Why use a super accurate cartridge protractor

Hi Thekong, the null points will shift and the curve will be a different one. If you go to Vinyl Engine and play a bit with the alignment comparator - you will see, that small alternations have huge impact.
Cheers,
D.

Dear Thekong, the alignment I did choose actually minimizes distortion in the last 2/3 ( not just last 1/3) of the record groove's radius.
Cheers,
D.

Hi Photon46

In the cartridge setup instructions with the Vacuum State Guru protractor, Allen Wright says that after checking many cartridge alignments with final adjustment tunings done by ear, there is a consistent trend of finding settings about 1.27mm behind traditional Cotter points on an alignment arc. After spending part of last Sunday setting up an Ortofon Kontrapunkt H with a super fineline stylus, I ended up very close to those points myself.

Don't get misled by vague statements which offhandedly negate or discard existing knowledge, and appear to have discovered something new in promoting a product. Another way of saying the quote above is:

"If you try a Lofgren B DIN alignment you might find it suits your LPs better than the Lofgren A/Baerwald IEC (which is the usual alignment with nulls at 66 and 121), which is what I (the Guru) am doing, but not telling you."

But that doesn't quite have the same mystique.....

That is in effect what is happening with the new alignment - it is LofgrenB-ish - for a 230mm arm, it now has effective length of 228.73, overhang reduced to 16.78 and offset angle reduced to 22.87degrees.

John
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Hi Nandric,
you said

But there must be
the corresponding max. distortion at some other 'points'.
Well it seems to me that we should worry about those also.
I have never seen any numerical values for those in this forum. It may be the case that while I feel 'proud' about my own selection of the zero points my records are in a
sade state because of my choice?

For most alignments there are three maxima (Stevenson being a special case). Typical distortion values for these are (for a 230 arm) 0.65% for the three equal LogrenA/Baerwald IEC maxima and 0.42% average across the side.

For Lofgren B IEC the average is 0.38% but the maximum is now 1% at the innermost groove.

For DIN alignments, there is more distortion when playing a DIN LP but less at the inner grooves when playing a IEC LP. This is why I chose a DIN alignment 30 years ago.

Dertonarm's Uni-DIN alignment is a variation on this which reduces the inner maximum to 0.5% for DIN LPs and lowers the middle max to 0.5% while increasing the outer max to over 1%.

John
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Hi Thekong

Dertonarm said

the alignment I did choose actually minimizes distortion in the last 2/3 ( not just last 1/3) of the record groove's radius

He should have said

...the alignment I did choose reduces distortion....

The alignment reduces it. It doesn't minimize it.

It can easily be reduced further, but at the expense of an increase elsewhere, which is the point being ignored.

Regarding changes in overhang and offset. For a 9" arm, if the overhang is increased by 0.5mm, and offset increased by 0.5 degree, they tend to compensate, as they also do when reduced by similar amounts.

If one is reduced as the other is increased, the errors add and the distortion increases. So you could have made unintended errors in your setup and they could sound ok. Or not.

As an illustration, if the overhang is increased by 0.5mm without the offset changing, you basically get Lofgren B, which may well sound better on your favourite album...

John
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