What causes distortion at the end of a record?

[N. Abstentia]

I've got three different turntables, a Rotel, a Pioneer, and a Denon. I've noticed that on all three, the last couple of tracks have sort of a distortion or 'breaking up' sound on loud passages and vocals. The start of the record is crystal clear, but as it goes on it starts breaking up. What can cause that?

[dean_martin]

I've experienced this too. I've read that the last song closest to the label is the hardest to track, but I've never come across a thorough explanation of why and how to remedy it.

I didn't have this problem with every record, but only a couple. I adjusted my tracking force until I found a setting at which I don't experience the distortion anymore. After some experimenting, I ended up at 2.2 grams for my table/arm/cart. I have no idea what other adjustments work for this problem.

[SlumpBuster]

I'm surprised all three tables do it. What you describe is common, and in my experience more of a function of your stylus vs. your table.

As the arm moves towards the center of the LP the stylus angle in relation to the groove changes. A properly aligned cartridge and arm can minimize the degree of change, but there will always be some. This is where linear tracking tables came in. They are tables where the arm does not pivot, but slide across the face of the LP on a set of rails. Some ultra high end tables still use this approach, but cheaply made linears of the 1980's gave it a bad rap.

The poorer mans solution is a good stylus. I have a Goldring 1022 on my Music Hall deck that tracks inner grooves with no problem on records that I've had problems with on other decks. I also have an Technics of 1978 vintage that is basically a belt drive 1200. That table had known tracking errors with inner grooves until I replaced the $30 Audio Technica cart with a Goldring 1012. The problem disappeared immediately.

Other than swapping out carts your best bet is to tinker with alignment, tracking force, level out the table, anti-skate, ect.

[E-Stat]

The start of the record is crystal clear, but as it goes on it starts breaking up. What can cause that?
As SB mentioned, this is the well known inner groove distortion effect suffered by non-linear arms. Likewise, I would suggest breaking out the protractor and checking the azimuth of the arm and ensuring absolute tangency with the cartridge body.

rw

[N. Abstentia]

Thanks guys, at least I know it's not my imagination! I guess I need to think about getting a better table, as the ones I have are not the highest end tables. I picked up the Rotel used for $40 and it's got speed issues (too slow) then a buddy gave me the Pioneer Direct Drive which also has speed issues (constanly fluctuates) and both of them had the 'inner distortion' and I kinda had a hunch it could be a tracking/alignment thing because I put a brand new Grado on the Pioneer with no change. So while I was trying to decide how serious I wanted to get with a turntable I picked up the Denon which is also direct drive and has a P-mount so I figured there would be no tracking/alignment issues. It came with a Shure cartridge which I replaced with an Ortofon and both of them had the distortion so I guess I'll just live with it unless I decide to get a nicer table.

Thanks for the info!

[slate1]

Inner groove distortion is much more a function of your cartridge, alignment and stylus configuration than the table. Although - sounds like you may need a new table as well if you're having speed stability issues.

The Grado's are well known for not being very good trackers and are more likely to exhibit inner groove disortion than some of the others mentioned like the Goldrings. I had a Grado Reference Platinum that I could not get to track well on inner grooves no matter what alignment I used.

As you stated, you can't adjust alignment on the P-Mount Denon table so your only choice there is going to be a better stylus. Even then, without knowing what alignment configuration Denon uses it's impossible to say if it's going to solve the problem or not.

The problem is caused by the fact that more program material must be recorded per revolution and more information must be crowded on inner grooves of the record due to the records constant rotational speed - i.e the inner groove area is playing back at a significantly lower speed than the outer grooves. This makes the inner grooves much more of a challenge for the stylus to track.

There are numerous alignment methodologies that put the null points - the points at which you have zero tracking error - closer to the inner groove to reduce or eliminate the distortion. Some of these include the alignments developed by Rega and Technics as well as the Stevenson Alignment.

The most common alignment method, Baerwald, puts the null points such that tracking error is pretty much evenly spread across the disc. If you've used any downloaded or commercial alignment protractor it's most probably using Baerwald's geometry. I've always used Stevenson on the tables I've run because his null points are closer to the inner groove. This means, of course, that you have greater tracking error on the outer grooves - but that's been insignificant in my experience because those grooves are naturally easier to track. I'm using a Technics table now and their alignment method and geometry is very close to Stevenson - i.e. no inner groove tracking problems.

[squeegy200]

I think this is one of the best bargains in Audio today. I purchased one of these MG-1 Tonearms last March for $300. It is virtually identical to the $11k Air Tangent tonearm. Depending on who you ask, the creator of the MG-1 will tell you his arm was under development long before AT introduced their arm. Air pump and tubing was an additional $100.

I previously used a Sumiko Profile II arm with a Grado Reference Platinum. The long sweep of the Profile arm minimized tracking errors on the inside tracks.

But the MG-1 Air Bearing tonearm was a dramtic improvement over an already decent tonearm. Infinite adjustability and zero tracking angles. It's also a lighter mass tonearm which theoretically makes for less wear and better performance of stylus arm compliance.

On a good condition album, there is utter silence inbetween tracks. There is no discernable surface noise, and this linear tracking arm will play warped records that I was unable to play otherwise.

I understand the creator has recently partnered with in international distributor and the prices have since gone to ~$600. But that's still a fraction of what some high end pivotal arms cost today.

I took me about two days to properly set it up and another two weeks to fine tune it. But it now plays flawlessly.
http://img.photobucket.com/albums/v78/squeegy200/av/mg1.jpg