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When I do longer sweeps from 20-70 I begin to see what you mean by the inductance. There is mild unevenness in sound (whether it be from the room acoustic, inductance, whatever), but I think I might be able to pull a good portion of that out with an equalizer.
You can see the effect of inductance in HornResp, just run the sim, then change Le to 4mH, run it again and compare the two. There's very little difference in the passband, a major difference above 100Hz. OTOH the room will have a huge impact on response. That's why measuring outdoors is critical, lest you drive yourself nuts trying to fix something that isn't broken, or trying to fix something so badly broken that it's un-fixable.
 
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You can see the effect of inductance in HornResp, just run the sim, then change Le to 4mH, run it again and compare the two. There's very little difference in the passband, a major difference above 100Hz.
As I mentioned before, Hornresp can't simulate inductance correctly. A very high inductance driver absolutely will have huge effects below 100 hz in reality. The entire response shape can change and you can see it in the measurements. But Hornresp won't show anything like that.

Data-bass.com is probably the best resource for this. Pick a high inductance driver from the list. Simulate it in the same box they measured it in. Look on in shock and horror while you realize your sim doesn't look ANYTHING like the measurement. In the ultra high inductance drivers the inductance effects can affect response almost as much as problems caused by the room.
 

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Correct. You need complex inductance modeling to even get in the ballpark with those types of drivers and HR can't do it. You can fool with the single generic LE parameter all day and you cannot make the simulation act like these drivers actually behave in a basic sealed enclosure.
 

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Correct. You need complex inductance modeling to even get in the ballpark with those types of drivers and HR can't do it. You can fool with the single generic LE parameter all day and you cannot make the simulation act like these drivers actually behave in a basic sealed enclosure.
That very well may be, but this isn't a basic sealed enclosure, nor would one call 1.8mH high inductance. I can't say what a truly high inductance driver would do in a horn, as I don't use them.
 

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Being familiar with the name Sundown but not this particular driver, when I looked it up tonight it wasn't really what I expected. 2 inch VC, 400 watt power handling, 12 mm xmax, I wasn't even aware that they made anything cheap with low excursion and a tiny VC like this. That Le seems really low for a low end driver like this (which is why I didn't pay much attention to the Le spec in the sim) and now that I've looked it up I'm not sure I trust the published spec for a few different reasons (even though Sundown's more recent and higher end drivers seem to fairly accurate published specs based on third party testing) but it is possible that inductance isn't an issue with this one.
 

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I wasn't actually talking about this particular driver or the OP's situation with that last post but in general about using the LE parameter in HR. I'm not familiar with the OP's driver. It is likely much better behaved than drivers with heavier 3" coils and no shorting rings.

The point about a sealed enclosure is that it is the simplest alignment and if the simulated response cannot be made to match the real response of even a simple sealed system then there is no hope for a much higher order system like a tapped horn.

Basically before spending a lot of time and effort developing a horn for a driver based on simple or incomplete manufacturer specs it is advisable to take measurements of the driver to be used and learn some things about its behavior. In general what I have found is that the more xmax the driver claims the more important it is to do this...

Sorry OP...I'm not really directing this at you but for others who may be reading and thinking about DIYing a horn.
 

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Discussion Starter #27
@diy speaker guy
This actually is newer than the higher end SA series (I own both; from what I can tell, everything is the same except for the ever-important motor and consequential specifications, not that there similarities mean much). That being said, there is no saying that this lower end model has measurements as accurate as the SA series. My friend is needing to trade vehicles with his dad, so he is needing a new box for his sub, so it seems I'm going to be doing TS measurements sooner than I thought, at which point it becomes worthwhile to measure the E-15 while I'm at it.
@Ricci
No worries - the discussion is much appreciated.
 

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C-weighting is [email protected], [email protected] and [email protected]; but between 4khz to 40hz it should be almost deadflat (+- 3db or so).

200 watts according to my multimeter.
How did you measure it? Is that music-power or sinewave power? The cheaper multimeters tend to give inaccurate results, especially below 40hz.
Play a 60hz sinewave and measure the volts and amps, it should give a realistic number on that. If you don't have an ammeter, that could be why your readings are off (you are not taking the ACTUAL impedance into account, which could be as high as 20-30ohms).

Well, my SPL meter hits about 120-122 right in the mouth of the sub at C weighting and about 105-110 from one meter. Now, I'm already aware that reality seems to yield lower SPL results and less flatness (due to a variety of factors) based on what I've seen in project threads, but this difference is pretty huge.
I'm currently amplifier-limited, but I get 115 to 121db continuous @ 10ft with 4 to 8 sealed 18's on my termlab meter with bass-music; if I had more watts it would probably go even louder.



jbrown plays his system at around ~105-113db at his 10ft LP, at which point we had to stop going louder for fear of breaking his house or upsetting the wife / cops.


We measured a ported HO-15 doing 113db @ 50hz with ease @ 3ft.


I love my termlab because it is specifically designed for measuring loud bass (105 to 183db) and there is no way to cheat the device, short of putting it inside the port and/or blowing air directly on the sensor hole, but the turbulence would likely show as wideband spectral-noise so you probably couldn't get away with it.
 

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I don't suspect that much of anything is wrong here.


the horn probably achieves its target, but the reality is a 2pi space model in a room with reflections (that cancel) and modes (the may do either).


the dual 15 black widow are loaded with top end punch and the tapped horn has a huge suckout there. so bass vs. no bass. bass wins, no surprise. :)


the inductance may affect the response a little, but my guess is that isn't the big factor here.


the expansion rate in the model may also affect things a bit, but again, probably not the primary culprit here.
 

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Discussion Starter #30
How did you measure it? Is that music-power or sinewave power? The cheaper multimeters tend to give inaccurate results, especially below 40hz.
Play a 60hz sinewave and measure the volts and amps, it should give a realistic number on that. If you don't have an ammeter, that could be why your readings are off (you are not taking the ACTUAL impedance into account, which could be as high as 20-30ohms).
I'm using a sinewave to measure the power. Now that you mention it, I do have access to an ammeter, but I don't think it is necessary to be very precise with power output. When the DDT turns on, I know that I'm pretty close to my power limit. Plus, I'm not worried too much about power output because this is the same amp that the previous subs were using (though they used two channels, each channel was providing less power considering the higher impedance; so based on amplifier rating - the widow enclosure put out 240w and the tapped horn is putting out 200w; yes, I know these numbers aren't going to be perfectly represented in reality, but it provides ballpark numbers). I do thank you for the information you have provided.
@LTD02
It is pretty unfortunate I wasn't able to make that range less awful, but I did want a strong low end. I knew I could make up that range with something else easily if needed, but until I actually built the tapped horn I was guessing I probably wouldn't need anything to compensate.

I'll post some test results tomorrow involving a direct comparison of the widows vs the horn. I'll also gladly try them together as I have enough power (I have a CS800X in my server rack right now because I had been testing the Sundown @ 400w in the Peavey enclosure; on a side note, it made little to no difference, hence why I built a new enclosure :) )
 

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Discussion Starter #31
Well, I did the test but just realized after the fact that the ohm loads for the widows in parallel and the sundown are quite different. Widows are 2.8 ohm and Sundown is 4.0 (both measured with amp off; multimeter resistance already has been deducted), so the power output would be different even though I left the gain the same :p

That being said, I'm not about to go through the 3 ring circus involved with moving the enclosures, wires, and anything else in the way (I have them positioned where I want them) to do a retest. I have the results if anybody is interested in readings taken at ambiguous power output, but I assume that the information wouldn't do much good.

I will say that after adding the widows back in, the system sound fantastic from high to low bass. I need an equalizer to flatten out the response (or whatever I feel preference to), but generally all is well. Additionally, it was handy that I still had the CS800X in the rack because I have all the power I need for the two enclosures. I think I'll just call this situation done. I do appreciate assistance offered as I have learned quite a bit from it and I can use that knowledge going forward.
 
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