Clarence's F-20 Build - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 64 Old 04-02-2015, 03:50 PM
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After starting my 2 Lhorn cabs and now 2 pending fusion 15 Sentinels in 3/4 ply,
looking at this my first BF THTLP in 1/2"
as much "fun" as a good design/build is


whew!


and +1 for cleaning threads - ALWAYS
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post #32 of 64 Old 04-03-2015, 03:34 PM - Thread Starter
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Quote:
Originally Posted by wvu80 View Post
Why do you need a tap? The inserts are threaded.
Sorry... I'm out of town this week and I missed this question.

I asked the same question in the main F-20 thread:
https://www.avsforum.com/forum/155-di...l#post33041001

I get back home tomorrow. Hope to finish the build on Sunday. Probably hook it up to the amp on Monday. And then duratex it. And then decide if I want another F-20 or try the THTLP with my 2nd JBL driver.
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post #33 of 64 Old 04-05-2015, 03:33 PM - Thread Starter
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Quote:
Originally Posted by Clarence View Post
After routing the 14" baffle circle and marking the mounting holes for the JBL GTO1514D, if I build another one I think I'll use a diameter of 13.75", which is where the foam rubber surround ends and the hard rubber frame gasket begins. This would give me another 1/4" to pre-drill the 8 mounting holes. As it is, they're pretty close to the edge. And it will give more room for gasket tape.

Mike now recommends these inserts instead of hurricane nuts so I ordered those plus these 1-1/4" 10-32 screws and this tap. According to the product information page, the inserts use a hole size of 0.281 in. (which is 9/32").
Another recommended change for anyone who is going to use the JBL GT1514...

The 1-1/4" screw is barely long enough to mount the speaker to the baffle. I can only get one to reach the threads of the inserts.

I'm going to go to HD tomorrow and see if I can find 1-1/2" or even a little longer. I could probably even use up to 2" if that's all they have... there's enough room in front of the baffle where the horn starts.

Amazon has these at 1-3/4" long. I only need 8, not 100. I'll update if I find something better at HD.
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post #34 of 64 Old 04-05-2015, 03:55 PM
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Small mom and pop hardware stores sometimes have a much wider selection of screws/bolts than the big box stores. Or even an auto parts store like pepboys.
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post #35 of 64 Old 04-06-2015, 11:13 AM - Thread Starter
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I got 2" screws and they worked fine. They stick out maybe 1/4".

Here are the braces.





Next step is to run a bead of caulk along the corner edges. I did that with the PL before it dried, but just to make sure everything's air tight. I'm also going to run some caulk along the mounted rim of the driver. It's bolted in very tight on top of the PE speaker gasket, but I trimmed off the overhang and I'll run a bead of caulk just because.

And I got a hole bit kit for the round speaker terminal. 1-3/4" is a little too small and 2" is a little too big. So I'll use PL adhesive and caulk on that too. I'm going to put the speaker wire terminal on the baffle door. Easiest access if I need to change the wiring.

I have to decide whether to wire the JBL GTO1514D as 2-ohm or 8-ohm. I leaning toward 8-ohm since I'm using a iNuke 3000DSP which isn't driving anything else (eventually a second sub), so there's no reason to wire as 2-ohm for more (potentially too much?) power, right?

2-ohm:


8-ohm: (my choice)


FWIW, the iNuke manual says NU3000DSP has 315W RMS at 8-ohms per channel, stereo. 1040W per channel @ 2-ohms. So 315W should be enough for the F-20 (and 315W on the other channel for a future sub).

JBL GTO1514D spec says 350W RMS, 1400W peak.

So wiring the JBL GTO1514D as 8-ohm is fine?
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post #36 of 64 Old 04-06-2015, 01:29 PM
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a clean mean rockin' machine


can't wait for your impression etc. . . .

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post #37 of 64 Old 04-06-2015, 03:45 PM
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Quote:
Originally Posted by Clarence View Post
I have to decide whether to wire the JBL GTO1514D as 2-ohm or 8-ohm. I leaning toward 8-ohm since I'm using a iNuke 3000DSP which isn't driving anything else (eventually a second sub), so there's no reason to wire as 2-ohm for more (potentially too much?) power, right?

2-ohm:


8-ohm: (my choice)


FWIW, the iNuke manual says NU3000DSP has 315W RMS at 8-ohms per channel, stereo. 1040W per channel @ 2-ohms. So 315W should be enough for the F-20 (and 315W on the other channel for a future sub).

JBL GTO1514D spec says 350W RMS, 1400W peak.

So wiring the JBL GTO1514D as 8-ohm is fine?
I would wire it at 8 ohms and bridge the NU3000 --- then turn down the adjustable limiter to X-max on your subs. I think it has an adjustable limiter--a nice bonus to prevent damage. Really like the F-20 and at $150 for a pair of GTO 15's...I am tempted.

Alas, my wife looks like this when she sees the F-20 I throw in "I need two" I get this I can pay her off with a new car though...
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post #38 of 64 Old 04-06-2015, 05:37 PM
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Quote:
Originally Posted by Clarence View Post
I got 2" screws and they worked fine. They stick out maybe 1/4".

Here are the braces.





Next step is to run a bead of caulk along the corner edges. I did that with the PL before it dried, but just to make sure everything's air tight. I'm also going to run some caulk along the mounted rim of the driver. It's bolted in very tight on top of the PE speaker gasket, but I trimmed off the overhang and I'll run a bead of caulk just because.

And I got a hole bit kit for the round speaker terminal. 1-3/4" is a little too small and 2" is a little too big. So I'll use PL adhesive and caulk on that too. I'm going to put the speaker wire terminal on the baffle door. Easiest access if I need to change the wiring.

I have to decide whether to wire the JBL GTO1514D as 2-ohm or 8-ohm. I leaning toward 8-ohm since I'm using a iNuke 3000DSP which isn't driving anything else (eventually a second sub), so there's no reason to wire as 2-ohm for more (potentially too much?) power, right?

2-ohm:


8-ohm: (my choice)


FWIW, the iNuke manual says NU3000DSP has 315W RMS at 8-ohms per channel, stereo. 1040W per channel @ 2-ohms. So 315W should be enough for the F-20 (and 315W on the other channel for a future sub).

JBL GTO1514D spec says 350W RMS, 1400W peak.

So wiring the JBL GTO1514D as 8-ohm is fine?
I'd recommend wiring it 8-ohm, running things stereo. The amp will run cooler and the amp's stereo power output matches the needs of the sub.

When bridged, the NU3000DSP will be too much amp for that driver.

Normally, I'm a fan of a bit too much amp, but in this case, there is a strong potential to damage the driver (either due to excursion or thermal limits) with close to a kilowatt on tap. While it is certainly not junk, the 1514 is just not that robust of a driver, it simply can't be at that price point.

If you elect to run your amp bridged, learn to set your limiter. The smoke and bad noises will happen before you can turn things down. If you set your limiter to 350 W, there's no real difference between that and the 315 W the amp's rated at in stereo. The difference is less than 1/2 of a dB, and since you're already at 120 dB, why go through the trouble?
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post #39 of 64 Old 04-07-2015, 09:07 AM - Thread Starter
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Quote:
Originally Posted by 18Hurts View Post
I would wire it at 8 ohms and bridge the NU3000 --- then turn down the adjustable limiter to X-max on your subs. I think it has an adjustable limiter--a nice bonus to prevent damage.
Quote:
Originally Posted by lilmike View Post
I'd recommend wiring it 8-ohm, running things stereo. The amp will run cooler and the amp's stereo power output matches the needs of the sub.

When bridged, the NU3000DSP will be too much amp for that driver.

Normally, I'm a fan of a bit too much amp, but in this case, there is a strong potential to damage the driver (either due to excursion or thermal limits) with close to a kilowatt on tap. While it is certainly not junk, the 1514 is just not that robust of a driver, it simply can't be at that price point.
I let the PL dry overnight. Wired the dual voice coils to 8 ohms. Attached the chamber side panel. Wheeled the F20 from the garage into the HT on a handtruck. Disconnected my old subs. Connected my Onkyo AVR to the iNuke NU3000DSP. Wired the Neutrik NL4FC output from the iNuke 3000DSP to the F20.

I read through the iNuke Quick Start Guide, but there's not much there... just a basic listing of the menus.

Right now I've got a 120Hz-20Hz sweep playing on loop from a Disney WOW Calibration Blu-ray. Good news... I get a nice clean tone. But I have no idea what settings I should use on the 3000DSP.

First priority is protection.
Second priority is breaking in the driver.
Third priority will be setup (I bought a UMM-6 but haven't started studying how to use it).

So let's start with the basics for setting limits and crossovers on the 3000DSP.
AFAIK, I don't plan on Bridging the amp.





Menu "XOVER A#1" has the following options:
  • HP type: Off
  • HP freq: 20Hz-20kHz
  • LP type: off, BUT6, BUT12, BES12, LR12, BUT18, BUT24, BES24, LR24, BUT48, LR48
  • LP freq: 20Hz-20kHz
  • Gain: -12dB to 12dB
  • LinkAB: Off, On
But for now I just want a good, safe starting point.

So I'm guessing XOVER: LP, 1000Hz?



Quote:
Originally Posted by lilmike View Post
...learn to set your limiter. The smoke and bad noises will happen before you can turn things down. If you set your limiter to 350 W, there's no real difference between that and the 315 W the amp's rated at in stereo. The difference is less than 1/2 of a dB, and since you're already at 120 dB, why go through the trouble?


Menu "LIMIT A#1" has the following options:
  • Thresh: -36dB to 0dB
  • RTime
  • Hold

And other menus for I/O, DELAY, DEQ, PEQ.
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post #40 of 64 Old 04-07-2015, 09:08 AM
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I believe you want a high pass to protect the sub. I'd think 20hz would be good, no? Butterworth 12db slope should be ok, if I am understanding what I've read thus far correctly. Low pass @ 100hz or so as well.

Can't help on the gain side as I don't know that one.
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post #41 of 64 Old 04-07-2015, 09:43 AM - Thread Starter
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I'm going to try to read through this again slowly and see if I can follow along...

https://www.avsforum.com/forum/155-di...l#post23037462

Quote:
Originally Posted by LTD02 View Post
Many have asked how to set this up in the iNuke DSP. The filters are the same.

Here is an example of how to set the filters i would suggest a 2nd order 16hz high pass filter.

iNuke can't set filters below 20hz, but that is no problem. We just start with one at 20hz, then add a little shelf to push it down to 16hz.

Here is exactly what to put into the iNuke DSP.

Step 1: On the FILTER tab, enter 2nd order High-pass filter at 20hz (Butterworth, 12db / octave)



Step 2: On the PARAMETRIC EQ tab, enter Filter 1, Gain -4db, Frequency 20hz, type: HS12

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post #42 of 64 Old 04-07-2015, 10:19 AM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post
Here is exactly what to put into the iNuke DSP.
Step 1: On the FILTER tab, enter 2nd order High-pass filter at 20hz (Butterworth, 12db / octave)
Step 2: On the PARAMETRIC EQ tab, enter Filter 1, Gain -4db, Frequency 20hz, type: HS12
Right now I'm just using the front-panel controls on the 3000DSP.

Here's what I entered for my interpretation of LTD's steps above:

XOVER A#1
  • HP type: BUT12
  • HP freq: 20.0 Hz
  • LP type: Off
  • Gain: 0.0 dB

PEQ A#1
  • Type: HS12
  • Freq: 20.0 Hz
  • Gain: -4.0 dB
  • Qual: 1.0 (selectable range is 0.1 to 10)

My AVR (Onkyo TX-NR626) volume goes from 0-72. My "normal" movie number is 50. When in the mood, I crank it up to around 60. With the settings above, I get one blinking indicator light on the iNuke knob when it's turned up 15/20 clicks (~2 o'clock position). The single light goes solid when I crank the iNuke knob all the way to 20/20 clicks (~5 o'clock position). I get 2 lights on the iNuke Channel B knob, even though nothing is hooked up to the Channel B output and the right-hand knob is turned all the way down (0/20 clicks).


I'll install the Behringer PC software, but I'm not sure if that will complicate things or simplify it.
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post #43 of 64 Old 04-07-2015, 11:21 AM - Thread Starter
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Ah... this makes a HUGE difference... I clicked thorough the audio settings on my Onkyo and subwoofer was set to -16. I changed that to 0 and NOW I'm getting the thumps I can feel in my chest and the puffs of air coming out of the mouth of the F20 which could blow out a candle.

Now I'm getting the 2nd and 3rd indicator light on the 3000DSP knob... but still not clipping when I crank it all the way.

So I think I'm ready for the next step...
https://www.avsforum.com/forum/155-diy-speakers-subs/1628609-setting-inuke-amp-gains.html
Quote:
Originally Posted by chalugadp View Post
I know there are more detailed articles but I asked a couple of people how to set gains on inuke amps for subs (others as well, i just own inukes) and ltd02 sent me a very logical explanation . I figured I'd make it a thread for others with the same question. Here's the steps :

the quick and dirty way is:
1. DISCONNECT your sub from the amp
2. get a bass heavy movie clip like War of the Worlds, Lone Survivor, Pacific Rim, etc.
3. play the track at full reference -0db on the avr ( make sure your speakers can handle this spl. If they can't turn volume up as high as speakers can play clean)
4. turn the gain on your amp up until the clip light comes on
5. if the clip light DOES NOT come on, increase your subwoofer/lfe trim until it does
6. if it still DOES NOT come on, you need a voltage increaser/bump box
7. if the clip light DOES come on, then your AVR have plenty of voltage the way it is set up
8. turn the amp gain down until the clip light only flickers when the track is played.
9. go back to your avr and turn the volume down
10. reconnect your sub
11. play the track and increase the subwoofer/lfe ON THE AVR if necessary leaving the gain knob on the amp alone
12. if that DOES NOT get you enough bass, then turn up gain on the amp by as little as possible because you will be eating into the amplifiers headroom trading off the possibility of clipping some signals for more spl on average.

Now I am sure something similar has been posted in many threads but its tough sometimes to find. Hope this helps someone.
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post #44 of 64 Old 04-07-2015, 11:55 AM
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if you like where your subwoofer level is relative to your mains and you don't clip the amp on big bass passages, you are done. :-)


also, when you enter a shelf filter, the quality factor doesn't matter (I saw a ? on PEQ A#1 above).

Listen. It's All Good.
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post #45 of 64 Old 04-07-2015, 11:57 AM
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Quote:
Originally Posted by Clarence View Post
I got 2" screws and they worked fine. They stick out maybe 1/4".

Here are the braces.





Next step is to run a bead of caulk along the corner edges. I did that with the PL before it dried, but just to make sure everything's air tight. I'm also going to run some caulk along the mounted rim of the driver. It's bolted in very tight on top of the PE speaker gasket, but I trimmed off the overhang and I'll run a bead of caulk just because.
just saw your picture... FANTASTIC!

Listen. It's All Good.
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post #46 of 64 Old 04-07-2015, 12:31 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post
if you like where your subwoofer level is relative to your mains and you don't clip the amp on big bass passages, you are done. :-)


also, when you enter a shelf filter, the quality factor doesn't matter (I saw a ? on PEQ A#1 above).
OK, thanks. I didn't even have a guess at what QUAL should set to.

I also added a low pass at 200 Hz... (is this a good number? or 500? 1k?)


XOVER A#1
  • HP type: BUT12
  • HP freq: 20.0 Hz
  • LP type: BUT12
  • LP freq: 200.0 Hz
  • Gain: 0.0 dB

PEQ A#1
  • Type: HS12
  • Freq: 20.0 Hz
  • Gain: -4.0 dB
  • Qual: 1.0

Quote:
Originally Posted by LTD02 View Post
just saw your picture... FANTASTIC!

Thanks! I'm going to keep playing with it tonight. Then tomorrow I'll do some final sanding to clean up some PL smears, round-over the edges with a router, apply 2 coats of Duratex, attach the metal corner guards, post some final pictures, then hide it behind my AT screen.
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I would put more bracing. Between panels 11/4, 10/9, 3/6. Don't let panel vibration rob you of SPL.

JSS
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If your AVR is handling the crossover duties--you don't need a low pass filter on the iNuke

My reasoning for bridging the iNuke and turning the adjustable limiter down around 5dB (350 watts) is to allow both channels to provide half the power and that should make the amp run cooler (in theory) This might help keep the fan noise down which is a good thing.

Game on!
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Quote:
Originally Posted by 18Hurts View Post
If your AVR is handling the crossover duties--you don't need a low pass filter on the iNuke

My reasoning for bridging the iNuke and turning the adjustable limiter down around 5dB (350 watts) is to allow both channels to provide half the power and that should make the amp run cooler (in theory) This might help keep the fan noise down which is a good thing.

Game on!
That's a good idea for 1 sub, BUT....
Then he will have to rewire when he builds the second one to get individual dsp for each one.
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Quote:
Originally Posted by More is Better View Post
That's a good idea for 1 sub, BUT....
Then he will have to rewire when he builds the second one to get individual dsp for each one.
True--just an option until the second sub is built. He can also build four of the F-20's and run a 4 ohm load on each channel--More Is Better!

I find when building two subwoofers, the second one takes about 5 times longer than the first once due to already having one working. Gives you time to reconfigure the amp around 10 times to get the best sound. Also gives time for the back to heal up and get stronger--horns are heavy!
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post #51 of 64 Old 04-08-2015, 06:08 PM - Thread Starter
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I used the router to round-over all edges. Removed the screws from the perimeter (most of the kreg pocket holes are on the inside, but the outside screws were just to hold until the PL adhesive dried).

I decided to leave the screws on the interior panels because I like seeing the horn path... kind of a bedazzle look. And I sanded everything down.

I love the Duratex. I used a foam roller so I got a nice, light texture. It was rainy here today, too cold to paint in the garage, so excuse the paint tarp on the basement floor...

First coat of Duratex:
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post #52 of 64 Old 04-09-2015, 03:45 PM - Thread Starter
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I finished painting the F20. Added the metal corners. Rolled it back into the HT with a handtruck.

I've never tried REW before, but I downloaded it and opened the UMM-6 calibration microphone I ordered from PE.

I skimmed AustinJerry's REW 101 Getting Started Guide. I didn't have an SPL meter so I ordered one. I thought the UMM-6 did SPL, but it looks like you use the SPL meter to calibrate the UMM levels.

Anyways, without knowing what I'm doing I ran my first tests in REW:
1) no subwoofer
2) one of my old 15" subs (Cerwin Vega LW15)
3) my other old 15" sub (DefTech Powerfield 15)
4) my new F20
5) F20 plus the stronger of the 15" subs (CV15)

The biggest surprise is that F20+CV15 has lower measured output than the F20 alone? Why?

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I thought of one more test to run... "before and after":
before = both of my 15" subs
after = F20

I must really be doing something wrong because the test of both subs is very similar to the results from just the DT15 alone.

Anyways, if I'm reading this correctly, the yellow highlighted area is the extra bass (~20dB?) that the F20 gives compared to my old 2 subs, right?

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post #54 of 64 Old 04-09-2015, 04:28 PM
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nice measurements. looks like another successful build.


"The biggest surprise is that F20+CV15 has lower measured output than the F20 alone? Why?"


it takes some time for the sound to travel down the horn path. that is the same effect as if the driver itself were about 15 feet or so further off in the distance. as a result the sine waves emanating from each sub will not be in phase and so can create cancellations. if you add about 15 feet or 15 milliseconds of delay to the cv15. the cv is also ported, which creates some more phase roll. i'm not quite sure if it is possible to eliminate that cancellation. normally it isn't a problem, but the cv15 is probably tuned pretty high, so I can see it mucking up the middle of the bass.
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post #55 of 64 Old 04-09-2015, 05:19 PM
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congratulations on your success
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post #56 of 64 Old 04-09-2015, 05:21 PM
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Nice! Do you know how many watts were you running?
Clarence, what are your impressions of the sound vs your ported subs.

Hypothetically, if someone built two and laid them on their sides with the mouths next to each other, you would get lower extension correct?
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post #57 of 64 Old 04-09-2015, 06:05 PM - Thread Starter
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Quote:
Originally Posted by dtmeyer View Post
Nice! Do you know how many watts were you running? ?

Is there something like a watt meter in the iNuke DSP software that will tell me?


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Originally Posted by dtmeyer View Post
Clarence, what are your impressions of the sound vs your ported subs.
I'm hooked. It just sounds so clean. I'm tempted to rewire it to 2-ohms just to push it harder. But it reminds me of the Calvin and Hobbes cartoon... to determine the load limit of a bridge, build it, then drive heavier and heavier trucks across it until it collapses, then just rebuild it. I really want to know the load limit of this sub.


On the Disney calibration bluray 20-200Hz sweep, my old subs would just fwop-fwop-fwop on the lows. But the F20 pumps out a growl. My wife called my build "the crooked box" because of the angles of the internal flares before I attached the final side panel. We cranked up some concert clips last night... she said "I don't know what that crooked box does, but I like it."


Trying to decide what to do with my other JBL 1514 and the other channel of my 3000DSP. I was originally torn between another F20 or the THTLP that I bought plans for. But now I'm tempted to try to build a folded horn sub within my 2nd row riser. I've got a rough sketch... basically using a full uncut 4x8 sheet of ply for top and bottom. And then use 2x10's as structure and as flares.


But the F20 fit nicely behind my screen and there's still room for one more. Maybe I'll build the riser AND another F20.
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post #58 of 64 Old 04-09-2015, 06:12 PM
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That is one sexy Monolith. It looks FANTASTIC!


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I used the router to round-over all edges. Removed the screws from the perimeter (most of the kreg pocket holes are on the inside, but the outside screws were just to hold until the PL adhesive dried).

I decided to leave the screws on the interior panels because I like seeing the horn path... kind of a bedazzle look. And I sanded everything down.

I love the Duratex. I used a foam roller so I got a nice, light texture. It was rainy here today, too cold to paint in the garage, so excuse the paint tarp on the basement floor...

First coat of Duratex:
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post #59 of 64 Old 04-09-2015, 07:08 PM - Thread Starter
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Here's the first rough sketch of my folded-horn riser sub made from 2 uncut 4x8 sheets of ply and 2x10's.

The main challenge was how to fit a 15" sub in a 10" riser. I'm hoping I can lay it flat, facing up, then build an angle above the baffle where the throat starts.

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post #60 of 64 Old 04-10-2015, 05:59 AM
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Quote:
Originally Posted by LTD02 View Post
nice measurements. looks like another successful build.


"The biggest surprise is that F20+CV15 has lower measured output than the F20 alone? Why?"


it takes some time for the sound to travel down the horn path. that is the same effect as if the driver itself were about 15 feet or so further off in the distance. as a result the sine waves emanating from each sub will not be in phase and so can create cancellations. if you add about 15 feet or 15 milliseconds of delay to the cv15. the cv is also ported, which creates some more phase roll. i'm not quite sure if it is possible to eliminate that cancellation. normally it isn't a problem, but the cv15 is probably tuned pretty high, so I can see it mucking up the middle of the bass.
OP, Take this advice and set your delays. Start by taking a measurement of the sub farthest away from your mlp. Then take a measurement of both subs together and increase the delay on the second sub until it graphs similar to the first sub but a few db's higher. Once you have a parallel or close to parallel line to the first sub measurement, you will have your delays set correctly. Then your subs will be playing nicely together. Like LTD02 said, you are going to need a lot more delay because of how horns work.
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