DT - Turntable alignment/set-up problem - can you help?

Hi there,

I recently bought a second TT for the bedroom(!) and have encountered a strange problem.

The first 15 minutes of an LP sound great, but as the tonearm reaches the last 5 minutes, the treble becomes quite scratchy & distorted.

I assume its a cart alignment problem, but I've tried adjusting the headshell, counterweight & anti-skate, to no avail.

It's not the build-up of dust & grunge on the stylus either.

Any ideas?? Its a project RPM4 btw.

Rgds,
DT

 

sound like similar problem to mine...
http://zerogain.com/forum/showthread.php?t=11940

bad cartridge is now looking like most likely expalantion.

 

hmm, well, I could always switch the 510 for the MC15 on my RPM9 to see if that makes a difference, but that wouldn't explain why things only ever go tits-up in the last 5 minutes of the LP's playing time.

I used the HFN test record to calibrate the deck and it performed fine on all the benchmark tests.

Guess I'll just have to fiddle with alignment etc. again to see if I can engineer an improvement.

Rgds,
DT

 

remove the anti skate weight (if you have one).

definately the most likely culprit

 

Yeah - having posted on other forums, I've determined that this is probably the most likely culprit - Someone reminded me that the tonearm should drift towards the centre of the records (ever so gently) when released. Mine drifts outwards slowly. I guess the bias isn't set high enough - I just set it on peg 3 for a 7g cart, as instructed in the manual.

DT

 

I thought it's the other way 'round? Surely with the needle in the groove, the arm is being pulled inward? So anti-skate should be pulling outward? Thus with the arm floating free, it should be drifting gently outward?

Or have I got my lions crossed...?

Dunc

 

No, you are correct dunkyboy. The arm will have a tendency to move towards the centre of the platter when playing and the anti-skating weight is designed to counter that movement so that the stylus does ride up the sides of the grooves in either direction.

 

Well, I've tried it with the anti-skate on the lowest setting and inner-groove performance has improved slightly. I will try it with anti-skate removed completely, to see if that improves performance further.

Rgds,
DT