Please...it's "repair". Good luck
15 responses Add your response
You have to track down the source of it. Start off by isolating the preamp from ALL other components other than the amp. This means removing all of your interconnects and power cords while leaving the preamp hooked up to the power amp. If there is no buzz, start attaching one component at a time via the interconnects and power cords. Keep hooking up components one at a time and checking for the buzz after each one. Keep going until you find something that does generate the buzz.
For clarity sake, let's say that you've hooked up your tuner with no buzz. Then you hook up your tape deck with no buzz. Then you hook up your CD and the buzz is there. Here's where it gets tricky.
Once you've found that specific component ( in this case, the CD player), remove all the others from the circuit and leave it hooked to the preamp by itself. If it still buzzes, there is some type of problem occuring between that component ( the CD ) and the preamp / amp combo. You might be able to correct this by either reversing polarity on the power plugs ( if they are two pronged ) or lifting various grounds. Try various combos of the above.
If you've removed all of the other components and only left the buzzer ( CD ) hooked to the preamp with no more apparent hum, there is a problem occuring between the CD and another source component with the common connection being the preamp. Leave the buzzer ( CD ) hooked up and hook up the other sources one by one. By this, i mean the CD and tuner only. If no buzz, then try the CD and tape deck while removing the tuner. If no buzz, then remove the tape deck and try the CD and phono, etc... Do this until you find the two that are "fighting" with each other.
If you are able to find the problem this way, you once again have to start playing with power cord polarity or lifting grounds. This can be VERY tough and tedious work but it will be the only way to solve it short of replacing components. You may find that you end up with only ONE ground for the whole system. This is fine so long as you're using a power cord with a heavy conductor for the ground.
If after all of this, you still have a buzz and can't seem to get rid of it, narrow it down to which component is creating the problem. It's quite possible that everything will work fine until you install one specific piece ( the CD in this case ). Some components just will not work in specific systems and you end up having to replace it. I ran into this with one specific piece of gear and it drove me crazy. The really bad part about it was that it performed awesome in the system except for a low level hum. I ended up having to sacrifice that one source, which i was really happy with, in order to maintain the level of reproduction that i was able to assemble throughout the rest of the chain. Hopefully, you won't end up in that same boat. Sean
Thanks Sean for your reply. I actually tried all those things you mentioned (and some more) with the help of the comments I found in this forum. Even with everything completely disconnected except for a preamp, power amp plugged into the wall (or into the power conditioner) and just one interconnect between them (also tried different ICs, power cords, power amps) the buzz is stil there. It is not volume sensitive and does not go to the sub speaker when the 80hz crossover is engaged (but it is there if not). So, I am at the stage where I am seriously consider to go to a repair (Sorry Subaruguru) shop and wonder if this helped someone, ever.
Make sure the ground connection of your cable TV is clean and solid. Next, I would check if you have any halogen lamp dimmers and/or ceiling fan variable speed controls. These devices throw a huge amount of noise into AC power. If that fails, the repair shop may be the only option left, after you have isolated the problem component by deduction.
Good luck, I know this must be annoying.
It might not be your gear, but the room itself. Sometimes, if there are tracking lights present, or if any of the room's lighting is on a dimmer switch, that might be your problem.
I have that problem now - the lighting in my room is dimmer-switched, and it is wired to all the electrical sockets in my room (all my room's electricity is on one fuse). My preamp is significantly more buzz-y when the dimmer is set higher on the switch. Try taking your preamp to another room with a separate fuse/socket and plug it in. If you don't hear any more buzzing, it might be the lighting.
Is all your gear on one plug or circuit, meaning components on one circuit and amps on a seperate. If so, you may have a ground potential issue.(use an extention cord and test by plugging all devices and amps in same circuit) I am presently experinecing the same thing and found cheater worked on my pre-amp and amps, I basically lifted the ground..
Confused about the x-over issue, see if you can borrow the same preamp or another and test.
Many thanks to all the participants of this forum. I am trying to use all your help and have some answers and more questions to ask.
It is an interesting possiblity. I indeed have the room's lighting on a dimmer switch in a different room, which is exactly above the listening room. In my experiments, I made sure that it is swithched off, but I wonder if, even so, it may still creat a buzz???
Mzn50: I plug them all into one power surge protector and
line conditioner. I tried the cheater and checked the polarity too. I also connected the chassis of the preamp to other various components. The crossover I mentioned is in the separate power amp for the sub, that is, not in the preamp in question. So, I can run the full range signal from the preout in the preamp, and then can cut it off below 80hz, by engaging the sub amp crossover. This kills the buzz in the subwoofer speaker. Hence, it is not a 60hz ground loop hum?
I'm not an electrician, but I know dimmer switches emit heavy ac waves, even when turned off. So your gear might buzz even with the lights off. If it doesn't buzz hooked up to another socket elsewhere (without a dimmer attached to that fuse), then it's the dimmer switch. Or, if the buzz gets louder when the dimmer switch is set higher, that's a good way to find out too. Also, if the lighting is track, there will be transformers present somewhere - maybe in between the wood beams between floor levels. They also emit ac waves. If you find the dimmer/track lighting is the reason, you can replace the switch will a standard on/off switch, and that might reduce it a bit. If it's the tracking light/transformer, then short of gutting your ceilings and installing new lights, I guess you'll just have to deal with it (I have to). Make sure to throw the fuse switch before installing a new light switch. Hope this helps.
On the off-handed chance this may help....a few years ago I found the source of a buzz in my system thru luck. The system was completely ground-floated except for the tube preamp and, at higher volumes with no source signal, it was very clear - annoying bzzzz. After trying quite a few things, I grabbed the metal rack to support myself and moved to the back of the preamp to take another look and touched the case. No, no shock! Just no buzz. It completely disappeared! I wound up taking a lead from the pre's grounding post to a connection on the rack and have been happy ever since....well, except for that tweaking stuff! Good Luck!
I manage to reduce my ``buzz'' plugging these cheap 5-cents IC's into the unused RCA input sockets. (I cut the connectors off and isolated their wires first.) I found this ``recipe'' in the forum discussing those Cardas caps (well, they seem do not help but look just great). This method does not kill the buzz but made it somehow much less annoying and not that loud. How long I can live with this remains to be seen though. Thanks again for all your help.
I am going to assume the crossover frequency was higher before? I am going to take a guess that you have a bad filter cap in the power supply. I base my conclusion on the following: your woofer has a better low frequency response then your higher frequency drivers so when you switched your crossover to 80 Hz the signal was attenuated. I also assume you have a full wave rectifier where the ripple is at 120Hz and would sound more like a buzz then 60 Hz hum. If you have a good old VOM (non digital volt-ohm meter) you can do some rough checks. You can disconnect one end of the filter capacitors (after they have had enough time to discharge) and on the R x 1 scale [lace the leads across the capacitor the needle should move to the right very quickly toward 0 ohms and slowly move to the left toward infinity. If one of the capacitors does not do this this it is probably bad. What you are doing is simulating putting DC power across the capacitor. Whena capacitor is fully discharged it should look like a short hence the meter move toward 0 ohms. As the capacitor charges it looks more and more like an open circuit hence the meter moving toward infinity. I hope this helps as I have made some assumptions.
Thanks very much, but unfortunatelly I am not that capable technically to be able to follow your suggestions.
You might be right about the problem. I may use it if I find someone who can help me. So far I use these home-made caps, which are sort of helpfull and provide so far a relief. Maybe, the buzz is due to some RF noise? Can it be consistent with your comments?
About the assumption: I can run a full range signal through the subwoofer amp or engage the low pass filter at 75hz. When I have it full range, I have the same buzz in the sub
speakers (taht is, amplified by the separate sub amp) as in the other speakers amplified by their amp. When I engage the low pass 75hz filter, the buzz disapperas from the sub speakers.