SuBXeRo Posted February 15, 2011 Share Posted February 15, 2011 I just called emotiva to talk to a tech about my xpa-5 power amp. Not doubting their knowledge on the subject but i'd like some others input on the subject. I apparently have about 1-2 very sensitive channels in my amplifier and its amplifying a low level hum (sounds like a ground loop hum). They are saying that the tolerances of the components can be such that it will "embellish" some of the noise. Not all of my channels make this hum noise, i can identify the loudest one, it is the same everytime, no matter what is hooked up to it, as long as 2 or more channels are receing a signal from my phone via rca-mini jack or from my umc-1, that channel is the loudest when a connection is made from either the XLR or RCA jack. I also tested to ensure that the sensitivty of the rf-5's wasn't the cause and well, what better to test it with than a bose speaker. What the F do you know, hum noise is still present and just as loud. They suggested i purchase a RCA line attenuator to reduce the gain of the channel as a possible solution. Basically, i felt like i kinda got a cold shoulder with the issue, like its "normal". Is it normal? Is this what you get for hifi at a sub 1000 dollar price tag? Is this something i would/should expect from a parasound or B&K amp? Edit: Read the newest post down below! Quote Link to comment Share on other sites More sharing options...
Rich_Guy Posted February 15, 2011 Share Posted February 15, 2011 I have never had any hum issues with either my XPA-5 or XPA-3 but I have started using attenuators at my amp inputs and like what they do for the overall sound quality. Here's a good article on using attenuators http://www.enjoythemusic.com/magazine/equipment/0803/rothwell.htm'> http://www.enjoythemusic.com/magazine/equipment/0803/rothwell.htm I really like the result, I have -15db on all my amp inputs I use the XLR type as pictured. Regardless of the hum issue you might want to try some attenuators. But as far as the hum issue goes if you are sure it is the amp, I bet that if you are a little more persistent that Emotiva will exchange your amp for another. Quote Link to comment Share on other sites More sharing options...
Rivernuggets Posted February 15, 2011 Share Posted February 15, 2011 The XPA-3 I had did not have a hum. They are saying that the tolerances of the components can be such that it will "embellish" some of the noise. If attenuators do not solve the issue, I agree with Rich in getting a replacement amp from Emotiva. One where the tolerances of the components do not embellish some of the noise. Your ear is now trained and tuned into this hum. It will be hard to enjoy music and HT at this point. Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted February 16, 2011 Author Share Posted February 16, 2011 to me, the suggestion of an inline attenuator was kind of a slap in the face. I asked what we could do to fix the issue, what were my options and this is what the guy suggested. To me, this is a now, $900 dollar unit with an issue from the manufacturer andan attenuator is hiding the problem, not fixing it. I, for the time being have moved the bad channel to one of my rears where i dontreally notice it but the hum is still just as prevalent. My fronts are pretty much dead quiet, one is for sure, the other has a slight hum to it as well. Attenutors, after reading the article, are something i would explore if i believed, or was looking to change what i hear. The xpa-5 is meant to accept those higher voltage inputs from the umc-1 so to me, reducing that gain shouldnt have to happen. I mean, when i call, i feel on the ignorant side with them. Like i always feel like they are thinking im trying to take advantage of them. I dunno, just the feelin that i get. I can say it felt more friendly when i first bought the equipment but now it seems to have dwindled. Maybe its because of everything going on and i am agitated with it. Its also one of those things where, if something is wrong, i have to ship it back, its not like a brcik and mortar store where i can bring it in and go, loook, look what it does, Quote Link to comment Share on other sites More sharing options...
Rich_Guy Posted February 16, 2011 Share Posted February 16, 2011 Attenutors, after reading the article, are something i would explore if i believed, or was looking to change what i hear. The xpa-5 is meant to accept those higher voltage inputs from the umc-1 so to me, reducing that gain shouldnt have to happen. I would look at getting rid of the hum at the source not through attenuators, if necessary exchanging the amp with Emotiva. If you return a defective amp to Emotiva they normally send you the replacement amp and include a prepaid shipping label for you to send the return amp back to them at their cost. But don't think that the XPA-5 is meant to accept the higher voltage outputs. Actually Emotiva amps are designed with a very high gain (32db), this along with high voltage outputs of the UMC-1 (common in most pre/pros today) and add to that efficient Klipsch speakers, attenuators are absolutely perfect for this combo. Here is some more on adding attenuators http://www.rothwellelectronics.co.uk/html/attenuators.html I think you will like what adding attenuators will do to the sound quality, they will make a very noticeable improvement to music adding new levels in detail. Here is a link where you can buy them at a good price, you can try them to see if you like the change and they have a good return policy if you don't. Available in either RCA or XLR. http://www.parts-express.com/1/1/9714-dayton-audio-xatt20-line-xlr-attenuator-pad-15db.html Quote Link to comment Share on other sites More sharing options...
carbon summit Posted February 16, 2011 Share Posted February 16, 2011 I also own a UMC-1 and XPA-5. I have no hum. Emo made both to work together, so I can't imagine the voltage output of the UMC-1 is an issue. One thing to keep in mind is how many guys over at the Emo Lounge have the UMC-1 mated with XPA 3s and 5s and don't complain about humming. SuBSXeRo, I've seen you over there so I'm sure you hear where I'm coming from. There would be thread after thread complaining about it if it was a common issue. I don't think it is. I think you've got a bad XPA-5. How long have you had your XPA-5? Hopefully you're in your 30 days, then you'd have a little more wiggle room with them. But if not I can't imagine they are not going to stand behind an amp with a 5 year warranty with a guy who has purchased an amp and a pre/pro from them recently. I'm actually surprised they have hassled you at all about it with work arounds instead of just offering to fix the amp. I hope things are not going down hill in their customer service because that was always their strong suit and the reason I've done business with them. Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted February 16, 2011 Author Share Posted February 16, 2011 I called emo again today and again got xfered over to their tech support and it was kind of the same run around. Well, i put my foot down and twisted it a little bit with them and told asked them, is this the quality i should expect for a 900 dollar amp or is this something i should worry about in a brystol amp or a parasound. I Said, line attenuators will hide the problem and not fix it. He thinks its not the amp because when one channel is plugged in, there is no hum, but when a second channel is applied a signal, the hum starts. He thinks its an externality. Well, i tested it with my phone, and my umc-1, two completely different devices, one connected to sa wall, one with its own power generation and the same problem happen. That kind of tells me that its the amp right? None the less, i am shipping it in for repair, i told em that this was unacceptable and the root cause needs to be fixed. And i was honest too, i told them, look, my expertise in this area is none compared to yours but something is amiss here, and tbh, i dont think that im in the wrong with this, not after all of themonths of troubleshooting i have done. Quote Link to comment Share on other sites More sharing options...
nezff Posted February 16, 2011 Share Posted February 16, 2011 I have a brand new home with brand new wiring. I should be ok and not have ground loops. I have a xpa5 also, when turned on, I get just a hiss in all my speakers, when the onkyo is turned on, I get a very very small buzzing hum. You actually have to put your ear inside the horn to hear it. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted February 16, 2011 Moderators Share Posted February 16, 2011 You actually have to put your ear inside the horn to hear it. What are you doing with your ear INSIDE the horn? LOL Quote Link to comment Share on other sites More sharing options...
Olorin Posted February 17, 2011 Share Posted February 17, 2011 I called emo again today and again got xfered over to their tech support and it was kind of the same run around. Well, i put my foot down and twisted it a little bit with them and told asked them, is this the quality i should expect for a 900 dollar amp or is this something i should worry about in a brystol amp or a parasound. I Said, line attenuators will hide the problem and not fix it. He thinks its not the amp because when one channel is plugged in, there is no hum, but when a second channel is applied a signal, the hum starts. He thinks its an externality. Well, i tested it with my phone, and my umc-1, two completely different devices, one connected to sa wall, one with its own power generation and the same problem happen. That kind of tells me that its the amp right? None the less, i am shipping it in for repair, i told em that this was unacceptable and the root cause needs to be fixed. And i was honest too, i told them, look, my expertise in this area is none compared to yours but something is amiss here, and tbh, i dont think that im in the wrong with this, not after all of themonths of troubleshooting i have done. How did you test with your phone? With a 3.5 mm headphone to stereo RCA cable? Quote Link to comment Share on other sites More sharing options...
Rich_Guy Posted February 17, 2011 Share Posted February 17, 2011 You actually have to put your ear inside the horn to hear it. What are you doing with your ear INSIDE the horn? LOL What's that you say sonny? [] Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted February 17, 2011 Author Share Posted February 17, 2011 I called emo again today and again got xfered over to their tech support and it was kind of the same run around. Well, i put my foot down and twisted it a little bit with them and told asked them, is this the quality i should expect for a 900 dollar amp or is this something i should worry about in a brystol amp or a parasound. I Said, line attenuators will hide the problem and not fix it. He thinks its not the amp because when one channel is plugged in, there is no hum, but when a second channel is applied a signal, the hum starts. He thinks its an externality. Well, i tested it with my phone, and my umc-1, two completely different devices, one connected to sa wall, one with its own power generation and the same problem happen. That kind of tells me that its the amp right? None the less, i am shipping it in for repair, i told em that this was unacceptable and the root cause needs to be fixed. And i was honest too, i told them, look, my expertise in this area is none compared to yours but something is amiss here, and tbh, i dont think that im in the wrong with this, not after all of themonths of troubleshooting i have done. How did you test with your phone? With a 3.5 mm headphone to stereo RCA cable? Yes, exactly. I dont really have much else i could test with but in the end, it presented the issue thsat i had been having so it actually worked out nicely and was electrically isolated, in the end, i suppose it turned out to be a great way to test. Quote Link to comment Share on other sites More sharing options...
Olorin Posted February 17, 2011 Share Posted February 17, 2011 Yes, it was the best way to test the amp in isolation. Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted March 9, 2011 Author Share Posted March 9, 2011 I received my XPA-5 in the mail on monday!! woot I hooked it back up and the hum is still there in one channel. Nick over at emotiva serviced my unit, fixed the one blinking status LED and the other super bright LED which had been driving me bonkers. Well, they sent me all the test schematics with the results and everything falls within the parameters that Emotiva has set for the XPA-5 unit. So at this point, im left with the idea that there is some sort of groundloop in the system no matter what or noise is somehow being introduced into the XPA-5. The one thing i wanted to ask, but i assume they did was an actual listening test. I mean, it sounds stupid but i get the feeling that they just did the tests via diagnotic tools and that was it. I think my next test method will be to use a ground loop isolator. A cheap one, i just want to see if this is indeed a ground loop. I do have a slight hum in another channel, not as loud, the one channel just may be more sensitive and is amplifying the loop more. I guess after having sent it in, i atleast know from a diagnostic standpoint that there is nothing wrong and everything is within spec. If it comes down to it, i might have to plunk down cash and get a good jensen filter, i mean in the future when i have like 100+ to dump into them. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted March 9, 2011 Moderators Share Posted March 9, 2011 Do you have a friend that you can take your amp to and hook up to his system? That would be one sure way to see if it is a problem with your setup or electrical. If you get no hum, then see if you can hook up another receiver. Through a process of elimination, you should be able to narrow it down to either a component issue or an electrical issue. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted March 9, 2011 Share Posted March 9, 2011 I think my next test method will be to use a ground loop isolator. A cheap one, i just want to see if this is indeed a ground loop. If it comes down to it, i might have to plunk down cash and get a good jensen filter, i mean in the future when i have like 100+ to dump into them. I can send you my Jensen isolator. If that doesn't fix it, send it back to me, you'll be out postage. If it fixes your problem, pay me 1/2 of whatever they're selling for now-a-days new. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted March 9, 2011 Share Posted March 9, 2011 I believe THIS is the one I have. I'd need to check to be sure. Quote Link to comment Share on other sites More sharing options...
SuBXeRo Posted March 9, 2011 Author Share Posted March 9, 2011 I believe THIS is the one I have. I'd need to check to be sure. Sorrym i should have specified, i meant rca ground loop isolators, it would go on via the rca terminal on the xpa-5. They are cheap like 10 bux. I am almost positive its not the cable line since if i disconnect it, the hum is still there Over the past 2 weeks i have been using my oold sony receiver to run things. I kept the UMC-1 and just used the receiver for the amp section only. Thr front l/r channels were staticy, just the receiver itself and i couldnt hear any audible hum in any of the speakers. Im going to ask the same guy i bought my heresys from to see if he has any suggestions since he has other audio stuff. Other than that, i got nothing friend wise, im the only audio nut. Quote Link to comment Share on other sites More sharing options...
Fish Posted March 9, 2011 Share Posted March 9, 2011 I just wanted to dispell the notion Parasound etc.....are hum free......I owned several Parasound amps, they sounded great but the hums did bug me.They even put a switch on later models to lift the ground,I'm sure you could read old threads for days.I would just say again, the Parasounds sound great. I bought the UPA 7 as it has all the power I could ever need to drive 7's in a very large room toward busting the cabinet apart with no noise. I do sympathize with your ground problem, they can be very hard to localize and solve. Quote Link to comment Share on other sites More sharing options...
Moderators Youthman Posted March 9, 2011 Moderators Share Posted March 9, 2011 I have a hum in my system as well. Unfortunately, I just ignore it and deal with it. Would love to get rid of it. Even tried the cheater plug. Quote Link to comment Share on other sites More sharing options...
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