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In Reply to: RE: Fidelity Research FR64S posted by Lew on June 30, 2020 at 10:48:17
I think it's that your cartridge lines up square in the headshell if you mount the FR64S at 231.5 mm P2S and align for Baerward. Versus having to twist/toe in the cartridge against the headshell if you're at 230 mm and want to hit Baerwald. Yes, my understanding is that it's because the FR64S's headshell offset angle (combined with the published P2S) reflects a different geometry, perhaps Stevenson. None of my other arms are like this (including my FR64fx - and on that arm I've also verified that the SMARTractor's Baerwald matches up to my GeoDisc) - they line up square in the headshell for Baerwald at their recommended P2S distance. I use a SMARTractor for setting P2S (pivotable arm boards on my Clearaudio Innovation) and then align to its Baerwald. The slight toe-in doesn't bother me - I'm aligning to the protractor grid, not the headshell. And it sounds great.Also as it stands, my Koetsu runs up to near the most forward point on my Ikeda headshell slots. If I further increase P2S I doubt I'd be able to hit Baerwald since I'd run out of room. I think the cool kids running 231.5 mm more often use those fancy Arche headshells - maybe they have more range.
Edits: 06/30/20 06/30/20 06/30/20 06/30/20 06/30/20 06/30/20Follow Ups:
What do you mean by "Baerwald"? In other words, I'd like to know what you mean when you constantly use the terminology "Baerwald"? Are you referring to a specific set of null-points? If that's the case, any two null-points can be called Baerwald null-points simply by selecting the required modulated groove envelope. Below are Baerwald's equations, which calculate a pair of alignment null-points from a specific modulated groove envelope.
The FR-64S tonearm has the following parameters:
Effective Length: 245-mm
Mounting Distance: 230-mm
Offset Angle: 21.5-degrees
Inner Null-Point: 59.17-mm
Outer Null-Point: 120.4-mm
These are Baerwald null-points only for the following modulated groove envelope:
Innermost Modulated Groove Radius: 53.53-mm
Outermost Modulated Groove Radius: 153.27-mm
Normally we use the IEC modulated groove envelope defined by the following values:
Innermost Modulated Groove Radius: 60.325-mm
Outermost Modulated Groove Radius: 146.05-mm
Given the IEC values above, Baerwald null-points would be:
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mm
These require the following tonearm parameters based on effective length of 245-mm:
Effective Length: 245-mm
Mounting Distance: 228.14-mm
Offset Angle: 22.42-degrees
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mm
Another set of tonearm parameters based on a mounting distance of 231.5-mm are listed below:
Effective Length: 248.13-mm
Mounting Distance: 231.5-mm
Offset Angle: 22.12-degrees
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mm
Best regards,
John Elison
The SmartTractor has 2 grids labeled Baerwald: Loefgren A IEC and Loefgren A DIN. I choose the IEC one over DIN, since I don't care too much about the innermost grooves which are compromised anyways. The GeoDisc grid matches the Loefgren A IEC (because IEC is generally more common). So IEC is my selected "groove envelope". My point is that hitting the Loefgren A IEC curve at 230 mm P2S requires a slight modification to the offset angle (by twisting a cartridge in its headshell) other than what the FR64S was originally aligned for. My guess is that people are slightly increasing the P2S, and thus increasing the effective length, in order to pull the prescribed "Loefgren A IEC" offset angle back into alignment with the FR64S (i.e. slightly decreasing it). BUT elongating things like this requires a headshell (and a stylus to mounting screw offset) that can support it.
Edits: 06/30/20 06/30/20 06/30/20 06/30/20
Okay, Baerwald and Loefgren A are one and the same. The Loefgren A parameters for the IEC modulated groove envelope with a tonearm mounted at 230-mm are as follows:Effective Length: 246.74-mm
Mounting Distance: 230.0-mm
Overhang: 16.74-mm
Offset Angle: 22.25-degrees
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mm> My point is that hitting the Loefgren A IEC curve at 230 mm P2S requires a slight modification to the offset angle
You're right! The offset angle of 22.25-degrees in the above scenario is slightly greater than the 21.5-degrees specified for the FR-64S tonearm. However, if you want to increase P2S so the offset angle will equal 21.5-degrees, you will need to extend P2S significantly farther than 231.5. Here are the tonearm parameters for that scenario.
Effective Length: 254.96-mm
Mounting Distance: 238.80-mm
Overhang: 16.16-mm
Offset Angle: 21.50-degrees
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mmThe only thing I can think of that would justify a mounting distance of 231.5 is if a different headshell had a 1.5-mm longer distance from its bayonet mount to its headshell slots. That would require mounting the tonearm farther from the spindle to maintain a 15-mm overhang.
On the other hand, it's more likely that someone simply made a mistake in thinking that by increasing mounting distance they were also increasing overhang thereby making the FR-64S more compatible with IEC Loefgren A. Unfortunately, by increasing mounting distance you are actually reducing overhang. Consequently, they should have specified a mounting distance of 228.14-mm to increase overhang to 16.86-mm for IEC Loefgren A as indicated by the tonearm parameters below:
Effective Length: 245-mm
Mounting Distance: 228.14-mm
Overhang: 16.86-mm
Offset Angle: 22.42-degrees
Inner Null-Point: 66.00-mm
Outer Null-Point: 120.89-mmBest regards,
John Elison
Edits: 06/30/20
I'm not a disciple of the 231.5 mm club myself, so I can't say exactly what curve they're recommended for use with it - it very well might NOT be the Loefgren A IEC that I use (and might be DIN envelope, etc).Anyways, as you've math'd out, my guess was wrong for Loefgren A IEC @ 231.5 mm P2S perhaps making things "square" in the FR64S headshell. 238.8 mm is a LONG ways off! Wow! Thanks for the calculation evidence.
Edits: 07/01/20
Thanks guys for the wealth of information. I have acquired a FR64S and a FR66 as well.
A bit of background. I had the blue Azule on SME V on an AVID Acutus SP & VPI 12in' tone arms on a VPI HRX (exact setup up as per review by PF a few years back) but somehow, these did nothing for me. I've had the blue Azule for 6-7 years and it has come to a point either to go for broke outside of my comfort zone to acquire a second hand no more in production arm and DIY an arm board to suit or to let go of the Koetsus. Last push to get this right.
My guess is you will be happy. Most who have used FR head shells With FR tonearms seem to prefer substituting a head shell made by some other company. In my case I am extremely happy with the 18 g Ortofon LH 9000 head shell, on my FR64S.
Like Mulveling, I too had assumed that the rationale for 231.5mm P2S had to do with at least reducing the required amount of cartridge twist. And at that P2S some twist is still required to align the cartridge for Lofgren A/Baerwald. My dirty little secret is that I am somewhat of a nihilist when it comes to cartridge alignment. Not a complete heathen, but an agnostic at least.
I was doing some search for compatibility between the Ikeda tonearm ehight adjustment thingy when I came across my old post. I am happy to report that the last ditch effort paid off and my FR64S + Blue Azule is mounted on the AVID ACUTUS SP. Meanwhile, I have gone off the deep end and acquire more Koetsus in the preceding years.
What tonearm wires are you using
I think it's smart and commendable you're trying a 64S before giving up on Koetsu. That pretty blue stone was no small investment! Meanwhile the 64S cost is (usually) quite reasonable; it's just a matter of investing the time for setup. If you don't like an Azule with a 64S, then you can rest assured Koetsu are not your flavor, and move on to different audiophile pastures.
I lent my Jade to a friend with a VPI 3D arm plus dual pivot. It worked OK overall but had some gremlins in inner grooves. Both of us agreed we'd never even try mounting to a VPI unipivot without the dual pivot. He now upgraded to a Fatboy Gimbal arm (Anniversary table) and reports good improvement. Still, in my experience Koetsu rewards a combination of rigid (gimbal) bearings, high effective mass, and not too much damping. Violate one of these and you might still get good sound, but not the "best". Violate two and you're probably not gonna be happy (e.g. my Clearaudio Universal 12" VTA sounded quite bad with Jade). But you get all 3 with the 64S.
I don't have experience with the SME V, unfortunately. I know people run Koetsu on them, but I haven't seen much postings very strongly for or against this match over the years. That indicates to me it might be a "middling" match. And then there's the question of what arm most of the Koetsu lovers and evangelists run - usually not an SME.
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