Cartridge Alignment & "Phase"

[Allan]

have been playing with a cartridge alignment.

 

I created Baerwald Protractor from measured arm parameters and also tried the supplied Protractor, both came up with the same result. I then used a Fozgometer to set minimal crosstalk. Sound was good, well balanced but I thought the focus could be improved. Scratching my head, I thought what can I now do besides VTA and VTF, maybe Zenith again.

 

But before I attacked Zenith I wanted to measure what I had already done, so before adjusting anything again I hooked up an oscilloscope and couldn't believe what I saw. With a 1kHz sine wave the left ~ right phase was off by a small degree, channel balance was off too. Damn, this must have an impact on imaging I thought, so back to square one I went.

 

Knowing just how important phase is with lots of things, cartridges being no different, I set about to correct this error. The only way I could see a change in phase on the scope was by sliding the cart forward and aft in the headshell, Zenith and Azimuth didnt change phase at all... this is contrary to what I've read too!  

 

By the time I had the phase sorted (balance simultaneously levelled out), the cartridge was back further towards the arms pivot, probably by about 3mm compared to where both Protractors had originally set the cartridge. Next, I just lined Zenith and Azimuth by eye and checked crosstalk with the Fozgometer, it was off, but I thought I'll give it a try as is first and see how it sounds.

 

WoW!  I could not believe what I was hearing, Soundstage was wide, focus was now pinpoint sharp, bass had great snap, mids where gorgeous and symbols rang beautifully. It also now had an ease to the sound, like it was doing everything with very little effort, it was easier to listen too as well. I tried various LPs but could not detect any distortion whatsoever, regardless where the needle was playing on all LPs!

 

I then thought maybe my phonostage was throwing a phase error, so I grabbed my signal generator and fed a 1kHz sine in, it was bang on!

 

So anyone who has a scope, I challenge you to check your cartridge phase. If its out, throw your protractor back in its box and set your cartridge up by phase instead, then Zenith and Azimuth by eye. Come back here and comment... please.

 

 

Edited November 10, 2023 by Allan

[Warren Jones]

Did you check phase at different points in the arm arc. Moving the cart back and forth will alter  diamond orthogonality to the groove tangent. This also varies across the arc. You don't say what arm you are using, a lot of Japanese arms use a modified Stevenson alignment. My preference is Lofgren A which is what I use in the tonearms I've built.

 

I use a bit of 1mm copper wire between the cart and headshell, this allows me to rock the cart in the HS to adjust azimuth. It also increases the contact pressure between the cart and HS with far less tension on the bolts (the stiletto principle).

[Grimmie]

 

Thought I'd give this a check; - orthogonality

 

 

Yeah! I'm sure mine's perfect.

[Warren Jones]

It can't be perfect because you have a pivoting arm which has tracking error. It will only perfect at the null points if adjusted correctly.

[Allan]

I dont want to name arm or cart makes here, its beyond the scope of this thread. I will say the arm has full adjustability, the cart is a MC.

 

Good point @Warren Jones, no I didnt check phase over various arc points. Phase was set on Track #1 on the HFN test record. I also have the AP test LP on which a phase test is possible on Track #4 (midpoint) so I do some tests using track #4 and see how it goes.

 

The tests I'll do will be;

- phase set on Track #1, check for phase error on Track #4.

- phase set on Track #4, check for phase error on Track #1.

 

Changing both azimuth & zenith did "absolutely nothing" for phase in my tests. The only thing that changed phase was varying the null point, ie moving the cartridge forward or back in the headshell. This is the very reason for me posting this thread because up until now I had believed Zenith and or Azimuth changed phase, I can assure you they do not! My tests say, of the two only Zenith could possibly have an effect on phase, but its that small I cant measure it, well I could but I'm not that anal.... we are talking a shift the size of your diamond tip. I'm not a micro surgeon.

 

I would think irregardless of cartridge alignment, due to orthogonality a phase error would occur away from the null point. I'm now convinced the amount of error will differ between alignments, my tests so far already prove this. The best alignment should have minimal phase error, this is the direction I'm heading to find out what really is the best alignment for minimal phase error.

 

To illustrate just how important phase is in any audio system. In a sound engineers mixing room they have a mixing console, all mics (vocals, drums, guitars, sax, everything) from the studio connects to this console, the console combines all these to produce either 2, 5.1 or 7.1 channels out, whatever the preference is, 90% of times its 2 channel out. On the engineers console, they have whats called PAN & TILT pots or sliders. There are individual PAN & TILT controls for every mic in. These control the position of the respective mic within the stereo image, they provide a depth of perception too. Its sort of similar to balance though balance gives no depth perception. Why doesn't balance give a depth perception, simply because balance swings the voltage whereas PAN & TILT swings the phase. If your reel to reel deck, CD player or turntable phase is out your are not reproducing what the sound engineer wanted you to hear. Pink Floyds album "Amused to Death" provides without doubt one of the best examples of what PAN & TILT can do to stereo reproduction. When playing this album, I hear dogs and cows behind my head, yet I've only 2 speakers in front of me. So how important is phase, extremely! 

 

 

Edited November 12, 2023 by Allan

[aussievintage]

All you are doing is choosing different null points according to where your phase test track is.  Nothing special is happening, even though there are three or so "standard" alignments, there's nothing stopping you choosing different null points.  They may not be optimising certain parameters, and/or may be prioritising others.

[Allan]

2 hours ago, aussievintage said:

All you are doing is choosing different null points according to where your phase test track is.  Nothing special is happening, even though there are three or so "standard" alignments, there's nothing stopping you choosing different null points.  They may not be optimising certain parameters, and/or may be prioritising others.

 

All you are doing is choosing different null points according to where your phase test track is.

I just tested the phase using 2 different test LPs, regardless of what track number (inner or outer) the phase remained spot on.

 

They may not be optimising certain parameters, and/or may be prioritising others.

What other parameters are you referring too? 

 

Like I outlined earlier, if phase is out its pointless expecting any sort of quality in channel balance, imaging, depth perception or timbre in the soundstage

 

I need to try another cartridge to eliminate a possible cartridge induced phasing error. If this is the case, it won't be a lost exercise because I've learnt adjusting Zenith and or Azimuth has absolutely no effect on phase, country to what I keep reading.

 

 

Edited November 12, 2023 by Allan

[andyr]

Very interesting, Allan!  

 

On 10/11/2023 at 2:29 PM, Allan said:

But before I attacked Zenith I wanted to measure what I had already done, so before adjusting anything again I hooked up an oscilloscope and couldn't believe what I saw. With a 1kHz sine wave the left ~ right phase was off by a small degree, channel balance was off too. Damn, this must have an impact on imaging I thought, so back to square one I went.

 

Can you please confirm ... what you did was to:

• plug the L&R outputs of your phono stage into your 'scope
• and put the cart on a 1kHz track on your test record?

 

(I'd like to try it out.)

 

[Allan]

G'day AndyR

 

correct. Initially I tried going direct from the cart but its voltage was too low for the scope to paint a clear pic. So I then used my phono stage, I did do a phase check on the phono stage too to see if it was inducing a phase error, it came back clean.

 

I didnt use the scopes probes, I just went direct from the phono stage to the scope via RCA to BNC connectors, scope set at 1x. My scopes good for line stage voltages.

 

I set the cart null by aligning the phase using the Analog Production test LP, side A track #1 (1kHz reference tone, 7cm/s lateral in phase - mono). I've since also used various other test tracks including the HFN test LP and so far all tracks, regardless where they reside on the LP's the phase remained aligned.

 

I've to do a few things outside so will get back to this a little later after I fit a different cartridge to eliminate any cartridge induced phasing error.

 

Please revert back AndyR and let us know how your phase test goes..

 

 

Edited November 12, 2023 by Allan

[andyr]

Thanks, @Allan.

 

I have the Analog Productions Test LP, so can use Track A1.

 

It won't be for a few days tho'.

 

[aussievintage]

3 hours ago, Allan said:

I've since also used various other test tracks including the HFN test LP and so far all tracks, regardless where they reside on the LP's the phase remained aligned.

 

Which tends to indicate the slight geometric error of stylus alignment across the groove, as the tonearm (and stylus) pivots across the record playing surface, is not showing up as a signal phase shift in your test.  I was wondering if such a small change would be detectable on a scope. 

 

So whatever caused the initial phase shift is now a mystery.  If you realign your cartridge to a normal protractor, does the phase shift return?  Is this repeatable with different cartridges and headshells?

Edited November 12, 2023 by aussievintage

[Allan]

@aussievintage I dont understand why you say my alignment is wrong when I have zero phase shift across an LP. Can you explain your theory behind this please?

 

I just entered my arm parameters into the spreadsheet calculator (below), it just so happens these results marry up exactly with how my arm is currently aligned, which was done by phase and not by protractor.

 

So its pointless me changing carts to verify any potential of manufactured integral cartridge phase error. The below results prove alignment by phase is accurate, more so than the damn protractors I have. 

 

EDIT Nov 22: the below Alignment has been updated after realising I had incorrect parameters in the original upload.

 

 

There is a very slight voltage imbalance (right channel) though small enough to be insignificant (to me)

 

Torture test of phase, not bad. For the real fussy a bit of anti skate and or dampening would help here

 

I'm happy with these findings. I've learnt..

 

- dont trust protractors, regardless the money you've spent, check your cartridge phase!

- phase alignment is performed by varying the overhang

- neither Azimuth or Zenith has any effect on phase

- setting the null point by phase simultaneously corrects any L~R cartridge output voltage imbalance (assuming cartridge integrity)

- setting correct cartridge null by phase is certainly accurate, very very accurate

 

I would even go so far as to say, setting your cartridge alignment null by phase will consistently be more accurate than protractors ever will, regardless of protractor brand. Reason being protractors simply cant read phase, only scopes do that. Sure, there are various alignments we can use, some produce more distortion than others however some also produce more phase errors than others too, the knock-on being way more dramatic than a bit of distortion.

 

Oh and by the way.. it just so happens my results have landed on the same alignment thats known to produce the least amount of distortion.

 

It will be very interesting to see how AndyR's testing goes.

 

 

 

 

Edited November 22, 2023 by Allan

[aussievintage]

10 hours ago, Allan said:

@aussievintage I dont understand why you say my alignment is wrong when I have zero phase shift across an LP. Can you explain your theory behind this please?

 

You basically proved your test is not sensitive enough to show the phase shift when you said you get zero no matter where the track is on the record.  Simple geometry tells us it can only be zero at the two null points.

 

Edit:   and I don't say the alignment is wrong, I believe I said you are just choosing different null points.

 

 

 

Edited November 12, 2023 by aussievintage

[Allan]

@aussievintage the test most certainly is sensitive enough, I am not concerned with the minuscule phase shift across an arc, if its not visible on a sine wave pattern then thats good enough for me. I could use the scope measurement tool and look at rise and fall times but I'm not that anal. Besides there is nothing you or I can do about arc phase shifts, however we can minimize arc phase shifts by having the phase correct in the first place.

 

From the get go if your overhang and or phase is wrong the arc phase shift will be significantly emphasized. But get the overhang and phase right and you'll be in the best position possible.

 

Sure there are protractors that will set the phase correctly. Its just the two I have dont cut the mustard and one of them was supplied by the tonearms manufacture and this is a high dollar arm, they use the same protractor for all their arms too! The other one I created from software has marks you measure to ensure its in scale, it measured perfectly yet it also threw my arm out ~3mm!  Is your protractor doing the same?

 

 

 

Edited November 14, 2023 by Allan

[Allan]

Article by Ortofon re cartridge phase testing

 

https://www.gammaelectronics.xyz/audio_03-1983_phono.html

 

[andyr]

8 minutes ago, Allan said:

Article by Ortofon re cartridge phase testing

 

https://www.gammaelectronics.xyz/audio_03-1983_phono.html

 

How very interesting.  

 

[colinm1]

Maybe that is why amongst other factors my Grado ,sounds best with a loading on the south side of the recommended 47 k,

 

[cafe latte]

On 12/11/2023 at 10:33 AM, Warren Jones said:

It can't be perfect because you have a pivoting arm which has tracking error. It will only perfect at the null points if adjusted correctly.

Exactly 

[Grimmie]

On 12/11/2023 at 7:18 AM, Grimmie said:

 

Thought I'd give this a check; - orthogonality

 

 

Yeah! I'm sure mine's perfect.

 

He, He, I have to chuckle.

That exasperated claim wasn't at all made through confidence, nor from the slightest understanding of this thread or my Wikki search result quoted. No, it was pure desperation at the fact that no matter how much I learn regarding TT's, arms, carts, stylus' etc. etc. and their interaction (which has been quite a lot) there is always something else that totally confounds me and has me throw up my arms in surrender. Hence the bogus and obviously sardonic claim.

[Allan]

@Grimmie if you cant add anything of value to the thread, please take a walk

[colinm1]

Although my eminent technology et2 arm ,

fixes some issues it presents others 

to navigate through,

in a world that had this design as the normal ,

I wonder how far it would have been pushed ,

once I got my head around the concept ,a lot of things fell in place ,

to the point ,that room and vinyl came into play ,more so,

 

[andyr]

On 12/11/2023 at 2:30 PM, Allan said:

 

Please revert back AndyR and let us know how your phase test goes..

 

 

Hi Allan, I finally was able to get around to doing my own phase test!  

 

Now, given this pic of yours:

 

 

 

... it's obvious that you have a much better scope than I have!  

 

Bcoz I can't get a nice clear pair of the 1kHz sine waves on the screen - they dance aound (even with the scope leads plugged into the output of my phono stage).  So much so that I am unable to take a pic to show here.

 

But when I superimposed my L&R channels on each other ... as near as I could tell, I had no phase difference between the two.  So as that is the desired end-point ... it would seem that the arc protractor which I use has enabled me to align the cart correctly.  

 

I will now repeat the exercise with my other cart - an MM - which again was set up using an arc protractor (not a 2-null-point protractor).

 

Edited November 16, 2023 by andyr

[Allan]

@andyr Try setting the scope to show an average of the signal, this should help smooth the display out. On my scope I select Aquisition/Average then from there I select it to average over 16 points.

 

Also I have all signals set to AC and the trigger is also set to AC... leading edge. Also use 1x probe setting on the scope and make sure the probes themselves are set to 1x too.

 

In anycase if the signal is overlapping nicely then it appears your phase is in good shape..

 

[andyr]

Hi Allan,

 

I can't find any averaging controls on my cheapie Dick Smith scope - as I said before ... you seem to have a much higher-spec one than mine.

 

But I did get a good result from my MM cart - and was able to successfully take a pic:

 

 

 

Once again ... phase seems to be spot on.  Perhaps this is an advantage of using an arc protractor to set up a cart?  (Of course, they are only applicable to one arm length!)

 

Unfortunately, though ... I seem to have a signal level difference between the channels.    I'll have to do some further research to see whether this is due to the cart ... or the phono stage I'm currently using.

 

[andyr]

25 minutes ago, andyr said:

 

Unfortunately, though ... I seem to have a signal level difference between the channels.    I'll have to do some further research to see whether this is due to the cart ... or the phono stage I'm currently using.

 

 

It's the phono stage (not one of my own 'Muse' phono stages).