Before you go for power conditioner, get(they're refundable) AudioQuest RF traps(junior model) from www.needledoctor.com and try to place them onto power cords, interconnect and speaker cables.
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When you disconnected the interconnects was it at the amp or the source end ? You should have disconnected at the amp end to make sure the interconnects were not acting as antennas. Not all interconnects are well shielded, but you can build very good ones quite cheap.
I doubt your power cable will help since none of the wire between the circuit box and the outlet is shielded. You're right to be thinking about a power line filter to remove interference from the mains.
I would try to home demo a power conditioner to make sure the amp is not susceptible to air-borne RFI interference. RFI can get into the amp from the power supply OR just from the air into the preamp section of the integrated amp. Just hope it's not the latter. A power conditioner may not help ... so I would try before you buy.
Either the amps are sensitive to RF signals or the cords ( power OR speaker ) are acting as antennas. Sometimes, simply moving the cords into a different pattern can cure the problem. Sometimes altering their length can cure the problem.
I would start off by trying to wind up any excess power cord into a small coil as tightly as possible near the amp. This will create a choke and may get rid of or minimize the problem. If that doesn't work, you can try attaching a ferrite clamp to the power cord very near the amp. You might also try shielding the amp ( large metal pot, turkey pan, etc... ) to see if the tubes or circuitry are picking up the signal if it doesn't already have a "cage" covering the tubes. While i would think that your speaker cables would be okay due to their geometry, try substituting some different cables to see if that helps..
Depending on the situation, it can be a tough one to solve. Take your time and do it step by step. Sean
I hope I am not accused again of trying to schlep HMS cables here if I spread some information of HMS cables concerning a specific topic.
I will notify anybody that my opinion could be biased by the fact that I am the importer of said cables and I admit also that HMS is not the only good cable out there, (but probably one of the few cable brands, reasonably priced for that kind of performance)
I have discussed this topic of RFI/EMI rejection extensively with Dr. Strassner , since he said that rejection of EMI/RFI will be a growing issue in the future (more computers, more cell phones, more broadcasting towers, etc.)so he believes in extreme shielding of all of his cables, plus an additional 6 step filtering, which accumulates in a 99% rejection of EMI/RFI with his cables.
So if someone really suffers from that kind of problems, he should audition several brands of cables to find out, if cables are the cure for his problems or if investing money in a power conditioner will help. Actually the HMS power cords come with a build in power conditioner and cleaner, but there are several good brands available as stand alone power cleaners if you would like to invest more money. I also use the Stealth power cleaner along with said power cords.
I will repeat my Matra all over again: Audition, audition, audition.
FWIW I did the test of disconnecting all IC's at the amp not the source. I switched the power cable from one outlet to another.
I do seem to have more noise from the speaker nearest the outside wall.
My question is - If the sound is not amplified by the amp (volume knob has no impact) is it likely that the speaker wire is the problem?
are ferrite rings on the speaker cables a possiblity?
Ha! now I'm catching on...
No one mention about input small signal tubes(or a poorly designed input circuitry). I'm not sure what input tubes are there in Jolida but I think that 80% of your problem are either inside or outside the input tubes + you've probably got a sensitive amp. I believe that further follow-ups can advise you which tubes you should try. IMHO the circuitry have to have a free of microphonics designe no-matter what tubes you're using.
Sound not being affected by the volume control just means RFI somewhere after the volume control, which could be in the power amp (that section of your integrated amp) or in the speaker cable. I think it's more likely in the amp, since speaker signals are generally too big (in voltage and current) to suffer from RF interference.
Since one speaker is worse than another to me this points the finger at the amp and not the power supply (the mains).
This is making more sense to me as well.
I just replaced all of my pre-amp tubes and the situation seems to be worse. I got rid of the 'junk' Chinese tubes that everyone says I should throw away and replece them with military grade Mullards and Phillips. I'll go back and change them again. Is a copper cage the answer?
I designed a recording studio once in Brooklyn (as and Architect not a sound engineer). due to proximity to the World Trade Center and the Radio Frequencies emmitted therefrom we shielded the whole studio with coper paint and put a copper mesh grid in the air space of the double pane windows.
Thanks Marakanetz, Sean and Seandtaylor99 for saving me the cost of more power cables for nothing.