hi-Fi" speakers I'm pretty certain are highly conditioned to their ills.
Now for a large part of my life I was a committed full ranger. I still think the full ranger community has some very valid points in their camp.
The point is that I think being a full ranger listener for so many years, I think it sensitized me to the effects of crossovers.
So I try and minimize the number of crossovers, and when I do use them, my crossovers are often incomplete, relying as much as possible on acoustic roll off. For instance of the 9 crossovers in my front three, only three are complete crossovers, the rest incomplete and not full crossovers.
All this is to keep as many of the virtues of single full range drivers, in my complex designs as possible.
Now I fully understand there would be many, probably most who would regard that approach as off in left field. Would I say, that every designer should take that approach, absolutely not.
One of the big advantages of being a DIYer, is that you can adapt bend and break rules and spear sacred cows all you want.
However I do believe, my approach is valid. Others, and especially professional musicians, who a very wary of sound reproduction in general, seem very pleased. A horn player from the Minnesota orchestra summed it up best and noted a believable perspective, and that solo instruments had their correct acoustic space, and did not sound reproduced.
So I am very happy indeed with this rig. Some revisions have taken place over time, getting closer and closer to the original sound. Another benefit of DIY, you can continuously upgrade without buying new speakers!
That is what John Wright of TDL used to do. He listened to a design for years before releasing a product and only made changes every three to four months. You just can't part a TDL owner from their speakers, and they hardly ever appear on the used market, but a lot were sold.
Peter Walker tinkered with the ESL 67 for 16 years before bringing it to market!
