F20 vs Sealed Stereo Integrity 18 - AVS Forum
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post #1 of 53 Old 04-25-2013, 08:20 AM - Thread Starter
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I am try to figure out which has more output. Most things I have read have said the F20 will have a lot more output, but the measurements seem to disagree.

Comparing a 1000W SI 18 or Dayton 18 vs an F20, LTD02 said, "the f20 will slaughter them both. more than 10db higher spl at 25hz and about 6db higher in the upper bass".

It looks like the measurement for the F20 is about 117dB from 20-80Hz and the 20-80Hz long term avg on Data-Bass for the SI 18 is 113.3db. I think the SI 18 was measured at 2 meters though and the F20 was measured at 1, so the SI would output 119.3dB at 1m. The F20 is flatter, so it has a more output at 20Hz, but from 25Hz up, they are similar with the SI winning overall. More than 10dB louder at 25Hz would put the F20 only a few dB shy of a Gjallarhorn and decently surpass a DTS-10.

Am I looking at something wrong, or is the F20 and SI 18 a lot more comparable than people make it seem?

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post #2 of 53 Old 04-25-2013, 01:12 PM
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Distance matters, but only in context...

The SI18 data in Ricci's Data-Bass is taken using the ground plane measurement method. This method uses a 2m measurement distance, it's true, but only as compensation for the ground plane reflection so the result is the same as free space at 1m.

Horns can be louder, if designed to be, but the real advantage is reduced distortion, especially at high SPL.

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post #3 of 53 Old 04-25-2013, 01:37 PM
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you are misinterpreting the data.

1000 watts into a si 18 in 4.2 cubic feet will get you about ~111db @25hz @1m.

1000 watts into an f20 will produce ~122db @25hz @1m

ricci's numbers are sometimes maximum burst levels. if you plan on runinng your sub at that level sustained, you are going to cook the si or dayton coils in short order.

both the si and the dayton in 4.2 cubes require 10x the power (or more after compression) to reach 10db higher (or 5kw based on the impedance at 25hz). either way, that would be around 5-10kw of power to hit 122db at 25hz.


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post #4 of 53 Old 04-25-2013, 02:00 PM
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post #5 of 53 Old 04-25-2013, 02:11 PM
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The F-20 can handle about 300 watts each, I ran 400 watts to each one and never used the full power but I had 4 of them. The F-20 will have more output for sure from 18hz and up. Probably like the Chase passive numbers.

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post #6 of 53 Old 04-25-2013, 02:21 PM
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I love the output of folded horns, but I love sub 20hz more smile.gif
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post #7 of 53 Old 04-25-2013, 02:25 PM
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Here is a comparison of simulations for both, each fed with one watt, in a groundplane setting.



SI HT 18D2 in a sealed 4.2 CF box vs an MFW in an F-20.
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post #8 of 53 Old 04-25-2013, 02:30 PM
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Quote:
Originally Posted by bhazard View Post

I love the output of folded horns, but I love sub 20hz more smile.gif

I like both...
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post #9 of 53 Old 04-25-2013, 02:37 PM
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I like the output and sub 10hz.

Lilmike,
I am deciding if I want to change anything at all anymore since I just turned up my LFE by 10 dBs and it crushes me and the house. This is the gain I would get from horn loading or so. It might be wise to just leave well enough alone.

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post #10 of 53 Old 04-25-2013, 02:48 PM
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Quote:
Originally Posted by MKtheater View Post

I like the output and sub 10hz.

Lilmike,
I am deciding if I want to change anything at all anymore since I just turned up my LFE by 10 dBs and it crushes me and the house. This is the gain I would get from horn loading or so. It might be wise to just leave well enough alone.

I wish I had your problems when it comes to bass... In my current situation, the sub amp is not powered on most of the time. I'll have a proper theater soon enough.

If I were you MK, I'd just drive it and like it for a good long while. Not many have experienced what your theater can do. Sit back, relax, and enjoy the ride. I think you're at the point of diminishing returns.
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post #11 of 53 Old 04-25-2013, 05:24 PM - Thread Starter
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I know people talk a lot about models or just claiming the F20 is x dB louder, that's why I was trying to look at actual measurements. So was the F20 measured ground plane or free space? If it was measured ground plane, then ~6dB should be added to the SI measurements?

I avoided using the max burst numbers for the SI because I didn't think they would be a real world number. Shouldn't the max long term average numbers be realistic to what you could get as a real life max?

Even if the numbers are directly comparable, it looks like the avg output for the F20 is ~117dB from 20-80Hz and Ricci got 113.3dB for the SI. ~3.5dB over this range from actual measurements is much closer than the models show. And if dB should be added to the SI for being measured at 2m, the gap between them is even less or switches. Lilmike's model he just posted is only for 1 watt too. I'm not concerned about efficiency, but what they will do with the max power, and the SI would take over 3 times the power of the F20.


So overall what I'm curious about is whether the F20 was measured ground plane at 1m, so ~6dB should be added to the SI number, and is lilmike's max SPL measurement comparable to Ricci's max long term output measurement for the SI?

I am not concerned with the difference in power required between them, like comparing 1W to 1W or 1000W to 1000W. I know the F20 is more efficient, I'm just wondering about the max long term output of each, without damaging anything, using each box's max power.

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post #12 of 53 Old 04-25-2013, 05:55 PM
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if you are referring to lilmike's measured results here: http://www.avsforum.com/t/1329971/lilmikes-cinema-f-20

and comparing to ricci's measurements here: http://www.data-bass.com/data?page=systems&type=2

you are comparing apples with potatoes.

lilmike was using a cheap amp rated at "300 watts" and ran out of amp while testing. ricci was using a top of the line $8,000 amp with something like 12,000 watts and was pushing the drivers to their absolute limits.

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post #13 of 53 Old 04-25-2013, 06:13 PM
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also, the next to the top line in the lilmike plot is about 20 volts. that corresponds to 100 watts into 4 ohms, or about 118 watts into the 3.38 ohm resistance of the driver. the next line above that is compressed out, so the measurement series was severely amp limited.

at the next to the top line, the driver excursion is only around 7mm above 22hz, so there was a lot of driver potential left on the table.

to your other question, lilmike's measurements are consistent with a 1m measurement, so adding 6db for comparability to ricci 2m results is about right, if all other things were equal, which they weren't.

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post #14 of 53 Old 04-25-2013, 06:15 PM - Thread Starter
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Yes, but with that 300W amp, he was past the thermal limit of the driver according to him. So that is probably the max power of the F20, or less to be under the thermal limit.

I don't know how much power was used on the SI, but I was using the max long term average measurement, not the max burst measurements. The max long term average isn't a limit-pushing, dangerous measurement, is it? From it's name, I would guess it is the max power you could use over a long time period, haha. What is the definition of a max long term average then? Would that use a power level that would be safe for a long term use of the driver in a home theater?

The max burst output of the SI at 100Hz was 123db. The max long term average at 100Hz was 113dB. So even if the full 12,000 watts was delivered during the max burst, the long term average was 10dB lower at a reasonable 1200W. Based off that, it looks like the max long term average of the SI is using it's max safe power.

I'm not trying to crap on the F20, it puts out a ton of output with a lot less power, I'm just trying to compare the max safe output of the 2 with their own individual max power levels.

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post #15 of 53 Old 04-25-2013, 06:23 PM - Thread Starter
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I am assuming a couple things too that might be wrong. Isn't 300W what lilmike recommends running with the F20? And he said 300W was over the thermal limit of the driver, so could it really take more than 300W?

So just for comparisons sake, using 300W into an F20 you get about 117dB from 20-80Hz and using 1 - 1.2kW into the SI you get about 119dB at 1m. That is comparing lilmike's 300W graph and Ricci's long term max average at 1m. So based off the SI long term average chart, the F20 has about 2dB more output at 20Hz, but the SI catches up at 25Hz and up with a 2dB average advantage over that range.

So overall based off these charts, the F20 has more output at 20Hz, but the SI has a little more output above 25Hz and below 20 using their max powers.

Even if you ran 600W into the F20, it would only have a 1dB advantage over the SI from 20-80Hz average.

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post #16 of 53 Old 04-25-2013, 06:40 PM
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"he was past the thermal limit of the driver according to him"

the smaller brother of that driver, the dayton dvc has a 350 watt rms rating, 700 watt peak.

"I'm not trying to crap on the F20, it puts out a ton of output with a lot less power, I'm just trying to compare the max safe output of the 2 with their own individual max power levels."

that's a good approach and it was clear that was what you were attempting. one thing that is typically missed though with horns is that the sensitivity doesn't just impact the 1w1m measurement, it also figures into the max spl numbers.

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post #17 of 53 Old 04-25-2013, 07:13 PM
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"I don't know how much power was used on the SI, but I was using the max long term average measurement, not the max burst measurements. The max long term average isn't a limit-pushing, dangerous measurement, is it?"

it is confusing because there is not a direct way to compare the thermal limits of both drivers given the two different testing conditions and driver specifications from the manufacturers.

si rates the 18" at 650 watts rms. i'm not sure what a reasonable max rating would be, but it seems reasonable to spec 1300 watts or so of amp for it unless you intend to run sine waves at 70hz for extended periods of time. iirc, 650 watts sine wave will cook a driver after about 5 minutes and somebody has already cooked one.

in order to hit the numbers in ricci's "long term" output chart, you'd need to put about 2,000 watts or so into the driver, so obviously that doesn't include running constant sine waves.

3x rms is around 1kw for the f20. with a protective highpass, it might survive that, but i wouldn't suggest pushing either driver that hard.

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post #18 of 53 Old 04-25-2013, 07:41 PM - Thread Starter
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Where did you get the 2000W number from for the SI? Based on what I said earlier, it hits 113dB during the max long term output at 100Hz. It hits 123dB at 100Hz max burst, so a 10dB increase would be 10 times the power. If it was taking 2,000W during the max long term output test, it would need 20,000W to hit the max burst number it did. Could his amp really output 20,000W and could the SI really take that much?

Here's what I get overlaying lilmike's F20 graph with the Ricci's long term output graph adjust for 1m for the SI:



And here's what I get if I subtract 3dB for running the SI at 1000W, assuming the max long term output was measured with 2000W:



I'm not sure how to post a pic that isn't full screen width...

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post #19 of 53 Old 04-25-2013, 07:58 PM - Thread Starter
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Looks like his KPA-2400 amp claims 12,000W at 4-ohm bridged. So assuming it can put out what it claims and the burst test used all 12,000W, that should mean the max long term average test used 1,200W at most, right? So the fist of my last 2 graphs should be pretty accurate.

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post #20 of 53 Old 04-25-2013, 08:55 PM
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"Here's what I get overlaying lilmike's F20 graph with the Ricci's long term output graph adjust for 1m for the SI"

again, you are comparing an overpowered si 18ht with an underpowered f20. if that is what you want to go with, that's fine. it's just not the best comparison.

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post #21 of 53 Old 04-25-2013, 09:31 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

"Here's what I get overlaying lilmike's F20 graph with the Ricci's long term output graph adjust for 1m for the SI"

again, you are comparing an overpowered si 18ht with an underpowered f20. if that is what you want to go with, that's fine. it's just not the best comparison.

How is the SI overpowered? Unless my calculations/assumptions in the last post are wrong, 1200W (at most) during the max long term output test isn't overpowered and is only a little more than the 1000W I plan to run. 1000W is what seems to be recommended on here from what I've seen in a sealed box.

How is the F20 underpowered? The power handling of the MFW is 225W I think. Why didn't lilmike test the F20 with a more powerful amp if it could take more than the 300W he gave it. Doesn't he recommend using a 300W amp with the F20?

Adding up lilmike's graph every 5Hz from 20-80Hz, I get ~117.3dB. The SI gets 119.3dB at 1m. Even if you run 600W to the F20, which is 267% of the MFW's power rating, that would result in the F20 only have 1dB more output than the SI from 20-80Hz. I don't know how to model the horn to see if 600W would be a useable amount of power of if it would go over xmax, disregarding the thermal limit. To hit the 6dB higher you said earlier, you would have to run 1900W to the F20. I doubt that is a reasonable number for that sub.

The top graph represents the recommends powers that people have said to use with each box (if my assumptions are correct). Is that not a fair comparison?

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post #22 of 53 Old 04-25-2013, 09:40 PM
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on ricci's long term power compression test of the si ht18, the first level is 4 volts.

http://www.data-bass.com/data?page=system&id=90&mset=97

4 volts into 3.5 ohms is 4.6 watts. the top line or last very compressed run is at 118 volts. 118 volts into 3.5 ohms is 3,978 watts.

you are comparing the f20 with an amp that is compressing at 300 watts to a si ht18 running at 3,978 watts.

you are also miscalculating the burst power.

since burst is not power compressed, start with the 4 volt measurement, which gave 89db. to get to 123db requires 10^((123-89)/10) times as much power. 10^(34/10) = 10^3.4 = 2511 times. 2511 * 4.6 watts = ~11,500 watts.

so 11,500 watts burst, no compression = 123db.

3,978 watts, long term compressed output = 112db.

now, the great revelation. the digam k10 amp outputs 200v max. 200v into 3.5ohms is 11,428 watts.

so the burst figure is actually an amp limitation on a k10!! somebody call ricci!!

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post #23 of 53 Old 04-25-2013, 09:57 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

on ricci's long term power compression test of the si ht18, the first level is 4 volts.

http://www.data-bass.com/data?page=system&id=90&mset=97

4 volts into 3.5 ohms is 4.6 watts. the top line or last very compressed run is at 118 volts. 118 volts into 3.5 ohms is 3,978 watts.

you are comparing the f20 with an amp that is compressing at 300 watts to a si ht18 running at 3,978 watts.

you are also miscalculating the burst power.

since burst is not power compressed, start with the 4 volt measurement, which gave 89db. to get to 123db requires 10^((123-89)/10) times as much power. 10^(34/10) = 10^3.4 = 2511 times. 2511 * 4.6 watts = ~11,500 watts.

so 11,500 watts burst, no compression = 123db.

3,978 watts, long term compressed output = 112db.

now, the great revelation. the digam k10 amp outputs 200v max. 200v into 3.5ohms is 11,428 watts.

so the burst figure is actually an amp limitation on a k10!! somebody call ricci!!

Ok, I didn't know how to calculate watts from the information he gave. So that would mean if I quarter the power of the max long term output, I would get the 1000W comparison I want, which would be 6dB down. So it would be the same as just using the 2m numbers. So a 1000W SI comparison to a 300W F20 comparison would give the F20 a 4dB advantage from 20-80Hz average.

The max long term average is kind of dumb then, what's the point? Does it mean you can run 4kW through one SI all the time and be fine? 4kW would go way over xmax.

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post #24 of 53 Old 04-25-2013, 10:04 PM
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I will post something tomorrow...

John that is 200v peak and 125A... per channel...we are talking bridged...Everything is run wide open no limiting or soft clipping circuit. I don't know the max burst power but I would guess around 15kw into full clip. Yes that gets put into virtually every driver above 50Hz. They do compress and they do not die a horrible death because of the very short split second duration.

More later.
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post #25 of 53 Old 04-25-2013, 10:13 PM - Thread Starter
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So you get a 4dB 20-80Hz advantage and an 8dB 20Hz advantage with 1 F20 vs 1 SI. Does room gain affect the horn differently than a sealed sub? I know lilmike's said you will pretty much get no gain below 20Hz in room or in a corner or anything I think, but a sealed sub should gain a good bit down low.

Going off your numbers, here is the new comparison graph:


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post #26 of 53 Old 04-25-2013, 10:29 PM - Thread Starter
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What is Ricci's max long term output measurement supposed to represent? At 4000W, the SI would hit xmech and 36 or 30Hz, depending on if xmech is 30 or 35mm. How could he have any usable output below 30/36Hz if the driver is bottoming out, let alone long term output?

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post #27 of 53 Old 04-25-2013, 10:33 PM
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Quote:
Originally Posted by bradthebold88 View Post

Yes, but with that 300W amp, he was past the thermal limit of the driver according to him. So that is probably the max power of the F20, or less to be under the thermal limit.

I don't know how much power was used on the SI, but I was using the max long term average measurement, not the max burst measurements. The max long term average isn't a limit-pushing, dangerous measurement, is it? From it's name, I would guess it is the max power you could use over a long time period, haha. What is the definition of a max long term average then? Would that use a power level that would be safe for a long term use of the driver in a home theater?

The max burst output of the SI at 100Hz was 123db. The max long term average at 100Hz was 113dB. So even if the full 12,000 watts was delivered during the max burst, the long term average was 10dB lower at a reasonable 1200W. Based off that, it looks like the max long term average of the SI is using it's max safe power.

I'm not trying to crap on the F20, it puts out a ton of output with a lot less power, I'm just trying to compare the max safe output of the 2 with their own individual max power levels.

Then stop comparing apples to oranges. The F-20 is a simple to build bass horn that used an inexpensive driver and makes a lot of noise. An 18 in a sealed box is not the same, and is not a fair comparison.

As far as thermal limits? I'm an end-user, a consumer. I don't set thermal limits. The engineers that designed the drivers do. Eminence rated the MFW at 225 watts.

According to that same credo, the stereo integrity has a thermal limit of 600 watts.

Doesn't really matter what Ricci tested them at. Just cause you can pour the power to it short term and get away with it doesn't mean you should. The folks at Stereo Integrity are on the record re-affirming the driver's 600 watt thermal limit. Jerry McNutt and the crew at Eminence rated the MFW at 225 Watts, but Seaton used double that, I split the difference, and chose a number that corresponded to a cheap, yet decent amp that is widely available.

Why did I test with such a cheap amp? Cause you didn't send me that LabGruppen FP14000 or that Powersoft K10 that I asked for.

Seriously? Because it is what I have to work with, and as the F-20 was all about most bang, least buck, I figured using what I have and what others would likely use would be a fair test.

I'm a hobbyist. Nothing more. I do this stuff for grins, in my spare time, with some of my spare funds. Not everyone has the discretionary funds or available time to destroy drivers and push things to their absolute limits, regardless of what the forums want to see. Sure - I coulda pulled out my EP, bridged it and really put the coals to the F-20 during testing. The numbers woulda got a bit higher, but with swept-sine sweeps, I would have killed the driver dead on the next sweep (~600 watts applied). I lack the cash to use the sophisticated burst testing techniques Josh uses, so I'm "stuck" with REW - which is a FANTASTIC piece of software, I wish all the software I was "stuck" with worked as well. Swept-sine testing is BRUTAL, and will kill a driver deader than dead before you can turn it down. Since I can't exactly wave another driver in without spending cash that goes towards other things, I tend to honor the driver's limits as set by the folks that made em.

Looking only at maximum output without considering bandwidth, distortion, and power requirements is a bit short-sighted.
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post #28 of 53 Old 04-25-2013, 10:40 PM
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Originally Posted by bradthebold88 View Post

So you get a 4dB 20-80Hz advantage and an 8dB 20Hz advantage with 1 F20 vs 1 SI. Does room gain affect the horn differently than a sealed sub? I know lilmike's said you will pretty much get no gain below 20Hz in room or in a corner or anything I think, but a sealed sub should gain a good bit down low......

No, I didn't, certainly not on purpose.

I don't "invoke" boundary loading to make my subs flat, nor do I discuss room gain.

Room gain is, regardless of the sub you use. It is also unique to your room.

What a sub does in my room is of no consequence to you, because your room is different.

I measure in my driveway or on my patio. Not a perfect 2pi environment, but it is what I have to work with.
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post #29 of 53 Old 04-25-2013, 11:08 PM - Thread Starter
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"Stereo Integrity confirms that the power rating for this driver is based on the mechanical overload not what the coil will handle thermally."
This is on Ricci's page and why I felt safe using 1000W like others recommended in an excursion controlled sealed box.

I don't think I have said anything bad about the F20 in any way, I am just trying to find the max safe output for each sub. I have enough power to power either subs adequately, so power consumption was the lowest priority to me. And considering you can get used EP amps for the same price as a 500W plate amp, power is pretty cheap. The SI will definitely go lower, so I was mainly looking at how many SI's it would take to match the output of an F20 above 20Hz. Another big factor is that 1 F20 has the same external volume of 4 SI boxes. I'm not sure, but I think the F20 would have the distortion advantage.

I don't really care what the max burst power is, I'm not sure how that data is even useful? I'm not sure how Ricci's max long term power measurement is useful if it's way over thermal limit and xmech either? The problem I had was assuming the long term power measurement was comparable to a reasonable amount of power to run with the SI, but it isn't.

For the goal, it doesn't seem like the F20 can be beat for price, distortion, output, or power usage. For my limited floor space though, 4 SI's would have a lot more potential in the same volume, though they would cost a lot more. And so far I've needed two subs to smooth out the response in my room, so that would require 40cf of F20's to get a decent response. I am looking at all aspects of this, not just which one can I make the loudest. The main reason I brought this up was because of the claim that the F20 had a more than 10dB output advantage compared to an SI at 25Hz when my interpretation of Ricci's data made it seem like the they should have the same output. Still though, based on my last graph (which still might not be accurate), the F20 only has a 5dB advantage at 25Hz, which is much different than >10dB.

I assumed 300W was the limit for the F20 because I think you have said that before. LTD02 was saying that was an underpowered model to compare with though.

Living room: Definitive BP2000TL, CLR3000, BPVX, Quad SI 18" subs
Bedroom: Definitive BP30, CLR2000 Also have had: BP7000SC, BP8B, BP10B, BPX, Dayton 15" HF subs, Rythmik F15
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post #30 of 53 Old 04-25-2013, 11:13 PM - Thread Starter
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Originally Posted by lilmike View Post

No, I didn't, certainly not on purpose.

I don't "invoke" boundary loading to make my subs flat, nor do I discuss room gain.

Room gain is, regardless of the sub you use. It is also unique to your room.

What a sub does in my room is of no consequence to you, because your room is different.

I measure in my driveway or on my patio. Not a perfect 2pi environment, but it is what I have to work with.

Sorry, those were two kind of different questions that I stuck side by side and probably didn't word precisely enough. First I was just wondering if room gain affected horns the same as sealed subs, which you just answered. The second question was whether putting the sub in a room or in a corner would result in more useable extension below 20Hz compared to your outdoor measurements. I think your response to that question was that no placement would extend the F20's frequency response below 20Hz.

Living room: Definitive BP2000TL, CLR3000, BPVX, Quad SI 18" subs
Bedroom: Definitive BP30, CLR2000 Also have had: BP7000SC, BP8B, BP10B, BPX, Dayton 15" HF subs, Rythmik F15
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