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Topic: Home speakers unequal volume/'fullness' (receiver issue - caus (Read 15206 times) previous topic - next topic
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Home speakers unequal volume/'fullness' (receiver issue - caus

I have a NAD 7400 PE stereo receiver (late 80's) and I've recently noticed that one side is louder and sounds "fuller" (switching the balance between the two sides). This happens with both speaker settings (A and B - different sets of speakers), and regardless of source (CD/video/tuner). Not sure how long this has been happening. Does anyone know of a potential cause and/or solution? I like this reciever so I hope it's fixable. Any help is appreciated!

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #1 –
To make there isn't a problem with your speaker placement, did you try swapping channels (drive the left speaker with the right channel and vice-versa)?

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #2 –
Quote from: greynol on
To make there isn't a problem with your speaker placement, did you try swapping channels (drive the left speaker with the right channel and vice-versa)?



Thanks - yes I tried swapping the channels (in fact, right now the 'B' set of speakers (generally unused) are sitting on top of the 'A' set, with the channels reversed, so that when the balance knob is to the left, the LEFT A speaker and the RIGHT B speaker are weaker than the opposite speaker - in other words, the left channel is weaker (significantly) than the right, and it's not a speaker issue). I am in a small apt. and they are on either side of the TV, a few feet from each other in front of a flat wall, so placement is not an issue either.

I'm guessing that it's something to do with the power supply to the left channel, but I am no expert in audio electronics so I have no idea. I'm hoping it might be an easy/cheap fix since I'd like to keep using the receiver.

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #3 –
Check your wiring connections.  The times I've had a similar problem of significant channel imbalance, it was always the result of a speaker wire with poor contact or a line input from a source device not fully plugged in.  The latter is the most common in my experience with 3.5mm minijacks, such as the kind used to connect portable audio players to a home theater receiver.  Twisting the connection a bit in the socket has always resolved the issue for me.

(I know this something you've probably already checked, but it's worth mentioning based on the commonality of the problem.)

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #4 –
Since you said that it's from the late 80's, I'm pretty sure that your volume pot is starting to fail.
It's a stereo pot, and after some period of use, due to the uneven wear and dust accumulation, it's no longer symmetric (I mean, the resistance is not the same for the both channels at a given angle, usually at the beginning).

Sometimes, applying some good quality contact spray (but not WD40!) can prolong the life and cure this effect that you are experiencing, but if were you, I'd replace the volume pot.
If age or weaknes doe prohibyte bloudletting you must use boxing

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #5 –
Good advice.  And if you don't have any contact spray to use at the moment, you can do a "rough" cleaning by simply turning the volume pot all the way up and down several times (with no active audio source, of course).  This works well to remove crackling during volume changes with an older pot; I'm not sure if this would also work for balance issues, but it may be worth trying.

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #6 –
I agree that it's probably the volume or balance pot (potentiometer).  If there is a problem with one of these controls, usually, you will hear some scratchiness, or the volume will not change smoothly when you move the control.  You could also try "playing" with any other switches & controls that you may not have touched for awhile.  A bad contact in a tape-monitor switch or in a loudness switch might cause a similar problem. 

If it's just the level, and you don't notice any distortion, its most-likely not the power supply or any "active" electronics. 

Since it happens with all of the inputs and all of the speaker outputs, it doesn't sound like an external connection, unless you have an equalizer or something else in the audio-chain, it's got to be something inside the reciever.

Here's an example of tuner/control cleaner.  You use this stuff the same way S-12 said to do it without cleaner...  Take the cover off of the unit and with the power disconnected, spray some cleaner into the openings in the back of the control (or switch) and operate the control/switch rapidly.  (You can turn the power back-on when you "play with" the controls to see if you are making any progress, but be careful not to get "zapped", and don't turn the volume full-up with power on, or you might blow your speakers!)

If none of this works, try wiggling the wires & connectors around inside the unit when you have the cover off.  Do this with the power-on while the unit is playing so you can hear any changes in the sound.  To be safe, push the wires & connectors around with a wooden stick.  (Most of the circuitry is low-voltage, but if you don't know what you are doing, it's better to use a stick.)  If you find a loose conector, disconnect the power to protect yourself.  Then touch the metal chassis just-before you touch any circuitry. This is to protect the electronics by discharging any static electricity from your body. 

If you do find a bad connection inside the unit, you may be able to fix it by simply unplugging it an re-plugging it in, or you might need to spray the connector with some of that cleaner, or maybe scrape some corrosion off of the contact with an X-Acto knife or something....

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #7 –
Quote from: tman on
I have a NAD 7400 PE stereo receiver (late 80's) and I've recently noticed that one side is louder and sounds "fuller" (switching the balance between the two sides). This happens with both speaker settings (A and B - different sets of speakers), and regardless of source (CD/video/tuner). Not sure how long this has been happening. Does anyone know of a potential cause and/or solution? I like this reciever so I hope it's fixable. Any help is appreciated!


I had a similar problem with my Marantz amp. When I power up, there is a crackle/hiss in the left speaker, which improved but does not disappear after a few minutes. The volume is also about 1/2 in this speaker. I hit the side of the amp a few times (lol) and this has (at least temporarily) fixed it.

Quote from: tman on
I have a NAD 7400 PE stereo receiver (late 80's) and I've recently noticed that one side is louder and sounds "fuller" (switching the balance between the two sides). This happens with both speaker settings (A and B - different sets of speakers), and regardless of source (CD/video/tuner). Not sure how long this has been happening. Does anyone know of a potential cause and/or solution? I like this reciever so I hope it's fixable. Any help is appreciated!


I had a similar problem with my Marantz amp. When I power up, there is a crackle/hiss in the left speaker, which improved but does not disappear after a few minutes. The volume is also about 1/2 in this speaker. I hit the side of the amp a few times (lol) and this has (at least temporarily) fixed it.

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #8 –
Quote from: danhackley on
I had a similar problem with my Marantz amp. When I power up, there is a crackle/hiss in the left speaker, which improved but does not disappear after a few minutes. The volume is also about 1/2 in this speaker. I hit the side of the amp a few times (lol) and this has (at least temporarily) fixed it.
Both your problem and the OP's could have several causes. Volume pot problems are clearly the most likely.

The second most obvious is a dry solder joint, which is makeing poor/intermittent contact. Another is that the filter caps on the power supply have died, or are busy dying (electrolytic capacitors have a fairly short lifetime, especially inside a warm case). A third possibility with module (chipamp) based amps is that the chip has come partially off it's heatsink and it's thermal protection is operating - which can cause exactly the symptoms described.

If you don't own suitable test and repair equipment then you should either take the amp to a decent electronics repair shop, or ask the same question on diyaudio.com -- the people there are generally more hardware orientated than the HA crowd.

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #9 –
My 11 year-old NAD 302 stereo integrated amp has the exact same problems. Several years ago, crackle/hiss started appearing in one of the speakers on power-up. Volume balance between left/right channels also went problematic at the same time. Didn't had the time to send it for repairs though.

Having read the above excellent replies I wouldn't be surprised if it's due to uneven resistance and/or wear and tear. The amp attracts dust with alarming ease, and I am guilty of not cleaning it often - who knows what else besides rust and dust is slowly killing my trusty old amp. Considering the potential cost of repairs I think I might just be better off getting a new unit.

Home speakers unequal volume/'fullness' (receiver issue - caus

Reply #10 –
A similar problem had developed & been gradually worsening on my Mission Cyrus II amplifier. Sometimes one or both channels would be attenuated & distorted, lots of scratchy crackling noise occurred when adjusting the volume, & the source selector caused loud thunks. Wiggling the controls would randomly fix or worsen the symptoms.

I saw the above link to RadioShack's Tuner Control Cleaner & Lubricant & found similar switch & control cleaner products in Australia: Servisol Electrical Clean & Lube & CRC Switch Cleaner Lubricant. The latter was in stock at the local Dick Smith.

It came with one of those extension tubes, for precision squirting, clipped into the lid. This is nice because rubber bands never last long, the tube gets lost, & not all tubes fit all aerosols (in fact this one didn't fit well & was a very tight push fit to get it only part way into the nozzle). But it also means the tube is shorter than average so I couldn't get the tube end exactly where I wanted it every time.

After squirting some into each rotary control & selector pot & spinning them back & forth, I mopped up the not inconsiderable spillage from the circuit board with an artist's paint brush. I was a bit nervous about this as I couldn't get it all off the top of the board, & certainly didn't want to dismantle the amp further to clean the back of the board. This stuff leaves behind a presumably conductive lubricant & I didn't want it shorting anything out, but after leaving the amp a while for anything to evaporate that might, I powered it up to find all is now good! Problem solved & nothing so far (after several hours) apparently shorted. Very nice to have my much loved amp back on form.