Help with hiss

@carlsbad2  I had given that some thought, and I agree that it is likely upstream from the amps/speakers. Question: my preamp is a tube pre that is not on or in standby mode. It is plugged in, but fully “off”. Could it still create a problem? Thank you!

@soix Thank you. Excellent question and something I forgot to include.

I’ve owned this system in its current iteration for a few years now. This hiss started maybe 2 or 3 months ago, but I lose track. The only new “thing” I’ve added to my home is a conversion of a kitchen ceiling light from fluorescent tubes to LED. Fearing this may have cause it, I turned the light off but the hiss continued. It also does it in the bright of day when no lights are on. I’ve also studied if the hiss appears when the refrigerator cycles on. It does not coincide, and again, I’ve had all the same stuff for years.

@soix Thank you so much. This is definitely a drag. It does happen at night, but my listening may start before the hiss starts. Once the hiss starts, it’s pretty obvious. Even my wife noticed it. I had feared that it might be something in the grid. My neighbor had recently built a wood shop. When I heard the hiss, I asked him if he was using any of his shop tools (sometimes the hiss sounds like a saw starting up). He denied using anything in the shop. It also occurs when he’s not even home.

@ditusa  Since you ask, I’ll assume it matters….Odyssey Audio Kismet Reference monos and Odyssey Audio Kismet monitors. Flawless performance for years. Thank you!

@nd1der  All the rest of my gear is plugged in to a Brick Wall, which is plugged into the same circuit. This includes the Mac laptop that I use for steaming. Knowing that computers can cause issues, I unplugged that from the Brick Wall with no relief. I’m not sure if it’s on the same circuit, but my internet modem is in the same room. Concern that might be an issue, I turned off and unplugged the modem with no relief. Thank you! Keep it coming!!

@erik_squires Oh, I did not take it that way at all!🙏🏻 I think I was trying to address the very real issue of shielded vs. unshielded. I’m not sure which of the cables are which, but it will be very easy to get that information. I’m afraid my Brick Wall is loaded with wall warts, but there has been no recent addition, unless one is beginning to fail (which is possible). I’ll end up systematically unplugging each one and seeing if that has an effect.

I don’t want to jinx it, but since I got up on this quiet Sunday morning, the system is absolutely silent. I’m thinking you guys may have scared away the gremlin!! He knew I called in the big guns!

@erik_squires I had that thought as well. I didn’t so much change any cables, but I did add a cable around Christmas time. I got a Schiit Loki for Christmas, so I broke out a pair of Raven Audio cables to use to put the Loki in the system. Unfortunately, right now, I have a hodgepodge of cables and not a full loom from one manufacturer. I have mostly Audioquest, but a couple of Zu Missions (I think), and the Raven. My turntable is a Rega, so the cables are captive. 

Man, I am so appreciative for all these suggestions and help! I knew I came to the right place!

@erik_squires As far as the LED thing, this is a large kitchen ceiling light that I converted from 2x4’ fluorescent bulbs to 2 LED bulbs. I didn’t replace the fixture, but bought the LED’s that have the built in ballast to be able to operate them in the same fixture. I’ll replace the entire fixture when I find one I like. So, no strips, wall warts, etc. And they are not dimmable. Like I said, the hiss occurs whether or not that light is on.

The WiFi modem/router is in the same place it has been for years (20+). It’s also the same one I’ve had for years. I did eliminate it on the off chance that it was creating a problem, but the hiss continued. 
I may have to shut down the whole house to find this. I am not opposed. Thank you!

@soix I can’t argue that the Mac is less than ideal. I was an early adapter of Roon and, at the time, the options were pretty thin. The Mac was something that could run Roon and I was familiar with them. My next upgrade is a real streamer, so the MacBook’s days are numbered. Even so, I’ve had this configuration for years. The only thing this Mac does is run Roon. It is the only thing it has ever done. I have never used it for any other purpose. I did unplug it from the Brick Wall ( those wall warts can be problematic), but the hiss continued.

@carlsbad2 I will unplug the outputs from the preamp. Good idea. Power and one input (from the preamp) are the only things plugged into the amps. I, too, fear that this is less system related and more power grid or power supply problem (from outside). That makes it beyond my control which I don’t want to think about right now.

@oddiofyl I don’t have anything like that. I’m hard pressed to remember that last “new thing” I introduced to this house. I’m not a big change person. I research the life out of something, make a decision and then live with that decision until it breaks or becomes so outdated that it no longer serves a useful purpose. That’s why this is a little baffling….nothing has changed, but the system suddenly began to exhibit this annoying feature. Thank you!

@audiojan Thank you so much for that! I do what I can to route the cables that way. It’s quite a mess back there without a lot of room to spread things out like they should be. I am cognizant of it, though. I will also do as you suggest and disconnect the interconnect to the amp. I agree that isolating the amp from the rest of the system may provide some answers or direction. 

@ditusa Hi Mike, The Loki does have a wall wart. I’ll unplug it to see if that helps. I have several components that use wall wart style power supplies. I’ll check them all while I’m at it.

I had thought of the bias issue. I’ve read several discussions, especially pertaining to Odyssey, about adjusting bias to change the sound. The only thing perplexing about the bias drifting is that both amps exhibit the identical behavior at the identical time. Can drift in one effect the other so directly? I understand that bias exists and that it is a “thing”, but that is the extent of my knowledge. It is not anything I would attempt myself. You’ve been very helpful. Thank you so much.

@tee_dee I may have to spend the rest of my life figuring this out! It can’t stay like this!

@wturkey Thanks! I may have one left over when I had to chase a ground loop hum in my (home theater) subwoofer.

@panzrwagn Thank you so much for this! Very informative. I’ll read those articles if for no other reason than to learn more about our crazy hobby! I can’t rule this out, either. These amps have pretty high input sensitivity and, I believe, are a high gain design.

@perkri I did not disconnect the RCA’s from the amp..from either end. I did swap out power cables and I did plug them in directly to the wall outlet and into a PS Audio Power Center. Nothing changed in any scenario. Unplugging the inputs at the amp is what I will try next, based on a previous recommendation 🙏🏻. The hiss stays constant. No change with volume adjustment, nor input selection on the preamp. It does it with nothing but the amps turned on. Thank you!

@rbull11 Great thought! Alas, everyone hears it. It is real. But I, too, suffer from Tinitus and have often made sure it was the speakers hissing and not my head! Thanks!

@amtprod I’m definitely going to look into the issue of bias. I hear a lot about it, so it clearly has great impact. This is a “on or off” kind of hiss. It’s either doing it or not. And it does not change with volume or input changes at the preamp. And you can hear it quite noticeably “under” the music when it’s playing. Like a lot of background noise. Quiet passages aren’t quiet. It’s very annoying not to have the clarity I’m used to. These are pretty “crisp” speakers (Scanspeak beryllium tweeters). Thanks!

@serjio I will have to look in to that. Sounds intense. I was concerned that something else from someone else was shitting into my system, but hey, you never know! Thanks!

@campoly Similar story. These monos started life as Stratos and later upgraded to Kismet status. I think. I brought them to Klaus and said “do something”. He did. They sound great. 

@boxcarman Thank you for that. I do have a couple of pieces I could swap out and I had thought of that. But I don’t have another pair of monos and I have a passive preamp. So, not apples to apples.

@ditusa These were upgraded to Kismet status in August of 2021, same time as my Candela preamp was made.

@audphile1 I agree that the hiss is a symptom of a problem and not a problem with the speaker. I will do a systematic elimination of components as you (and others) have suggested. I appreciate it. I also can’t eliminate a power problem as they are monoblock amps exhibiting identical behavior. The amps themselves are silent (no buzzing, humming, hissing) coming from the amps. I agree that the most likely suspect at this point is something with the amps, as no other component is on. Some are in standby (Oppo BDP 105D), but I shut everything down if I’m not playing music (except the amps). Thank you so much for your valuable input!

@barts Thanks for that! An easy thing to overlook!

@rockadanny Thanks! I’m humbled. If there were a problem with, say, my CD player but the player wasn’t on could it still cause the symptoms I’m suffering? Or any other component, for that matter? I might suspect a capacitor in the crossover (good call), but it’s doing it in both speakers identically. I’m really not leaning towards the speaker(s) being the culprit, just a victim of whatever the real problem is.

@2psyop Thanks for sharing. I’m really sorry to hear of your experience. Mine has been the complete opposite. I’m sure there’s stories of great successes and not so great in every manufacturer’s history. I’m glad you found your resolve and are back to digging’ the tunes!

@audphile1 👍🏻 I’m with you!

@tempostarship Thank you for that. I had given some thought to doing that, but I wanted to isolate components first. It would be a lot of moving, as there are no other outlets in close proximity. I don’t want to use an extension cord because that could create problems of its own. So, I’d have to move the amps and speakers to another location. That would be the easy part. Putting them back where I had them would be the hard part!

@rockadanny Thanks. I wouldn’t expect it from static gear either, but I’m glad for some confirmation.

There have been some magnificent suggestions here, which is exactly what I was looking for. I had thought this thing to death and I was running myself in circles. I remain open to any ideas or thoughts people may have. I am not quick to fault the amps themselves, primarily because the hiss level, frequency, constant vs. pulsing, silence etc. is identical in both channels. It seems that if it were an issue with one of the amps, some of which were suggested here, I would expect one channel to have an issue but not both. In fact, while troubleshooting, I turned off and unplugged one amp but the other continued to hiss. I turned off and unplugged the other amp and the other one continued to hiss. 
Maybe coincidental, maybe wishful thinking, maybe an Audiogon forum exorcism, but since I got up Sunday morning I have not heard them hiss. I also have not played any music yet. And my neighbor hasn’t been home🤷‍♂️🤔