How does a the air energy from the bass woofer of a synergy horn, reflecting back into the cone, not cause a ton of distortion? As the holes in the horn for the 15" woofers seem far too small, inadequate in size to allow a proper amount of air to pass through to avoid said issue. For near and midfield listing, is there advantage to horn loading woofers rather than having an array of multiple midrange drivers around a tweeter on a flat baffle to achieve the same coaxial effect? I get an increase in sensitivity is achieved though if using an active crossover, who cares?
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Bump... with a simplified version of my question. I would like to know to anyone who can provide a non begrudging answer. Honestly like many things I observe, the synergy horns are a rather cumbersome looking unintuitive design. The choppy frequency response of the SH50 horns that has been posted elsewhere leads me to suspect that there are some issues with regards to distortion possibly related to the issue of reflected air energy back into the woofer cone.
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As long as the cones' Sd : port area ratio isn't too high, the energy goes through the ports just fine. 8:1 has worked ok in my builds
Smaller ports keep the cone from reaching as low in freq as it can wide open, but proper port placement in the horn can give some gain back to mitigate that.
Ports smaller than Sd also provide an acoustic low-pass function which helps lower overall speaker distortion.
Yes, big advantages. Both acoustic gain from horn loading (tricky to get right).
And perhaps more important, having the drivers mounted on a pyramid reduces the c2c distances between drivers compared to same drivers on a flat baffle. (the c2c distances perpendicular to listening axis)
Not sure what you mean ....
It's kinda hard to know how to begin answering the questions....lot's going on. I'd suggest patent searches for synergy, unity, and Danley.
Here's one for starters https://patents.google.com/patent/US8284976B2/en?inventor=thomas+J+danley&oq=thomas+J+danley
Thanks for information and the link.
"Not sure what you mean..." if one is using active crossovers and amplifiers per channel and presumably one can set the desired gain within the crossover/dac then one is married to needing to maximize the sensitivity of LF drivers to match the high sensitivity compression tweeter -- or vice versa apply an LPad to the compression tweeter. Assuming everything is operating within the headroom limits of the driver, amplifier, crossover, dac, sensitivity shouldn't effect performance under these circumstances. If trying to achieve maximum loudness as is the case with Synergy Horns in most applications, then it's a different story presumably.
In addition I think some assume that sensitivity is synonymous with detail which in my understanding it is not. Maximizing the sensitivity of a driver through horn loading that isn't extended and or capable of rendering detail to begin with isn't going to dramatically increase the amount of detail rendered by that driver.
I understand as a general rule that horn designs especially those with narrow throat which in turn minimizes the physical impedance of air at the diaphragm though that has nothing to do with the sensitivity of the driver.
"Not sure what you mean..." if one is using active crossovers and amplifiers per channel and presumably one can set the desired gain within the crossover/dac then one is married to needing to maximize the sensitivity of LF drivers to match the high sensitivity compression tweeter -- or vice versa apply an LPad to the compression tweeter. Assuming everything is operating within the headroom limits of the driver, amplifier, crossover, dac, sensitivity shouldn't effect performance under these circumstances. If trying to achieve maximum loudness as is the case with Synergy Horns in most applications, then it's a different story presumably.
In addition I think some assume that sensitivity is synonymous with detail which in my understanding it is not. Maximizing the sensitivity of a driver through horn loading that isn't extended and or capable of rendering detail to begin with isn't going to dramatically increase the amount of detail rendered by that driver.
I understand as a general rule that horn designs especially those with narrow throat which in turn minimizes the physical impedance of air at the diaphragm though that has nothing to do with the sensitivity of the driver.
Glad to try to help'
I think the process of matching the acoustic output of drivers sections is the same for all types of speakers. And I don't think that process is any different for trying to achieve maximum SPL. Because maximum SPL needs to be defined as maximum linear SPL.
Sensitivity is kinda a bad concept to follow anyway, if it's the usual 1W sensitivity. Equal voltage sensitivity is a better spec. And getting equal voltage sensitivity is again the same process, max SPL or not.
Agreed. I don't think high sensitivity has anything to do with greater detail. However, I do think high sensitivity correlates with a greater chance of unclipped, uncompressed sound as SPL is turned up....which is a form of greater detail, albeit level dependent.
The impedance at the diaphragm is a function of the entire horn, not just the throat design.
Thanks. To clarify my previous post, I wrote haphazardly: "if one is using active crossovers and amplifiers per channel and presumably one can set the desired gain within the crossover/dac then one is married to needing to maximize the sensitivity of LF drivers to match the high sensitivity compression tweeter..."
I intended:
"if one is using active crossovers and amplifiers per driver** and presumably one can set the desired gain within the crossover/dac then one isn't** married to needing to maximize the sensitivity of LF drivers to match the high sensitivity compression tweeter..."
And also: "I understand as a general rule that horn designs especially those with narrow throat which in turn minimizes the physical impedance of air at the diaphragm though that has nothing to do with the sensitivity of the driver."
"I understand as a general rule that horn designs especially those with a narrow throat which in turn minimizes the physical impedance of air at the diaphragm will in theory increase the detail the driver is able to render, compared to it operating without a horn in free air, though that has nothing to do with the sensitivity of the driver."
I intended:
"if one is using active crossovers and amplifiers per driver** and presumably one can set the desired gain within the crossover/dac then one isn't** married to needing to maximize the sensitivity of LF drivers to match the high sensitivity compression tweeter..."
And also: "I understand as a general rule that horn designs especially those with narrow throat which in turn minimizes the physical impedance of air at the diaphragm though that has nothing to do with the sensitivity of the driver."
"I understand as a general rule that horn designs especially those with a narrow throat which in turn minimizes the physical impedance of air at the diaphragm will in theory increase the detail the driver is able to render, compared to it operating without a horn in free air, though that has nothing to do with the sensitivity of the driver."
In addition to the possible distortion issue that I mentioned previously which I intend to look into further, does the angular mounting of the mid and bass drivers to the horns render an off axis response of those drivers?
The angles of the horn walls and the entrance points of the drivers all affect the axial response of the MEH (multiple entry horn).
Apparently... The question reworded: Do the drivers being mounted at angles render an off axis response or do the ports function in such a way to render an on access response of the mid and bass drivers?
What do you mean, are you suggesting the side drivers are at an angle so they will shoot sound sideways?
It goes forward, backward and sideways.
It goes forward, backward and sideways.
As far as I understand, by virtue of the drivers on the walls being located within 1/4 wl of each other, they function like a virtual driver that would be located at the center of the horn.
The original commercial Synergy horns were passive. I'm not sure if all of them are still passive.
The designer made some choices for the sake of simplicity and a relatively low parts count, so there might be a bump or two in the on-axis FR plot that a more complicated crossover could fix if you were doing a cost-no-object copy.
It does. There's a big null in output that, as I understand it, is set by the distance between the port for the mid or woofer and the horn apex.
The closer the ports are to the horn apex, the higher in frequency that null is pushed.
Say you make a test rig. Say you want the mids to go to 1200Hz. If so, you might start by drilling a pair of ports for a pair of 5" mids ...and you find that gives a null at 900Hz. That's bad.
...so you plug those holes, and drill closer holes for a quad of smaller mids, which you can crowd closer to the apex. The null is now at 1300Hz. That's good, that's possibly a viable build, because the "ton of distortion" (the big null) is out of the passband.
Making a test rig out of scraps, and trying out some of these ideas, isn't super hard or very $$$
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I'll first echo diyuser2010's comment....that keeping the drivers within 1/4WL span allows them to collectively act as a single driver.
That said, there is still some off-axis variations in each passband's section using multiple drivers at more extreme off-axis angles.
It's simply due to increased times-of-flight differences between the multiple drivers, stretching effective driver spacing. (This is where narrower pattern horns have an inherent advantage over wider.)
Plus, even closer to on-axis, 1/4WL summation kinda guarantees worst case +3dB summation , whereas fully in-phase summation gives +6dB. So there's that source of magnitude ripple too.
Not a big deal imo, in comparison to the benefit of integrating different passbands within 1/4 WL.
I take it from reading your comments, that you mean the reflections from the horn wall facing the cone, not reflections inside the horn.
I guess it works the same way any compression driver, or speaker design that uses a slot to let output from a cone flow though....
Just works is all i know....need to be a modeler to answer this one I guess...
Wavelengths from a bass woofer are so long compared to the reflections under the cone would be my answer. but I don't think that's the case for CD's so i dunno. Maybe my comparison to a CD is bull
Put your hand tight over your mouth with a small gap between two of your fingers. Do you feel a reflection when you breathe?
Another good point. That said I imagine whatever is happening to the volume of air between the woofer cone and the interior edge of the baffle during operation is a more complex scenario than that -- partially due to pressure and the compression and rarefaction of the driver.