Issues w/ SRA on a PC-1S

kroslos

Well-Known Member
Feb 7, 2015
38
0
238
Naperivlle, IL
All,

I'm having difficulties with my Air-Tight PC-1s set-up; so I sent a private message to another PC1S owner, PeterA, and he suggested that I post a thread and include some pictures to see if someone can provide guidance. I have the cartridge mounted on a Graham Elite and my TT is an Oracle Delphi MkVI. My other cartridges are Koetsu's - an Onyx Platinum Diamond and a Rosewood Signature. Both cartridges sound very good, and I mention this only as a "reference" because I don't believe there are any downstream factors that are impacting the set-up and sound of the PC1.

When I mounted my PC1 and was attempting to set it up, I could not get my SRA anywhere close to the desired 92 degrees. Even with my VTA on the Elite raised all the way up, I could only get to about 88 degrees. At this stage, the cartridge didn't sound bad; however, it didn't sound as good as I was expecting. So I decided to shim the front of the cartridge and ended up using a small piece of bronze sheeting cut to about 4x10x1.5 mm (WxLxThickness). Bingo! I was able to get 92 degrees with the arm of the Elite very close to parallel. I've attached some pictures below taken with my digital microscope with the cartridge at 2.1g VTF.

When I played some of my reference recordings the cartridge didn't sound good at all - somewhat dead and lifeless. So if my set-up is accurate (all other set-up parameters are correct and in line with both Bob Graham's set-up tools confirmed with a SmarTractor), then what's going on here?!! Is it the shim material I've used? Is something wrong with the configuration of the PC1? There are quite a few embedded measurement in the pictures below that I'm hoping someone more seasoned than I can interpret and provide some potential recommendations and solutions.

Thanks much!
Kyle


PC-1 Shimmed w Cantelever angle small.jpg PC-1 Shimmed 2d.jpg
 

Billy Shears

Well-Known Member
Jul 27, 2015
255
1
150
Hi Kyle
I am sure you will get plenty of input from this Forum.
So here is mine: I too am a big fan of Mr Fremers Publication and got the whole 92 degrees digital microscope thing to a point. What i have problems with is when a measurement produces poorer results than if you set it by Ear.
That is something that seems to be happening alot with this fixation on 92 deg.SRA under a microscope.
So in theory it could be that adding the Brass shim is increasing the effective Mass to much and causing the problems you are hearing but i doubt that is what is happening. Can you describe in a little more detail what you are hearing that is not sounding good at all?

Regards
 

ddk

Well-Known Member
May 18, 2013
6,261
4,040
995
Utah
All,

I'm having difficulties with my Air-Tight PC-1s set-up; so I sent a private message to another PC1S owner, PeterA, and he suggested that I post a thread and include some pictures to see if someone can provide guidance. I have the cartridge mounted on a Graham Elite and my TT is an Oracle Delphi MkVI. My other cartridges are Koetsu's - an Onyx Platinum Diamond and a Rosewood Signature. Both cartridges sound very good, and I mention this only as a "reference" because I don't believe there are any downstream factors that are impacting the set-up and sound of the PC1.

When I mounted my PC1 and was attempting to set it up, I could not get my SRA anywhere close to the desired 92 degrees. Even with my VTA on the Elite raised all the way up, I could only get to about 88 degrees. At this stage, the cartridge didn't sound bad; however, it didn't sound as good as I was expecting. So I decided to shim the front of the cartridge and ended up using a small piece of bronze sheeting cut to about 4x10x1.5 mm (WxLxThickness). Bingo! I was able to get 92 degrees with the arm of the Elite very close to parallel. I've attached some pictures below taken with my digital microscope with the cartridge at 2.1g VTF.

When I played some of my reference recordings the cartridge didn't sound good at all - somewhat dead and lifeless. So if my set-up is accurate (all other set-up parameters are correct and in line with both Bob Graham's set-up tools confirmed with a SmarTractor), then what's going on here?!! Is it the shim material I've used? Is something wrong with the configuration of the PC1? There are quite a few embedded measurement in the pictures below that I'm hoping someone more seasoned than I can interpret and provide some potential recommendations and solutions.

Thanks much!
Kyle


View attachment 22408 View attachment 22409

Hi Kyle,

I don't know where it started or who recommended setup procedure by scope but I do know that this isn't a substitute for your ears and imo a complete waste of time and here's why. For precise measurements besides your flat and level surfaces you need to get both your scope and stylus aligned 100% together on the same parallel plane, a near impossibility in a home setup. Even if you did get it right by chance, your measurements are based on the stylus resting on a flat and level surface, a groove on a vinyl disc is anything but flat and level. Then there are the system variables to deal with, you can only get this right tuning with your ear.

Shimming a cartridge is usually a bad idea in a high quality setup specially the way you're doing it. There's a lot of resonance from the cartridge and arm and the best ones are controlling these resonance with their design and choice of materials, you disrupt the connection and the flow with introducing new materials and in your case unevenly by shimming only part of the head. The best way is to add a spacer to the base of the arm like the ones made by SME for their arms; maybe Oracle can provide with one too.

david
 

Billy Shears

Well-Known Member
Jul 27, 2015
255
1
150
Hi Kyle,

I don't know where it started or who recommended setup procedure by scope but I do know that this isn't a substitute for your ears and imo a complete waste of time and here's why. For precise measurements besides your flat and level surfaces you need to get both your scope and stylus aligned 100% together on the same parallel plane, a near impossibility in a home setup. Even if you did get it right by chance, your measurements are based on the stylus resting on a flat and level surface, a groove on a vinyl disc is anything but flat and level. Then there are the system variables to deal with, you can only get this right tuning with your ear.

Shimming a cartridge is usually a bad idea in a high quality setup specially the way you're doing it. There's a lot of resonance from the cartridge and arm and the best ones are controlling these resonance with their design and choice of materials, you disrupt the connection and the flow with introducing new materials and in your case unevenly by shimming only part of the head. The best way is to add a spacer to the base of the arm like the ones made by SME for their arms; maybe Oracle can provide with one too.

david

So good to read this, i thought i was the only one that feels that way about this usb microscope lark...
 

kroslos

Well-Known Member
Feb 7, 2015
38
0
238
Naperivlle, IL
Hey Billy - thanks for the response.

Regarding why happened when I shimmed and was at 92 degrees, everything collapsed, became restricted, and all the magic was gone. I'm not sure what was causing it and I think it wasn't the SRA but the interaction with the shim; but I'm not sure. The Graham Elite headshell has about a half inch circular soft "coupling disc" that the cartridge rest upon when mounted to the headshell. With the shim in place, the orientation and coupling between my cartridge body and the headshell became "compromised" - the cartridge was only seating on the rearward portion of the coupling disc and the forward portion had the brass shim between the cartridge and headshell. I'm not sure if it was this or the brass shim negatively interacting somehow; but be that as it may, I ended up taking the darn shim out. Couldn't stand it! And once removed, guess what happened? The articulation, bass and treble response, and ease and naturalness of the sound all returned. Go figure....

I didn't make any additional adjustments other than the VTF, getting my arm to parallel, and using Adjust + to dial-in my azimuth. I didn't want to mess around with the digital microscope as it's quite an ordeal to prepare and mess with it, and I knew from past attempts, I couldn't get it set to the proper 92 degree SRA anyway.

So what are my learnings here... Well, first of all, I do believe there is something behind Fremer's, and other's, touting of the 92 degree SRA. It makes sense and there are a multitude of advocates who agree with him. I believe that all of us realize that there is a certain range of tolerance here and that there is really no perfect "ideal" given the overall lack of standardization in the recording industry; however, the overall basis of ~92 degrees is sound. My other learning is either my shim was of the wrong material or it interfered with the proper cartridge-to-headshell coupling that I assume is also integral to the overall musical chain. And probably my final learning was to quit obsessing and just enjoy what I already have!

Does the PC-1S sound good? Absolutely; however, would it improve with the proper ~92 degree SRA? Maybe; but I guess I won't be able to prove that out unless/until I figure out how to achieve it without injecting other compromises into my system (i.e., shim) in order to attain it.

Kyle
 

Billy Shears

Well-Known Member
Jul 27, 2015
255
1
150
Hey Billy - thanks for the response.

Regarding why happened when I shimmed and was at 92 degrees, everything collapsed, became restricted, and all the magic was gone. I'm not sure what was causing it and I think it wasn't the SRA but the interaction with the shim; but I'm not sure. The Graham Elite headshell has about a half inch circular soft "coupling disc" that the cartridge rest upon when mounted to the headshell. With the shim in place, the orientation and coupling between my cartridge body and the headshell became "compromised" - the cartridge was only seating on the rearward portion of the coupling disc and the forward portion had the brass shim between the cartridge and headshell. I'm not sure if it was this or the brass shim negatively interacting somehow; but be that as it may, I ended up taking the darn shim out. Couldn't stand it! And once removed, guess what happened? The articulation, bass and treble response, and ease and naturalness of the sound all returned. Go figure....

I didn't make any additional adjustments other than the VTF, getting my arm to parallel, and using Adjust + to dial-in my azimuth. I didn't want to mess around with the digital microscope as it's quite an ordeal to prepare and mess with it, and I knew from past attempts, I couldn't get it set to the proper 92 degree SRA anyway.

So what are my learnings here... Well, first of all, I do believe there is something behind Fremer's, and other's, touting of the 92 degree SRA. It makes sense and there are a multitude of advocates who agree with him. I believe that all of us realize that there is a certain range of tolerance here and that there is really no perfect "ideal" given the overall lack of standardization in the recording industry; however, the overall basis of ~92 degrees is sound. My other learning is either my shim was of the wrong material or it interfered with the proper cartridge-to-headshell coupling that I assume is also integral to the overall musical chain. And probably my final learning was to quit obsessing and just enjoy what I already have!

Does the PC-1S sound good? Absolutely; however, would it improve with the proper ~92 degree SRA? Maybe; but I guess I won't be able to prove that out unless/until I figure out how to achieve it without injecting other compromises into my system (i.e., shim) in order to attain it.

Kyle

Well if it was the SRA causing trouble you would be having problems with Tonality and bass more than soundstage so it probably was the shim. What i dont understand is: you could not get the SRA you wanted with the VTA all the way up? adding a shim to the Headshell is what you do when you cant lower the tonarm any mor like Rega Tonearms with fixed VTA...... you need to add a shim to the Tonearmbase if you want to incease VTA even further....

Regards
 

kroslos

Well-Known Member
Feb 7, 2015
38
0
238
Naperivlle, IL
David & Billy - Thanks for your replies and assistance. As David notes, digital microscopes can be problematic. If you're not set-up so the microscope is exactly on plane with the platter/horizontally, then all measurements will be off. I am aware of this potential issue and was able to get things properly aligned to the best of my ability. Does this mean that everything was exact? Probably not, and I'm sure my measurements may have been compromised a degree or two as a result.

As things stand now, I will cross-off shimming the cartridge/headshell from my list of solutions. Too many variables here and the interaction and coupling between the cartridge and the headshell are too important to compromise with a makeshift approach. Therefore, I believe I'm left with one other option - to raise (or shim?) my armboard. However, I'm concerned that this would result in my tonearm being considerably off level; in other word, canted down from back to front. Is this something that I should be concerned about, or will it matter?

One issue that I haven't delved into is the fact that maybe my PC-1s is off-spec and either the cantilever is set an an improper angle or the stylus is mounted incorrectly to the cantilever? Are there any other PC-1S owners on the forum who can compare the pictures I posted when I started this thread to some that they may have? If so, I'd like to hear some comparative comments.

Thanks again...

Kyle
 

ddk

Well-Known Member
May 18, 2013
6,261
4,040
995
Utah
David & Billy - Thanks for your replies and assistance. As David notes, digital microscopes can be problematic. If you're not set-up so the microscope is exactly on plane with the platter/horizontally, then all measurements will be off. I am aware of this potential issue and was able to get things properly aligned to the best of my ability. Does this mean that everything was exact? Probably not, and I'm sure my measurements may have been compromised a degree or two as a result.

The simplest way is to start with the arm straight, use a small bubble level on the headshell if you want and then play with the VTA. Go both up and down to see where it would sound best. Trust your ears!

I believe I'm left with one other option - to raise (or shim?) my armboard. However, I'm concerned that this would result in my tonearm being considerably off level; in other word, canted down from back to front. Is this something that I should be concerned about, or will it matter?

You won't be off level or canted, the SME P1 spacer is less than 11mm enough to give you that extra lift that you might need for your cartridge. But first try setting your VTA by ear and forget about the 92 degree nonsense.

david
 

PeterA

Well-Known Member
Dec 6, 2011
12,522
10,688
3,515
USA
As a PC-1 Supreme owner, I find this thread fascinating and I hope that it helps answer the issues in the OP. First, I agree that shimming the cartridge is a bad idea. You want a clean, rigid, uncompromised coupling between the cartridge body and headshell. I agree with those who suggest raising the arm board instead is a more effective solution. But it should be raised uniformly, with a spacer, not by shimming the front or back up slightly.

I bought a USB Microscope for this purpose also, but I quickly found what the critics write. It is nearly impossible to align the lens with the stylus for an accurate reading. I now only use it to get nice images of tiny things uploaded to my computer. I will post some images of my Supreme stylus.

I agree with ddk that all final adjustments should be done by ear. I am one of those insane analog guys who adjust VTA/SRA for each LP. Once I find the setting I like, I record the value (height of my arm rest above the arm board) so that I can repeat it for the next time I play the LP. I set my SME arm parallel to the platter. I then use a 10X loupe to inspect the angle of the stylus shaft while it sits in the lead in groove. If it looks slightly past vertical from a loupe position that is "nearly" aligned square to the side of the cartridge, I know that the SRA is "just" beyond 90 degrees and in the ballpark of 92. I then listen and adjust by ear.

Remember, that with a 9" arm, each 1mm of arm height adjustments is roughly 1/4 degree of SRA, according to Fremer. So, every arm that I know of has at least 1 cm or 10 mm of height travel, meaning that SRA can be adjusted at least +/- 1.5 degrees. My SME arm has perhaps three times that adjustability as do most arms, meaning that with the arm parallel to the platter, you should be able to adjust SRA by 4.5 degrees or so. That is why seeing by eye that the stylus shaft is just past 90 degrees is enough to begin the process. There should be plenty of adjustability to get close to the ideal 91.5-92.5 SRA setting.

If your arm is not close to the middle of its range of height adjustment when it is parallel to the platter, the arm board itself needs to be adjusted where it meets the plinth.

I am comparing my Supreme now to my MSL Signature Gold cartridge. They have different stylus profiles and the latter is more sensitive to SRA. One other suggestion I have is that the Supreme has an ultra low internal impedance of 1 ohm yet it has an output of 4.5 or 5 mV. I have found that reducing the cartridge loading on my Pass SS phono from 100 to 1K ohms has improved the sound. The 100 ohm setting does make it sound lower in resolution and slightly duller/darker and less open.

Here are some photos without measurements which you can use to make rough angle comparisons:

DSC_0933.JPG

frame4.jpg

frame7.jpg
 

kroslos

Well-Known Member
Feb 7, 2015
38
0
238
Naperivlle, IL
Peter - Thanks for the reply and posting the pictures of your cartridge. I'll look into raising my armboard; however, even though ddk advises otherwise, I can't see how my arm will end up being anywhere close to parallel once I've raised it enough to come in close to 92 degrees SRA. As I noted in the OP, with my VTA tower raised all the way, I'm only at ~88 degrees. Therefore, if I add 16mm to the armboard (seems like a lot!), I should be able to get my SRA angle to 92 degrees, but with a tonearm very much canted back-to-front. And one final comment... I have not heard back from the cartridge distributor on the possibility of my cartridge being out of spec.

Kyle
 

About us

  • What’s Best Forum is THE forum for high end audio, product reviews, advice and sharing experiences on the best of everything else. This is THE place where audiophiles and audio companies discuss vintage, contemporary and new audio products, music servers, music streamers, computer audio, digital-to-analog converters, turntables, phono stages, cartridges, reel-to-reel tape machines, speakers, headphones and tube and solid-state amplification. Founded in 2010 What’s Best Forum invites intelligent and courteous people of all interests and backgrounds to describe and discuss the best of everything. From beginners to life-long hobbyists to industry professionals, we enjoy learning about new things and meeting new people, and participating in spirited debates.

Quick Navigation

User Menu

Steve Williams
Site Founder | Site Owner | Administrator
Ron Resnick
Site Co-Owner | Administrator
Julian (The Fixer)
Website Build | Marketing Managersing