Way60 Posted February 23, 2022 Share Posted February 23, 2022 I have a brand new RelT7x sub that sounds incredible in my stereo music system, but..hums with no connections other than mains power. The sound is not coming from the drivers, it sounds like the transformer. It is a constant hum that does not vary no matter what I switch or adjust. It it as quiet as a mouse in the two offsite locations I have plugged in into to. My house has two power circuits, I have tried shutting each off while using the other..still hums. I have tried many gpo's in the house..still hums. I have shut down, a/c's lighting, pumps and it still hums. I borrowed an Isotec power conditioner and it has no effect on the hum. My guess has been D/C offset and will next try an Audiolab D/C Blocker. Also looking at installing a separate power line for the hifi and have been reading a few interesting threads here. My house is 160 meters from the power connection out on the road, goes underground to the Switchboard on the house. Has anyone had similar issues and solved them? Any suggestions? Cheers Link to comment Share on other sites More sharing options...
Snoopy8 Posted February 23, 2022 Share Posted February 23, 2022 It could be a power chord or sub cable picking up noise. Try different ones, moving them, move sub. Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 Snoop I have done that. Tried just connecting to power only not signal from the power amp. Power cord was clear of all interference, and tried it in lots of different power points. Link to comment Share on other sites More sharing options...
mwhouston Posted February 23, 2022 Share Posted February 23, 2022 How is it with RCAs plugged in and feeding unit turned on but no music? Link to comment Share on other sites More sharing options...
Snoopy8 Posted February 23, 2022 Share Posted February 23, 2022 12 minutes ago, Way60 said: Snoop I have done that. Tried just connecting to power only not signal from the power amp. Power cord was clear of all interference, and tried it in lots of different power points. Try a different power chord? Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 21 minutes ago, Snoopy8 said: Try a different power chord? Have tried an audiophile grade power cord, still hums.. Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 (edited) 30 minutes ago, mwhouston said: How is it with RCAs plugged in and feeding unit turned on but no music? It connects via High Level Input to power amp. I have tried all earthing suggestions suggested by Rel to eliminate humming. The hum remains the same. So I feel it is a power issue, not an earthing to system issue Edited February 23, 2022 by Way60 Link to comment Share on other sites More sharing options...
Snoopy8 Posted February 23, 2022 Share Posted February 23, 2022 I suspect you have a ground loop. It is a pain to find, but you need to disconnect all cables except the sub, then add cables 1 at time. Note that powering off a component is not sufficient and you need to take out the physical cables. Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 7 minutes ago, Snoopy8 said: I suspect you have a ground loop. It is a pain to find, but you need to disconnect all cables except the sub, then add cables 1 at time. Note that powering off a component is not sufficient and you need to take out the physical cables. Snoop the hum is there with no cables connected...only the power and it hums. I have tried all Rel solutions to grounding hums. Hum does not change either connected to the system or not. My power amp does not hum at all. Note the sub does not hum if I take it to another site and plug in power Link to comment Share on other sites More sharing options...
Snoopy8 Posted February 23, 2022 Share Posted February 23, 2022 (edited) The power cord itself can be part of the ground loop. As I mentioned, it is a pain to find what cables (power, interconnect etc) of all the other components that are causing it. Edited February 23, 2022 by Snoopy8 1 Link to comment Share on other sites More sharing options...
Snoopy8 Posted February 23, 2022 Share Posted February 23, 2022 https://www.techhive.com/article/582313/how-to-get-rid-of-hum-and-eliminate-other-noises-from-your-audio-and-video-systems.html Perhaps this will help Link to comment Share on other sites More sharing options...
VanArn Posted February 23, 2022 Share Posted February 23, 2022 Could the hum that is being heard be from the mains transformer in the plate amplifier and not from the 8'' woofer ? If that is the case then it is a problem that could be caused by a high mains voltage or disturbances contaminating the 50 Hz waveform. Plate amplifiers tend to have switch mode power supplies these days and what I am suggesting would in reality be for a typical bridge rectifier, capacitor filter arrangement amplifier power supply. Link to comment Share on other sites More sharing options...
ICUToo Posted February 23, 2022 Share Posted February 23, 2022 2 hours ago, Way60 said: Has anyone had similar issues and solved them? Sounds like you need a new transformer- hard to arrange these days unless you know how to safely DIY. or New plate amp Link to comment Share on other sites More sharing options...
Cono28 Posted February 23, 2022 Share Posted February 23, 2022 I have the same problem with my Rel , have high output connection with the integrated amp , but when I connected the Ht receiver with a sub cable to the LFE input,the hum disappeared . Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 5 hours ago, VanArn said: Could the hum that is being heard be from the mains transformer in the plate amplifier and not from the 8'' woofer ? If that is the case then it is a problem that could be caused by a high mains voltage or disturbances contaminating the 50 Hz waveform. Plate amplifiers tend to have switch mode power supplies these days and what I am suggesting would in reality be for a typical bridge rectifier, capacitor filter arrangement amplifier power supply. That is what I am leaning towards, transformer hum caused by average power supply. Hum is not coming from the drivers. I have very little electronic knowledge, I think the Rel has a Toroidal Tranformer which hum when DC makes and appearance in the alternating current. So I think you are suggesting a DC blocker? Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 4 hours ago, Cono28 said: I have the same problem with my Rel , have high output connection with the integrated amp , but when I connected the Ht receiver with a sub cable to the LFE input,the hum disappeared . So are you using the LFE as the signal now and not the High Level? My amp does not have that option to connect. So must use High Level which is what they suggest for 2 channel music playback. Rel have an earthing option to connect the LFE to an unused RCA on pre-amp. I tried this and nothing changed so I have basically ruled out an earth problem.. Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 5 hours ago, ICUToo said: Sounds like you need a new transformer- hard to arrange these days unless you know how to safely DIY. or New plate amp The Rel is a brand new item, has hummed from day one. I thought it was faulty, and retailer/dist agreed to replace the unit. But when tested at the shop there was no hum at all. Also no hum at another site. I don't think it is a faulty product, it only hums at my place.. Link to comment Share on other sites More sharing options...
afa Posted February 23, 2022 Share Posted February 23, 2022 Here is an explanation of what might be causing your problem https://sound-au.com/articles/xfmr-dc.htm Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 6 hours ago, Snoopy8 said: Perhaps this will help Thanks, from this I think an Isolation transformer is worth a try, I will ask my electrician if he has one so we can try that.. Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 2 minutes ago, afa said: Here is an explanation of what might be causing your problem Yes I think it is a DC problem from my online research [haven't read your link entirely as yet thanks] And I also hope a simple DC blocker will fix it, if not a separate circuit and a good look at the earthing arrangement in the house my be on the cards. It's not helping I feel that it is a long run from the power pole to my meter box on the house Link to comment Share on other sites More sharing options...
andyr Posted February 23, 2022 Share Posted February 23, 2022 33 minutes ago, Way60 said: Yes I think it is a DC problem from my online research [haven't read your link entirely as yet thanks] And I also hope a simple DC blocker will fix it, I think you mentioned earlier, Wayne, that the humming was not coming from the sub driver - so it's mechanical humming from the plate amp's transformer? If you're interested - PM me if you are - as I believe it's always important to test out whether a DC blocker does in fact fix your problem, I can lend you a DC blocker to try out. The arrangement would be something like: you pay me half and I send it to you if it doesn't work - and you want to send it back to me ... when I've received it, I refund your deposit ... less postage. Andy Link to comment Share on other sites More sharing options...
Way60 Posted February 23, 2022 Author Share Posted February 23, 2022 5 minutes ago, andyr said: I think you mentioned earlier, Wayne, that the humming was not coming from the sub driver - so it's mechanical humming from the plate amp's transformer? If you're interested - PM me if you are - as I believe it's always important to test out whether a DC blocker does in fact fix your problem, I can lend you a DC blocker to try out. The arrangement would be something like: you pay me half and I send it to you if it doesn't work - and you want to send it back to me ... when I've received it, I refund your deposit ... less postage. Andy Thanks Andy, my retailer where I purchased the sub is getting a blocker in for me to try, hopefully by the end of this week, will see what happens and go from there Cheers 1 Link to comment Share on other sites More sharing options...
GB73 Posted July 30 Share Posted July 30 On 23/02/2022 at 10:15 PM, Way60 said: Thanks Andy, my retailer where I purchased the sub is getting a blocker in for me to try, hopefully by the end of this week, will see what happens and go from there Cheers I have what I think is the same quiet hum from the plate amplifier on my Rel T/7x when only mains power is connected (and nothing else connected to the SW). I've tried different power points in my home and in my partner's home. So, I'm yet to find a house in which the hum disappears but I'm curious as to whether you ever resolved this? Cheers Grant Link to comment Share on other sites More sharing options...
Frank Prowse Hi-Fi Posted August 1 Share Posted August 1 On 30/07/2024 at 10:18 PM, GB73 said: I have what I think is the same quiet hum from the plate amplifier on my Rel T/7x when only mains power is connected (and nothing else connected to the SW). I've tried different power points in my home and in my partner's home. So, I'm yet to find a house in which the hum disappears but I'm curious as to whether you ever resolved this? Cheers Grant Usually a mechanical hum is a sign of DC on the mains. Borrow a DC Blocker from your local retailer to confirm. Link to comment Share on other sites More sharing options...
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