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Multi-Way Conventional loudspeakers with crossovers

Amount of hornloading in a Synergy horn
Amount of hornloading in a Synergy horn
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Old 13th June 2019, 01:16 AM   #61
Cask05 is offline Cask05  United States
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Since you're not using the same horn, driver, and off-axis port locations, those bass bin response peaks will be different for you. I recommend a calibrated microphone and REW to measure them. You're going to need it anyway to dial in the MEH assembly.

"Qualitative" means the opposite of quantitative. It means that you can see areas on sim plots where the frequency response will differ, but it will not be measurable differences, only visual indications that the response will differ and approximately where those frequencies will be.

Chris
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Old 13th June 2019, 01:37 AM   #62
mark100 is offline mark100  United States
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Originally Posted by AllenB View Post
A little misleading, calling them this, don't you think?
Seems misleading to me too.
Never heard anyone else rename the ports, 'off-axis ports'.

What's the rationale?
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Old 13th June 2019, 03:50 PM   #63
Soldermizer is offline Soldermizer  United States
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Default Confused about notch filters

Would someone please explain why we want to notch out some frequencies? I understand the basic principle of the Unity/Synergy mids and the (I supposed) need to crossover to "tweeter" before the first notch (1/2 wave reflection). If this (and multiples) are already minima, what is the point of a notch filter? What am I missing in this concept? Is someone trying to bend the "rules" (physics!) and get more HF output of of the mids???
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Old 13th June 2019, 08:11 PM   #64
Cask05 is offline Cask05  United States
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Originally Posted by Soldermizer View Post
Would someone please explain why we want to notch out some frequencies?

When you look at the raw response of the woofers on both the SH-50 and the K-402-MEH, you can see response peaks above the first notch frequency:


Click the image to open in full size.


The idea is to provide a steep crossover slope without the accompanying phase shifts inherent in typical IIR crossover filters (i.e., Butterworth, Bessel, Linkwitz-Riley, Chebyshev, etc.). All the woofers need is a 90 degree phase lag at their ~500 Hz crossover frequency to match the phase of the next higher driver (the midranges in the SH-50 and the compression driver in the K-402-MEH). All you need to do with either woofer channel is to attenuate the peaks above the first notch frequency, i.e., 1320 Hz and 2600 Hz in the K-402-MEH. Once you do that, the resulting low-pass crossover slope of the woofer is about 10 dB/octave--by itself without added electrical crossover filters.

Click the image to open in full size.

Once you attenuate those response peaks above first notch frequency, then you get almost flat phase response out of the entire loudspeaker, as seen in the phase plot that I posted earlier:


Click the image to open in full size.


The "secret sauce" of the Danley Synergy is this almost-flat phase response across the entire audible bands without the use of FIR filtering. Once you hear the difference from a full-range MEH that can control its polars down to below 200 Hz (SH-50) or 100 Hz (K-402-MEH), you'll understand why the Synergy series horns are held in such high regard.


Chris

Last edited by Cask05; 13th June 2019 at 08:15 PM.
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Old 13th June 2019, 11:10 PM   #65
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Originally Posted by Cask05 View Post
When you look at the raw response of the woofers on both the SH-50 and the K-402-MEH, you can see response peaks above the first notch frequency:


Click the image to open in full size.
Chris
Thanks for clearing that up. Really nice graph. I can also quite clearly see you 475hz "acoustical crossover" in action. Is this how you get there? Model the horn till you see the curve becoming something like this? Starting from the 1/4th WL distace, and seeing where it starts dropping of, as to change the off axis distance till it matches is?
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Old 13th June 2019, 11:42 PM   #66
Cask05 is offline Cask05  United States
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Yes. That's what I did.

Chris
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Old 13th June 2019, 11:49 PM   #67
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Awesome, I'll play with it some and send you the graph for you to confirm. Also here my message I sent you in mail. Maybe more relevant here:

"I love playing with the software, but it’s good to know it’s really accurate for predictions like the one I’m trying to make. How did you figure you needed 2x 15” instead of 2x 12”? I also noticed there is almost 0 horn loading visible in hornresp. As you already told me not to look to hard at it, I didn’t. But still.. I know from you it cant be 0 hornloading right?

I will definitely start with the Em Kappa 15C I have, so modelling is not that important for now, but for later it maybe is. In the end I want to match the BMS 4594 down to at least 100hz. What would be the best way to go about this? I’m figuring I need 130dB for 1 woofer (including the hornloading) to get there (142dB) with 4 woofers, or 127dB with 6 woofers (x6 12” maybe?).

Could I just look at their performance in a similary sized sealed box to guess their performance in the MEH? "
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Old 14th June 2019, 01:57 PM   #68
mark100 is offline mark100  United States
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Originally Posted by Cask05 View Post


The "secret sauce" of the Danley Synergy is this almost-flat phase response across the entire audible bands without the use of FIR filtering.


Chris
Hmmm....i believe that is a misleading and inaccurate conclusion.

Whether FIR filtering is used or not is immaterial in evaluating the Danley Synergy crossover design.
It is a passive IIR x-over design, which means it can be fully replicated with traditional IIR active processing....with no FIR is sight...

The use of passive x-overs is much more about business strategy than anything else, imo.

FIR could/can be used to improve the sonic performance.

I've had the pleasure of conversations with Tom, Mike, Ivan, and a number of other fine Danley folks this week at infocomm.
I asked opinions about the use of active FIR processing in place of the passives. I learned that some HT enthusiasts have done that, and were very pleased with the results.

There's no 'secret sauce' in the crossovers imo, just a lot of great balanced innovative engineering.

I tried to express a huge appreciation on behalf of our DIY community to those guys for their continued willingness to share information (that doesn't jeopardize their business interest. Really cool, down to earth folks!!!!
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Old 14th June 2019, 02:55 PM   #69
Cask05 is offline Cask05  United States
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Originally Posted by mark100 View Post
FIR could/can be used to improve the sonic performance...

...There's no 'secret sauce' in the crossovers imo, just a lot of great balanced innovative engineering.
If you're willing to do what it takes to do FIR filtering, you will experience even lower phase response wander. What I've found, however, is that FIR filtering is typically not needed if you stick to the precepts that Tom Danley put out there: stay within 90 degrees of flat phase and you're going to get a lot more than 90% of the benefit in terms of subjective listening performance.

To the OP: there is a secret sauce, and I've heard it--in spades. You can also talk to user: Delicious2 and user: MisterVego on the K-forum about their recent crossover filter upgrades using K-402-sized horns that control their polars down to ~100 Hz. In my experience, it's a quantum jump in subjective listening performance while using full-range directivity controlled (fully horn-loaded) loudspeakers.

I believe that the issue comes when you lose polar directivity control in-room well above ~200 Hz (as I believe the quoted individual has exclusively experienced, but hasn't mentioned this little tidbit yet), then you lose a great deal of the effects of phase flattening across the board, like Danley gets with its passive crossovers and full-range directivity loudspeakers. I've heard it in the K-402-MEH and the Jubilees, vs. using typical "named" crossover filters that introduce phase distortions, and I can tell you that the effect is dramatic, but difficult to verbalize exactly how it sounds different (see https://community.klipsch.com/index.php?/topic/182419-subconscious-auditory-effects-of-quasi-linear-phase-loudspeakers/&do=findComment&comment=2379562...about 3/4 way down the page where it starts with "Well, I learned a lot over the past two days...").

Chris

Last edited by Cask05; 14th June 2019 at 03:03 PM.
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Old 14th June 2019, 03:28 PM   #70
AllenB is online now AllenB  Australia
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Synergy crossovers do come together quite readily. It's the nature of the beast, nothing untoward or 'special' going on. The notch doesn't prevent phase changes, and passive is suitable.

If by special, you mean it sounds good, OK but this is not unique to synergies. There are other ways to account for the regions mentioned.
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