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Multi-Way Conventional loudspeakers with crossovers

Well I suppose the shallow vs. steep argument will just go on and on
Well I suppose the shallow vs. steep argument will just go on and on
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Old 26th October 2017, 05:57 PM   #1
andy2 is offline andy2  United States
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Default Well I suppose the shallow vs. steep argument will just go on and on

I didn't know someone who may be more analytical in his designs would prefer more shallow slope filters. I seem to find more and more evidence to support my case as time goes on.

Well from the man himself - Zaph.
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Part of the magic of this system is simply due to the fact that it's a solid LR2 design. Accurate 2nd order slopes are hard to pull off, and only very wide bandwidth drivers with smooth response and low distortion need apply. Make no mistake that shallow slope crossovers sound better than steep slope crossovers. But doing shallow slopes right amounts to much, much more than just throwing a cap and coil on the tweeter and woofer. My Waveguide TMM design was more of a hardware solution addressing some typical LR2 design issues. This Scan Speak / Vifa system is more of an electrical solution.

In the end, an LR2 design has 180 degrees of phase wrap through the crossover while an LR4 has 360 degrees. The lower phase wrap directly equates to an improved midrange coherency. Honestly, most drivers and system designs require LR4 or greater slopes just to work properly. But when everything comes together for a LR2 system, it's the sweet spot in speaker design.
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Old 26th October 2017, 06:23 PM   #2
system7 is offline system7  United Kingdom
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A well-behaved 5" bass plus 1" tweeter must be the easiest speaker in the repertoire! Umpteen ways to do it. Shallow or steep. LR2, BW3 or LR4.

Zaph has had his disasters: Zaph|Audio - ZRT - Revelator Tower

That 6" one sounds terrible by all accounts. Troels regards it all as experimental.
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It's all just trade-offs IMO. You get what you get.
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Old 26th October 2017, 06:55 PM   #3
chrisb is offline chrisb
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zaph is certainly "a" but not conclusively "the" man in this field

couldn't agree more with Steve above - or at least how I interpret this particular comment
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Old 26th October 2017, 07:15 PM   #4
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Well my point really has nothing to do with any particular design. It's just a matter of physics. A shallow slope means less phase shift which always help.
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Old 26th October 2017, 08:17 PM   #5
Lojzek is offline Lojzek  Croatia
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Well I don't know about arguing about it but whatever works is fine with me. I'll never be able to low pass a metal cone bassmid with a single inductor only, and I surely won't put a 3rd order electrical on a nice paper or poly cone unit. I need steeper order HP on tweeter for phase alignment anyway so it's minimum 2nd order electrical, and I would hate to fry the delicate unit, so it stays 2nd order or higher.
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Old 26th October 2017, 08:28 PM   #6
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I wouldn't do low order on metal driver either. I usually try as low order as possible and if I can get away with.
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Old 26th October 2017, 08:37 PM   #7
system7 is offline system7  United Kingdom
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We'd all like to use shallow filters, no doubt. Even none at all like your headphone driver which is just a glorified plastic tweeter. They sound good on detail.

But a loudspeaker needs big displacement in a room to do bass, so we end up multiway.

Problem is cone breakup, non-linearity caused by excessive excursion, and strain on tweeters, leading to distortion at certain frequencies. And some dispersion issues, I suppose. Not too hard with a good 5" bass and a 3.5kHz crossover. 12dB/octave LR2 will do. But don't forget the BBC did famously well with BW3 on the LS3/5A.

But these speakers don't go loud or bassy. Phase alignment is what we often want in speakers too. But phase linearity is not such a big deal. The main event is actually group delay, which worsens with higher orders and higher Q. Because in our Universe the ringing always follows the impulse. The arrow of time always points forwards.

That is what you hear. And the tradeoff is really that reducing distortion involves worsening group delay. Choose your poison!

Much incomprehensible stuff here for the interested student: Crossovers

Well, actually I did this at College. But I have forgotten most of it now. We now have speaker simulators.
Attached Images
File Type: jpg Klippel Metal Cone Breakup.JPG (40.4 KB, 953 views)
File Type: png S7 Second order LR2 Theoretical.PNG (17.9 KB, 946 views)
File Type: png S7 Third Order BW3 Theoretical.PNG (18.4 KB, 1074 views)
File Type: png S7 4th order LR4 Theoretical.PNG (20.8 KB, 935 views)
File Type: jpg Duelund_3way_tg1.jpg (37.1 KB, 995 views)
File Type: jpg Duelund a=4.JPG (60.7 KB, 134 views)
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Last edited by system7; 26th October 2017 at 08:46 PM.
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Old 26th October 2017, 10:44 PM   #8
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Well I suppose the shallow vs. steep argument will just go on and on
Context is very important in this argument, and the set of compromises they designer chooses to make.

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Old 26th October 2017, 10:45 PM   #9
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[QUOTE=system7;5225341]We'd all like to use shallow filters, no doubt. Even none at all like your headphone driver which is just a glorified plastic tweeter. They sound good on detail.<snip>/QUOTE]

I wish your writing could show a bit more clarity so to make your point a bit easier to understand.
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Old 27th October 2017, 12:37 AM   #10
system7 is offline system7  United Kingdom
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No-one uses images like I do. That is because I have a very visual imagination. Not mathematical, not wordy.

Here's something I am listening to right now, and that is a SEAS 19TAF/G 3/4" metal tweeter:

Click the image to open in full size.

Well-behaved 8" paper bass on second order electrical has goodish natural 4th order LR4 rolloff, but is not without problems. Time-alignment is difficult. It breaks up around 3kHz, as you can see on the phase plot. IMO, this produces mushy and annoying 2nd harmonic distortion at 6kHz. So a notch filter (15R plus 0.68uF across 1mH) takes those out quite considerably. By 10db here. Which is a lot.

But you might as well use a steeper third or 4th order filter with the benefit of hindsight. As Harbeth do. LR2, BW3 and LR4 happen to be elegant solutions in filtering. As I see it, phase and group delay and dispersion issues are not distortion, they are more a transform or tonality with a slight ringing quality. Distortion or breakup however IS fatiguing. And you usually cure it with some steepness, and keeping drivers in their comfort zone.

So like Dave says, context is important. A 5" bass is an entirely different animal. The breakup is much higher, around 8kHz. So LR2 might sound OK with a well-behaved driver. And 5" polycones are the easiest example.
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