Putting it simply by Robert Harley of TAS Inner Groove Distortion or IGD is the “shattering” sound you may experience in the upper register towards the end of each side of the LP. Quoting from Issue 172 TAS from the same author it is “caused by the imperfect tracking of the groove by the stylus (the stylus momentary loses contact with the groove) – a phenomenon exacerbated at the inner grooves where tangent error is the greatest and the linear velocity as seen by the stylus is the lowest. As the stylus moves toward the inner grooves, the linear velocity as seen by the stylus gradually decreases. The recorded wavelengths become shorter and shorter, making it increasingly difficult for the playback stylus to accurately track high frequencies as well as high groove modulation.”
I agree with Robert that it is unfortunate that the most demanding passage of western classical music climaxes at the part that is most difficult to play well – symphony’s fourth movement. As a result, it is a common knowledge that song orders often used to be created with the softest songs coming at the end of an album’s side, so that the inner grooves would be less subject to distortion. But I ASK – is this the fault of the LP technology (so we workaround it) or simply because many of us did it wrongly?
But is it the fault of the LP technology?
The industry standard for a playable area of a LP extends from the spindle centre [i.e. Zero Centre] 60mm to 145mm. Often the paper label is 50mm in radius and hence the playable area is around 10mm from the paper label. Inner groove refers to the last 2 to 3 tracks of an ordinary LP.
Journey’s Faithfully from the LP Frontiers and Jennifer Warnes’ The Well are very good test tracks to evaluate your turntable setup/alignment. Here’s some more good test tracks:
Linda Ronstadt “Simple Dreams” – I Will Never Marry (Side A Last Track) Billy Joel “Innocent Man” – Innocent Man (Side A Track 2), Longest time (Side A Track 3) Neil Diamond 12 Greatest Hits, Vol 2 – You Don’t Bring Me Flowers (Side A Last Track) Rickie Lee Jones (debut) – Easy Money (Side A Track 5) Dan Fogelberg Greatest Hits – Longer; Same Old Lang Syne; Run For The Roses Linda Ronstadt “Hasten Down the Wind” – That’ll Be the Day (Side A Track 4) Carol Kidd “All my tomorrows” – Round Midnight (Side A Track 5)
Some of the best tracks are often cut last. From left to right – Jefferson Starship “Save Your Love”, Iron Maiden “Hallowed Be Thy Name”, Journey “Open Arms” and Yes “Let’s Pretend”.
What is the cause of Inner Groove Distortion?
We do not think IGD is a phenomenon or a limitation of the LP technology. Assuming all things normal i.e. the record, the cartridge, the overall system then IGD is most likely caused by improper turntable/tonearm setup. By that, I mean the basic parameters of setting up a turntable system – cartridge alignment, mounting distance, overhang and turntable leveling. In a properly setup turntable system, the listener should not detect any noticeable degradation in sound performance from the outer tracks to the inner tracks whether he is listening to simple passages or some demanding tracks. Of course, IGD becomes more evident in demanding tracks and vice versa.
Even the most INTELLIGENT and BEST designed tonearm in the world today cannot compensate enough to avoid IGD if the BASICS are not done right!
Litmus Test LP for IGD
For your evaluation if your turntable system passes the IGD test, we have come up with some common pop/rock titles that many of you would have. We now stock them in our shop too so that you may request to play them to listen for yourself and even perform an A/B (if possible) of how an accurately setup turntable system should sound.
In a lesser setup turntable, playing the song Africa from Toto IV (Side B last track) would turned ugly in the chorus section when the band is in full gear. You would sense some dynamics compression as the music becomes messy in the middle. AOR fave Journey’s two multi-million selling singles were also cut in the last track – Faithfully from Frontiers (Side A last track) and Open Arms from Escape or E5C4P3 (Side B last track). Incidentally, they are also our favourite test tracks after each fine-tuning and fresh setup done. Play them loud to listen if your turntable setup can get pass them without Steve Perry sounding anything but cracking and/or straining in his strong, high- pitch vocals.
Like an automobile that needs to be checked regularly by a car workshop to stay roadworthy, your turntable needs to be fine-tuned once every 9 to 12 months to perform its best. Leave this to an expert (like us) if you are unsure or do not have the time to do so.
Do note that we would happily fine-tune turntable systems that are purchased from us FOC but we are unable to fulfill such requests (at this time) for turntable systems not purchased from us.
A turntable system that is IGD free will sound more relax, grain-free, quieter and more dynamic – yes all true! The more expensive a turntable system, the more revealing it is and therefore the more critical and responsive it is to setup/alignment. We encourage you to listen to our showroom setup using some of the above mentioned LP and then compare it at home.