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| Home recording studio - noise with guitar amps - who to call? |
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| fourfathom:
--- Quote from: Red Squirrel on October 11, 2019, 01:55:14 am ---I also second the idea of trying to run on a UPS just to rule out electrical noise, though you will want to make sure it's pure sine. --- End quote --- Even if it's not a sinewave output, as long as the noise changes he will have a very valuable clue. |
| Red Squirrel:
--- Quote from: fourfathom on October 11, 2019, 02:04:49 am --- --- Quote from: Red Squirrel on October 11, 2019, 01:55:14 am ---I also second the idea of trying to run on a UPS just to rule out electrical noise, though you will want to make sure it's pure sine. --- End quote --- Even if it's not a sinewave output, as long as the noise changes he will have a very valuable clue. --- End quote --- Yeah that is true. Might still be a useful test and he may already have one handy. |
| BrianHG:
--- Quote from: DaveNJ on October 10, 2019, 11:50:22 pm --- --- Quote from: Red Squirrel on October 10, 2019, 10:29:13 pm ---Can be a lot of things, such as ground loop. Is it a 60hz buzzing sound by chance? Could be a dimmer, pretty much anywhere in the house. Those make a lot of electrical noise. You could maybe try putting everything on an isolation transformer to see if it helps. --- End quote --- It seems to be higher than 60 - that sound file I put has a large hump at 180, so it's a harmonic. I've removed all the dimmers from the house. The chattering noise is the thing that gets me the most. Yeah, ISO Transformer is my next thing to try --- Quote from: fourfathom on October 10, 2019, 10:56:37 pm ---Simplify and eliminate -- this is how you track it down. --- End quote --- --- End quote --- I analyzed that .mp3, it's 60 Hz on the dot... There are other harmonics due to repeated voltage spikes at repeated intervals along the 60hz sine wave. 1) How old is this amp? 2) Is it vacuum tube? 3) Could it need internal mains filter DC cap replacement? 4) Could the amp just be poorly designed being very sensitive to any disturbance on the AC mains? 5) Does the Amp do the same thing at another location? 6) Has that Amp ever been serviced by an amateur without proper experience with the sensitivities of guitar amps? |
| DaveNJ:
--- Quote from: BrianHG on October 11, 2019, 04:26:57 am --- --- Quote from: DaveNJ on October 10, 2019, 11:50:22 pm --- --- Quote from: Red Squirrel on October 10, 2019, 10:29:13 pm ---Can be a lot of things, such as ground loop. Is it a 60hz buzzing sound by chance? Could be a dimmer, pretty much anywhere in the house. Those make a lot of electrical noise. You could maybe try putting everything on an isolation transformer to see if it helps. --- End quote --- It seems to be higher than 60 - that sound file I put has a large hump at 180, so it's a harmonic. I've removed all the dimmers from the house. The chattering noise is the thing that gets me the most. Yeah, ISO Transformer is my next thing to try --- Quote from: fourfathom on October 10, 2019, 10:56:37 pm ---Simplify and eliminate -- this is how you track it down. --- End quote --- --- End quote --- I analyzed that .mp3, it's 60 Hz on the dot... There are other harmonics due to repeated voltage spikes at repeated intervals along the 60hz sine wave. [ Attachment Invalid Or Does Not Exist ] 1) How old is this amp? 2) Is it vacuum tube? 3) Could it need internal mains filter DC cap replacement? 4) Could the amp just be poorly designed being very sensitive to any disturbance on the AC mains? 5) Does the Amp do the same thing at another location? 6) Has that Amp ever been serviced by an amateur without proper experience with the sensitivities of guitar amps? --- End quote --- Brian, good info - thanks! To answer your questions: 1. One amp is 10 years old (Suhr Badger 30), the other is 51 (Fender Princeton Reverb) :) . I can also get the noise with a line6 Helix, so its not necessarily due to tubes and electrolytics. 2. See above 3. I had the Princeton serviced two years ago, the Suhr has not been serviced. 4. I don't think so 5. No. Even in another room (upstairs in my home) 6. No, I only bring them to top folks in the area. I'm going to go through a full debug session on Sunday - turning off all other breakers, running the amps from battery, etc so I can try to narrow it all down... I'll post back with what I see. |
| floobydust:
I've had to troubleshoot oddball noise and hum in two recording studios. It's very difficult because finding the interference source or type of noise, figuring out where on the electromagnetic spectrum it is and how it behaves, is not easy. You may find the interference disappears on weekends and evenings, this is due to pollution from industrial electricity users. Although some welding shops run night shifts, I found some days and times the interference disappeared. Listening to your recording, I hear annoying crackles that are periodic, so likely from some industrial process. You can use a guitar to confirm. Rotating the body 90 degrees and you can at least see what axis the interference is coming in on. Buried power cables, or the airborn power conductors on utility poles are fabulous transmitting antennas. Another technique is using a Walkman (with no cassette inside), the tape head will pick up the same as a guitar pickup as far as low frequency B-fields. That will tell you right away if the noise source is outside your house. A cheapola AM radio also can be used to find an interference source. It's good to first know the (electrical) noise floor of the studio, before blaming the equipment and grounding etc. One studio has arc welding or smelter interference, so the guitar players are oriented 90 degrees and sessions are done on weekends. |
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