Discuss The Viv Lab Rigid Arm

How did you create an underhung Schroeder? Does it have zero headshell offset too?

All of the offset is applied at the single mount screw.  The only thing preventing a 0° offset is the back of the cartridge hitting the armwand.   I made a shim to get the clearance so the cartridge could be set straight. 

I looked at the math and suspect the best setup for this type of arm puts the single null point about 80% of the way into the record.  I have found that the predicted distortions by the math need another factor of 2 added beyond the traditional weighting to match what I hear. I also suspect stevenson was on the right track since things get really ugly as you pass the second null and approach the lead-out groove.

dave

Do you detect a greater uniformity of any colorations, from lead in to lead out grooves?  That's what I thought I heard with the RS Labs, less in degree and fewer variations in sonic character, compared to a typical overhung tonearm, as it traverses an LP.  Which made it sound more like a good R2R playback.  (That's my best metaphor for it.) This effect was not probably as great as may come across in my writing about it, due to the fact that we must use words to describe it.

I could probably underhang my Sperling arm---like the Shroeder, it just has a bolt at the headshell to set offset angle. How large is your underhang with the Schroeder, Dave? With the RS Labs it was between 5 and 10mm.

@lewm 

My best guess is for some reason the underhung arms handle the TAE differently than a traditional arm.  I think i would liken the sound to that of the conical vs advanced profiles.  In all but the best setups the conical will sound better but leave a lot of the music in the groove.  If you want a quick simple setup that will sound good use a conical and an underhung arm.  If you have the ability / time to nail the setup an advanced profile on an offset arm will be better.   For some reason in spite of all of its problems, the RS-A1 can get plopped down and be playing music in 5 minutes at a level of a fairly well set up traditional arm.

@maxson 

I am about 12mm and I would listen to the last track as a test for alignment.  For the last third of the record the single null moves about 3mm toward the spindle for every reduction of overhang of 1mm.  Zenith also plays a role here and the chances of actually getting it to 0° is slim so this will change the theoretical ideal.  I suggest starting with coarse moves and the last two tracks of a side since thats where the gross errors are most apparent.  I do want to note that unlike the three underhung arms discussed here,  the arm you are going to try this on is rigidly coupled in all but the lateral and vertical planes so i would be very interested in your results.

At the risk of giving all of the naysayers here some ammunition I believe this is what the math says about the resultant distortion of an overhung and underhung setup.  It is this huge disconnect between what the math says and what people hear that has me interested in this topic.

dave