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Subwoofer auto bypass?

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karyoker

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I am not an audiohpile fanatic snob, just a working, joe sixpack electrician with a mid grade home theater set up, who thinks my old sub could use an improvement. With this apparently common problem, you would think all subs would have off/on/auto, but some do not. I figured someone here on this electronics forum may have heard a mod and have some ideas. My new sub, which the brand doesn't matter, is doing just great. Thanks
I am familiar with that sub and was ready to help you with it. Now you are on your own.
 

98falstaff

New Member
Jumper installed, Problem solved. Took the amp out of sub, took it to work and looked it over good. Found a 12V relay on one of the circuit boards, the only relay in there. Looked up the relay on internet for coil and contact pin locations. Removed upper board for access to lower board. Traced contacts to speaker output. Powered up amp and green LED came on, Took voltage tests. Waited for LED to turn fron green to red. Verified contacts opened. Powered down. Soldered jumper wire across normally open relay contacts and reassembled. Took amp home and installed in sub cabinet and hooked up to system. Got normal bass out of sub, green light on, all cool. Waited for timer or low bass signal to auto off. Red LED came on and still had sub sound, which is exactly what I was trying to do. Now output to sub speaker is on all the time, awsome. Mission accomplished! The relay is a Goodsky UDH-SH-112D. Thanks again for all input.
 

tarquinkrikery

New Member
Falstaff, I know this post is a little old, but maybe you can help me.

My sub keeps turning off after loss of LFE signal and doesn't come back on unless I change phase from 180-0 of vica versa etc. FYI I never had a green light on - is only ever RED on the back although this could just be for power? (to be honest I can't even remember if it does go green!)

Anyway, would by-passing the relay keep my sub on all the time? I have a filter (I think 270hz-35hz) so I could filter out noise about say 150hz to try and ensure the sub isn't damaged by being on all the time. I just want the damn thing to stay on during movies so I don't have to keep messing around with it! (i don't really have it on for normal TV etc).
 

98falstaff

New Member
I'm an electrician and not an electronic genius. Check to see if your LED is green when you know the sub is putting out sound. I don't know what brand yours is but on my Cerwin, the amp was on all the time and that relay closed directly to the speaker wires when detecting a strong enough LFE signal. Before I added the jumper, I would have to turn the volume up extremely loud for the speaker to come on. It would do fine for a while until, at normal volumes, quieter passages in the program like dialogue, would let the sub fall out. Some brands have an Off/auto/on switch that would solve this problem. Cerwin Vega has Off/Auto only. Apparently different AVRs have different LFE signal output for subs. Mine is Yamaha. Keep in mind, all this was all done after adjusting all setup parameters ( large, small, frequencies, etc. as recommended on this forum ). After being disgusted with this problem I went ahead and bought another sub with Off/On/Auto. While waiting for that one is when I tore into the Cerwin and was luck that it was easy to fix myself. Now I have two subs on my system. I don't know if I helped you any but I searched this entire forum and this problem does pop up. If you need any more info just ask, or start a new thread and other members should reply. Good luck
 

98falstaff

New Member
To your original question, yes, a jumper might do the trick. Do you have a Cerwin Vega? I dont see how the phase switch would have much to do with this problem unless there is a faulty connection.
 
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