Overhang question

Hi folks, I need your help. I have a Fidelity Research FR-66S tone arm and Ortofon SPU 85 Anniversary cartridge. How to set the overhang with such a fixed cartridge/head shell SPU? I mean I cannot move the cartridge back and forth to fine tune the overhang. So what should I do if I could not set the correct overhang? Should I adjust the spindle to pivot distance a bit so the overhang could be set correctly? Thank you in advance.

"Should I adjust the spindle to pivot distance a bit so the overhang could be set correctly?"

Yes, Chris, that ought to work.
Sorry if this response turns out to be incorrect, since my own tonearm is the FR-64fx which has a different head shell, but I just looked at my old FR-60 series manual. Copying from page4: "...by loosening the large screw on top of the head shell with a coin you can slide the cartridge and spacer forward and backward. The distance from the front of the head shell to the stylus tip should be adjusted so that it is 7mm. If this cannot be achieved by sliding the spacer, try attaching the cartridge in a different position on the spacer, or turning the spacer around." Perhaps this will help.
Palewin, thank you for your reply. The SPU cartridge is integrated with the head shell, so I can't move the cartridge itself back and forth. There is only one solution in my opinion and that is to adjust the spindle to pivot distance a bit, so the overhang would be correct. I suppose it is more important to get the overhang correct even if the measured spindle to pivot distance deviates a bit (a few mm's) from the specified value.

"I suppose it is more important to get the overhang correct even if the measured spindle to pivot distance deviates a bit (a few mm's) from the specified value."

Chris, do the spindle to pivot distance adjustment with your alignment protractor in place. Adjust the arm pivot position for perfect alignment on the inner guide (if you're using Baerwald, which you probably should unless you have a Mint).
Tobias, I'm using the DB Systems gauge. Does it use Baerwald?

Chris, there are a number of alignment protractor configurations that have inner and outer positioning guides like your DB Systems gauge. One such configuration, the Baerwald, is the classic and most popular. (Others include the Lofgren and Stevenson systems ; they all use slightly different math but look similar in use.)

The chances are that your DB Systems (which I haven't used myself) uses the Baerwald alignment. No matter. The inner position is the one to use to set your combined overhang/stylus-to-pivot distance.

Thank you Tobias.

This issue of the interrelationship between effective length and pivot to spindle distance has perplexed many a sophisticated turntable owner.

Even manufacturers like SME make compromises fixing the cartridge location in the headshell (no slots), and thereby not accounting for varying stylus positions relative to the mounting bolts.

If you can establish your effective length, then you can use the John Ellison spreadsheet on the Free Stuff section of the Enjoy the Music website to establish the correct pivot to spindle distance.

This spreadsheet has a Baerwaald tab as well as a Loefgren tab. I have a link to that page on the Support Page of my website. Frank Schroeder and I consider it an invaluable tool and a great gift to the audio community from John.

It may disagree with what FR has defined as the ideal alignment as many of the Japanese tonearms have ideas that vary from those of Baerwaald and Loefgren.

The archived threads on this forum relating to the Mint LP arc style protractor have a lot of good general information which attempts to cut through many of tho common misconceptions about the relationship between the three parameters: eff. length, pivot to spindle, and offset angle.

I also have a thread on my forum relating to this topic. It's something that's worth chewing over, to better digest. I maintain a permanent link to this thread on the lower right section of my home page - considering it to be THAT important to one's understanding of this topic.

Thom @ Galibier
Thanks very much Thom.

Oh, and to state the obvious - yes, if the position of the cartridge in the headshell is fixed, adjusting the pivot to spindle distance is a viable option.

While a fixed cartridge mount hobbles you in not being able to adjust the third parameter (offset angle) there's no reason to not go for two out of three.

I'm wondering if offset angle isn't the least important of the 3 parameters to optimize. Yip (Mint LP) and I had a conversation about this, and while neither of us have done exhaustive experiments, we're thinking along the same lines.

Note - I'm thinking out loud here and not stating this as a matter of fact. I keep trying to dedicate some time to perform this experiment, but something always supersedes it.