Distortion problem when playing LP

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gkold67

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I am experiencing a strange problem with playing LPs on my very basic Dual 510 TT, fitted with original(!) Shure M95 GLM cart and a new stylus.

In the treble, I am hearing the following nasties.
  • distortion, for example quavering of voices that is particularly noticeable on female vocals
  • enhanced sibilance
  • crackle not attributable to surface noise
In the rest of the range, I hear the following
  1. listless dynamics,
  2. slow sound (almost like it is running under speed)
  3. shrunken soundstage
  4. veiled sound.
I have run the HFN test record and nothing obvious shows up, it is even tracking the anti skate tests quite well for such a basic deck.

I have checked the deck is level, cartridge alignment was roughly OK when I checked it a few weeks ago. I even swapped in a spare brand new stylus which made no difference.

The Dual TT is running into the (eerily quiet) phono stage on my normally reliable student days Yamaha AX300 amp that I have been using in absence of a phono stage. The din output of the TT is run thru an old DIN-2 RCA converter that was probably supplied with the TT.

Unless my ears are deceiving me, the problem seemed to happen almost instantly. I was quite happily thinking how good everything sounded when playing some rock. When I spun a few LPs later the same day, the problem just leaped out at me. I played the same LP I had enjoyed earlier and it just did not sound the same.

Any advice, help or tips on diagnosing the problem (assuming it is not my head!) would be most appreciated.

Many thanks,
 
Good point - In a house with 2 kids, anything is possible!

I will get out my scales and check tomorrow!

thanks!
 
Is it any worse on the inner tracks, do the clicks and pops also have the same trait, when you say tracking the anti skate test quite well when does it start to break up and and on what channel, do the test sounds give a sold response quavering sound more like a speed fault than a grove tracing one, as this happened instantly I would first look for something a long the lines of mechanical interference, ovality etc
 
When was the last time you replaced the belt on your TT?

I suspect the belt needs changing and the stylus is worn (needs replacing) - as suggested the traking weight probably needs adjustment (and perhaps alignment).
 
thanks I will check all those things, particularly the tracking weight. The belt age is unknown, however the deck has a strobe light and platter and speed adjuster, and it is running at the correct speed, according to the platter markings.

The alignment looks to be OK on outer grooves but is skewed on inner tracks according to the HFN cardboard disc and my AVID mirrored alignmnent tool.

However I can't see how to resolve this as if I make it correct on the inner, it will be skewed on the outer tracks. The arm is the original 9" gimbal from the age when light arm weight was king, so it is certainly not very flash!

Thanks for all the advice
 
gkold67 said:
However I can't see how to resolve this as if I make it correct on the inner, it will be skewed on the outer tracks. The arm is the original 9" gimbal from the age when light arm weight was king, so it is certainly not very flash!

Thanks for all the advice
Click to expand...

Use a two-point aligment protractor. You can download loads on the vinylengine site. Measuring the pivot to spindle distance you can even print a custom two-point arc protractor tailored to your deck's null points here. Conrad Hoffman's courtesy. I'd try Lofgren B first.

http://www.conradhoffman.com/chsw.htm

Be patient with alignment and get the right overhang too. I'm pretty sure the blemish's to be found there.

Keep us informed :)

Regards,

Vincula
 
Unfortunately my hifi has had to be packed up due to building works, so I have not yet solved the distortion problem.
I will investigate it again in late january. Thanks for everybody's help
:-)
 

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