Dd67000 crossover points?

@ptss Wrote:

Do any others speakers do this?

Yes, JBL M-2’s and JBL 4435’s both are two-way speakers!

Mike

The JBL 4367 is a passive two-way (15" woofer and 1.4" throat horn) with a crossover at 700 Hz.

Imo it’s a good idea to cover the range from about 1 kHz on up with a single driver, and crossing over a bit lower than that would be even better as long as there are no unacceptable consequences, such as significantly reduced pattern control and/or power handing.

I’ve covered the region from about 750 Hz on up with a single compression driver in custom studio monitors, but have not yet done so in anything that I have in production.

Duke

Without taking anything from the Everest, I would really want confirmation about the super tweeter coming in at 20 kHz. That seems supremely wasteful.

Otherwise, this is almost what the DIY community calls a Woofer-Assisted Wide Band (WAWB) which has quite a following. The idea is to use a wide-band driver and/or horn to keep any crossover issues out of the human voice range, but adding a woofer to cover the lowest octaves. It’s a neat idea with many positives and also a lot of negatives but definitely an approach worth considering. I think of a WAWB as a variation on the full-range, single driver designs and a way of overcoming the limitations in bass output in a tidier manner than folded bass horns.

The DD67000 seems to take this to the extreme by adding a second woofer and a super tweeter, but I’d consider it more or less in the same faimly. Check out all the articles over at DIYaudio on the pros and cons of a WAWB.

Also worth noting, this is an ideal speaker for Sanders amps.  The impedance is worse in the high frequencies than in the bass, a situation which is the opposite of what most normal amps are expecting, which have higher damping factor below than above.  Do you need it to play from 20kHz to 40 kHz though??? That's another story.

Interesting also that the crossovers are 24 db/octave.  This helps reduce power to the drivers but also offers excellent vertical response.   That is, you can sit or stand up and still hear an excellent frequency response without destructive interference in the crossover regions.

An approach rarely seen in passive crossovers.  This shows they are leaving nothing to disturb the carefully chosen horn designs.

Analysis Audio Planar Ribbon speakers use a first order crossover at 600 Hz.

Arion Audio Apollo speakers use fourth order filters at 120 Hz.

If the drivers and system are designed for it and the drivers have the headroom it can work very well. There are very many things that have to be taken into account. For example our Arion AMT drivers are mechanically damped so they are able to follow complex wave forms which is exacerbated by the extended range they must reproduce.

I have enjoyed DD67000s on many occasions. A wonderful speaker by many accounts. I'm sure the engineers at JBL did their homework and met their design objectives.

My Electro-Voice main speakers are crossed at just over 600Hz to a large format midrange/tweeter horn (2" exit) that runs up to 17-18kHz. An important takeaway here is that the Constant Directivity horn controls directivity all the way down to the crossover point to the woofers (dual 15", vertically aligned), even lower, with a very uniform dispersion pattern at the crossover. Slopes are 36dB/octave L-R throughout, actively configured, and the mains are high-passed at ~85Hz for subs augmentation below. The EV DH1A compression drivers used here are built to withstand a crossover point at 500Hz 12dB/octave for pro cinema use, but I find they sound better crossed just over 600Hz, and with the steeper slopes. They’re an immensely well-sounding and powerful speaker system.

JBL talks about their drivers in their white papers. They are capable of covering this range. The 4” compression driver in the S9900 shows some non linear breakup above 10k but The 4” driver in the Everest is beryllium and probably addresses it. Also the ring driaphrams in the M2/4367 are also show to eliminate the breakup. I think cutting out the center removes the breakup and adding two brings back the surface area needed for SPL/heat reduction.

With all that being said I think the D1 driver (used in M2, 4367, SCL-1) is about cost reduction as they needed a cheaper driver for the pro market as the exotic metal driver have to cost a tone and the pro VTX line array has 3 D1s per box, times how ever many you want 10,12… more…

Anyway the 4367 has the cleanest mids and highs I have heard to date, really special. I have never heard the other top models but based on them being made by the same designer I would imagine they are all pretty great.

white paper here.

@erik_squires . Interesting research--

 AES preprint 3207 by Oohashi et al. claims that reproduced sound above 26 kHz "induces activation of alpha-EEG (electroencephalogram) rhythms that persist in the absence of high frequency stimulation, and can affect perception of sound quality."

@erik_squires . More from same research-

Oohashi and his colleagues recorded gamelan to a bandwidth of 60 kHz, and played back the recording to listeners through a speaker system with an extra tweeter for the range above 26 kHz. This tweeter was driven by its own amplifier, and the 26 kHz electronic crossover before the amplifier used steep filters. The experimenters found that the listeners' EEGs and their subjective ratings of the sound quality were affected by whether this "ultra-tweeter" was on or off, even though the listeners explicitly denied that the reproduced sound was affected by the ultra-tweeter, and also denied, when presented with the ultrasonics alone, that any sound at all was being played.'

@ptss Very interesting!!!

My speakers are flat to 30kHz, i wonder how much of that I’ve been experiencing??

I’ve also read positive things about damping ultrasonic resonances in tweeters during crossover design, but I thought that was because of distortion artifacts being introduced at a lower frequency.

Along the same lines, I wonder how much of our perception of music and sound is through our skin, and therefore how poorly our measurements may understand human perception.

That’s very interesting.  Can you share what some of those subjective comments were with and without the ultra tweeter?  I am curious how it was perceived.

@james633 . Thanks. I'll be looking into-for fun :)

@jc4659  from my post  AES preprint 3207 by Oohashi et al.  I didn't look into much detail - but it would be interesting for sure. As erik_squires mentioned, perhaps skin? 

I distinctly remember a very unique "sensation" - that was more than sound- when going into a Jazz venue in Seattle back in early 80's.  Big venue, high ceilings, horns and cymbals full tilt. Exciting.  Perhaps Erik is right- skin picks up those ethereal sounds. Magic :)