I am at the end of my rope, please help


I have a problem that I can not solve and makes no sense to me at all.
My right channel is stronger than my left by a large margin. I can plug my tonearm cable directly into a Fozgometer (measures left and right output) and I get a substantially stronger signal on the right side. I confirmed this with my Voltmeter to make sure there was not a problem with the Fozgometer. So, as far as I can tell, this narrows the problem down to the Cart, Tonearm, Tonearm wire or the table.

Here is what I have tried:
1. Changed Azimuth in both directions. Small change but still much stronger on the right side.
2. Changed antiskating. Very little change.
3. replaced the cartridge. No Change.
4. replaced the tonearm and cartridge. No Change.
5. replaced the tonearm, cartridge and tonearm wire. No change.
6. I have used a second test record. No Change
My turntable is perfectly level.
I simply do not see how this is possible! I have an $83,000 system that I can not listen to. Any ideas would be much appreciated.

My system:
DaVinci Turntable > Lyra Titan i > Schroeder Reference tonearm > Manley Steelhead > Stealth Indra cables > VTL 450 amps > Stealth Mlt speaker cables > Vienna acoustic Mahler speakers
audioraider

Showing 6 responses by atmasphere

Audioraider, the measurements you described indicate a problem with the tone arm cable. The center of the right channel RCA should have continuity to the red lead, ground of that RCA has continuity to the green lead. They should not have continuity to each other. The same goes for the other channel.

The way you described it sounds as if there is a short. Amazingly (and somewhat counter-intuitively), many LOMC cartridges can drive a short fairly well since they are high current and low voltage.

So if you stand by your description/those measurements, get your cables fixed. If I am right about this, the system will sound a lot better when you are done.
From the last set of measurements, it sounds like the arm wiring is fine.

OK- so with 2 different cartridges the same thing happens. And if you swap the cables from the tone arm left for right at the input of the phono section, the problem moves. All that is left really is the cartridges. So its either something common to their setup in the arm, or both have a similar problem. Now, the latter is really rare, but it could happen if both cartridges got subjected to something that could damage them.

I would put the DVM on DC voltage, and connected it to the inputs of the phono section, just to make sure you are not dealing with a malfunction that is putting DC on the inputs (like a shorted tube). If that's OK- the idea that you got 2 bad cartridges at the same time gains credence.
Good point David. I had that demonstrated in spades at the recent RMAF. The complaint in the system was that the image was off to one side and it was being blamed on the amps. What was really going on was that the speaker was out of phase in one channel. As soon as that was corrected, the image was exactly centered.
In the old days it was not a good idea to do a resistance check of an MC cartridge because the meter would put a substantial DC current supplied by a battery through the coils which might leave a magnetic field.

Then in the new days the DVMs put an AC signal through the circuit under test instead. The concern is really not a lot different- an AC current through the coils could demagnetize the cartridge somehow. In practice I've not seen it happen, but if you are concerned I would get a 50-ohm resistor and put that in series with the cartridge when doing the test, then subtract the actual resistance of the resistor from the reading.
Hifihvn makes a good point. The way you assure that the reading you are looking at is real is to start out by shorting the leads of the DVM together and looking at the reading you get. If the leads are in good shape you will see about 0.1 ohm.

Now if the leads in the tone arm, say from the red lead to the center of the right channel RCA are more than about 1 ohm I would say that you have a problem. Now you might see a reading like 1.1 ohms; don't forget to subtract whatever the reading of the DVM is when you short its leads together. You are going to see some resistance because the wires are very thin. Some phono cartridges have source impedances as low as 5 or 6 ohms, so you can see that a series resistance like that could have an effect.

If you have beeper in the DVM that register continuity, it might beep if you have anything less than 400 ohms, so it cannot be trusted.
Audioraider, if you swapped the arm wiring at the cartridge clips and the problem moved, its the cartridge.

However now we have 3 cartridges that all seem to have the same problem, so its getting less likely that the cartridge is to blame. I also doubt setup, and I also doubt that moving the 'table will do anything.

Right now I suspect that the problem is very close to the cartridge. It could be that the arm wiring is damaged right be the cartridge clips (although I am struggling with how that would work) but the other thing that is worrying me is that you might have DC at the input of one channel of your preamp, so that any cartridge you put on there gets damaged. The only problem with that idea is that if that were the case, swapping the channels would introduce the 'damage' to the other channel of the cartridge and it seems like that has not happened.

Since there are all dead ends, I suspect that there is a procedural error that is confusing things, like a channel that was swapped with the other but for some reason really was not, even though you were sure it was- some sort of thing that you are convinced of and so you can't see it.

If it were me at this point I would start from square 1:

swap the interconnect cables at the inputs of the amps and see if the problem moves

if no => amps, if yes => preamp

if preamp then swap inputs to the preamp (phono input since CD seems OK).

if problem moves then its the arm

if stays put then its the preamp

If arm, swap channels on the cartridge. if problem moves its the cartridge, if not its the arm.

Now I would do this and take notes, being certain that at each step you *change only one thing*. So this means you can't touch the volume or balance controls. Sorry to lay it out like this, but I can see why you are at the end of your rope...