Channel balance

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Nick Hudson
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Channel balance

Post by Nick Hudson » 03 Aug 2018 21:59

Hi Folks,

I wonder if you could help? I recently bought an AT LP120 and a Goldring Elan cartridge. Since putting it all together the right channel is fractionally louder than the left and not giving a total equal balance between the two speakers. I have checked all the connections at the back, also the wires into the cartridge, balanced the tone arm and cartridge tracking but still it happens. Any ideas folks? Your comments are much appreciated.

JohnMcC
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Re: Channel balance

Post by JohnMcC » 03 Aug 2018 22:05

As a quick check try switching the cartridge connections (left to right) leaving everything else as it is - if the stronger channel switches sides then I'd say it's a cartridge problem. If the same channel is still louder then look somewhere else.

whitetrashrocker
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Re: Channel balance

Post by whitetrashrocker » 03 Aug 2018 22:08

Try switching your inputs. Make left-right and right-left.
See if the left channel is louder.

It might be in your receiver/amp.
I have 2 vintage Sylvania, my Marantz, and a newer (90's) Sony that all have a slight favor towards the right side.

I have probed the Sylvania with an oscilloscope and found the signal going into the volume pot is balanced, but on the output side the right is slightly hotter.
Like the internals of the pot aren't perfectly clocked in sync with each other.

Just compensate by sliding the balance just off center I guess.

whitetrashrocker
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Re: Channel balance

Post by whitetrashrocker » 03 Aug 2018 22:47

I have no idea if that's your problem but that's what I found was my balance problem.

Here's a signal pre volume pot.
IMG_20180803_154059.jpg
(636.42 KiB) Downloaded 177 times
And here's the same signal post volume pot.
IMG_20180803_154141.jpg
(603.95 KiB) Downloaded 177 times

Patrice Brousseau
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Re: Channel balance

Post by Patrice Brousseau » 04 Aug 2018 03:14

whitetrashrocker wrote:I have no idea if that's your problem but that's what I found was my balance problem.

Here's a signal pre volume pot.
IMG_20180803_154059.jpg
And here's the same signal post volume pot.
IMG_20180803_154141.jpg
+1

On my Scott 222D, right side is louder. On an Eico HF-81, it's the left. I just use my balance pot...

Solist
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Re: Channel balance

Post by Solist » 04 Aug 2018 10:25

Probably incorrect antiskate/azimuth.

If the force of the antiskate is too strong or to weak it means the stylus will put more force on one groove than the other, which will cause the signal to be stronger on one side = left/right channel imbalance.

The AT LP120 is notorious for having problems with antiskate. The problem is that the antiskate values are not correctly balanced.

Easiest way to set the antiskate is to use a CD like you would a vinyl and then let the stylus ride it. Use the bottom part of the CD, never the side on which you write! Be careful since the stylus can quickly fall of the CD.
Then just slowly adjust the antiskate until the arm becomes stationary. If you apply too litle antiskate the arm will move towards the spindle, too much and it will start moving away from the spindle.

Misaligned azimuth can also cause left/right channel imbalance. This is when the stylus is not sitting at a 90 degree angle in respect to the record. If you look the cartridge from the front look at the stylus tip. You if you see this ./. instead of this .!. you have a problem. The dots are the record and the / ! is the cantilever/stylus. If the stylus is tilted, will once again ride one groove more than the other, which will cause channel imbalance.

To set the azimuth properly is a pain in the butt, but well worth the effort. First check the azimuth. Easiest way is to put a small mirror on the platter and then put the cartridge on it. The mirror will emphasize the error which will make it easier too see. Also a magnifying glass can come in handy. Then use pieces of electrical tape to use as shims between the cartridge and the headshell. This will tilt the stylus in the direction needed.

Needless to say take your time with these adjustments. When the nerves kick in (which they usually do, just go drink a beer :D ) The first time it might take the whole evening to set them correctly, but its well worth it.

Solist
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Re: Channel balance

Post by Solist » 04 Aug 2018 10:37

If you decide to do all this work check for the SRA also. When looking the cartridge from the side when playing a record the stylus should ride the groove at a 92 degree angle. If the angle is too big you will have more emphasis on the treble if the angle is below 92 degrees you will get more basy sound.

You set the SRA the same way you set the azimuth, using pieces of eletrical tape (this time on the front and back of the cartridge to tilt it in the desired direction).

analogaudio
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Re: Channel balance

Post by analogaudio » 04 Aug 2018 15:57

QUOTE

If the force of the antiskate is too strong or to weak it means the stylus will put more force on one groove than the other, which will cause the signal to be stronger on one side = left/right channel imbalance

END QUOTE

This statement is true only when a force sensitive cartridge is in use, they are uncommon, one type is the strain gauge cart. This poster does not have a strain gauge cart. With a magnetic cart the signal is proportional to the velocity of the motion of the cantilever as it tracks the modulated groove. When there is no modulation the velocity is zero and there is silence. When there is maximum modulation the velocity is maximum and the signal is loudest. Magnetic carts have no mechanism that can convert sideways pressure changes into signal changes. The cause of the imbalance lies elsewhere.

The balance specifications for many magnetic carts allow a variation of around 5%, this is easily measured and may produce a small de-centering of the sound. The usual remedy is to use the balance control on the amplifier.

Doug G.
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Re: Channel balance

Post by Doug G. » 04 Aug 2018 19:48

The quickest way to determine whether the imbalance is from the turntable or the rest of the system is to feed exact amplitude signals, most easily obtained feeding in a mono signal, into both inputs. If the signal strength remains balanced throughout, the rest of the system is cleared and the problem is almost certainly an imbalance in the cartridge.

Almost without exception, cartridges have a 1dB balance tolerance between the two channels. A 1dB difference is audible. I have seen some with a 2 dB spec.

As others have said, use the balance control (unless you are a purest-of-the-pure audiophile and don't have a balance control). :D

Doug

Solist
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Re: Channel balance

Post by Solist » 04 Aug 2018 23:42

analogaudio wrote: This statement is true only when a force sensitive cartridge is in use, they are uncommon, one type is the strain gauge cart. This poster does not have a strain gauge cart. With a magnetic cart the signal is proportional to the velocity of the motion of the cantilever as it tracks the modulated groove. When there is no modulation the velocity is zero and there is silence. When there is maximum modulation the velocity is maximum and the signal is loudest. Magnetic carts have no mechanism that can convert sideways pressure changes into signal changes. The cause of the imbalance lies elsewhere.

The balance specifications for many magnetic carts allow a variation of around 5%, this is easily measured and may produce a small de-centering of the sound. The usual remedy is to use the balance control on the amplifier.
Just when I thought I knew something about this topic, then I see this :)

I did a bit of reading about strain gauge cartridge, really interesting. I just wish the price was "a bit" lower.

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