• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Inner groove distortion, caused by cartridge or tonearm mounting?

T

TrevorBarten

Well-Known Member
I have a luxman pd-121a that I have mounted a jelco sa-350 tonearm on. I have mounted this arm slightly to far to the bottom left. I was able to correct this by mounting the cartridge further back on the headshell and using a protractor this seems to be ok calibration wise. However the turntable has quite a bit of inner groove distortion. I currently have it equipped with an ortofon black cartridge. Now my question is whether this is due to the cartridge (which I find unlikely) or due to the poor mounting of the tonearm (which I think is pretty likely). I would test it with a different cartridge but I do not have many cartridges on hand that I would trust the results for as the carts I do have are mainly high/med compliance MM. I have been looking for a replacement arm board but they don't seem to be common. Any ideas and tips?
 
Register to hide this ad
What is 'slightly'? A millimeter or two shouldn't have much effect, an inch or two probably will. And if inner groove distortion is a problem, try using the Stevenson alignment, which minimizes it.
I wouldn't worry about using a medium compliance cartridge in your arm. Even a high compliance one. If you see oscillation, groove hopping, or inability to track small warps, you have a problem. But I bet you won't. And a bit more mass makes the bass a bit more weighty, which for most people is a plus.
 
Nat said:
What is 'slightly'? A millimeter or two shouldn't have much effect, an inch or two probably will. And if inner groove distortion is a problem, try using the Stevenson alignment, which minimizes it.
I wouldn't worry about using a medium compliance cartridge in your arm. Even a high compliance one. If you see oscillation, groove hopping, or inability to track small warps, you have a problem. But I bet you won't. And a bit more mass makes the bass a bit more weighty, which for most people is a plus.
Click to expand...
I have seen those issues using a stanton 681 and Shure cartridge before. I did a bunch of tests and stuff on that when I first got the tonearm last year. The resonant frequency on the shure was too low and it was not tracking properly. On the stanton the brush was keeping the resonant frequency in check but it was still having issues with tracking properly. I currently have a 440ML audio technica cartridge laying around so I can try with that just to test since micro line styli are supposed to be great at combatting IGD. I also have a few others like the philips 412 and stanton 981 which I believe are both also high compliance, not sure on the Stanton. but I really don't want to run this with high compliance atleast considering my prior issues. It is off by about 0.5-1cm IIRC but it has been a while since I checked. I think just enough to make a possible impact but not too much to the point that I cannot calibrate the cartridge properly.

Tomorrow I will try the Stevenson alignment and check performance with atleast the at cartridge, thank you.
 
Last edited:
Nat said:
That may not be a safe assumption. Can you look at it under a microscope?
Click to expand...
Maybe not but considering how new these carts are I am not particularly worried. I doubt there are many people that have even gone through one stylus organically (excluding user error ofcourse).

I do not have a microscope. I will check the performance of the arm with a different alignment and different cartridge tomorrow. I will also try the ortofon on my other turntables to see if the sane issue persists.
 
TrevorBarten said:
Got it for basically free when I bought a recordplayer. No clue how many hours it has but judging from the condition of the other stuff included I don't think it has many.
Click to expand...
Can't tell just by looks, but IGD is the first sign of a worn stylus. It might be not that bad, just that if you took it off another arm and the azimuth of the new one is a tiny bit different, the wear flats won't line up with the groove anymore, making it sound worse, especially at the inner groove where tracking is already the most challenging.
 
ripblade said:
Can't tell just by looks, but IGD is the first sign of a worn stylus. It might be not that bad, just that if you took it off another arm and the azimuth of the new one is a tiny bit different, the wear flats won't line up with the groove anymore, making it sound worse, especially at the inner groove where tracking is already the most challenging.
Click to expand...
Of course you cannot tell just by looks. That is why I said I think. It was originally mounted on a sa-250 which is pretty much the same arm as the sa-350.

I have the analogue productions test lp. Is there a way to measure the amount of IGD and adjust accordingly using that? I have kinda just used it for Wow and Flutter but mine is kinda noisey....
 
From your report, it seems the cartridge plays fine everywhere on the LP, except the inner grooves. To my mind, this means that the cart is probably fine.

As the vinyl groove spiral gets smaller and smaller towards the centre of the LP - creating tighter and tighter arcs - the requisite total absence of harmful lateral movement in the turntable platter becomes absolutely critical and a far bigger IGD factor, than any slightly worn or slightly misaligned stylus.

That is to say, the more IGD you are hearing, the more likely it is that there are minuscule (unhelpful) lateral vibrations reaching your turntable's platter, which sends the well-aligned stylus crashing into the ever-reducing groove walls. IMHO, it is wrong to blame IGD on a well aligned stylus.

To summarise: If you have a reasonably well aligned ORTO Black - a fine cartridge! - and you are experiencing IGD, IMHO you will likely find your turntable, its location or its support, is responsible.

Is it possible the turntable is exposed to high levels of acoustic feedback from a nearby loudspeaker?
 
Last edited:
TrevorBarten said:
Got it for basically free when I bought a recordplayer. No clue how many hours it has but judging from the condition of the other stuff included I don't think it has many.
Click to expand...
A Shibata is done in 500 hours which comes around quicker than you might think and inner groove distortion is what you will hear when this happens.
These are far better with Micro Ridge with less issues on the inner grooves and thry last twice as long too.
Chris
 
A long shot but worth checking based on my experience with an OM 20. I had a cantilever twisted slightly to where the tip was pointing at roughly 1:00 position when turned upside down. After a lot finesse and some very small tweezers I got it aligned and the IGD disappeared. Admit a long shot but that turned out to be my problem.
 
After extensive testing with both turntables I am pretty certain the issue is caused by the cartridge. With the Stevenson alignment method I can minimize the IGD, however it never truly goes away. It kinda sounds like how a bad tape sounds that is recorded at clipping. Really only on the last few minutes of an lp though which I find strange. Before I really decide on anything is there a concrete measurement I can do ? I really don't like deciding things like this by ear.
 
TrevorBarten said:
Before I really decide on anything is there a concrete measurement I can do ?
Click to expand...
The HF loss test on the CBS -STR100 test record might give some indication of wear, but the most definitive will be a microscope exam to inspect the size, shape and spacing of the wear facets.
 
TrevorBarten said:
Now my question is whether this is due to the cartridge (which I find unlikely) or due to the poor mounting of the tonearm (which I think is pretty likely).
Click to expand...
If the mounting distance is off, but you can still align the cartridge, all should well. But there can be quite a bit of tolerance in cartridge alignment. What kind of protractor did you use?

TrevorBarten said:
With the Stevenson alignment method I can minimize the IGD, however it never truly goes away.
Click to expand...

Stevenson actually has quite a bit of distortion in the area where most records end. When compared to Baerwald, it's at an advantage for the last four or five millimeters of IEC groove specifications. Many records don't even have modulated grooves there.
 
ripblade said:
The HF loss test on the CBS -STR100 test record might give some indication of wear, but the most definitive will be a microscope exam to inspect the size, shape and spacing of the wear facets.
Click to expand...
But the distortion is audible so should I not be able to measure that somehow?
 
The easiest way to test this is to install new cartridge or new stylus. Especially since when the condition of the current one is unknown. Microline stylii tends to have the lowest distortion, generally. So this is my best bet.
 
TrevorBarten said:
But the distortion is audible so should I not be able to measure that somehow?
Click to expand...
Measure against what? Beginning tracks? Only if the music is exactly the same. Music is too random so you need some kind of control. The HF loss test uses a 10khz sine at the beginning and end of the record. Wear will show reduced output at the end as the stylus will no longer be able to follow the modulations.

Better yet, get a microscope. You'll be able to see not only wear, but other problems that can lead to tracking issues. Problems that can exist even with brand new stylii...
 
You must log in or register to reply here.
Back
Top Bottom