Jarrod Harrison Posted August 21, 2019 Share Posted August 21, 2019 Hi All. I have a subwoofer that hums when I connect the rca cable. I don’t think it’s a noisy amp because when the rca is not connected but the power is still on it’s dead quiet. I am using pretty high quality cables. Also the previous subwoofer didn’t do this. The cable run is pretty long though. Wondering if perhaps a wireless subwoofer kit might help. Link to comment Share on other sites More sharing options...
a.dent Posted August 21, 2019 Share Posted August 21, 2019 Can you use a balanced connection? Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 21, 2019 Author Share Posted August 21, 2019 The sub does have XLR connectors so I have used an XLR to rca adaptor. Link to comment Share on other sites More sharing options...
Bustlin Battletoads Posted August 21, 2019 Share Posted August 21, 2019 99% chance it's the cable. Find a cheapy RCA and see if it follows. Have had this with cheap and expensive cables a like. Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 21, 2019 Author Share Posted August 21, 2019 I’ve tried 2 RCA’s and both the same. Maybe it’s the connector. I’ve found an RCA to XLR cable so I’ve ordered that. We will see how that goes. They claim it’s balanced (whatever the hell that means) [emoji16] Link to comment Share on other sites More sharing options...
hopefullguy Posted August 21, 2019 Share Posted August 21, 2019 what sub is it? Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 21, 2019 Author Share Posted August 21, 2019 It’s a berringer truth B2092A. I just got 4 of them for free!!!! Link to comment Share on other sites More sharing options...
Guest Karl Rand Posted August 21, 2019 Share Posted August 21, 2019 1 hour ago, JOH1975 said: It’s a berringer truth B2092A. I just got 4 of them for free!!!! Four of them for free? Well, you can place two under your bed to add excitement to your - - - - - - - Link to comment Share on other sites More sharing options...
stereo coffee Posted August 21, 2019 Share Posted August 21, 2019 (edited) 11 hours ago, JOH1975 said: I’ve tried 2 RCA’s and both the same. Maybe it’s the connector. I’ve found an RCA to XLR cable so I’ve ordered that. We will see how that goes. They claim it’s balanced (whatever the hell that means) Balanced audio divides the audio waveform into a negative half and a positive half with earth separate so is at advantage explained here, to reject noise. However it is NOT the only way of rejecting noise in audio systems. The problem is very few audio systems have exclusively balanced source, attenuator and power amplifier devices, rather unbalanced invariably gets mixed with balanced, requiring conversion. Opto coupling unbalanced audio signals, https://lunainc.com/wp-content/uploads/2016/06/NSL-32SR3.pdf rather solves the issue entirely neatly at the attenuation point between source and power amp, bringing into question the need for using balanced audio equipment in domestic audio systems. Balanced though is entirely necessary in broadcast and recording studios's where excessively long cable runs exist. Edited August 21, 2019 by stereo coffee Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 22, 2019 Author Share Posted August 22, 2019 2 hours ago, Karl Rand said: Four of them for free? Well, you can place two under your bed to add excitement to your - - - - - - - to add excitement to my bedroom home cinema.... That's what you mean right? They are actually a very tuneful, tight and fast subwoofer. I'm very impressed. Much much better than my Richter 10". Link to comment Share on other sites More sharing options...
Guest Karl Rand Posted August 22, 2019 Share Posted August 22, 2019 4 minutes ago, JOH1975 said: to add excitement to my bedroom home cinema.... That's what you mean right? They are actually a very tuneful, tight and fast subwoofer. I'm very impressed. Much much better than my Richter 10". I’m devoted to my Velodyne DD15’s but that could be because I had real problems with a number of full range speakers. If I positioned them so that imaging was spot on the bass was crap. If I positioned them so the bass was well sorted the imaging fell apart. Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 22, 2019 Author Share Posted August 22, 2019 Moved the sub to another spot on the room and a different power point and the noise is gone. Wife ain’t gonna like it though. Link to comment Share on other sites More sharing options...
Guest Karl Rand Posted August 22, 2019 Share Posted August 22, 2019 10 minutes ago, JOH1975 said: Moved the sub to another spot on the room and a different power point and the noise is gone. Wife ain’t gonna like it though. This hints there’s something's not correct with the earthing &/or polarity of the wiring in your house. I’d have an electrician check the outlets purely on safety grounds . Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 22, 2019 Author Share Posted August 22, 2019 That could be totally correct. It’s an old house. We had some work down stairs and there was lots of changes needed to made to find earths. Link to comment Share on other sites More sharing options...
joz Posted August 22, 2019 Share Posted August 22, 2019 Could be an earth loop you’re experiencing due to the sub being on a different circuit? Link to comment Share on other sites More sharing options...
a.dent Posted August 23, 2019 Share Posted August 23, 2019 15 hours ago, Karl Rand said: This hints there’s something's not correct with the earthing &/or polarity of the wiring in your house. I’d have an electrician check the outlets purely on safety grounds . 13 hours ago, JOH1975 said: That could be totally correct. It’s an old house. We had some work down stairs and there was lots of changes needed to made to find earths. 12 hours ago, joz said: Could be an earth loop you’re experiencing due to the sub being on a different circuit? I had the exact same problem. A horrible hum from one sub. I fixed it by plugging the sub into my Hi Fi circuit rather than the separate one and moving the sub closer to the processor. The problem is I try to keep all SMPS's off the Hi Fi circuit so it really defeats the purpose of having separate circuits. I get the impression that a really long run of unbalanced cable will be more prone to hum than balanced. I had a 10m run. Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 23, 2019 Author Share Posted August 23, 2019 Is a cable balanced if it starts off with RCA? I've got an electrician coming to check out the power point next week. Link to comment Share on other sites More sharing options...
andrewyuri Posted August 23, 2019 Share Posted August 23, 2019 I think that Joz is correct - the hum appears when the sub is plugged into a different mains circuit. If that's the case, try running a separate earth wire from the chassis of the system amplifier to a screw on the chassis of the sub amp. This will prevent the difference in earth levels from running through the RCA cable connecting the amp to the sub. Link to comment Share on other sites More sharing options...
The Drake Posted August 26, 2019 Share Posted August 26, 2019 I ended up getting rid of the hum by earthing from subs to ground pin on my preamp Link to comment Share on other sites More sharing options...
Dwizzle Posted August 26, 2019 Share Posted August 26, 2019 To answer that question. From some research I did a while ago balanced cable need to be fitted into balanced components at both ends. If it is converted to RCA at one end then it is the same as using an RCA cable. Is a cable balanced if it starts off with RCA? I've got an electrician coming to check out the power point next week. Link to comment Share on other sites More sharing options...
Jarrod Harrison Posted August 27, 2019 Author Share Posted August 27, 2019 7 hours ago, Dwizzle said: To answer that question. From some research I did a while ago balanced cable need to be fitted into balanced components at both ends. If it is converted to RCA at one end then it is the same as using an RCA cable. Thats what i thought. Turns out the issue is 3 phase power in the house.... Looks like i'm going to have to run a long extension cable to another power point.. Bugger. Link to comment Share on other sites More sharing options...
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