Sloped baffle

Some great speakers have it, some don't. Is it an important feature?

I am glad to know my previous writings were appreciated, and it's become easier to explain since then.

I can clarify some basic technical concepts above, without reference to our products, if you like.

Please let me know.

Thank you,
Roy Johnson
Just took a look at this thread; the title didn't obviously say "read me" so it took me a while to check it out.

Lowpass drivers lag behind highpass drivers in both time and phase, and a sloped baffle can introduce a limited amount of compensation for that, along with a tilting of the driver axes (which may be desirable in some cases). In and of itself, it's not enough compensation to make much difference, but could be part of a full-scale time-coherent effort such as Roy Johnson's magnificent speakers.

"Phase coherence" and other phase-based terms have been used loosely and don't necessarily mean what we think they mean. For instance, the woofer can lag the tweeter by 360 degrees at the crossover point, yet the system could be called "phase coherent".

Roy's designs are truly "time coherent", and that puts them in a different league; they're the real thing. His designs do everything we might have optimistically hoped for, such as waveform preservation, when we first came across the term "phase coherent".

As for how small manufacturers can do decent design work without access to an anechoic chamber, one answer is time-gating. That's a measurement technique wherein the microphone is turned on briefly to catch the direct sound from the speaker, and then turned off before the first reflection arrives. Time-gating has limitations relative to what can be done with a true anechoic chamber, but it sure costs a lot less.

Roy, I'd be very interested in reading any clarifications you care to post, and have zero problems with your making specific references to your products. The inherent rapid rolloff at the bottom end of the horns I use prevents me from ever doing what you do without totally changing directions (and going back to college), but that doesn't lessen my admiration for your work.

Hi Roy,
good to see that you discovered this thread. :-)

Duke, you are always gracious.... :-)

hope that Bifwynne takes advantage of your resp. presence here & gets some deep technical dialogue going..... :-)
>>>In both the Green Mtn Audio speaker specs, now, we are talking flat impedance & phase response. :-) Nothing like that in the Magico S5.

Interesting. Any independent measurements you can point us at to verify your claims? The ones we see in SP are not that impressive. In fact, they are quit awful (and are not even time coherent as claimed). Even the so polite JA had to say that: “..the listening axes on which the speaker is (almost) time-coherent and offers the most neutral response don't coincide”. Which is just one typical issue this concept have. Not to mention that distortion level with first order XO will be significantly high: “…occasionally thought I caught a hint of lower-midrange congestion”. All and all, a concept that does not really work, due to all the other problems it creates.
Hi guys, I'm back to the real world... first, Al, thank you for your gracious words...
If Green Mountain audio meet specks, what Bombaywalla posted are truly amazing, it takes a lot of crossover work to bring phasing in line to plus or minus 3 degrees. I've never seen a graph of a speaker with specks that tight. 6db pads done correctly will keep you within 15 degrees or so. I'm not a pro and have nothing to lose by showing my stuff. I'm using HiVi D6.8 woofers (same as Totem Forest) and a low to mid Scan Speak Tweeter in an MTM. I've never used photo bucket, so hopefully this works, but I just uploaded my graphs & crossovers to photo bucket... Hopefully, you can view this, if not, I'll try to figure it out and post again.