Thanks for the ideas everyone.
I am experiencing a few different types of distortion. In the outer grooves of some records, I've noticed some midrange tones struggling to hold their pitch. For example a guitar string pluck wavering back and forth.
Another form of distortion I've come across is a strange scratching high frequency sound almost like an aggressive tape hiss that occurs rhythmically with each platter rotation. This behavior occurred several times on one record I was listening to in more central grooves as well as the edge of the record.
I've probably listened to a dozen records over the last few days - each seems to have different sonic behavior and cause differing amounts of woofer pumping. Some records don't cause my woofers to pump at all.
@bill_k interestingly enough, a few warped records that listened to last night exhibited the least amount of woofer pumping. They actually played better on the side with the edges cupped upwards. I have a record weight that flattens them out on the other side.
@jsalerno277 I want to go through your list here:
- Warped Records - as stated above, some of my warped records actually exhibited the least amount of woofer pumping. The cupped side exhibited different behavior from the flattened size. I'm confident that I nailed the alignment with my recent reinstallation.
- Turntable Rumble - I have a 3 year old MoFi Ultradeck. I recently cleaned and relubricated my inverted bearing. I would think there has been no change with my setup here.
- Turntable Isolation - I have my turntable between my speakers which are about 7 ft apart. The turntable is sitting on a custom steel and wood shelf that I designed. Heavy butcher block shelves are supported on black and blue heavy duty equipment vibration pads you might install under an industrial fan or refrigerator. I don't have any issues with footfall due to this shelf. I don't really have the ability to move my turntable elsewhere. I know that I have a pretty serious hum somewhere in my system that is audible if I don't ground the turntable but absolutely fine otherwise. I have a combined HT and 2 channel setup with a HT bypass integrated amp, processor, TV with eARC, and sub. Sometimes if my cables shift around, I need to position my right channel phono cable just right for the right channel to play. There are plenty of places I could be getting feedback from.
- Speaker to Stylus Feedback Loop - I never had the distortion or woofer pumping issues with my previous factory fitted MoFi master tracker cartridge. Perhaps the phasemation is more sensitive to feedback?
- Tonearm Mass/Compliance Mismatch - The online calculator I used has my system resonance at 6.4hz assuming the 25.14g tonearm mass. I have reached out to MoFi to confirm this assumption. I think this is likely what I'm dealing with. Unfortunately I think I will need to swap out the Phasemation cartridge. I don't love the idea of the rumble filter as I doubt it will solve the high frequency distortion I was hearing.
@lewm I hate the antiskate mechanism on my turntable, its inaccurate and unverifiable. You set an O-ring and counter weight on various notches that are supposed to pair with different cartridge weights. I have tried to play records with the setting at each end of the possible spectrum without any noticeable change in behavior.
I'm to the point of searching for a low compliance cart that will work with my current stage phono preamp. I'd rather not abandon the Sutherland if I don't have to. I'm thinking the Ultragold MC could be a good match. It has a proven compliance match and its 12 ohm resistance should function with the Sutherland. The only specification I'm missing is the inductance of the cartridge. Another option I was considering is the Miyajima Shilabe but this is a much more expensive option. I don't really want to go down this rabbit hole again and find I still have mismatch issues.