Channel balance tool for few bucks

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Channel balance tool for few bucks

Postby mandym » Mon Jul 05, 2010 10:17 am

For more than a month now, I have been chasing my tail trying to get spot-on channel balance. Before my AI preamp got smoked,I used to get the balance by adjusting the separate volume controls ( I now know this is not exactly the right way to do it). With the replacement Seduction preamp there is no way to set the balance independently, I had to suffer through vocalists singing a bit left of center. I did the usual rituals of swapping, substitution, speaker relocation, room treatment, etc,etc. What made matters worse is that the problem was not gross,I even suspected it to be intermittent, either due to equipment or my very own EARS! There are just so many possible sources of problems from contacts, tubes, interconnects, SUT, speakers, room, etc. It is overwhelming, after a month, I was no closer to the solution.

The best way then, I thought is to isolate the problem through elimination, starting from the speaker/room, all the way back to the source. STEP BY CAREFUL STEP!

I made up a tool which has proved indispensable in isolating sources of imbalance. It is a simple signal splitter. A signal is fed at the input, the output being two exactly identical signals. The parts used are 2 capacitors (.1 mfd each), 2 RCA jacks, 1 RCA plug and a capacitor can:

Image

I started by feeding one channel (left or right does not matter) to the splitter and feeding the output to the inputs of the amplifier. This tests the amp-interconnect-speaker-room chain. Amazingly (and luckily) the image snapped to DEAD CENTER! I left the set up for a day's listen to be sure of what I am hearing. It was true, the problem DOES NOT originate from the amplifier onwards, the signal comes unbalanced as supplied to the amp input!

Now, that's settled with finality, I will be moving on to the preamp section, then all the way back to the source if necessary. To paraphrase Sherlock Holmes...if all possibilities have been exhausted, what remains must be the answer no matter how improbable.
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Re: Channel balance tool for few bucks

Postby Mamimili » Mon Jul 05, 2010 10:24 am

the world is full of Watson's waiting to be enlightened :^)
Brilliant :clap:
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Re: Channel balance tool for few bucks

Postby kabubi » Mon Jul 05, 2010 10:56 am

pls reserve!
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Re: Channel balance tool for few bucks

Postby mandym » Mon Jul 05, 2010 12:31 pm

kabubi wrote:pls reserve!


Reserve for purchase, no. Reserve for loan, OK.

After I finish troubleshooting, I will have it available for members to borrow :) :)
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Re: Channel balance tool for few bucks

Postby kabubi » Mon Jul 05, 2010 12:44 pm

thanx, Herr Mandy.

i have had issues with the balance of my systems. i dont know if it's my hearing or imagination, or if there is any problem at all. your gadget will surely take away the guesswork :)
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Re: Channel balance tool for few bucks

Postby Superman » Mon Jul 05, 2010 12:54 pm

kabubi wrote:pls reserve!


Me too! :D
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Re: Channel balance tool for few bucks

Postby Fourplay » Mon Jul 05, 2010 1:05 pm

Superman wrote:
kabubi wrote:pls reserve!


Me too! :D


+ 2 ;) ;) ;) ;) ;) ;) ;) ;)
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Re: Channel balance tool for few bucks

Postby mandym » Tue Jul 06, 2010 9:13 am

kabubi wrote:thanx, Herr Mandy.
i have had issues with the balance of my systems. i dont know if it's my hearing or imagination, or if there is any problem at all. :)


My feelings exactly. Nothing is as unsettling as lingering doubts about my system's health. My current struggle is to get the balance dead center. The signal splitter is surely helping pinpoint the source. Although the problem has not yet been fixed, I now know definitely that the speakers, the room, the amplifier are NOT the culprit! That narrows down the number of suspects by quite a bit; today I will put the preamp section under test. I will not stop until the source is identified.

I believe that channel balance is of prime importance. Zu Audio sells their modified Denons by grades of channel balance. Those within 5% tolerance cost $399, those within .1% cost $699!!

My descents to the netherworld of Audio Nervosa has left me with disturbing questions:
1. If I "fix" the imbalance by repositioning the speakers, adding room treatments or resetting the balance control, is it just possible that I am merely covering up a cartridge imbalance/alignment problem?
2. If I "fix" the imbalance by realigning the cartridge, is it just possible that I am only compensating for other system problems thus compromising the performance of the cartridge?

To avoid these pitfalls, again, a STEP BY CAREFUL STEP procedure is absolutely necessary. Once the problem is resolved you might be very amazed how good your system sounds :clap: :clap: :clap: .
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Re: Channel balance tool for few bucks

Postby mandym » Wed Jul 07, 2010 1:20 pm

BY GEORGE, I FOUND IT!!!

I have tested the preamp and it passed but not with flying colors. There was the slightest hint of imbalance which however was fixed through a tube change.

I then reconnected the preamp to the source...the frustrating problem was still there!

Bad interconnects? I interchanged them, no change. The ICs were not the problem
Bad contacts? I carefully cleaned ALL source contact with contact cleaner, no change. The contacts were not the problem.

As a last ditch effort, I changed the cartridge. BINGO... problem solved. A slight touch-up on the azimuth snapped the image to dead center, sharp focus!

OH BLISS! Once again I can spend endless days in happy tweaking of VTA, VTF, Azimuth, et cetera, et cetera, et cetera. What more can an Audiophile ask for?

Sir Kabubs, I am done with the splitter. Please PM me where to send it.
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Re: Channel balance tool for few bucks

Postby JoeyGS » Wed Jul 07, 2010 2:40 pm

Sir Mandy,

Is it possible for you to teach us how to make one? Or will you do it for us, for a fee?

Thanks and regards,
JoeyGS
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Re: Channel balance tool for few bucks

Postby Superman » Wed Jul 07, 2010 8:03 pm

mandym wrote:BY GEORGE, I FOUND IT!!!

I have tested the preamp and it passed but not with flying colors. There was the slightest hint of imbalance which however was fixed through a tube change.

I then reconnected the preamp to the source...the frustrating problem was still there!

Bad interconnects? I interchanged them, no change. The ICs were not the problem
Bad contacts? I carefully cleaned ALL source contact with contact cleaner, no change. The contacts were not the problem.

As a last ditch effort, I changed the cartridge. BINGO... problem solved. A slight touch-up on the azimuth snapped the image to dead center, sharp focus!

OH BLISS! Once again I can spend endless days in happy tweaking of VTA, VTF, Azimuth, et cetera, et cetera, et cetera. What more can an Audiophile ask for?

Sir Kabubs, I am done with the splitter. Please PM me where to send it.


Happy Birthday, Sir! Next in line please :D :D :D :D :D
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Re: Channel balance tool for few bucks

Postby mandym » Wed Jul 07, 2010 10:09 pm

JoeyGS wrote:Sir Mandy,

Is it possible for you to teach us how to make one? Or will you do it for us, for a fee?

Thanks and regards,
JoeyGS


It is as easy as 1,2,3.
1. Solder 2 .1mfd/100v capacitors to the signal wire of the pigtailed RCA plug seen in the photo. This will be the input.
2.Solder the free ends of the capacitors to the output center terminals of the RCA jacks, one jack per capacitor.
3.Solder the ground terminals of the RCA jacks to the ground shield of the pigtailed RCA plug.
That's it.

*I don't know if the value of the capacitor is critical. I don't think so but matching them should not hurt. I used them for DC isolation between the channels.
*The pigtailed jack is salvaged from a cheap IC from a TV set or a VCR.
*If you want it to look good, put it in a nice box :) :) .
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Re: Channel balance tool for few bucks

Postby qguy » Thu Jul 08, 2010 6:09 am

Hi Mandy,

Whats the difference when using this device vs a regular Y jack ?


mandym wrote:
JoeyGS wrote:Sir Mandy,

Is it possible for you to teach us how to make one? Or will you do it for us, for a fee?

Thanks and regards,
JoeyGS


It is as easy as 1,2,3.
1. Solder 2 .1mfd/100v capacitors to the signal wire of the pigtailed RCA plug seen in the photo. This will be the input.
2.Solder the free ends of the capacitors to the output center terminals of the RCA jacks, one jack per capacitor.
3.Solder the ground terminals of the RCA jacks to the ground shield of the pigtailed RCA plug.
That's it.

*I don't know if the value of the capacitor is critical. I don't think so but matching them should not hurt. I used them for DC isolation between the channels.
*The pigtailed jack is salvaged from a cheap IC from a TV set or a VCR.
*If you want it to look good, put it in a nice box :) :) .
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Re: Channel balance tool for few bucks

Postby mandym » Thu Jul 08, 2010 7:57 am

qguy wrote:Hi Mandy,
Whats the difference when using this device vs a regular Y jack ?


Hey! Dummy me, I forgot there is such a thing...another of my senior citizen moments :D :D ! Talk about reinventing the wheel!

Well, as it turns out that there is a difference, its the capacitors in the output side. I just did not feel comfortable having the channels directly tied together.
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Re: Channel balance tool for few bucks

Postby JoeyGS » Thu Jul 08, 2010 8:29 am

Thanks for the tips, Sir Mandy. :)

mandym wrote:It is as easy as 1,2,3.
1. Solder 2 .1mfd/100v capacitors to the signal wire of the pigtailed RCA plug seen in the photo. This will be the input.
2.Solder the free ends of the capacitors to the output center terminals of the RCA jacks, one jack per capacitor.
3.Solder the ground terminals of the RCA jacks to the ground shield of the pigtailed RCA plug.
That's it.

*I don't know if the value of the capacitor is critical. I don't think so but matching them should not hurt. I used them for DC isolation between the channels.
*The pigtailed jack is salvaged from a cheap IC from a TV set or a VCR.
*If you want it to look good, put it in a nice box :) :) .
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