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Post by phatfos1 on Oct 31, 2013 18:51:29 GMT -5
Hello. I am just starting out with a DIY sub build. First thing I bought was a Behringer EPX4000. I'm already in trouble. As soon as I plug the pre outs (RCA) from my Denon 3808 into the new Behringer I get a low frequency hum that is clearly not normal. If I go straight into the Behringer with the RCA out of my iPad and then out to a speaker all is well. It's connecting the Denon to the Behringer that seems to create the hum. I hesitate to call it a "hum" because it's pretty loud. Very obviously not normal. I thought perhaps it was a voltage issue or something. But I am really at a loss. Unplugging everything and only having one speaker connected to the Behringer with one source (I've tried various sources--HDMI, Comp. etc.) into the Denon and then out to the pre outs results in the same issue. No ground loop because I've tried various outlets. Any idea what could cause this issue?
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Post by GreenKiwi on Oct 31, 2013 21:24:44 GMT -5
Is it a ground loop 60hz hum?
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Post by PGT on Oct 31, 2013 21:32:05 GMT -5
swap RCA's out with a different set between the AVR and the amp. I've seen more than a few RCA's with a bad ground weld. Easy to fix if you've got a soldering iron.
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Post by phatfos1 on Oct 31, 2013 21:51:53 GMT -5
I tried several different RCA cables. I used a tone generator and yes, it's 60hz. The Denon does not have a ground plug on the power cable but the Behringer does. So does my XPR, though. Really frustrating. I've been switching cables for two hours. I've unplugged every last wire, cable and power cord in my system. And there is a lot of crap in there!
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Post by phatfos1 on Oct 31, 2013 22:01:39 GMT -5
To clarify, I have been using Source to Denon to XPR to Speakers. When I go Source to Denon to Behringer (.1 Channel)+XPR(5. Channels) to Speakers the issue presents itself. If I take the Denon out of the mix it's fine. If I leave the Behringer out of the mix (as I was before) it's fine. So it's the Denon and the Behringer not playing nice.
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Deleted
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Post by Deleted on Nov 1, 2013 0:04:10 GMT -5
na, unplug your cable/sat box (if one is hooked up) and see if it goes away. It's not your denon or the amp, you have a bad ground somewhere and cable boxes are the first thing to look at. Next, try a cheater plug on the amp, if the humm goes away, it's for sure a bad ground. Pro amps tend to bring out the noise in an otherwise noiseless system lol
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Post by phatfos1 on Nov 1, 2013 11:07:12 GMT -5
Hmm there's no third prong on the Denon power cord. What is a "cheater plug"? I unplugged every last thing in the system. Only thing plugged in was the EPX and the Denon. Denon works fine on its own or with the XPR As the amp stage. EPX works fine from my iPad RCA cable. Connecting the two creates the hum. Should I get an RCA to balenced and see if that helps?
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Post by garym on Nov 1, 2013 13:16:58 GMT -5
You might try the Zone 2 and 3 pre-outs. Does the hum occur on both L & R main pre-outs?
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Post by GTPlus on Nov 1, 2013 14:12:17 GMT -5
You stated the XPR and Behringer have ground prongs. Maybe a ground loop through outlet->XPR->Denon->Behringer>outlet. Is the Hum present when the XPR is not connected to the Denon?
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Post by dally on Nov 1, 2013 14:21:58 GMT -5
It definitely sounds like a ground loop. Is everything plugged in to the same outlet? If not try plugging everything into the same outlet. If it is a ground loop this will usually stop it. Not a permanent solution, but it will at least help you diagnose the problem. A "cheater" plug is a three prong to two prong adapter. There is no ground prong, so it lifts the ground when you attach it.
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Deleted
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Post by Deleted on Nov 1, 2013 15:38:26 GMT -5
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Post by phatfos1 on Nov 1, 2013 16:36:46 GMT -5
XPR has a ground. Denon does not. Behringer has a ground. Taking XPR out of the mix doesn't change the hum. Whenever the Behringer is in the mix with the Denon the issue is there. Plugging everything into the same outlet doesn't help. I will go buy the cheater plug. Denon and Behringer were of little assistance. Both said it was a problem cause by the other unit.
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KeithL
Administrator 
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Post by KeithL on Nov 1, 2013 16:50:07 GMT -5
Try simply running a chassis ground wire between the Behringer and the Denon. (A wire with one end under a screw on the case of the Denon and the other end under a screw on the Behringer. Scrape off a little paint if necessary to ensure that the wire makes good contact at each end. Or, even easier, just HOLD the wire against both chassis - some clean metal portion - and see if it fixes the problem; if so, then find some screws to make the connection permanent.) XPR has a ground. Denon does not. Behringer has a ground. Taking XPR out of the mix doesn't change the hum. Whenever the Behringer is in the mix with the Denon the issue is there. Plugging everything into the same outlet doesn't help. I will go buy the cheater plug. Denon and Behringer were of little assistance. Both said it was a problem cause by the other unit. |
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Post by phatfos1 on Nov 1, 2013 19:33:44 GMT -5
Love this forum. Always cool folks willing to help. It was in fact a really bad group loop. The Behringer just made it very audible. All my power outlets in the theater room is apparently on one line. I used an extension chord to another floor and the system is silent again. And now I have "4000" watts to play with on my sub project ;-) probably more like 1500.
Thanks so much everyone. The help is greatly appreciated.
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Deleted
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Post by Deleted on Nov 1, 2013 19:56:20 GMT -5
Well, now that you know for sure the problem, you get to try and fix it!!! LOL ahhh the REALLY fun part!
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Post by Jim on Nov 1, 2013 20:01:05 GMT -5
Love this forum. Always cool folks willing to help. It was in fact a really bad group loop. The Behringer just made it very audible. All my power in the theater room is apparently on one line. I used am extension chord to another floor and the system is silent again. And now I have "4000" watts to play with on my sub project ;-) probably more like 1500. Thanks so much everyone. The help is greatly appreciated. If you're in bridged mode @4 ohms, you're looking at around 1957 watts  Around 1300 in 8 ohms. A great link: www.avsforum.com/t/855865/measuring-amplifiers/0_100#post_10755565If you scroll up, you can see other testing that was done in 4/8 in stereo. The EP4000 and EP2500 are basically the same amp. |
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selkec
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SCREW YOU GUYS, IM GOING HOME!!!
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Post by selkec on Nov 3, 2013 8:35:06 GMT -5
Hello. I am just starting out with a DIY sub build. First thing I bought was a Behringer EPX4000. I'm already in trouble. As soon as I plug the pre outs (RCA) from my Denon 3808 into the new Behringer I get a low frequency hum that is clearly not normal. If I go straight into the Behringer with the RCA out of my iPad and then out to a speaker all is well. It's connecting the Denon to the Behringer that seems to create the hum. I hesitate to call it a "hum" because it's pretty loud. Very obviously not normal. I thought perhaps it was a voltage issue or something. But I am really at a loss. Unplugging everything and only having one speaker connected to the Behringer with one source (I've tried various sources--HDMI, Comp. etc.) into the Denon and then out to the pre outs results in the same issue. No ground loop because I've tried various outlets. Any idea what could cause this issue? How do you use rca cables to connect the denon to the ep4000?  I have 2 ep4000 and there is no rca inputs |
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Deleted
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Post by Deleted on Nov 3, 2013 9:49:45 GMT -5
Hello. I am just starting out with a DIY sub build. First thing I bought was a Behringer EPX4000. I'm already in trouble. As soon as I plug the pre outs (RCA) from my Denon 3808 into the new Behringer I get a low frequency hum that is clearly not normal. If I go straight into the Behringer with the RCA out of my iPad and then out to a speaker all is well. It's connecting the Denon to the Behringer that seems to create the hum. I hesitate to call it a "hum" because it's pretty loud. Very obviously not normal. I thought perhaps it was a voltage issue or something. But I am really at a loss. Unplugging everything and only having one speaker connected to the Behringer with one source (I've tried various sources--HDMI, Comp. etc.) into the Denon and then out to the pre outs results in the same issue. No ground loop because I've tried various outlets. Any idea what could cause this issue? How do you use rca cables to connect the denon to the ep4000? I have 2 ep4000 and there is no rca inputs there is rca iputs on the EPX model though www.behringer.com/EN/Products/EPX4000.aspx |
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Post by phatfos1 on Nov 3, 2013 13:00:54 GMT -5
I have the EPX. That model comes with RCA inputs. It also has balanced and a few other types. |
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Post by phatfos1 on Mar 25, 2014 10:44:14 GMT -5
Done. Did a 3cf cube sealed with 1" Baltic Birch double baffle double back. Using my Denon 3808ci to manage the bass while I figure out how to use a MiniDSP. I used the LMS-R 15 and a Behringer EPX-4000 bridged into the 4ohm configuration instead of a 5400 Ultra so that I can do two for about the same price and have them even out the response in the room (this was recommended by the owner of TC Sounds). I swapped the fans in the amp and it's dead silent unless I'm a foot away. It was intolerably loud prior to the swap no way it could be in the same room. I am very happy with this sub, though I did go through some trials and tribulations (two defective TC subs with unglued spiders and a nasty ground issue with the Behringer discussed above--the latter was "fixed" with a cheater plug recommended by N8DOGG, thank you!) It sounds fantastic. It looks like the Denon is boosting quite a bit from about 18hz-32hz given the EQ plot it shows in the "check crossover" section. I get lots of output down to 20hz, really shaking everything. When I play 15hz tones I can't hear it, obviously, but it will rattle the plates in the kitchen on the first floor quite a ways away from the listening room. I have a very difficult room with very little gain in the lower octaves it seems, but this sub has really brought the movie experience to the next level. It's a "loft" type room with the entire back wall open to the first floor. The room is about 20ft x 22ft. I'm going to do a second like this when time permits, but this took longer than I thought it would. I must say, finishing box with stain, clear, wet sanding and polish was labor intensive but certainly worth the effort as the box has what I would call a furniture-grade finish that I prefer. For a first effort I'm happy. I will get a few shots of it in my listening room tonight. The first photos are after 400 grit. I went to 800, 1500 and finally 2000 grit prior to thorough buff with Meguiar's Ultimate Compound. All in I have about $1000 into this sub and maybe five or six hours of weekend time (a valuable commodity these days!) I can say without a doubt it sounds as good as the JL Audio F113 I've heard a few times although I know that some further tweaks with the MiniDSP will really flatten things out even more. |
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Around 1300 in 8 ohms.
