ACV92 Posted February 5, 2017 Share Posted February 5, 2017 I've noticed in the last couple of days that my old SW-10 sub started picking up an FM radio station. It's in a master bedroom setup with some just as old KG 5.5's. It's the same station with each iteration of testing. I've changed nothing in the setup where it's been and have tested theories on cable coax, different sources causing it, cables, outlets, etc. Ultimately, it boils down to this; if the RCA cable is not plugged into the receiver, but is still plugged into the jack on the back of the sub I hear the radio station, slight humming. With the RCA cable still unplugged from the receiver and then I unplug it from the back of the sub the radio station goes away, still very slight hum. Having the cable plugged into the receiver did not worsen or make the problem better. I'm just wondering if the old girl is starting to die. I'm curious as to what might cause this such as amp going bad, bad RCA jack, etc. So, I need to know if you're going to give me permission to start shopping for a new friend for the 5.5's. Any input is appreciated. Quote Link to comment Share on other sites More sharing options...
jason str Posted February 5, 2017 Share Posted February 5, 2017 Could be the RCA cable, try unplugging it from the subwoofer and see if it goes away. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 Yeah, I did that with a couple of different cables. As soon as I plug an RCA into the sub jack the station comes back. Thanks. Quote Link to comment Share on other sites More sharing options...
jason str Posted February 5, 2017 Share Posted February 5, 2017 Did you plug in both ends of the cable or just the sub side ? If you plugged both ends in and its still happening you are getting interference from somewhere, normally the cables are the culprit. Have another sub to plug in to see if the problem is eliminated ? Quote Link to comment Share on other sites More sharing options...
jason str Posted February 5, 2017 Share Posted February 5, 2017 Forgot to ask if these RCA cables are shielded or not. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 I tried plugging my various cables into the receiver and sub with no audible difference. As far as shielding, I'm not totally sure. Had a 'Y' splitter to the original set of RCA's. Tried another set of dual RCA's and same issue. Went with a single Audioquest cable that I've had and same thing. The Audioquest cable was supposed to be mid level but I don't about it's shielding. I do have a couple of other subs that I could try. Like I said before, as soon as I plug an RCA into the sub jack the radio station comes in. Whether it's connected to source or not. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 I tried my other subs and no noise with cables connected to, or not, to the receiver. I'm starting to think it's time to go shopping...... Quote Link to comment Share on other sites More sharing options...
jason str Posted February 5, 2017 Share Posted February 5, 2017 Sounds like it, at least we figured it out without too much difficulty. Not really worth repairing but if you need suggestions for something new just ask. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 Alright, let's set the world on fire. I mainly use this setup for music. I have my other Klipsch/SVS setup in the basement for movies and music. So, what do you guys like for subs? I'm not in the ultra premium, or premium, level range. I have two daughters. They eat money. I never thought I'd buy makeup, let alone at truck load levels. Anyway, I'm not a rap guy, old rock, new rock, R & B, etc. The SVS in the basement has always seemed lacking in upper frequency bass levels. The old SW-10 was/is, well, a little on the muddy side. I'm leaning towards a good sealed unit. Ported units drop lower but I like it on the tight side. Any good midrange price level suggestions to pair with the KG 5.5's? Quote Link to comment Share on other sites More sharing options...
jason str Posted February 5, 2017 Share Posted February 5, 2017 The only Klipsch i could recommend would be the THX series. Have not heard a HSU i did not like. If you need something cheaper the Dayton Sub series are great for the price, never heard the 8" or the flat low profile models. Quote Link to comment Share on other sites More sharing options...
zeron Posted February 5, 2017 Share Posted February 5, 2017 "I'm just wondering if the old girl is starting to die." Probably not. Most likely, a small part of her is weakening. Should be curable. http://electronics.stackexchange.com/questions/71727/why-is-my-audio-amp-picking-up-am-and-fm-radio-stations Try connecting only one RCA cable to only one of LINE IN Left or LINE IN Right (not both at the same time or through a Y-adaper) to see if you hear less radio signal on one. If that's the case, all you need to do could be as simple as replacing one resistor. near the input connector on the other side. If there's no difference, you may have to change at least one capacitor, too. Will involve labor, but required parts should cost only a few bucks. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 Jason str - Thanks for the suggestions. I may have to look at the HSU line. I like the variability with port blocking, etc. The price point is definitely where I'm at. Have you listened to any of the Klipsch subs in the SW line? Just wondering how they would stack up. Zeron - I appreciate the link. If I would have to add a capacitor and a resistor to eliminate the problem would you say that something is going wrong with the amp? I'm not against trying the suggested methods but am I band-aiding the problem? I understand that if it works than don't worry about it, but I'm not against a little upgrade either. I'm trying to give myself an excuse to do the later. Thanks again. Quote Link to comment Share on other sites More sharing options...
zeron Posted February 5, 2017 Share Posted February 5, 2017 1 hour ago, ACV92 said: If I would have to add a capacitor and a resistor to eliminate the problem would you say that something is going wrong with the amp? No, I wouldn't think the whole amplifier is dying. Klipsch engineers must have designed and implemented a section in the amplifier of SW-10 to counter RF interference, like they did for my SW-12. So, this section of the circuit in your SW-10 may have weakened and/or have been weakening, and replacing resistors and/or capacitors in this section will be restoring the original condition of the section as intended by its designers. Have you tried connecting only one cable to L or R of LINE Input connectors? I'm looking at the schematic of SW-12 and I see only 6 resistors and 3 capacitors in this section that deals with RF interference. If I were you, I'd check these. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 I have a single cable to the left input now. I tried it in the right input and the noise persists. From what I've been reading I need to install a ground loop isolator. So, before I get into the amplifier I want to try this first. I've been using a 3 to 2 prong adapter since the unit was new. The owner's manual stated to do this and there was a card that Klipsch had put in as well that said the same thing. So, I never assumed I was doing something wrong. What isolators (brand) do most people use? Another question though, I was reading in the manual that if you use a 'Y' splitter to the inputs as I had been that there is a 6 db level increase. I'm assuming that works on a mono sub-out or as they referenced a 'single pre-amp output'. Just curious. Thanks. Quote Link to comment Share on other sites More sharing options...
zeron Posted February 5, 2017 Share Posted February 5, 2017 1 hour ago, ACV92 said: From what I've been reading I need to install a ground loop isolator. So, before I get into the amplifier I want to try this first. Didn't you write that you had tried two other subs at the same location and had no noise problems? Quote Link to comment Share on other sites More sharing options...
zeron Posted February 5, 2017 Share Posted February 5, 2017 1 hour ago, ACV92 said: I've been using a 3 to 2 prong adapter since the unit was new. The owner's manual stated to do this and there was a card that Klipsch had put in as well that said the same thing. So, I never assumed I was doing something wrong. [. . .] Another question though, I was reading in the manual that if you use a 'Y' splitter to the inputs as I had been that there is a 6 db level increase. I'm assuming that works on a mono sub-out or as they referenced a 'single pre-amp output'. The manual for my SW-12 says the same thing. I had been using a 3 to 2 prong adapter for my SW-12 until recently myself. It helps to eliminate or reduce severe hums but apparently takes away protection against some electrical surges and shorts. (I wonder if the adapter had something to do with the noises I started hearing from my SW-12. I noticed them for the first time on a stormy day.) Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 That's what I was thinking as well. The other two subs were two prong adapters. My SW-10 has hummed since day one when using the three prong adapter regardless of outlet, room, source connection, etc. That's why I used the two prong adapter. So, my thought here it to try an outlet side GLI vs a line level one for that reason. I may have had some noise at all times and didn't notice it before, or it started getting worse recently for some external reason. I'm not doubting what you said about about the amp board. I'm not experienced in soldering to boards and therefore don't really want to try it and fry the board. I figured I've give the GLI a try and see if it helps. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 5, 2017 Author Share Posted February 5, 2017 Sorry about the typos. Should have been "...is to try..." and "...figured I'd give....'. I hate that. Quote Link to comment Share on other sites More sharing options...
ACV92 Posted February 6, 2017 Author Share Posted February 6, 2017 OK, ground loop folks explain this one. My SW-10 was exhibiting some noise, as stated earlier, and here's what I did to eliminate it. Without source connected the sub would hum, and play an FM radio station with an RCA cable connected to the sub input jacks. Here's what I did. After reading reactions to a post about hum, Jason str pointed me in the right direction. I took some 12 ga wire and connected some ring terminals to both ends of the wire. I mounted one end of the ring terminals to a random screw on the amplifier board and one to the ground terminal on the receiver, What a difference. I have never been able to play this sub with the 3 prong plug set in the outlet. I don't know what changes happened with the ground wire but it is great. All I hope is that someone else with this issue can remedy it as I did. Kudos, to the Klipsch forum for solving a weird issue. Zeron, try this and see if the SW-12 plays as you want it to. I realize that you've messed with the amp but I can honestly say this dumb trick actually worked for me. Let me know what you find. Quote Link to comment Share on other sites More sharing options...
jason str Posted February 6, 2017 Share Posted February 6, 2017 Ground loop is just current flowing through the input cables, since the input cables were not plugged in for this to happen what you are experiencing is either a dirty/poor ground where you have the sub plugged in or something back feeding in the amplifier itself would be my best guess. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.