Distortion with Technics SL-DL 1

Hello everyone,

I have a Technics SL-DL1 automatic turntable. It is a direct drive one (not really sure what it means). When I play the last tracks of a LP (or a 7" single), I get some distortion. It happens on used records as well as new ones.
After doing some research, I've found that this type of distortion is called "Inner Groove Distortion".

However, I read that IGD mainly concerns misalignated cartridge, which can't be the case here since the SL-DL1 is a linear tracking turntable. I even tested it with a replacement stylus and I could still hear IGD. I adjusted the tracking weight to the max value recommended by the turntable manual, no change. Do you have any idea about this problem ?

 

What is typically called IGD can be from two causes. One is the cartridge alignment you mention, and a properly setup linear tracker resolves that cause, as does a well aligned pivoted arm with alignment chosen to minimize tracking error toward the center of the record. But the music wavelengths pressed in the record grooves are shortened at the smaller groove radius toward the center, so become much harder to track without added distortion, and this is common to all tonearms. That issue can really only be resolved by using good cartridges and narrower stylus profiles, especially if the records are not somehow compensated by the mastering engineer to reduce the levels near the end.

There's a few things that could be wrong with your table, it's pretty old and fairly complex. The tonearm has to be precisely driven across the record via optical sensors and a microcontroller, with help from a lot of electronics and belts and pulleys. If it isn't precise, the error can be much more than you would get with a pivoted tonearm, since the arm can pivot some.

What did you use for a replacement stylus? The original Technics EPC-P23 cartridge and stylus hasn't been made for a very long time, though of course there are modern replacements available, some probably OK, some probably not.

It's also a good idea to make sure the tonearm follows a path of groove tangency across the disc, sometimes you have to move the cartridge out a bit before tightening to assure this. It's relatively easy to check on linear decks, just need to see if the stylus follows a straight line out from the center of the spindle and adjust the cartridge if it doesn't, that's how you align a linear tracker, though the TP4 plugin style mounting doesn't allow much adjustment and is supposed to get rid of the need, but tolerances add up. The auto features on the Technics make it a bit more complex to check, so you may have to skip this check.

If you haven't already, it would also be a good idea to verify the tracking force by some means to assure you are tracking with enough force. I think the force is set by a spring on these arms.

 

@Davey mentioned this, but my first thought is how old is the stylus? If the tip is worn, no amount of "setup" will help. Assuming you hear the same IGD with your replacement stylus (and that it's new), then I'd ask what kind of stylus are you using? The narrower side radius, the better at tracing inner grooves. Hyper elliptical tips like Shibata, or more advances shapes like Fritz Gyger, Microline, Micro Ridge, etc. help eliminate inner groove ("tracing") distortion.

Then, follow @Davey's very good advice above about setup.

 

Thanks for your replies !

I don't have the exact reference for the replacement stylus... But it wasn't really expensive so that might explain something (in the 25-ish dollars). As for how old is the original stylus... I don't know. I bought this turntable at the flea market. I already adjusted the tracking force with the screw under the tonearm to the max value recommended by the turntable manual.

Since the stylus seems to be the problem (the needle doesn't make wild moves during playback so I don't think that's a misaligned cartridge), is it worth replacing it or should I just buy a brand new cartridge ?

 

I used to own one of these turntables. It was a long time ago, but I do know there are some adjustments that can be made. First the is VTF. You can also adjust the offset angle, which is likely your problem. And there is also a way to adjust the tonearm sensitivity, which is how much tolerance is allowed between the tonearm advancing and the trolley's movement. I would download the service manual from Vinyl Engine to check all these adjustments. While the tonearm should track linearly, it actually doesn't. It can't. The tonearm actually moves off linear and the trolley moves behind it and and straightens the arm. It seems logical that if the settings aren't correct, the angle of the tonearm could stack incrementally as it advances toward the center. So, IGD is possible.
Technics SL-DL1 - Manual - Direct-Drive Fully-Automatic Turntable System - Vinyl Engine

 

Inner groove distortion is a common "problem" of lower cost budget cartridges and styli. The SL-D1 is a good little turntable.
The problem probably isn't the turntable. Even so, it's never a bad idea to go through some check points to see that everything is operating normally.

1) First of all, let us know what cartridge and stylus you have. If it is a conical or mild elliptical, this explains everything. You'll get IGD with these.
2) Used records are usually not perfect, in fact usually groove wear, (previously played on a ceramic cartridge record changer)
which produces more distortion at the inner groove.. the area that wear occurs first, and most severely.
3) check that the tracking force is set to procedure.. the arm balanced first, and then moving the counterweight AND tracking scale ring as one piece ((do not touch the tracking scale when dialing in the tracking force... turn the counterweight only... this is a fairly common mistake)
4) Check the platter for looseness/wobble. The platter should feel solid. Check the arm for free movement (balance the arm for this) Check the antiskate... with the arm balanced at zero antiskate, the arm should remain stationary. Then dial in some anti-skate (doesn't matter how much.. 1 gram is enough) and observe the arm swinging outward. This indicates the antiskate is at least working.

Try doing the above, then get back to us with your cartridge make/model please!

 

I will try adjusting the offset today. But since I don't have a voltmeter yet (I can get one in a few days), I can't really adjust the tonearm sensitivity.

1) I don't know if my stylus is conical or elliptical but it's surely not microline. My cartridge is a Technics P23 (it's the cart which originally came with the turntable).
3) I read the service manual and there is not a lot of information about this... I haven't find a way to set anti-skate on my turntable. However, by simply balancing the arm, there is free movement.

I'm sorry if I sound a little bit ignorant about turntables, I'm not that knowledgeable on the matter.

 

Forget the offset and anti-skate adjustments, that doesn't apply to linear tracking arms like yours. And the arm balance stuff doesn't really apply either. He didn't understand which table you have.

 

Well there seems to be a part about offset in the manual :

 

Yea, sorry, I didn't see that the offset was from the post by @vinylontubes, I thought it was reference to cartridge offset, not the carrier offset, that is good to check, carry on

 

?? The OP has a Technics SL-D1.. it's a pivotal arm turntable! Why are we talking about a linear tracker? (the guy is already confused and on a learning curve)

 

SL-DL1

 

My Bad! terrible!

 

Uh oh...

 

Disregard my previous comments, very sorry, I did not see the "L" in the model number. Your turntable does not have an antiskate, not required for a linear tracking turntable. Good that the arm has free movement up and down, which rules out this potential problem.

The chances are the original stylus may be worn, or may have been replaced with a lower cost conical.

I suggest a new stylus or cartridge upgrade. Any P-mount cartridge will fit your turntable. Just be certain the arm has an adjustable counterweight to set the tracking force, as some lower cost linear tracking models have a factory preset non-adjustable tracking force. (a bad thing.) In such case it is better to replace the turntable. I could suggest the model I had mistakenly thought you had, the Technics SL-D1, or SL-D2 (a very good turntable) or any Technics direct drive.. but NOT a linear tracking model.

https://www.amazon.com/Audio-Techni...rds=technics+p23+needle&qid=1586482339&sr=8-4

 

Yeah, my bad...


Anyway, I can't set the offset for now since I discovered that I didn't have the appropriate screwdriver (the screw is very small in size).

I think I will buy a new P-mount cartridge. I already saw some models before creating this thread, just in case. Should I go with the AT-311EP or the AT-85EP ? Is there better models in this price range ?