Pickup SRA - starting from a 500x microscope

Hi O_holter. When you raise the SME pivot by 6-8mm, you are not only changing the SRA, you are also increasing the VTF, and reducing the overhang along with the tonearm effective length.

In order to isolate your findings to SRA only, you need to compare the VTF before and after raise and add the difference in VTF to the before raise position, or subtract the difference in VTF from the after raise position.

Also, you need to quantify how much the stylus position has moved and either pull the Atlas back a skosh in the before raise position, or nudge it forward a skosh in the after raise position.

I am not poo-poohing your findings at all, but good science demands that only one variable is changed at a time - even though you will have to fight the tonearm design to accomplish this.

Once you have confirmed the above and hopefully pinned the reason for the sonic improvement down to SRA increase and nothing else, I would be very interested in knowing what SRA and CRA (cantilever rake angle) your USB microscope reveals.

kind regards, jonathan

Thank you, JCarr. I will do it when I get the microscope back (may take some time). Very grateful for this help.
Let me assure everyone reading this, that I enjoy my Atlas a lot, each day - this is why I have used Lyra cartridges for almost twenty years.

If I can add my 2 paise worth. If the broad range for acceptable SRA is 90-95 deg, it doesn't require too much geometry to figure out that the cartridge body or tone arm underside will be parallel to the record surface. That's the starting point for most non SRA aficionados to start tweaking for optimal results. IOWs junk the usb microscope and NJoy the music.
Cheers

The angle at which the stylus is inserted into the cantilever varies greatly from sample to sample of even the best made and QC'd cartridge. This can be verified using a USB microscope. Setting the arm parallel to the record surface tells you nothing about SRA. Only a microscope does. By all means let your ears be your final arbiter if you so choose but having found 87 degrees and worse on some cartridge samples with the arm parallel to the record surface means the ear method sometimes will NEVER produce correct results. You need to know your starting point SRA and parallel to the record surface is false comfort. As for cutter head angles, the survey of cutting systems done nationwide by Discwasher's Jon Rich demonstrates that 92 to 94 degrees is the average range and that it MUST be greater than 90 degrees or the cut lacquer thread cannot be vacuumed away in real time, which is a necessity because the thread is highly explosive. Rich also published Intermodulation Distortion measurements at varies SRAs proving that 92 degrees is the average 'sweet spot'. If you wish to change for every record, see a shrink. By all means recheck VTF and overhang after setting SRA if you must but don't neglect setting SRA just because it might affect those other parameters! And here I just disagree with my friend Jonathan Carr: if you raise or lower an arm 6-8mm you WILL CHANGE SRA! On a 9" arm that would change it by almost 2 degrees. On the other hand those who hear differences between record thicknesses are blowing smoke since the difference in SRA will be a fraction of a degree. And Sunnykboy you are wrong and your post is JUNK. You obviously have zero experience here. Go measure a few dozen cartridges and you'd find some measuring 84 degrees and 87 degrees with the record parallel to the record surface. Stop passing along MISINFORMATION based on ignorance.

Dear Mr Graves
I really enjoyed reading your comments. Superb post. If SRA can cause such excitement, than surely all is well in this hobby that we love and enjoy.
Cheers