chowkwan%priam.usc.edu@usc.edu (Raymond Chowkwanyun) (03/07/91)
Satish Nair was asking about VTA. First I read the July 1990 Stereophile and issue 66 of Absolute Sound which describe how to set up a turntable. So, it's important to get the other adjustments like tracking angle, tracking weight, azimuth, and anti-skate down before you tackle the VTA. TAS says: when the arm is high the sound will sound too bright and hard with not enough bass. When the arm is low the sound will be dull and muddy, the lows lacking definition. Stereophile concurs with the above. My dealer says forget about all the above and just keep varying the height till you find the sweet spot. Your dealer is also a good place to start for advice about the right VTA setting for your cartridge. I have an Audioquest 7000 in an SME V arm. The dealer said that the arm should be either level or lower. So armed with all this advice, I set out to set my VTA. First I leveled off the arm. Use a ruler to make the front and back of the arm the same height off the record. Then I pushed the arm down as far as it would go without hitting the record. (One of the delights of the SME is that you can easily raise the arm but to lower it requires you to physically push it down. Thus if you raise the arm past the sweet spot, you have to cue the arm off the record, push it down and start over.) Which record to use? I used Karajan's recording of various Strauss waltzes. This is the recording of Blue Danube that was used in the movie 2001. I think an orchestral recording with a lot of detail will best highlight any VTA deficiencies. I started raising the arm, one turn of the VTA screw at a time. Damn me if I could really tell any difference. So I gave up, locked up the arm and let things lie. Over a period of weeks, I would intermittently attack the VTA setting task. Finally, I was able to hear that magic sweet spot when everything locks into focus. The soundstage gets wider, yet the instruments sound clearer. Look for detail that you didn't hear before. I think what happens is that the first few times you fiddle with the VTA, your brain is so full of all this advice that it's hard to just relax and listen. All the time you're thinking, "Now is the sound muddy or bright?". Compounding that I find adjusting the arm was to be a tense, nerve-wracking exercise. I have this unreasoning fear that I'll give the arm a good whack and send that expensive stylus skidding across the disc. Also I worried that I would raise the arm past the sweet spot and have to start over. Did I mention that the SME arm needs to be pushed down to lower it? After awhile though, you learn to relax and then you can hear better. Some people like to mark down the correct VTA for a number of records and then use an average setting that's good for most of their collection. There exists a fringe element that resets the VTA for *every* record. These persons end up getting hauled into divorce court on grounds of excessive VTA adjustment. Personally, I just set it using whatever's to hand and if I don't send my stylus flying across the disk in the process, I'm a happy boy. -- ray
Steve_Graham@ub.cc.umich.edu (03/11/91)
This is a sticky subject. In my own less-than-state-of-the-art system I've been able to drive myself nuts trying to get it right, without ever coming to any concrete conclusions. In general, I do have the impression that if it's too high (back of the arm, that is) the sound is a little bright and spitty, and too low, it's sort of overdamped sounding, a sort of slight muffling effect. But it's really hard to set the thing for a variety of reasons. For one thing, I find that I can hear what's going on far more clearly when I'm just listening to the music for enjoyment than when I'm trying to listen critically. (This is also a problem when I am trying to set up mikes and balances for recordings. I think it is a problem in the professional recording industry to a degree that is not generally acknowledged--but you can chalk it up as just one of SG's hair-brained theories if you like.) So when making adjustments it's just plain hard to be certain that I'm hearing a difference. Then there's the hardware problem. In the early days of stereo disks, the Westrex cutter was quite popular, and had a fairly fixed cutting angle of 23 degrees. Later 15 degrees became a standard, though it is not clear to me whether (or to what extent) it was adhered to. Later on 20 degrees was set as a new and improved standard. (I don't know the reasons for this, not having any cutting experience.) Again I don't know how closely this was adhered to. More recently we have DMM cutting, which cannot be done at these angles. What is done instead is to cut at approx. 0 degrees, and then add some form of electronic compensation to "simulate" the 20 degree nominal standard angle. Complications abound. First DMM: I don't know exactly how the compensation works, but I assume it is a form of predistortion, similar to what is sometimes added to prevent or reduce inner groove distortion. The way this works is that you generate a distortion product that is out of phase with the one the stylus will generate, and the two cancel each other out. However anything that relies on this sort of cancellation is hard to get right. Everything has to be just right for it to work. In this case, it will only work for a stylus of particular dimensions. With others there may be a lessening of distortion, or even an increase under some circumstances. I suspect there is a similar situation with DMM, to the extent that the thing works at all. Then there are the lacquer and vinyl problems. Both the lacquer medium which is used for non-DMM cuts, and the vinyl pressings themselves, will vary the apparent tracking angle to a certain degree. I gather that with the lacquers the degree of change is dependent to some extent on how soon plating takes place, and storage temperature, etc., though I'm no expert on this. But the point of all this rambling is that there is a rather wide divergence of proper tracking angles between disks. So the people who reset for each disk have the right idea...though I'm not willing to go that far myself. Since he is my favourite musician, I generally use a Bruce Cockburn LP to try to set VTA. Several of his records were cut at the same place and pressed by the same people, so I have a chance of getting it close on at least a few of my favourite records, and since those were cut at Sterling Sound or Masterdisk, and pressed by one of the majors, they will hopefully be close to other records in my collection. On the other hand, I may not be hearing those old RCAs to best advantage. Such is life.