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post #1 of 13 Old 05-16-2012, 05:19 PM - Thread Starter
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Hi all, it has been a seriously long time since I have really been doing anything with my subs. Back in the fall I built 2 F20s to go with my THTs. My father passed away in December from a long battle with lung cancer, so everything I was doing from October till recently has been on hold. Im finishing up my theater room and decided to roll the F20s in and use them as my stage.


The F20 on the right is missing an access panel atm and a sub. The one on the left will just not play loud. I am using an EP1500(the same amp that has powered both THTs for over a year) and an MFW driver. My THTs are corner loaded, not sure if this makes a huge difference. I also never sealed the MFW drivers with silicone like I did the Dayton DVCs. Any idea what I might be doing wrong?
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post #2 of 13 Old 05-16-2012, 05:30 PM
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Sorry about your dad's passing - cancer sucks.

Did you check for leaks? Did you try switching the wires from the amp to make sure both channels are OK?
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post #3 of 13 Old 05-16-2012, 06:00 PM - Thread Starter
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He beat cancer 11 years ago, but this time it was stage 4.

Both channels work. how would I check for leaks?
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post #4 of 13 Old 05-16-2012, 09:03 PM
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Quote:
Originally Posted by Krbass View Post

He beat cancer 11 years ago, but this time it was stage 4.

Both channels work. how would I check for leaks?

Easiest way is with a lighter. Hold the lighter and move it around all the joints, especially the access panel while playing a test tone. If you see e flame move sideways due to air, you have a leak.
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post #5 of 13 Old 05-16-2012, 09:37 PM
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^^ what he said, they should be very loud. The most typical reason is leaking air.
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post #6 of 13 Old 05-17-2012, 02:27 AM
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Placement could also be having an affect on the sound too depending on what your version of "not very loud" is. I know if I push my F20 in the corner up against the wall the sound drops off big time compared to pulling it about a foot away from the wall. When you walk around the room does the F20 get louder in some spots?

Sorry to hear about your Dad btw... That's terrible news.
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post #7 of 13 Old 05-17-2012, 08:16 AM
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My condolences.

As far as the F-20's performance? Really - I can't help unless we have some data. Measure impedance and SPL, that way I have data to compare, and I can help identify a problem.

As others have said, leaks will kill the performance. Also, room placement is huge. Not that the F-20 is all that, but putting the best sub in the worst spot will still sound bad.

The F-20 is essentially in the same league as the THT, they measure within a dB and a Hz or two where it matters most. As I understand it, you have THTs, so if your F-20s do not compare, something is wrong with the F-20s, the signal feeding them, or the room placement.
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post #8 of 13 Old 05-17-2012, 10:43 AM
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I'll be home Saturday, I can stop over and help take a look this weekend if you want.

 

Originally Posted by Bill Fitzmaurice:
It's also the very sort of Voodoo Engineering that should never be done.

 

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post #9 of 13 Old 05-17-2012, 10:50 AM
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Quote:
Originally Posted by lilmike View Post

My condolences.

As far as the F-20's performance? Really - I can't help unless we have some data. Measure impedance and SPL, that way I have data to compare, and I can help identify a problem.

As others have said, leaks will kill the performance. Also, room placement is huge. Not that the F-20 is all that, but putting the best sub in the worst spot will still sound bad.

The F-20 is essentially in the same league as the THT, they measure within a dB and a Hz or two where it matters most. As I understand it, you have THTs, so if your F-20s do not compare, something is wrong with the F-20s, the signal feeding them, or the room placement.


Hi lilmike,

or it is the leaks or worst spot. Could you tell me how long is the horn path in the F-20 and if you know how long is the horn path in the THT. Thanks.
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post #10 of 13 Old 05-17-2012, 12:56 PM - Thread Starter
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I will post results later after work. I also plan on corner loading it in the same place I had the tht.
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post #11 of 13 Old 05-17-2012, 03:36 PM
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Quote:
Originally Posted by ZivkoF View Post

Hi lilmike,

or it is the leaks or worst spot. Could you tell me how long is the horn path in the F-20 and if you know how long is the horn path in the THT. Thanks.

All the F-20 information is in my thread fully documenting it.

THT information is tied to owning the plans. I bought a copy years ago, long before I learned how to design and fold my own horn cabinets.
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post #12 of 13 Old 05-17-2012, 05:06 PM - Thread Starter
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OK so I got home and got the f20 into the THTs spot. Room placement matters more than I ever knew. My house is splitting in half. Can't wait to have all 4 subs corner loaded.

As a side note I checked with a lighter and one screw in the access panel was missing. Sounds the same with or without it filled.
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post #13 of 13 Old 05-17-2012, 08:12 PM
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Quote:
Originally Posted by Krbass View Post

OK so I got home and got the f20 into the THTs spot. Room placement matters more than I ever knew. My house is splitting in half. Can't wait to have all 4 subs corner loaded.

As a side note I checked with a lighter and one screw in the access panel was missing. Sounds the same with or without it filled.

Glad it was an easy fix.
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