Turntable advice

Thanks. I've confirmed the scales are correct each time I print the protractors, never had one be even a tiny bit off... I've also been using 212mm as the spindle to pivot distance, although if I put a ruler up to it and try to eyeball the actual spindle to pivot distance, I get around 196ish. although it's hard to get mm-scale accuracy here with a ruler and eyeball, I'd have to say there's no chance in hell that distance is as high as 212mm.

I will give it a shot without aligning the spindle to pivot line...but if that works, wouldn't that allow for a range of overhang values? At least in theory... aligning Sol with a protractor, I can get a range of different overhang values if I don't bother with aligning the protractor to the pivot point.

 

Hmm. Yeah, 196 is different enough from 212 to suggest that the arm mount position is different from the ones referred to in that manual. Sorry, I don't know what to suggest other than more googling to see if you can find comparable examples, or to use @Ruby Rod 's own technique as described in his readme file to get as precise a measurement as possible yourself:

"I measure my P2S distance using a block having known square sides (a machinist's "1-2-3 block"),
and a thin 12" machinists steel rule. The block is placed up against the spindle, opposite the
arm pivot. Because the top bearing circle of my arm is visible, I just measure from the face of
the block, to the center of the bearing circle. I then subtract 1/2 the spindle diameter
because the scale is measuring from the far side of the spindle, not the center. To restate,
the P2S distance is measured from the rotating axis of the spindle, to the rotating axis of the arm
pivot, the center to center distance.

Sometimes you can't see where the bearing is. A cute way around this is to stick a
piece of easily removable tape to the area over the bearing. Hold a fine tipped marker on the
tape and move the tone arm over its arc. You may have to brace your hand so as not to move the
marker while you do this. The bearing center will be in the center of the arc drawn by the marker.
You should quickly find the location where the marker just makes a dot. Obviously this technique
only works if the area above the bearing turns with the arm. Now use the block method and measure
to the dot. When measuring P2S, be sure to keep the ruler level or you'll introduce an additional
error."

Larger/smaller overhang = longer/shorter arm effective length = larger/smaller arc radius, so the arc swept by the stylus shouldn't track the arc on the protractor at all positions.

 

I did my best over the weekend to try to measure the S2P distance as accurately as possible by laying a clear ruler over the table, making sure it was level, and measuring from the pivot point (which is easy af to identify with this arm) to the spindle as mentioned above. I'd give myself a +/- 1.5mm accuracy here due to the fact that the ruler was just shy of level and the horizontal position was hard to align precisely, but I can at least say confidently that the actual S2P of this table is somewhere around 195-197mm. I printed out a few arc protractors at S2P = 195, 196, and 197 mm. If it's some random bullshit like 195.23798mm then this method is probably going to fail, but hopefully one of them fits. If not, I'm going to break down and email Music Hall asking them what the f**k is going on.

I'll update this post with results later tonight. Maybe I'll be able to save someone else the time and bullshit involved in aligning this table... f@#%@$#

Update: 195mm seems to work. I am happy to say my best guess with the mirrored protractor was only about 0.5mm forward, which is great considering that the overhang was just a guess.

 

I recently got an oscilloscope as an early xmas gift--Siglent unit with a modest 50MHz bandwidth and two channels--and I've been using it with my Analogue Productions test record to verify my alignment. Turntable is Schiit Sol, and the cartridge is an Ortofon 2M Bronze. I'm hoping someone can give me some advice with regards to some weird results I'm getting.

First, most of the tracks give reasonable results--VTA is easy enough to do by ear, the 1KHz mono track meant to verify offset shows both peaks in phase and at the same amplitude, the anti-skate track gives me the best results with a 2g weight (VTF=1.75g, I even added weights to the 1g to get it to 1.5-1.7g, and still got best results with 2g). When I try to check the azimuth, however, that's when stuff starts looking bad.

For example, there are two tracks which have a 1KHz test tone in one channel only, and the goal is to adjust the azimuth so that the signal amplitudes in the opposite channel are equal and at a minimum. No matter what I do, the left channel output (right channel 1KHz tone) is always double that of the right. Any adjustments I make to anti-skate, azimuth, offset, etc., may decrease or increase the signal amplitude slightly, but nowhere near enough to account for the fact that one is twice the size of the other. Here are my measurements: the higher peak is left channel (right channel @ 1KHz), and the smaller is the right channel. Note that the phase of both is constantly changing so any difference in phase is just due to where I ended up catching the signal.


Another track uses two out of phase 1KHz test tones, which should cancel out when summed to mono. My results look like this, although I'm not even sure what I should be looking for here, if this is normal or totally fucked... but it does appear that these measurements are not perfectly out of phase, so I'm guessing this isn't how these results should look:


Here's the thing... I know my azimuth isn't totally fucked like these might suggest. I can place some pencil lead on top of the headshell and use that as a guide to get it close to level, and while it's just my eyeballs, I can do a decent job. Unfortunately, these measurements suggest that the azimuth is most correct when the cartridge is cocked off top to the right (looking down the front), where it's obviously way off. Maybe the needle isn't perfectly vertical, but it's definitely not at a 10 degree angle to the cartridge body...

This weekend, I went through just about everything I could think of to explain this discrepancy. I verified that the platform and platter are level; I made sure the anti-skate weight is at exactly the right height so that it doesn't cause any sway on the tonearm; I tried moving the tonearm wires to various positions; I triple checked other aspects of alignment like overhang (dead on), verified offset with pencil lead trick on stock protractor AND mirrored protractor; verified that both channels of my phono preamp (Eros 2) are roughly equal in terms of background noise... I just cannot for the life of me figure out what is going on.

Could anyone give me some advice, pointers, or help with interpretations? I'm at a complete loss for how to explain these measurements... thanks in advance. I'm open to the idea that I've fucked up some aspect of alignment that I've otherwise claimed is good, I just don't know where to look.

edit: I'll also note that, during the anti-skate track measurements, the right channel always has a slightly higher peak than the left... whether I increase or decrease the weight, from 0g to 5g. I get them matched the closest at 2g, but it seems to me that this is not how those measurements should go.

edit2: not sure if this is relevant but I was running the RCAs directly into the scope, using RCA to BNC adapters, so these are 1x signals, not 10x. I did try switching channels and cables but the results were identical.

 

By "results were identical" after switching channels, do you mean that R on the scope was still half the amplitude of L? That'd suggest an issue with the scope rather than the input. On your second graph that phase offset looks like 90 degrees rather than 180. @bazelio might have some ideas on setting up the scope.

Whatever, try an independent azimuth check with computer instead of oscilloscope using your L and R 1 kHz tracks to measure crosstalk:

https://www.superbestaudiofriends.o...setting-azimuth-with-a-pc-and-soundcard.1905/

This might also illustrate the degree of any real channel imbalance.

Good luck!

 

Thanks! I meant that even after swapping cables and channels, I was still getting double amplitude on the preamp's left channel output (with the right channel signal), than vice versa. The results were identical with respect to the preamp output, not the scope. That suggests it's not a scope issue.

Also, the technique you linked to is basically the same as what I'm doing here but measured with a PC instead of scope, so I wouldn't expect dramatically different results. I can certainly give it a try though.

 

Half the amplitude in one test, 90 degrees out of phase in another... That really seems like it's something to do with signal processing rather than the signal itself. Yeah, I think it'd be worth trying without the scope and initially looking at crosstalk using just amplitude vs frequency as in Purr1n's OP.

Hard to imagine it being anything to do with the preamp, but have you tried going into the scope without the preamp in the chain (or using another)? Should be enough voltage from your MM cart to give adequate S/N.

 

Welp, the mystery has been solved. After going at the measurements a lot more thoroughly, I found a point where the cartridge was cocked so far off top to the right that the results above were reversed, so the right channel (left signal) was huge relative to the left. It didn't take long after that to find a spot where both were matched.

I don't think the angle comes out that well in the photo, but it looks SO WRONG... if I hadn't measured it myself, I would never have believed it.


A few other notes:

• Crosstalk measurements were, sadly, beyond the reach of my scope without the preamp at any azimuth setting. The rest of the measurements are visible, although the out-of-phase tone had too high S/N to make out the minor 90 degree peak.
• Out-of-phase track still has that weird 90 degree phase thing going on but given everything else... I'm over it. Shrug emoji.
• Anti-skate looked a bit more reasonable once the azimuth was corrected, in that the right channel was no longer always dominant. I didn't spend a ton of time on this but the left channel was just slightly higher than right at 2g AS, so I concocted a 1.71g weight to bring it closer to the 1.73g tracking force.
  
• Sounds nice. Only spun one album so far... more to come.

 

It took a couple more sessions to get things really tuned in, but azimuth is as close as I'm going to get it, and anti-skate is settling somewhere in the 2.1-2.2g range, for 1.73g VTF. Either I'm doing something wrong (v possible) or the VTF=LTF rule of thumb does not apply.

The improvement is immediately noticable, not just in terms of staging/imaging but generally. More coherent and focused, cleaner, snappier... definitely worth the effort.

 

Anyone know if a VPI Periphery Ring will work on other brand turntables? I see that the VPI platters have a lip, which is presumably what supports/locks in the ring, but maybe it would work on a similarly-sized platter? My aftermarket/upgraded Garrard 401 platter is pretty much the exact same diameter as the VPI classic platter.

I'm aware of Wayne's Audio's rings, which are meant to be universal, but I've got a lead on a great deal on a VPI ring and am curious. Thanks.

 

@wbass
Theoretically it could work, however the inner-lip of the ring is only 3 MM wide so your platter would have to be almost the exact size of the VPI one. The ring is held up by the record edge but the platter perimeter still holds it in place in the horizontal plane.

In short, maybe but its a long shot.

 

Thanks, @ogodei ! How do you like your Classic 4 (?) next to your new/old Garrard?

 

i had a question on tonearms setup for a particular cartridge/shell combo on my Pioneer PLX1000.

Seems to me, that i have to back off the tonearm weight past the initial point since the combo of the cart/shell appears to be too high to balance the tonearm accurately.

Do they make additional weights to add to the balance of the tonearm? very much a noob in vinyl land.

Cart/shell combo are
Jelco HS25 and Nagoaka MP-110 - 22gm
Jelco HS25 and AT540ML - 20gm (able to balance this fine)
Pioneer headshell and Numark Cart - 16gm (able to balance this fine)

 

You should look for this:
Pioneer part # 200-PNTT-693
Sub Weight

 

Yeah looks like I didn’t get that part from the previous owner Thanks!

 

NP, it isn’t standard. I had to buy the equivalent for my Technics table when I had it. How do you like the Pioneer?

 

Honestly, i am shocked at how good the Pioneer sounds. I mean i have very little frame of reference. But from what i can remember with when i had my Empire 598 and Thorens TD124Mk2 10 yeas ago.. this feels like on another level.

 

almost looks like the same as the technics.

https://instrumentalparts.com/sub-weight-for-plx1000/

https://www.turntablelab.com/produc...counter-weight-for-technics-1200-sfpwg17202-1

But damn.. the PLX sub weight is ~3x more.

 

I would email Kevin at KAB, I bet one of the aux weights for SL1200 will work.
https://www.kabusa.com/frameset.htm?/m1200.htm

 

Anybody using Tergikleen?

Seems like it might be great stuff, but not sure if it'd be a meaningful upgrade over the homebrew solution recommended in the Squeakycleanvinyl RCM thread. I'm both lazy and cheap, so the one-step homebrew method appeals to me as does the slightly cheaper cost and considerably less hassle to get all the ingredients locally - even though the Ilfotol is only available by the litre.