Azimuth can best be confirmed with a mirror. The object is to have the cartridge perfectly perpendicular to the record. I'm no setup guru and could be wrong on this but it seems to me that if azimuth were wrong then the relationship between the arm and the platter is off which would be unusual with better tables.
Bias is a booger. Test records give dubious results, IMHO. If you don't have access to a proper blank track on a test record, which I believe is the best way, carefully cue the stylus on the outermost area of an lp. There is a small hump on all older recordings at the edge. What you are trying to do is que the stylus between the hump and the lead in groove. If the cartridge climbs the hump and goes off the record you have too much anti-skate.
Next, as the record is playing look closely at the cantilever and its angle in relation to where it exits the cartridge body. If the cantilever is obviously at an angle to where it isn't aligned with the cartridge body then you have too much or too little anti-skate. Playing a cartridge like this will eventually skew the cantilever permanently.
So, now you have it set up to not jump the hump and the cantilever remains centered in the cartridge body. You may then experiment by ear in minor adjustments to acheive equal left and right volume adjustments.
I believe the absolute best way to check bias is to use an oscilliscope to determine if the signals are of the same amplitude left and right. I've never known anyone that has done this however.
Hopefully Twl will chime in and write a clearer explaination than this attempt. |
Colitas, The HFN bias test tone varies from inaudible (good) to a steady "buzz" (needs adjustment) to a rough or warbly buzz (dangerously near mistracking). Unfortunately, bias force increases as the arm tracks across the record. So there's no "perfect" antibias setting, just a good compromise. As a rule, the anti-bias scales on Rega arms are off. Most people set it somewhat lower than their measured VTF.
Is there an azimuth adjustment on an RB300? I didn't know that. On my system switching to mono reduces the signal to a whisper, but not total silence.
Great post Lugnut. Agree about bias tracks on the HFN record. Why are they all near the inside? Tracks 1 & 2 are pretty useless anyway, they should have included just tracks 3 & 4 and duplicated them near the outer edge.
I've never looked to see if different antibias settings cause a visible change in cantilever angle. Might depend on the compliance of the cartridge. I suspect low compliance carts could be significantly mis-biased without displaying much visible deflection of the cantilever. You'd only know by stylus and/or groove wear.
Maybe Twl will straighten us out. |
An old fashioned way to check azimuth is to scratch or use a marker to draw a line perpendicular to the bottom of a small pocket mirror. Then, IF your platter is level, slide the mirror up near the cartridge and view from the back side. If the cartridge has a perpendicular side edge it should line up with (be equidistant to) the scribed line. If the cartridge isnt square its up to the eyeball for a manual setting, though even some of those have a vertical line on the front of the cartridge body. For anti-skate, I go with my ears, but Lugnut is correct that the only perfectly accurate way is to use a scope. Oh, and I have seen it set using a scope and having it subsequently fail the HiFi test record gauntlet!
Doug, did you mean azimuth test and not bias test with respect to the HiFi record when you say "Colitas, The HFN bias test tone varies from inaudible (good) to a steady "buzz" (needs adjustment) to a rough or warbly buzz (dangerously near mistracking)."?
My understanding is that there should ideally be no tone using a mono signal when doing the azimuth test. For the bias test, there should be a rock-steady tone and any "buzzing" indicates improper bias. If it is supposed to be silent, I can't get any of my cartridges past the first bias track! Ha!
Maybe we are mixing terms here. I just wouldn't want anyone that is using the test record for the first time to be confused. |
Doug,
Thanks for the compliment as I was a little nervous about writing. So many people here know much more about these types of subjects and it's a little intimidating.
I'm sure about the canitlever statements I made. While I don't have a clue as to the construction inside a cartridge it must have a suspension of sorts which is, by its nature, very sensitive and prone to damage. If one has too much anti-skate the stylus will still want to track the groove as the tonearm tries to keep it from doing so. The result would be a cantilever that is more or less permanently tweaked to the side.
I actually saw this when an acquaintence asked me to look at his table. I had brought my blank record and after seeing the stylus pushed way to the side tried the blank. It confirmed my suspicion. We left everything as it was except for the anti-skate which we adjusted, played a few junk records while we watched tv and lo and behold it was more centered in the cartridge body. The next time I went over it was back where it belonged. Damage? I don't think it helped the mechanics of the cartridge to be mistreated in that way but it sounded fine. I suspect his records took a hit though. This kind of stuff is what makes buying used vinyl so "iffy".
Anyone reading this that takes issue with what I've said please be kind to me. These are honest observations and I still don't know if my rationale is right on. Enlighten me if you know the truth. |
I don't use a test record. All my records are "test records". I just play them. I adjust everything by ear.
No azimuth adjustment on a Rega arm, except via shims. The above info on checking azimuth seems right to me.
On a mid to high compliance cartridge, if the bias is terribly off, it is easy to see by looking at the cantilever from the front. If it is angled off the center by the record during play, it is way off. With these more flexible cartridges, you can check for a basic center by looking at it, and then fine tune by ear. With low compliance cartridges, it is a little tougher because it won't be easily seen by looking. |
Thanks Tom. Lugnut and I are both right? Must be a good day! BTW, what would we hear with a non-optimal anti-bias setting? Channel/image imbalance? Harsh HF's in one channel?
David,
I was talking about the bias tracks but certainly didn't state it clearly, thanks. It's just like you said. Hey, wanna swap one of those bum cartridges? I've got an ADC XLM that should track at .75g on an Illustrious. Deal?
I didn't bother with the HFN record after my last cartridge realignment. I'm either getting lazy or pretending I can hear like Twl! |
MY 2CENT`S, Everything you have said is good.I also use a small level, I sit it behind the two screws on the headshell.that tell which way to ajust the arm.I might be wrong,but hope not.Thank all of you for your input. |
First off, thanks for all the response. Thanks to 4yanx for clearing up the question on dougdeacon's response. I always thought there must be something wrong with me cause I could never get all of the "esoteric" clues and directions on those test records. I also use regular records for testing also, especially adjusting VTA. I once read a thread were TWL suggested using your ear to adjust VTA, I never thought I could do it but I have gotten better. Shoot when I first started down this road I thought the VTA riser I bought for my Rega was to raise the cartridge to clear the record for when I was using the cueing function on my table. Matching cutter head angles meant nothing too me. I also found an interesting article on anti-skate, "buzzing in the right channel indicates more anti-skate force is required, whereas buzzing in the left channel indicates that less anti-skate is required." (audiophilia.com/features/cartridge-setup.htm) In this same article he mentions the HIFI record azimuth test. He states to adjust the azimuth until the signal is deminished. Lugnut, I do use the turntable basics mirror alignment tool for cartridge alignment, I guess now I can use it to check azimuth also. 4yanx I will try using the turntable basic's mirror for the azimuth test that you mention, also. Thanks TWL for reaffirming every one else's views too. I will also check on the cantilever angle when I get home at 5:00 am and start my listening session! happy spinning |
