Deang Posted July 10, 2002 Share Posted July 10, 2002 Is this normal? I mean, it's very low in volume -- but it's there. The other Super Amp I just sold didn't do it. Could this be a result of the larger transformer?f> ------------------ Deanf>s> Klipsch RF7s - AE-25 DJH - AE-3 DJH - Sony 9000ES f>s> Quote Link to comment Share on other sites More sharing options...
lynnm Posted July 10, 2002 Share Posted July 10, 2002 Dean Here is how I would troubleshoot this problem: Disconnect everthing from the amp and make sure that anything close to the amp is turned off except the speakers and then determine the following: 1.)Does the hum persist with all peripherals and their cables disconnected from the amplifier? If not then check the wiring and add the peripherals back in one by one until you isolate the source of the noise. Perhaps a cable has been damaged or the cinput connection on the amp is dirty or the cable ends need cleaning. If the hum persists: 1.)Is the hum coming from the speakers,(ie because of the signal being fed to them or from the amp itself,(ie a mechanical hum)? 2.)If the sound is from the amp chassis it is likely a mechanical noise caused by the slight amount of vibration that is typically induced in devices by the current passing through them interacting with magnetic fields which may have been generated by the device itself or even by the magnetic field of dear old mother earth herself. This is the process which makes electrical sound production possible. If this is the case check to ensure that the transformers etc are securely mounted to the chassis - Do not however use excessive force in tightening transformer mounting bolts etc. - you are not tightening the mains on a 440 after all and excessive tightening can actually aggravate this problem. 3.)On the other hand if the sound is coming from the speakers the next question is - does the hum increase or decrease in volume as the volume control is adjusted or does it remain at essentially the same volume regardless of the volume control setting? If the volume of the hum is essentially independent of the volume control setting I would be inclined to suspect that you may have a noisy tube,(or some other component),in the output stage of the amp - Be sure to determine whether the noise is uniform on the left and right channels. If one channel has a markedly louder hum than the other you may have an easier time narrowing the source of the problem. If the hum increases in step with the raising and lowering of the volume setting then your problem lies either in the preamplification stage of your amp which may be caused by a noisy tube etc. or by the connecting cables between your sources and the amplifier. On the other hand it may simply be due to the Forces of Darkness - Have you listened to a Bose Wave Radio recently. Perhaps your amp is merely punishing you ------------------ It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca.1900) Quote Link to comment Share on other sites More sharing options...
Deang Posted July 11, 2002 Author Share Posted July 11, 2002 The hum is the same out of both the left and right speakers. It is not a 60 cycle hum, it is higher -- 120 maybe? It is not a ground loop problem. It does not change with variation in volume. I can turn my volume control over all the way and it stays the same. It is barely audible. The uninitiated might not even notice it. Removing the interconnects from the amp, or turning off the preamp does not effect whether it is there or not.f> ------------------ Deanf>s> Klipsch RF7s - AE-25 DJH - AE-3 DJH - Sony 9000ES f>s> Quote Link to comment Share on other sites More sharing options...
lynnm Posted July 11, 2002 Share Posted July 11, 2002 It could also be originating from the amp's power supply circuitry. I would be inclined to ignore it - As I do with the the very slight buzz in my AQ1003DT. I find that the knowledge that there is a HUM IS MORE ANNOYING THAN THE HUM ITSELF 8~)> ------------------ It is meet to recall that the Great Green Heron rarely flies upside down in the moonlight - (Foo Ling ca.1900) Quote Link to comment Share on other sites More sharing options...
Deang Posted July 11, 2002 Author Share Posted July 11, 2002 Oh so true -- as soon as the music comes on I forget about it.f> ------------------ Deanf>s> Klipsch RF7s - AE-25 DJH - AE-3 DJH - Sony 9000ES f>s> Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted July 11, 2002 Share Posted July 11, 2002 Most amps have a hum pot but the AE-25 does not as I remember (the hum post is really needed in SET amplictions, IMO but advisable in most tube amps). But remember that your amp does have large nunber of magnetic fields involved. And the power trans is a major step up from your other unit. Some tips below to try again with #1 sometimes make a big difference. Some solutions: 1. Rotate your power cord. The hum has a chance of being less audible in the other rotation. 2. Work on you wires keeping all IC and power cords away from one another - this is less likely but does help some hum. 3. Change your tubes around. Actually remove and reinsert your tubes. Sometimes the power tubes in certain positions will bring about hum depending. This is another outside chance but it is true. Lynnm is probably right here in that you are going to probably have a bit of hum with more sensitive speakers. It is probably in the PS or in the amp being initially designed for a more conservative circuit. Dennis has changes some variables while leaving others the same. kh This message has been edited by mobile homeless on 07-11-2002 at 11:44 AM Quote Link to comment Share on other sites More sharing options...
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