Acoustic Horn Design – The Easy Way (Ath4)

Do you know what's cool about an axisymmetric device? It doesn't have a pattern flip :D
 

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As you can see above, it is very much "about CDs per se", specifically, are they unnecessary in home audio. The answer appears to be yes, if Toole himself eschews them, and he publishes graphs showing similar DI progressions achievable from conventional speakers that are readily available.

This is a great lead-in to where Floyd and I disagree, or not really disagree so much but have different Preferences.

First there are some things that need to be understood: 1) very early reflections (VER) are know to enhance spaciousness but degrade imaging; and 2) as the DI is increased the VER are decreased. These two factors are key to the discussion.

Floyd listens almost exclusively to live recordings of large orchestras in large venues. This type of recording is heavy on spaciousness and very light on imaging as a high number of instruments means poor source localization. The best playback in this case would be a low DI with a multichannel setup. This type of setup would indeed obliviate any importance of DI in the main speakers. This is precisely the situation that Floyd is in and why he does what he does.

On the other hand many people, like myself, prefer studio work where imaging is essential and multichannel more of a degradation rather than an enhancement. I never upmix my 2 channel sound to multi-channels. In this case a high DI is very important to recreating the image that is presented by the recording.

It's the high DI that is difficult to achieve in small designs and particularly with direct radiators, hence my preference for CDs and waveguide as this is the only way to achieve a smooth and constant high DI

In a very real sense one must taylor their systems to their musical preferences. This is what Floyd means when he says "There is much discussion of this in forums, and personal preference is a factor." Personal preference here means musical interest and expectation. There is no single right answer, Floyd knows this as well as I do.

My point here is to make it clear that we need to understand what we want from our recordings and this is a personal choice. So it can be wrong to use the recommendations or observations of one experts designs when applied to another's designs which may be seeking something different. This is the situation between Floyd and myself and many others I suspect. Many think that there is a single answer to the problem, but there isn't.

And I also agree with "Patrick" in that IMO as speakers get better and better they tend to converge on sound quality - sounding ever more similar. It's flawed speakers that sound different because there are a million different flaws, but flawless speakers should all sound about the same. Except for DI where there isn't a single right answer and some speakers will sound better with some material and rooms and others the opposite.
 
If the mouth is elliptical then it is different to what I have. Seems to me that left like that it always tends to narrow in the midrange. Maybe not so much in this case, it's hard to judge based on a photo.

This IS the trade off. An elliptical mouth will allow for a smaller spacing between drivers at the crossover making that situation better, but it also make the vertical polar control worse. Pick your poison.

This issue was central to my decision not to proceed because I found (in simulations, I never actually did acoustical tests) that while one problem gets better another gets worse and hence there is no substantial improvement overall. Given the much more difficult manufacturing situation I did not see that the elliptical made sense.

Hey, I've basically ended up with the OS waveguide! :wiz:

That's all, folks.

And yes "That's all folks" we have come back full circle!
 
Wrt to the test I didn't "imply" anything, except for the remark on the RCF ND350's lacking low end, which is a known fact.
I clearly stated: "Judge for yourself whether the differences are significant." ;)

Years ago I was tempted to buy EV DH1As. About 100 NOS pieces were offered locally at €100 each, which is less than the average resale price for (ab)used DH1As today. It's undoubtedly one of the best youngtimer large format drivers, but it's also a heavyweight and requires serious reinforcement of the horn's mounting plate.

Tastes/preferences may indeed (widely) differ from person to person. That's why we have measurements and afterwards all kinds of tools/methods to sugarcoat the acoustically optimized end product.

yes I understand you did not imply anything, I was referring to the test that was done, it seemed to me to suggest or imply that by testing a bunch of different drivers on one standard horn that some useful conclusion as to driver performance could be drawn and that is not the case.
The EV DH1A is fortunately inexpensive on this side of the pond. The heavy part is the extender nose which can be remover resulting in a smaller exit and a lighter overall weight but you would also need to contrive a mount for your horn. For me this is not too difficult to do with my K-Tubes. It is a nice driver. Sorry for all the confusion my comments were not intended to be directed at you but rather at what I see as flawed logic in the original test. Thanks for posting and the opportunity for discussion in this most interesting thread. Thank you also for you yourself posting such a vast quantity of information your efforts are very much appreciate.