isadorefarm Posted February 8, 2012 Share Posted February 8, 2012 Hello All, I've recently paired a new (to me) pair of Chorus IIs to my brand new 90 wpc tube amp. I love the sound, but have been getting a relatively loud hum without any imput. It's audible at 8-10 feet, not super loud, but still there. It's especially bothersome during quiet passages in classical music. I've run through the usual drills, disconnected all inputs, plugged them back in separately, changed outlets, changed power strips, removed the ground with a cheater plug etc. All to no avail. I've contacted the manufacturer, who was kind enough to send a new (and they thought) much quieter preamp tube to fix the problem. No dice, it's still there. In communicating with the manufacturer, they seem to think it might simply be that the Chorus IIs are too sensitive (101 dB, I see). Is that reasonable? Has anyone else had a similar issue with high sensitivity Klipsch speakers? I'm contemplating sending it back for them to check out, but at 55# it's going to cost some money to get it there and back. Thanks for any insight - Matt Quote Link to comment Share on other sites More sharing options...
USNRET Posted February 8, 2012 Share Posted February 8, 2012 Welcome Matt. The hum (ground loop) police will be here soon I suspect. As a past owner of Chorus IIs and current owner of Belles and tubes, my limited experience is that sensitive Klipsch "noise" is a hiss not a hum. Ground loop? Tube? Walk us thru this. With speakers connected to amp and only the amp powered does it hum? Brand/model of amp? Changed power strips? Power strips (of any kind)...hummm, may be an issue Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted February 8, 2012 Share Posted February 8, 2012 High sensitivity speakers can be very revealing. I suspect any 90wpc tube amp can be noisy compared to SS. I use a 30wpc Sansui tube amp with my Belles and love it. If I crank the volume way up I too can hear some noise but I dont care. [] Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 8, 2012 Author Share Posted February 8, 2012 Thanks for the reply USNRET. The hum is there with no inputs connected, at zero volume as well. With or without power strip, using an isolated ground or common receptical. The amp is a Rogue Audio Cronus Magnum. So far they have been nothing but helpful in terms of support, I can't say enough nice things about Mark OBrien and his team there. I'm just holding out hope that there's a fix without sending the unit back in...or worse that its an issue with the speakers and amp pairing. Quote Link to comment Share on other sites More sharing options...
Speakmeister Posted February 8, 2012 Share Posted February 8, 2012 Does the amp have AC filaments? Try shorting the input of the amp, not just disconnecting it to make sure it is from the amp. Quote Link to comment Share on other sites More sharing options...
davis419b Posted February 9, 2012 Share Posted February 9, 2012 I would be willing to say that the hum is not being caused by the Chorus II's. Quote Link to comment Share on other sites More sharing options...
davis419b Posted February 9, 2012 Share Posted February 9, 2012 I would be willing to say that the hum is definately not being caused by the Chorus II's. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted February 9, 2012 Share Posted February 9, 2012 Should re-title the name of this thread to "Rogue Audio Cronus Magnum with persistent hum" ..it isn't the speakers. Chorus II don't talk without an amp prodding them to do so. Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 Does the amp have AC filaments? Try shorting the input of the amp, not just disconnecting it to make sure it is from the amp. Thanks for the advice. Could you be more specific about the filaments? I'm not familiar with what they are, or if I have therm. Thanks Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 Should re-title the name of this thread to "Rogue Audio Cronus Magnum with persistent hum" ..it isn't the speakers. Chorus II don't talk without an amp prodding them to do so. Good suggestion, done Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 Welcome Matt. The hum (ground loop) police will be here soon I suspect. As a past owner of Chorus IIs and current owner of Belles and tubes, my limited experience is that sensitive Klipsch "noise" is a hiss not a hum. Ground loop? Tube? Walk us thru this. With speakers connected to amp and only the amp powered does it hum? Brand/model of amp? Changed power strips? Power strips (of any kind)...hummm, may be an issue To be clear, the noise from the tweeter is more of a hiss (sssss sound), while the woofer makes more of a hum (mmmmm sound) and the squawker is somewhere in between. Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 9, 2012 Share Posted February 9, 2012 isadorfarm, Rogue along with other tube equipment can hum with Klipsch. I had a Rogue Eighty-Eight that I loved on lower efficiency speakers but when I put the amp on my k-horns, serious hum. Tried shorting the inputs, everything, nothing worked short of sending it back to Rogue for a going through. I did discuss it with Mark and he thought that likely only the Rogue higer end amps would have lower hum on such an efficient speaker. I eventually sold the amp (though really good if on 93db efficient speakers). Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 isadorfarm, Rogue along with other tube equipment can hum with Klipsch. I had a Rogue Eighty-Eight that I loved on lower efficiency speakers but when I put the amp on my k-horns, serious hum. Tried shorting the inputs, everything, nothing worked short of sending it back to Rogue for a going through. I did discuss it with Mark and he thought that likely only the Rogue higer end amps would have lower hum on such an efficient speaker. I eventually sold the amp (though really good if on 93db efficient speakers). Thanks for the reply. Just to be clear, did sending the amp back have any appreciable effect on the hum? Would you advise me to have Rogue look it over, or is your opinion that the "budget" Rogue amps simply produce a hum through high efficiency speakers? Not something I thought of when buying the amp.... Quote Link to comment Share on other sites More sharing options...
NOSValves Posted February 9, 2012 Share Posted February 9, 2012 Is this amp new or did you purchase it used? There is absolutely no reason a quality push pull tube amp should cause you anything more then noise that you have to be within about a foot from the speaker to hear. That noise should be nothing more then hiss or white noise, not hum. When you say the amp hums what exactly do you mean? Hum is similar to the lowest notes you could hum via your vocal cords. I ask this since in my expereince many people call all noise hum. Buzz and hiss can be caused by many different things while hum is an entirely different thing. It sounds to me like you have ruled out all the ground loop and other causes of hum and since the amplifier has a volume control turning it to zero is pretty much shorting the input to ground. Rogue is not know to build low quality stuff so I suspect something is wrong with the amplifier. So describe this noise a bit more. Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 Is this amp new or did you purchase it used? There is absolutely no reason a quality push pull tube amp should cause you anything more then noise that you have to be within about a foot from the speaker to hear. That noise should be nothing more then hiss or white noise, not hum. When you say the amp hums what exactly do you mean? Hum is similar to the lowest notes you could hum via your vocal cords. I ask this since in my expereince many people call all noise hum. Buzz and hiss can be caused by many different things while hum is an entirely different thing. It sounds to me like you have ruled out all the ground loop and other causes of hum and since the amplifier has a volume control turning it to zero is pretty much shorting the input to ground. Rogue is not know to build low quality stuff so I suspect something is wrong with the amplifier. So describe this noise a bit more. Thanks for the reply. The amp was purchased brand new and I've had it for less than a month. The noise is more of a hiss from the tweeter (higher sssss noise), while the woofer makes more of a hum (low mmmm noise). For context, I have an old pair of Bose 301s that I've tried with the amp, and they produce a low volume hiss that is inaudible at more than a foot or so. Any help is greatly appeciated - thanks! Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 9, 2012 Author Share Posted February 9, 2012 Is this amp new or did you purchase it used? There is absolutely no reason a quality push pull tube amp should cause you anything more then noise that you have to be within about a foot from the speaker to hear. That noise should be nothing more then hiss or white noise, not hum. When you say the amp hums what exactly do you mean? Hum is similar to the lowest notes you could hum via your vocal cords. I ask this since in my expereince many people call all noise hum. Buzz and hiss can be caused by many different things while hum is an entirely different thing. It sounds to me like you have ruled out all the ground loop and other causes of hum and since the amplifier has a volume control turning it to zero is pretty much shorting the input to ground. Rogue is not know to build low quality stuff so I suspect something is wrong with the amplifier. So describe this noise a bit more. After additional listening, I'd like to add a few observations: - The noise is two-part, there's a high hiss (ssssss) accompanied by a low hum (mmmmmm) coming from both the tweeter and squawker. The squawker is by far the louder of the two. - These loudspeakers have the Crites titanium tweeter diaphragms (not sure if this might make a difference or not) - There looks to have been some soldering done to the leads to both tweeters. Each of the clamps has another wire soldered on to it, and the additional wires have been cut. I've never looked inside before, is this normal or a sign of something funny? I've attached a picture to show what I found. Thanks Quote Link to comment Share on other sites More sharing options...
djk Posted February 10, 2012 Share Posted February 10, 2012 Speakers know the words, so they don't have to hum. Amplifiers forget the words and therefore hum. Does your speaker make any sound with no wire hooked to it? If yes, call an exorcist. If no, fix the amplifier and/or groundloop. Quote Link to comment Share on other sites More sharing options...
pzannucci Posted February 10, 2012 Share Posted February 10, 2012 isadorfarm, Rogue along with other tube equipment can hum with Klipsch. I had a Rogue Eighty-Eight that I loved on lower efficiency speakers but when I put the amp on my k-horns, serious hum. Tried shorting the inputs, everything, nothing worked short of sending it back to Rogue for a going through. I did discuss it with Mark and he thought that likely only the Rogue higer end amps would have lower hum on such an efficient speaker. I eventually sold the amp (though really good if on 93db efficient speakers). Thanks for the reply. Just to be clear, did sending the amp back have any appreciable effect on the hum? Would you advise me to have Rogue look it over, or is your opinion that the "budget" Rogue amps simply produce a hum through high efficiency speakers? Not something I thought of when buying the amp.... Just to be clear, I did not send back the amp for a update because it wasn't clear that the update would have resolved the problem. From what I was gathering that there was a chance but the amplifiers were not designed to have a super low noise floor required by such efficient speakers. They were designed to work well with the typical efficiency speaker and sound very good. That they did but you would need the higher end amps if you wanted a black background. I think another thing was the biasing. Since they are auto-bias, maybe some noise can be dropped if you had to manually bias them. Quote Link to comment Share on other sites More sharing options...
isadorefarm Posted February 10, 2012 Author Share Posted February 10, 2012 Thanksfor the clarification Peter, What you found is essentially what I've been told by Rogue, and I would trust that they know what they're talking about. The Cronus is manual bias, but at least at the recommended 35 mv I haven't been able to get the noise to go away. Thanks again - Matt Quote Link to comment Share on other sites More sharing options...
fenderbender Posted February 10, 2012 Share Posted February 10, 2012 I own several pieces of rogue equipment and they are very very high quality.... even your Cronus which is Rouge's "entry" int. has better guts, build quality, and engineering than some other supposed "high end" fancy scmancy manufacturers offerings...... That being said I had a problem with my rogue phono pre producing a "hum" not a ground loop or RF and sent it back.... bad part and they fixed it right up.... I'm afraid you may have to send it in for a fix. If they find that it was a bad part, try to get them to pay for shipping back to you at least. one other thing it could be is RF interference..... have you tried turning off your WIFI? moving positions or in another room..... sometimes they can pick up RF and with the sensitive chorus it is amplified.... Just a thought.... Quote Link to comment Share on other sites More sharing options...
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