I think you are measuring (and mistaking) crosstalk for channel balance. If using the test record, channel balance is track #1. Center, left or right depending on lights on foz. I do not know why you can't get the reading to move. Sounds to me like your cart is just not aligned correctly to begin with. On my arm, I can get the fozgometer to move about 2 points either way with a simple azimuth screw. If the cart is improperly aligned, you'll never get there though with a "micro" adjust.
What are you using for alignment?
How much antiskate are you using?
I'd start over... sorry. |
If indeed you set up your arm correctly, I would have your cartridge and/or your pre checked out. I have a Benz LPS which nails 0 on that test. |
Cartridges can have pretty large channel imbalances even when there is nothing grossly wrong. I understand that a difference of up to 2 db higher for one channel is not uncommon (one reason a balance control is a MUST have item, particularly for analogue setups).
My understanding of the Fozgometer is that it accounts for channel imbalance, so I don't know what is up with your rig. I originally did my azimuth setup by visual alignment and confirmed that it was right by listening. When I got my Fozgometer, I found that I could get a perfect reading by moving the Vector azimuth screw by an exceedingly small amount,something like 1/16th of a turn(an amount so small I could not visually notice a difference). The meter appears to be extremely sensitive.
If you cannot get an acceptable reading, or you can only get an acceptable reading by severely tilting the cartridge, something is wrong with the cartridge. Also, I would prefer a less than ideal reading over tilting the cartridge such that the stylus is misaligned in the groove. |
This thread may be relevant. The link opens at the post which describes the conclusion in that particular situation. Regards, -- Al |
Others have already implied it, but azimuth adjustment has very little effect on channel balance, as you already have learned by direct experience. And the goal of azimuth adjustment is to minimize crosstalk, not to balance the channels. I was interested to read that Larryi says intrinsic channel imbalance of a cartridge is often more than 2 db. On the other hand, there is a prominent poster on VA who says that if a cartridge output is more than 1 db different, R vs L, that cartridge is defective and should be returned to the seller. I have no idea where truth lies on that spectrum.
One thing you might do is to swap tubes in your phono stage, R to L and L to R, and see what happens to the channel imbalance. It is possible that your entire problem is due to a difference in gain between the input tube on one channel vs the other; that's where most of phono gain is achieved. |
Thanks very much for all your responses. I tried switching the cart tonearm cable connectors from R to L and sure enough the discrepancy moved sides which means it's the cart and not the phono pre. There was a 15-20% difference in output and to me that warrants a repair.
Hessec, I have the Hi-Fi News test lp, on which tracks 3 and 4 are the Channel Balance tracks. I'm using the Basis Vector Alignment Jig and have used it to the best of my not totally incompetent ability (no snark intended). The anti-skate is set with an lp that had a large grooveless section.
Larryi, I'm curious about your statement about a balance control. If all the links in the line are properly balanced and working correctly wouldn't the final balance be correct, and therefore wouldn't using a balance control just be glossing over a problem as well as being more resistors in the line?
Either way, the cart is pretty clearly in need of repair so off it goes and I'll deal with a pretty compromised setup for 4-6 weeks. |
Moryoga,
I use the balance control to make pretty fine adjustments which I am sure involve a whole lot of different factors, including room acoustics affecting balance. Balance controls can also be used to compensate for channel imbalances of cartridges. My current cartridge has a small imbalance where one channel is a little less than 1 db lower in level compared to the other.
When I had a Levinson Ref. No. 32 linestage in my system, I could make really fine adjustments to channel balance (allowed for .1 db increments of change). I was really surprised to find that while 1 db of volume change with music playing is not something one can reliably hear, one can hear a .2 db shift in channel balance (noticeable with the position of a centered vocalist or with mono recordings). To me, life is just easier with a balance control when it comes to fine tuning a system.
The Vector alignment guage is an extremely accurate device that allows for very precise alignment. I have noticed that a tiny fraction of a millimeter off and the tonearm profile will be grossly mismatched with the outline etched on the guage. When everything matches, the alignment agrees with that of the Feickert alignment tool. Hence, if you did the alignment per the Basis instruction, you should have the cartridge perfectly aligned and there is no issue in that respect. |
Moryoga, Azimuth is a mechanical alignment of the needle in the groove, and is probably best set mechanically (visually-microscope). The fosgometer measures a voltage, as a surrogate marker for alignment. There may be discrepancies in the phonostage so best to leave this out of the circuit. There may be an electrical imbalance in the cartridge, and it would be wrong to misalign the needle to compensate. I would also try another test record, they are not perfect, and I have very different readings on the "fos" with different records.
For me it is all too hard, and I don't trust the test record, and I don't trust that electrical output means physical alignment. I suspect some high tech oscilloscope using a calibrated test record, minimising cross talk is the only "practical" way to do it properly.
Another way is, if it ain't broke don't fix it, in other words if the sound is good don't fiddle:)
That's as far as I've got, happy to learn from others. |
Thanks Dinster. This process stated because there was an obvious sound difference between the 2 channels.
The plot has also thickened in that I packed up the xv1s for shipping to repair and put on my old Dynavector 20x on as a fill in cart and wound up getting the exact same readings. I took the phono pre out of the loop. I figure there's only a few options left. Since the signal issue changes evenly when I change the tonearm wires on the cart pins from L to R, I think that this rules out the Foz and the test LP as variables. I either have 2 carts that have the exact same balance issue with the exact same output values or there's something going on with the tonearm wiring. I called Technetron NYC and asked for some advice and they said it's highly unlikely that the tonearm wire is the issue as they thought with wires it will either work or not. As unlikely as it seems, I might have 2 carts with the same issue. I'm going to make an appointment to bring the carts and tonearm to them to have it tested professionally as I'm obviously out of ideas and in over my head with figuring it out. |
Hi Moryoga: Changing the azimuth will affect the channel crosstalk, but will not accomplish much for the channel balance. A difference in channel output levels (balance) is better addressed with separate channel gain controls in either the MC headamp (if that is what you use), a phono equalizer (if that is what you use), or the line preamp (but this would entail different settings for analog and digital sources). Barring separate gain controls, the cartridge manufacturer may have to readjust (or even rebuild) the cartridge.
At any rate, could you verify that you have checked the channel balance under the following two conditions?
1. Switch the channels at the tonearm cable output connectors, and check the channel imbalance.
If this flips the channel imbalance, both the cartridge and the tonearm wiring or connector contacts are suspect.
2. Put back the tonearm cable output connectors, then switch the channels at the headshell lead clips, and check the channel imbalance again.
If this causes the channel imbalance to flip, the tonearm cable, internal wiring and connectors are innocent, but the cartridge (including the condition of its output pins) needs investigation.
It is a good idea to periodically clean every electrical contact in the tonearm system, including the cartridge output pins, the headshell lead clips, and the tonearm output cable.
hth, jonathan |
05-17-14: Moryoga
Since the signal issue changes evenly when I change the tonearm wires on the cart pins from L to R, I think that this rules out the Foz and the test LP as variables. Moryoga, note in the thread I linked to earlier that the Foz was found to be at fault EVEN THOUGH the imbalance it indicated followed a channel swap at the cartridge pins. I certainly have no idea how that could be, but note also that the OP in that thread reported several others as indicating to him that they had the exact same experience. With one of them indicating that his Foz worked fine with two of his turntables but exhibited the problem with another turntable. And it appears that in most or all of those cases it was the right channel which measured higher (when the cartridge connections were not being swapped). This process stated because there was an obvious sound difference between the 2 channels. That was also the case in the thread I linked to. As you may have already read, it turned out that an unrelated second problem was simultaneously present, which was causing the audible imbalance. Regards, -- Al |
Almarg, had similar experience with the Foz and an XV-1s. No audible issue though. I could never get the Foz to be similar in both channels as I adjusted azimuth. The difference was constant despite adjustments. Cart checked out fine with voltmeter. |
If anyone can point out a gap in my methodology, please point it out.
In somewhat careless fashion, I failed to do a pretty obvious test:
Using the Hi-Fi News test LP track 4 (L Channel, -20db, 25 sec.) Tonearm cables directly into Foz with L to L and R to R, get reading.
Switch L cable to R input Foz R cable to L inout, same reading.
Using Test LP Track 5 (R channel, -20db, 25sec.) Tonearm cables back to R to R, L to L, reading 20% lower than track 4. Same with L to R, R to L.
It seems Track 4 is putting out a 20% stronger signal. So,
Using a db app on a smart phone ( I know it's not the most accurate testing device, but it seems to register in tenths of a db) Play Track 4 L channel, through speakers for 25 seconds, get average reading. Track 5 R channel, which I expected to be 20% less, SAME READING! UGH!
Totally baffled.
Played Cannonball Adderley lp, tried to forget about everything for a little while :) |
This is exactly what happened to me. Tonearm directly into Foz. May hit have been 20% difference, but it was different side to side and stayed constant no matter the azimuth adjustments made. Sonically however, was dead equal, both with raw listening and dB measurements just like yours.
I would say don't worry, listen and enjoy the music! |
