Ortofon OM20 lousy tracking

[magiccarpetride]

Back to your sticky problem with the RB300/OM20 -- did you happen to check whether the arm lift might be out of adjustment? If it's set too high, or the curved arm is bent slightly upwards, then it could well be causing the sticking you describe if the arm is making contact with it while playing. The arm lift height is adjustable with a little grub screw, BTW. Worth checking...

Did check very carefully to make sure tonearm is not rubbing agains the arm lift, and no, that's not the case, not even close. At the point when the 'stuck in the groove' defect occurs, the tonearm is nowhere near touching anything or rubbing against anything. It really feels as if there is some friction inside the pivot, because I can feel a bit of resistance when I hold the tonearm in my hand and push it toward the centre of the platter.

[Svend N]

Yes Svend, I am aware that Jelco may be a better fit for Denon. Wasn't aware of the OM20 limitations when used on the higher mass tonearm, that's something to keep in mind.

I like OM20 because it seems to retain some of that mid-bass bloom that DL-103 excels at while providing better detail retrieval. Thinking of maybe upgrading to OM30 or OM40, if those retain the heft and the slam of OM20.

I also have a high compliance cartridge on my Heybrook (an ADC ZLM) and it's mounted on a low mass carbon fibre ADC tonearm. Works outstandingly well, and sounds terrific. I would think that if you like the OM20/30/40 sound then going to a low mass arm might be a good thing. I'm no expert on these, but lots of guys here like the Mission arms, and I think Grace made a low mass arm as well.

Anyway, I don't want to make you even more confuzzled and have you start second-guessing your choice of arm here. Jelcos are great arms, very well respected, and versatile with a wide range of cartridges. Whether they mate well with an OM20 I can't say -- maybe someone here has tried that and can advise.... In short, just because compliance and arm mass don't seem to match up, doesn't automatically mean that it will sound bad -- I have a high(ish) compliance Ortofon 2M Bronze that sounds far better on a higher mass R200 arm than on a lower mass RB300, so go figure.... Numbers don't always tell the tale.

Good luck, and hope you find the magic combo here.

Svend

[magiccarpetride]

I'm beginning to suspect that you have two problems, as mentioned above...

a) You have mistracking due to either having your alignment poorly set, and/or AS bias poorly adjusted, as well as a too-high tracking force for the high compliance cantilever on that cartridge; i.e. the very flexible cantilever cannot overcome the excess downforce and when it hits that inner section of a record it sometimes skips. Any alignment and AS misadjustments will exacerbate this, or vice-versa. The inner sections are well known for causing such difficulties, which are heard as inner groove distortion, as everyone often refers to it as. Try setting your VTF at 1.25g using a digital gauge and see what happens. And do try the AS test on a record with a wide lead-out area. And you didn't answer my question re. alignment? What's the scoop there?

....and...

b) Your cartridge lead connectors are too loose, and need tightening. This is what's causing your crackling sounds. Pull them off one at a time, snug them up as suggested....but gently and easy does it, you don't want to collapse them.

The alignment looks okay. My dealer is very good at that, he did originally set my DL-103 and it tracked perfectly.

Did try the experiment with wide flat space toward the end of the record, and did not notice the arm moving in any direction (until it caught the groove ans started riding it toward the end of record).

Originally, the dealer set anti-skate to very low -- something like 0.20. I tried playing with anti-skate, but it didn't fix the stuck-in-the-groove issue. I lowered VTF to 1.44 grams, no change. Next I'll try 1.25 grams, see what happens.

Thanks Svend!

[Barry]

The arm does not 'skip', it's more that it gets stuck in the groove. You know, like the proverbial 'broken record' that keeps repeating the same thing over and over.

Well it is skipping - it's jumping to the previous revolution. So either the anti-skate setting is too high, or the motion of the arm in the horizontal plane has become impeded, either because the bearings have become 'sticky' or the signal wires have become twisted.

You say the cartridge is new, the stylus and records are clean, so it must the arm that is at fault. Is there someone who could examine it for you and check it out?



One other thought - have you checked that the wires to the cartridge pins are neatly 'dressed' and none are touching the record surface?

[Svend N]

The alignment looks okay. My dealer is very good at that, he did originally set my DL-103 and it tracked perfectly.

Did try the experiment with wide flat space toward the end of the record, and did not notice the arm moving in any direction (until it caught the groove ans started riding it toward the end of record).

Originally, the dealer set anti-skate to very low -- something like 0.20. I tried playing with anti-skate, but it didn't fix the stuck-in-the-groove issue. I lowered VTF to 1.44 grams, no change. Next I'll try 1.25 grams, see what happens.

Thanks Svend!

I agree with Barry -- it sounds like your AS is too high. When you do this test the arm should slowly move toward the center before it snaps into the groove. For these light VTF carts you have to be very fussy about AS it seems. Try setting it to zero and see what happens, and adjust in small increments from there. I have read that even at Zero, Rega arms still have a bit of AS pull to them.

Not sure if anyone asked this already (it's late and I can't be bothered to read the whole thread again), but how does your VTA look? Is the arm tail down, flat/parallel, or tail up?

Are you using a digital scale to check your tracking force?

[magiccarpetride]

I agree with Barry -- it sounds like your AS is too high. When you do this test the arm should slowly move toward the center before it snaps into the groove. For these light VTF carts you have to be very fussy about AS it seems. Try setting it to zero and see what happens, and adjust in small increments from there. I have read that even at Zero, Rega arms still have a bit of AS pull to them.

Not sure if anyone asked this already (it's late and I can't be bothered to read the whole thread again), but how does your VTA look? Is the arm tail down, flat/parallel, or tail up?

Are you using a digital scale to check your tracking force?

Yes, using digital scale. The dealer told me that he put just a smidgen of anti-skate because OM20 apparently don't even need it on RB300. The arm looks a bit tail down.

The main quandary here is why is the arm/cartridge combo doing this intermittently, on the same LP? If there is an explanation, then it must produce consistent symptoms, right? If it's fairly random, then it's hard to do reliable detective work. Like for example earlier today it was again skipping at the 4 - 5 minutes point in the playback. Then, for whatever reason, decided a couple of hours ago to play just fine. So I've spent a few hours listening to LPs and enjoying myself. But I know that come tomorrow, it will again stat acting up at the 3 - 5 minutes mark. Wtf?

[Mike Reed]

The arm looks a bit tail down.

The main quandary here is why is the arm/cartridge combo doing this intermittently, on the same LP?

Measure the VTA with a ruler or marked card; the arm-tube should be the same height at the back as at the front, or even marginally up at the back. Best done with the cart. placed on the record at the inner grooves. If the VTA IS tail down (unless specified for that cart.), raise it, because this alters the S.R.A. (stylus rake angle). I've never had a cart. that sounds better with the tail down.

The same record? Must be getting a bit knackered by now. Random is really frustrating, and, from what you say, does point to bearings, assuming no other impediment. There's no point in setting a lower VTF; it's likely to bugger up your records more quickly as it mistracks.

[hifi_dave]

Ha, that's the ironic thing. I dread replacing the cartridge, because Rega RB300 is the absolutely least friendly tonearm for replacing cartridges. There is very little maneuvering space for me to get my fat butterfingers in and connect the wires.

Plus, Rega has this Mickey Mouse anti-skate which many people are not even sure how it works (or whether it actually works). Plus the Mickey Mouse spring for VTF, which rings and interferes with the signal. I'd much rather get a tonearm that allows me to quickly and easily swap various cartridges for auditioning.

I couldn't agree less. The Rega RB arms are the easiest to install a cartridge in and set up, they even have slots on top to hold the fixing nuts in place. Some arms have far less space for the cartridge and have very flimsy wiring, which can easily break. The best way to fit a cartridge is to install it loosely into the headshell and then attach the wires.

The anti-skate or bias is far from "Mickey Mouse" being a rather sophisticated arrangement of two opposing magnets which apply bias without friction and is very easily set. Some of the weight and thread arrangements are extremely crude, fiddly and imprecise.

As to the "Mickey Mouse" spring for VTF, did you get the "ring" and "interferes with the signal" from a forum ? Because, once again it is a much more sophisticated method of applying tracking weight than by moving a counterweight. As to the "ring", that really is a forum myth.

[rockhopper]

Say what you mean Dave. Don’t hold back.

[hifi_dave]

I didn't mean it to sound aggressive in any way. I have been setting up and using Rega tonearms since 1973 and have done it thousands and thousands of times, so I know their arms inside out, fitted with all manner of cartridges on numerous turntables and never had any troubles at all.

The OP's Rega arm was working perfectly before being fitted with the OM20 and now there are problems. First step should be to return it to the dealer who set it up - it's his problem.