GoodSoundClub - Romy the Cat's Audio Site - Inner Groove Distortion

Analog Playback
Topic: Inner Groove Distortion - Your experience?

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Posted by hifitodd on 12-04-2008

Hi Romy and others,

One thing that I have struggled with for some time is that I have always been plagued with inner groove distortion on the majority of my records (many new, all cleaned with Nitty Gritty). Inner Groove Distortion on the sibilants especially drives me nuts, seems to happen on about 75% of my records. I just bought a brand new 180g anniversary Dark Side of the Moon, and on the last track it goes "I'll Sssssssee you on the dark sssssside of the moon." Very annoying.

In classical music, this distortion represents itself on dynamic piano, string and horn passages, as well as in the sibilants in voices.

I've had this problem spanning several turntables and arms, (Rega P25, VPI HW19, Nottingham Spacedeck, and now a VPI Scoutmaster). I've tried 3 cartridges (Denon 103R, Dynavector 20x and Shelther 901) always with the same results. The table was professionally setup by my dealer, and I personally confirmed all the settings myself. The tables have been level, I've tweaked alignment with various protractors and tools, tested VTF all throughout the range (leave it on the high side usually, 2.0g on the Shelter 901), and tried different VTA and antiskate settings. I'm currently running the VPI Scoutmaster with the JMW 9 sig arm and the Shelter 901. I understand that the compliance on this cartridge is too low for this arm, but my understanding is that this shouldn't impact IGD. (correct me if I'm wrong)

Always, the inner groove distortion is there. I also just bought the new Guns n Roses album on vinyl (probably not your taste, Romy Smile

) , and it's got it too. Axl Rose doesn't even need to say something that starts with S.

Anyway, the one variable that has never changed, is the fact that I've been using a pivoted 9" arm. I have spoken with VPI and some others who feel that a well setup 9" should not have inner groove distortion, but the marketing on longer and linear tracking arms always mentions that they "reduce/eliminate IGD"

So the reason why I'm posting is just to get your take on things to see if you had any advice or thoughts to share. Have you run into inner groove distortion before? Did it seem to be a common theme in 9" arms? How did you deal with it? Do you think that a linear tracking arm would magically make this problem go away? (granted, it's probably not compatible with the Scoutmaster anyway, but this IGD is a dealbreaker for my vinyl enjoyment, so I've got to fix it one way or another). I'm talking with Mike at VPI concurrently, who thinks it's a setup issue, which I am hesitant to believe given that I've had the same problem spanning several completely different setups.

Thanks in advance,

Todd

Posted by Romy the Cat on 12-04-2008

Todd,

What you descried does not sound to me as inner-groove distortion, even though I am not exactly sure what inner-groove distortions are. The very first questing that I would ask if you have the same character of sound when you play your CD, or tuner, or tape, or whatever. If you say that the “problem spanning several turntables and arms”, so would it be possible that another common denominator of those “several turntables and arms” is responsible – speakers for instance. You might have some dust on your tweets that would be perfectly responsible for this character of sound. So, if you wish to debug it then eliminate one contributor per time until you TT with phonostage are left to blame.

The Cat

Posted by hifitodd on 12-04-2008

Hi Romy,

Thanks for taking the time to respond.

I am pretty sure what I am experiencing is related to the analog system somehow. I have tried playing the same tracks on CDs, and there is no distortion.

Also, this only happens in the last 2 or so tracks on any given LP side.

So I take it you have never encountered distortion on sibilants especially in the inner grooves?

Regards,
Todd

Posted by Romy the Cat on 12-04-2008

OK, you need to find out if the problem is in phonostage on in TT as the problem was “spanning several turntables and arms”. You might run your phonostage from anti-RIAA filter from your CD player:

http://www.hagtech.com/iriaa.html

or use one of many CDs with inverted RIAA curve :

http://www.graniteaudio.com/phono/page2.html

if your phonostage out of suspicion the you can look at TT and arm but I kind of skeptic as you have the same problem with turntables and arms. If it was just “several arms” than I might suspect that your arm in not properly located at your TT but it if spread across several turntables then it is something else. You said that this only happens in the last 2 or so tracks on any given LP side that is a clear indication of geometry problem but why would you have the same problem across the several turntables and arms! It is dose not sound right to me.

The only explanation that I have in case if it were be not phonostage is that your dealer that “professionally setup” your TT was just an idiots and had no idea what he is doing. BTW, many of them are idiot and I do not insult then but just publicizing the sad fact. I know a few very experienced professionally setup specialists who actually cheat and verify arm geometry only by the protractors at a single. This is wrong. Well, it is OK if the arm was mounted at right spot but it very frequently not the case and you need two point of protractors alignment. At one point of middle the arm is aligned but at the inner-side of the record it is not aligned anymore and the needle slide sideways. With short arms and Shelter 901- like cartridges that has not cylindrical needles but rather the contemporary profile with shard sided the alignment shell be very precise. Otherwise you will be destroying you record (which is not a bid deal - it is Pink Floyd anyhow) and you might pick up all imaginary noises in the peripheral of record. If it is the case then your anti-skating shell run away very un-smoothly when your Shelter begin to position itself sidewise.

The caT

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