QuestionQUESTION: I recently purchased a Yamaha receiver 400 w, 100 p/channel. I am trying to connect it to an older pair of Cerwin Vega midrange speakers. The speakers are approximately 8 - 10 ft from the receiver. I am using Monster Cables running about 15 ft. I get excessive feedback in the speakers when using them in conjunction with the TV/DVD. Am I using the wrong gage and length of cable, or is the feedback from something else. When I take the receiver out of the cabinet and test the speakers using shorter cable/wire and the stereo, I do not receive any feedback. Your thoughts would be very welcome and appreciated.
ANSWER: The cables are not involved in any way with feedback.
Feedback is usually when something goes "microphonic" or some component becomes sensitive to the acoustic wave coming from the speakers.
HOWEVER, I suspect you are not getting feedback but overdrive which is causing clapping of the midranges. If you are not using a crossover to limit the low frequency energy from getting into the voice coils of the mid range speakers they will bottom out and the rumbling noise you hear is caused by the voice coil clapping against the basket of the speaker mountings or something like that.
There may be something else going on such as a magnetic feedback due to the wires running too close to some other cables - or such phenomenon.
Could you investigate further based on my comments and let me know more. Especially, give me the model numbers of the receiver and the speakers that you are powering and any other description of the installation that will help me understand your setup.
Thanks,
cleggsan#cleggsan.com
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QUESTION: Thanks for the quick response. I am traveling and not at home. However, by referencing against the websites for Yamaha and Cerwin Vega, it looks like I have the Yamaha Model RX-V363 and the speakers VE-5M. Magnetic feedback could be a possibility as I have a Hi-Def DVD, a Blu-Ray, a Hi-Def TV, a tape player and a turntable all tied into the Yamaha receiver. All the wires run together through the back of an entertainment center. I have three HDMI cables hooked up (DVD, Blu-Ray and TV). For about 2-3 feet, all cables run together.
Not sure how I would check for overdrive or using a crossover.
ANSWER: Your last comment: Overdrive is just turning up the volume too loud causing either excessive distortion in the amplifiers or the loudspeakers. Crossover: Is a network ahead of the speakers to filter the sound going into the appropriate speaker drivers. The VE-5M is a complete speaker system with woofer and tweeter built in; crossover network is internal part of the system. So, unless you have modified them or unless you have disabled the crossover network, they are not mid-range but full-range speaker systems. They are also magnetically shielded and should not have any problem in an AV system. They are, however, not capable of large power inputs as they are a modestly priced system and overdrive could be a problem.
Back to the concept of feedback. The typical term of feedback is when in a PA system the level is turned up too far and the output of the speaker acoustic wave gets to the microphone sufficiently strong to increase the output again and it results in a kind of low frequency growling sound. So, normally that is the sound we are expecting when one uses that term. The other distinguishing factor of feedback is that it is gain sensitive; that is it will suddenly become predominant as the gain or volume is increased. Reducing the volume below the feedback point will kill the feedback.
In your case, we must determine what the sound is like; if it is constant but level dependent it is something getting into your amplifier ahead of the volume control. If it is quite high in frequency, such as a squeal or shrill sounding it is likely more of a crosstalk between channels or between inputs or outputs of the devices in your system. If it is a very high pitched tone it is more likely an oscillation from spurious crosstalk between devices.
So, if you could explain the sound you are getting and if it goes away completely when the volume is reduced or just lowers in sound level that will help me determine what you have.
And, finally, yes, it is possible the many devices you have in your system could be interacting with each other. The thing to do there is just temporarily unplug all inputs to the receiver. If the "feedback" goes away, then connect the other devices one by one until you get the sound back; that will clue you to the problem area.
Maybe this will get us to the bottom of it all.
C
PS: Combo TV sets are notorious for not working well in expanded AV systems, by the way.
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QUESTION: Sorry about not providing enough information. I guess it would have helped to describe the noise more. The issue is definitely not overdrive, because the noise happens at the lowest levels of volume. I have not even turned it up more than 25 - 30% of its capacity. It happens at even 5 - 10% volume level. As for crossover, I have not modified the speakers. They are as they came off the shelves of the store I purchased them (probably Best Buy) a few years ago.
As for the sound, it is a low humming, vibration sound. I don't even hear the audio from the tv or dvd, just the vibrating sound from the speakers. By the way, I forgot to mention that I do have a Klipsch Center speaker that does not have this issue. When I get home tomorrow, I can do as you suggested and disconnect component by component and try rerouting the wires.
I am basically just trying to set up a surround sound system for the family, now that we have a large Hi-def TV and newer equipment. The receiver is only a few weeks old.
Any other thoughts you have will be greatly appreciated. Just want to let you know that you have been a big help already and I greatly appreciate it. Reading through dozens of blogs on the speaker wires drove me nuts.
AnswerIf I could hear the sound it would be a great help. The nature of the sound is the most critical matter so far. The most telling thing you have described so far is that is that it "happens at the lowest levels of volume". This is very critical to know exactly how it behaves, so here is the question that I would like a definitive answer to: Does the sound come up gradually as you increase the volume from zero or does it suddenly or abruptly start at some point above the zero position of the volume setting? Another question: Do you hear the same exact sound out of both speakers? Are you sure? Is there any difference in the sound or instigation of the sound in one speaker from the other?
Sorry to give you these difficult questions, but they will help me to correlate it to the kind of ailment that can produce such a strange phenomenon.
Based on what you have described thus far I am leaning towards the speaker cables being wrapped around too close to the tv or receiver causing an electromagnetic feedback or crosstalk. Re-routing the wires may have an effect on the performance.
In any event, let me know what you find out after investigating for the answers to the questions above.
Tks for your labors.
C
