Was a bit heavy with my choice of 'big' there. I only meant 'big' as in 'big enough to matter.' I didn't know I had to consider it, at all, until I read the previous post.
Hornresp is all I've been thinking about since I last wrote. Everything below I couldn't do yesterday.
I think I've represented my my first box here. I tried to make sure I stayed within xmax at full power. Assuming a high pass of 30hz seemed to always be right where xmax is coming back down from being horrifyingly high.
I found an example file for a TH box with two 8" speakers and put my Focals in there (I think). Sine143 said compression ratio of 3 might be too high, so I tried to stay below that (not by much though, I'm at 2.8). One thing I noticed quickly is that I can't give the speakers full power without blowing way past xmax unless the box is really small and even then I had to pull back on the voltage a bit. I kept shrinking the whole thing down until I stopped blowing the driver. Ended up with only 77l and a very bumpy quiet response. I read I should keep the phase below 90 across the range, that seems to fit.
Very interested to hear what you think of all this. If I'm doing something obviously and terribly wrong, I don't know it yet. I'm at a loss of how I could build a bigger box and also feed the drivers a decent amount of power.
Hornresp is all I've been thinking about since I last wrote. Everything below I couldn't do yesterday.
I think I've represented my my first box here. I tried to make sure I stayed within xmax at full power. Assuming a high pass of 30hz seemed to always be right where xmax is coming back down from being horrifyingly high.
I found an example file for a TH box with two 8" speakers and put my Focals in there (I think). Sine143 said compression ratio of 3 might be too high, so I tried to stay below that (not by much though, I'm at 2.8). One thing I noticed quickly is that I can't give the speakers full power without blowing way past xmax unless the box is really small and even then I had to pull back on the voltage a bit. I kept shrinking the whole thing down until I stopped blowing the driver. Ended up with only 77l and a very bumpy quiet response. I read I should keep the phase below 90 across the range, that seems to fit.
Very interested to hear what you think of all this. If I'm doing something obviously and terribly wrong, I don't know it yet. I'm at a loss of how I could build a bigger box and also feed the drivers a decent amount of power.
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Your Le is wrong.... you used the LeS spec in the sheet. just use 1.5 like bjorno else you'll never get a half decent result
3 dB is a doubling of power. Most can hear .5 dB differences only under really controlled A/B testing, if at all.
It takes 10 dB difference at 1000 Hz to be perceived as twice as loud, though at 20 Hz a 5 dB difference does that.
Look at equal loudness contours at different levels and frequencies to get a "feel" for the changes. Listening to headphones, make a .5, 3, 6 and 10 dB change on one 1/3 octave EQ band to hear the difference at various frequencies.
I had mistakenly referred to Sine 143's pal12 as an Ipal previously, both the pal 12 and a split Keystone are similar in most regards other than shape.
Although FLH can be folded to almost any box shape, the spacing between driver and mouth exit makes some TH impossible to fold in to certain box shapes.
The Keystone exit can bend some of the TH rules in certain fold patterns, allowing a variable virtual driver location.
Art
the two driver can load symmetric into the throat from each side if last part of output ports are split into two
Now that sure changes things.
With that, it doesn't want to do much below 40hz although it seems much easier to get a decent looking response now. 170W and quiet but at least it seems to fit my size restriction and does well up to 80hz.
Starting to feel like things are crystallizing. I'm definitely going to work on this stuff more tomorrow and compare what I'm doing to what you've all provided. Isobaric or not I want to get a feel for doing different things.
Can't imagine a better way to spend a weekend! Having a great time now I feel like I have a good path to follow.
With that, it doesn't want to do much below 40hz although it seems much easier to get a decent looking response now. 170W and quiet but at least it seems to fit my size restriction and does well up to 80hz.
Starting to feel like things are crystallizing. I'm definitely going to work on this stuff more tomorrow and compare what I'm doing to what you've all provided. Isobaric or not I want to get a feel for doing different things.
Can't imagine a better way to spend a weekend! Having a great time now I feel like I have a good path to follow.
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And thank you for that reply Art!
I'd never heard of an 'equal loudness contour' and the info on the keystone is quite interesting. Definitely going to read more about that style of cabinet.
I'd never heard of an 'equal loudness contour' and the info on the keystone is quite interesting. Definitely going to read more about that style of cabinet.
Your L12 is kind of ridiculously long in that horn. the focal would require about 30cm of l12 for a pair of drivers in a line like your picture of the modified pal12. s2 would go directly in between the driver, not after the 2nd one.
Took your advice and have been plugging away every since.
Changes I've made:
1) Decided to see what one large box would do for me as opposed to 2 smaller ones.
2) I took your advice and shrunk L12.
3) Once I had something that seemed reasonable, instead of posting here again, I went ahead and attempted to build it in sketchup. Didn't end up with the exact same measurements of course, but they were close.
4) Measured the resulting box in sketchup and plugged the numbers back into hornresp.
Mind is blown by several things: 290l is quite a bit less than 400l (the combined size of two boxes I originally intended), yet response of this single box seems to be significantly better while using only 2 drivers. Efficiency skyrocketed, I'm using only 42W to reach xmax?! (never would have imagined that possible). Phase response is way better than anything I've built. The only drawback I can see with this design is my high pass filter will need to be 33hz at the very minimum, not quite sure what I could do to bring xmax down the frequency band but I'm not sure if I should worry about it anyway.
Changes I've made:
1) Decided to see what one large box would do for me as opposed to 2 smaller ones.
2) I took your advice and shrunk L12.
3) Once I had something that seemed reasonable, instead of posting here again, I went ahead and attempted to build it in sketchup. Didn't end up with the exact same measurements of course, but they were close.
4) Measured the resulting box in sketchup and plugged the numbers back into hornresp.
Mind is blown by several things: 290l is quite a bit less than 400l (the combined size of two boxes I originally intended), yet response of this single box seems to be significantly better while using only 2 drivers. Efficiency skyrocketed, I'm using only 42W to reach xmax?! (never would have imagined that possible). Phase response is way better than anything I've built. The only drawback I can see with this design is my high pass filter will need to be 33hz at the very minimum, not quite sure what I could do to bring xmax down the frequency band but I'm not sure if I should worry about it anyway.
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Oh yes and put the drivers side by side since I couldn't figure out a way to build it any other way.
with a low re of 2.9, configure the drivers in 2s (not 2p) so that your amp can handle the loade.
with drivers side by side, you could likely get by with a l12 of around 18mm with the focal (half driver width plus a couple extra cm so you can fit it in there).
also, although I know the pal12 was simmed using con segments you should really sim using Par segments.
with drivers side by side, you could likely get by with a l12 of around 18mm with the focal (half driver width plus a couple extra cm so you can fit it in there).
also, although I know the pal12 was simmed using con segments you should really sim using Par segments.
tinitus 🙂 That's actually two horns right? In a mirrored configuration. Or maybe you call it a split horn since the drivers enter a common chamber but exit in opposite chambers? I'd love to do something like this but I'm not sure how it affects the numbers. Is it as simple as splitting the S volume in half for each side after it splits and keeping the L1-5 the same?
(Clearly still trying to get the basics down)
Sine, I was planning on electrically wiring them in series. I thought hornresp's input was physical rather than electrical. Still, power should be the same right? When calculating E I was using 42 watts and 8ohms, if I go down to 2ohms my voltage will drop to 1/4 of that value but I'm still at 42 watts.
(Clearly still trying to get the basics down)
Sine, I was planning on electrically wiring them in series. I thought hornresp's input was physical rather than electrical. Still, power should be the same right? When calculating E I was using 42 watts and 8ohms, if I go down to 2ohms my voltage will drop to 1/4 of that value but I'm still at 42 watts.
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yes thats true however when you wire it 2s in hornresp it gives you useful data, telling you that you need an amp capable of at least 40v to go to xmax. . the parralel figure is not useful.
I see what you're saying. A single channel of a crown 402 could run it either way, couldn't it? I'm thinking I'll actually need to be careful not to overpower the thing.
i could not run it in parralel, as the impedance minima will dip below 2 ohms (aka, pissed off amp, likely go into protect). wiring in series actually *doubles* the voltage the box will take (your amp provides voltage, not wattage), thus insuring a bit more protection.
According to its specs it has a 31 dB max voltage gain, so 2^(31/3.01) = ~1260 W, ergo has plenty of headroom for any impedance dips.
GM
GM
with his current design, wired parralel, his average electrical impedance between 50 and 70 (wheelhouse) is about 1.55... I'd think this would be too low for most amps to be happy with.
I've bridged the 402 into 4 of these focals, 2 in series 2 in parallel. Played them hard. Amp didn't seem to break a sweat. Should behave the same at 2ohms a channel, no?
Anyway, my plan has always been to run these in series. I appreciate you're making sure I know that though 🙂
Does my previous design make sense? Does it look like I'm getting the hang of it?
Anyway, my plan has always been to run these in series. I appreciate you're making sure I know that though 🙂
Does my previous design make sense? Does it look like I'm getting the hang of it?
yes, I think so, but don't know much about it
throat and 1. path is mutual, and the splits
it ought to model like other with 2 drivers
how about a 4 driver 'Bailey style' with the inner baffles angled 🙂
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