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post #91 of 155 Old 03-17-2012, 11:44 AM
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Quote:
Originally Posted by Brad Horstkotte View Post

Are you sure its the driver bottoming out? I ask because I thought the same thing early after setting mine up, but in my case it was digital clipping - I had the signal running too high from the AVR to my EQ, forcing it into clipping - after reading more about gain structure, I turned up my power amp, turned down the AVR sub trim level, and all was well.

+1

Turn up the gain on the amp and (if you have to) lower the output on the receiver.

That should help a bit.

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post #92 of 155 Old 03-17-2012, 12:51 PM
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I know when I had my cheap RCA cables from a slipper my AVR didn't auto calibrate it because the gain was too high, but with a single line in jack the gain could be turned up higher. I think the sticky on sub hookup says turn turn gain to half power and set the AVR level to -5.0 dB and then adjust gain from there to your liking.
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post #93 of 155 Old 03-17-2012, 03:01 PM
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Sounds like there is still hum without the subwoofer cable connected to the amp. Does speaker wire pick up power cable interference easily? I just use standard 14 ga. wire from the amp to the sub. I know theater plugs are frowned upon so is there a more acceptable way use it? I was thinking of making a wood housing with leftover plywood, would that be okay? I'm not familiar with what could go wrong with an amp. I do know wood is not a conductor but it also burns very well. I've always tinkered with the idea of making a work computer case too, but figured it's a fire hazard.
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post #94 of 155 Old 03-17-2012, 03:19 PM
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Quote:
Originally Posted by anikun07 View Post

Sounds like there is still hum without the subwoofer cable connected to the amp. Does speaker wire pick up power cable interference easily?

Speaker cable does not pick up any hum. If the amp hums with no input connected it's defective.

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post #95 of 155 Old 03-17-2012, 03:24 PM
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A wood enclosure should work fine. They are made to be "installed" in a sub box which is wood. You may just want to make sure you allow it to breathe, but that may not even be too crucial due to the fact that they can be mounted in sealed subs as well. Still would probably be wise.

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post #96 of 155 Old 03-17-2012, 03:26 PM
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Thanks Bill, I didn't hear any humming last night, but for some reason I noticed it today. I'll check it out on a different outlet with no input. The electrical in my house is a little abstract in terms of which outlets are on which breakers. I think the logic was to wire it in whichever way was most convenient. Would it be A-Okay to make a box for the plate amp to sit in?

And by the way, you designed a fantastic subwoofer!
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post #97 of 155 Old 03-17-2012, 03:27 PM
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Thanks Dbl! Heh, we're typing at the same time.
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post #98 of 155 Old 03-17-2012, 03:29 PM
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I wonder if the slight hum you are hearing is the "low quality" amp itself. Not a knock on the amp, really. I run my THT off of an ep2500 and when I turn the gain to 100% on the amp, I hear a slight hum too. I have it at about 90% and the hum goes away.

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post #99 of 155 Old 03-17-2012, 03:35 PM
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Definitely play with the amp gain. There is no way it is bottoming out at the level you were playing it. I have run mine to 26+ volts with no bottoming.

I used a cheater plug on mine also. It helped quite a bit but, I still shut the amp off when not in use.
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post #100 of 155 Old 03-17-2012, 03:35 PM
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I just tried it with a cheater plug and as I raise gain and/or the high pass filter it will increase the volume of the gain. If I touch the cooling fins the hum decreases a lot BUT if I touch the plastic housing of the back it slightly, but noticeably, make the hum louder.
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post #101 of 155 Old 03-17-2012, 03:45 PM
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It also does it without a cheater plug. I did test it that with the subwoofer cable plugged in and the AVR on I think it's the same amount of hum. But when I yank the cable out if the line in on the amp it makes a pop sound and then it seems silent. I also have my ear inside the port so maybe that amount it normal, I don't know. Is there a way to ground the chassis/cooling fins? I'm not sure what I would connect the wire to. On the amp I would loosen a screw on the front, but would I just connect it to the outlet? Is the center screw that holds the outlet cover on connected to the ground if the outlet is grounded?
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post #102 of 155 Old 03-17-2012, 04:08 PM - Thread Starter
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It was digital gain. Thanks for the pointers! I recalibrated with audyssey and everything is playing together really nicely. I just listened to that seen from HTTYD again and hit 115db at LP and didn't hear that popping noise at all. I'm loving finally having a great sub! I have a pile of blu-rays sitting next to my Dune that I've been going through for the last couple of hours. I've been running the sub about 3db hot. Do most people run it a little hot or try to leave the calibration flat? I've read about house curves etc. and I guess I'll just tune to taste but was curious what others were setting their LFE at.

Hopefully you get that hum figured out Anikun. For the life of me, I have no ideas left. I dealt with that amp for a while and, at this point, think it may be a design flaw.

I had the clipping light blinking on the EP4000 during the pod emerging scene and was wondering, do other EP owners leave that clip limiter on or off?
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post #103 of 155 Old 03-17-2012, 04:11 PM
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Glad to hear the good news! I'm quickly making a housing for the amp. I will try ground the chassis to the outlet too and report back. I'm sure once there's a feed going to the LFE I won't hear it but it's pretty annoying when it's idling
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post #104 of 155 Old 03-17-2012, 04:47 PM
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Aud calibrates mine on the low side. So afterwards, I just increase it to where I like. I do the same for the center as my hearing isn't as good as it used to be. Wonder why...
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post #105 of 155 Old 03-17-2012, 05:03 PM - Thread Starter
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WOW! I just listened to a four minute drum solo and the kick drum was hitting just over 120db. Double kicks were tight, accurate, and packed a wallop. I truly felt like I was at a major live concert in the front. It was just an awesome feeling that I've been craving at home for years and finally have. This thing is just insane I love it! This is leaving the rest of my Def Tech system in the dust. I need high sensitivity mains and more juice to keep up with the THT.

Is there an end to this hobby?
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post #106 of 155 Old 03-17-2012, 05:07 PM
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That's why I made my TLAHs. Lots of choices for fronts.

Current HT: HTPC-->Epson 5010 projector-->135" screen, BFM TLAHs x7 & THT
Build log: DIY rotary sub for contemporary HT in 100 year old house?
Andreas' Slow Rotary Sub build
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post #107 of 155 Old 03-17-2012, 05:09 PM
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I created a simple housing for the amp to keeping vertical and not resting at an angle.


I did my final test on what creates hum and what doesn't. If I have the subwoofer connected to the AVR and the amp is grounded there is hum. If I use a cheater plug the hum is removed. If I use a cheater plug and then I ground the chassis to the outlet (the screw holding the outlet cover on) it will hum. So my conclusion is that any kind of ground will create a hum. My solution will be to use a cheater plug to remove the ground. I have all my devices plugged into a surge protector that has an LED to tell me that it's grounded, so I think all will be good with it. I just need to find a place for the amp to go.

Thank you for all the help, I can't wait to get this goin'!
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post #108 of 155 Old 03-17-2012, 05:10 PM
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Oh, and I also tried using the amp chassis ground to the neutral blade of the cheater and it also created a hum. Just wanted to add that.
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post #109 of 155 Old 03-17-2012, 05:40 PM
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When you say the electric isn't great in your house and you are trying to eliminate hum, it's good to know if your outlet is really grounded or not. People put three prong outlets in boxes with only 2 wires which makes for an ungrounded outlet. Buy or borrow and outlet tester so you know what you are dealing with. If you run a wire to the outlet cover screw of an ungrounded outlet, it will do nothing.
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post #110 of 155 Old 03-17-2012, 05:53 PM
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Quote:
Originally Posted by anikun07 View Post

Oh, and I also tried using the amp chassis ground to the neutral blade of the cheater and it also created a hum. Just wanted to add that.

You may be running under the assumption that ground loops are caused by insufficient grounding. They're caused by too much grounding, as in more than one ground path. This explains causes and cures:
http://www.rane.com/note110.html

And never user a 'cheater'. What you're cheating is death... most of the time. Disconnect ground paths on the interconnect cable.

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post #111 of 155 Old 03-17-2012, 06:05 PM
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Thanks Bill, I've read that page along with many others but I've haven't read anything or at least understood anything that would alleviate this situation. How is the ground path removed on the interconnect cable? Would grounding the chassis of the AVR remove that ground or would a ground loop isolator be needed?

I was also wondering if anyone put a cover over their THT opening? I definitely need this as it will get covered in cat fur. Right now because it's unfinished it's like a fur magnet, but once painted it won't be so bad. Our cat's tree gets to be right next to the sub and I think one has already claimed it as his perch.

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post #112 of 155 Old 03-17-2012, 06:08 PM
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Not only is it his perch but it's now also his cave. He's the biggest cat and of course he's the one to try and go inside for a nap.

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post #113 of 155 Old 03-17-2012, 08:28 PM
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I picked up a ground loop isolator from Radioshack this evening and am using that for the interconnect. I just wonder about the cables being so skinny, unlike higher quality shielded cables.
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post #114 of 155 Old 03-17-2012, 08:34 PM
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Quote:
Originally Posted by anikun07 View Post

How is the ground path removed on the interconnect cable?

Break the shield on one end. That's most easily done with a new RCA connector, though it can be done with a molded cable. Also make sure your TV cable is transformer isolated; that adds a ground path to the system running all the way to where the cable enters the building, and noise is proportional to the square of the ground loop path distance.
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I just wonder about the cables being so skinny, unlike higher quality shielded cables.

The size of the cable is no indication of quality, and for that matter the 'quality' requirement for sub interconnects is minimal. Just about anything will do.

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post #115 of 155 Old 03-17-2012, 09:08 PM
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The ground loop isolator reduced the entire LFE signal too much so that won't work. I had to turn the gain all the way up in order to get a reasonable volume and that was with both R/L inputs connected. I can't hear it from my main seating position, so maybe I'll just try to forget about it, but it's going to bother me knowing that it's there. I bought a stereo Auvio cable (Radioshack high end) to give the amp both line ins, I know it's not a must but it adds 3 dB from what I've read. Maybe I'll send the Dayton back.
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post #116 of 155 Old 03-17-2012, 09:20 PM
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Quote:
Originally Posted by anikun07 View Post

Not only is it his perch but it's now also his cave. He's the biggest cat and of course he's the one to try and go inside for a nap.


Set your camera on record, and crank that thing up
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post #117 of 155 Old 03-17-2012, 09:36 PM
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With him I doubt it would do much. But I certainly considered running a test sweep.
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post #118 of 155 Old 03-18-2012, 05:22 AM
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My cats do the same thing with my F20. The F20 is so tall though that I don't have to worry about them getting up in the horn. If your cats are as adventurous as mine (and they probably are) I wonder if there's a remote chance they could venture up in the horn of that and possibly get stuck in there.

I wonder if adding a few more braces to the mouth would make the holes too small for him to enter...
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post #119 of 155 Old 03-19-2012, 01:54 PM
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I decided to make a screen for the opening. Forgive the low quality of the picture I doodled it in go sms. The red will be a flange like the access cover has and then the blue will be identical to it, or marginally smaller with a mesh stapled to it. Maybe i'll use some sort of towel or pins to help keep it in place.

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post #120 of 155 Old 03-19-2012, 02:32 PM
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that might constrict the mouth of the THT causing some ill effects, but Bill will have to chime in there.

(European models do not accept banana plugs.)

 

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