• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

More on the AT-PL120 and theTechnics Overhang Gauge

G

guest102

Super Member
The recent debate over the suitability of using the Technics overhang gauge on the AT-PL120 tonearm got me thinking, so I dug out my Stevens protractor from Vinyl Engine and the Shure protractor from my M97xE cartridge to see what, if anything, they could do for my PL120. The results were disappointing. It was impossible to satisfy these protractors keeping the cartridge straight in the head shell no matter where they were placed in the slots, which meant that with a straight positioned cartridge the stylus would likely never find a null point on the record. I had to turn the cartridge inward to get things to line up with the protractors. The resultant sound with both protractors was muddy and missing most of the highs the Technics gauge setup provided. I downloaded and examined both the PL120 and LP120-USB pictures from the audio-technica web site. The cartridges in both pictures looked to be straight in their head shells with their front panels about even with the front edge of the head shells, and these cartridges come aligned from the factory ready to plug and play (it says so in the manual). It became obvious that I needed to go to audio-technica for an explanation so I sent an e-mail to tech support asking what procedure I needed to follow to put a new cartridge in a head shell for my PL120. On my second try I got a response which included a .pdf file of the free downloadable alignment protractor at EnjoyTheMusic.com.

http://www.enjoythemusic.com/freestuff.htm

This file prints out a protractor with null points at 70mm and 126.5 mm (my measurements), a bit farther out than the null points of my other two protractors. Again, with the cartridge straight in the head shell I could not satisfy the protractor. The setup I ended up with has the cartridge all the way back in the head shell and turned inward, but because the null points are farther out, the turn-in angle is not as extreme as with the other protractors. The sound clarity and high frequencies are there, it seems to image well across the record, and the setup provides two null points. What I have auditioned so far sounds "right". The setup looks nothing like audio-technica's pictures, but I plan to let things parked exactly where they are for a while and see what develops.
 
Last edited:
Register to hide this ad
My PL120 cart came installed with the same amount of overhang as a Technics. It was not exactly square in the headshell, but examination revealed that the headshell was not exactly straight and this compensation was right on for that.
If I were you, I'd just stick with the not-quite-any-standard, square-in-the-shell Japanese alignment the table is designed to use. Across an entire LP, it will give you about as good an average performance as anything else on this table. You should not assume that failing to match Stevenson alignment means that there are no null points.
By the way, VTA is the thing you should really be concerned with on a PL120, in my opinion. The arm is so high that even the lowest setting requires extra-thick mat(s) to get it right with most carts.
 
G'day all, the whole matter of optimum overhang is a fairly contentious matter. I recommend the use of a traditional Baerwald two point protractor such as can be downloaded from the VE and are supplied by Shure with the M97xE cartridge.

The approach I have developed works well. http://www.mds975.co.uk/Content/vinyl07.html Adjustment is necessarily a fiddly business and you need good eyesight, but this approach give accurate and easily repeatable results.

The important thing is 'parallel and centred' within the grid lines at each null point. Depending on the individual tonearm/ turntable, some adjustment of the cartrridge offset angle may be required (twisting of the cartridge in the headshell). http://www.vinylengine.com/twisting-your-cartridge-headshell.shtml

I've never found it necessary to do this on my three turntables but it might be necessary 'depending'. I hope this info is of some use. Regards, Felix aka catman.
 
Well, I say again, I tried setups with the Shure protractor and none of them gave the openness, clarity, and brilliance of the Technics gauge setup.

Actually, I have been doing more than fiddling with cartridge setups. Part of the previous debate touched on whether or not the Technics 1200 arm was the same as the PL120 arm. Both are "S" shaped arms, and just by looking, judging sameness of them is as easy as determining if two pretzels are identical. So I wondered how they would look if they had been straight arms. To pursue this question I got out my owner's manuals and found drawings of the turntables in question. Making an assumption that the manufacturers tried to accurately represent their products in these drawings, I drew a line in each drawing from the center of the counterweight through the horizontal pivot point out toward the head shell. I drew another line through the center of the head shell back through the tonearm line, and then measured the resulting angles. The Technics drawing gave me a 27-degree angle, and the PL120 drawing gave me a 20-degree angle. From those drawings the PL120 head shell appears to be mounted a little straighter than the Technics. I figure if the two arms were alike I should have gotten closer results. Finding offset angle may have been better, but there are no published figures about how a PL120 arm should look when properly aligned. And I got no help unraveling this from my Tech Support inquiry except for another protractor that offers a setup that works better on the PL120 than the 'standards' but looks nothing like audio-technica's product pictures. Maybe I'll see what else I can scare up.
 
I have run about 17 cartridges through my PL120. Most sound best with the Technics mounting distance and square in the shell. This is especially true of AT cartridge (duh) all the way up to the 150MLX. This is not true of any of my Grado cartridges. They all want to be turned inward slightly from the standard square mount. It's only a few degrees, but it always there. I took my mounting from the original cartridge and shell that came with the table.

My assumption is that the suspension and cantilever design of the Grado's is different enough from most of the others, that it needs different physical side loading and "pull" from the record surface. I'm not going to dissect the issue, because once I had this figured out, the Grados sound great (except for the slight buzz on the rest from the LED :( ).

I'll keep an eye out as you'all work through this. But, I chalk it up to "learning" the table and working out your own tweaks :) Final arbiter - the headphone never lie :music:
 
I don't think I read this other thread mentioned (sorry), but did anyone mention the issue of anti-skate on the PL120? It doesn't work very well, and its strength varies A LOT between tables. I wonder if that isn't at the root of what Broc is describing, with his adjustment compensating for inadequate anti-skate force?
 
On the pl120, baerwald alignment will put the cartridge toward the front of the headshell and skewed inward toward the spindle. The Stevenson alignment will put the cart near the middle of the headshell but it will still be skewed somewhat (not square in the headshell) in order to give the proper offset angle for the pl120 mounting distance of 215mm. The Technics guage will give null points that are close to Stevenson, but not the same.

In the previous thread, someone mentioned that they checked the alignment of the pre-mounted cart on the pl120 against the Technics guage and found it to be exactly 52mm, giving you an overhang of 15mm. If that's the case, then the recommended overhang on the PL120 is the same as the SL-1200. But the offset angle of the arms is different. So, on the pl120, if you square the cart in the headshell at 52mm, you presumably will get the null points AT intended for this arm. These nulls are different from the nulls intended for the Technics table (due to the different offset angles of the arms), and also different from Baerwald or Stevenson.

I'm pretty sure the EnjoyTheMusic protractor uses the bearwald nulls. This is going to sound nuts, but I was able to align to the baerwald nulls on a pl120 with the cart at different positions in the headshell--one at the front of the headshell and skewed inward and one at the back of the headshell and nearly square in the headshell. When I say back, I mean the screws all the way back as far as they could go in the slots. I'm just guessing, but I think the OP has lined the cart up to the baerwald nulls at the back of the headshell--which I found to be possible on the pl120 with a stock headshell. This, however, would give a different overhang than what baerwald would typically require for a mounting distance of 215mm, which I believe is between 17 and 18mm.

Basically, if you've lined up the cart to a known set of null points and it sounds good to you, then I'd stick with it. For me, I got the best results when I lined up the cart to the Stevenson nulls.

Paging Dr. Howard. I would definitely like to read your input on the OP's post.
 
dumptruck said:
I don't think I read this other thread mentioned (sorry), but did anyone mention the issue of anti-skate on the PL120? It doesn't work very well, and its strength varies A LOT between tables. I wonder if that isn't at the root of what Broc is describing, with his adjustment compensating for inadequate anti-skate force?
Click to expand...

Could not agree more.
 
I just got the reply from my second e-mail to AT Tech support in which I specifically asked for cartridge mounting specifics.

Basically:

[1] Turntable not made "here".:dunno:

[2] I ...Tech Guy ... know nothing about manufacturing.:dunno:

[3] Buy a better cartridge. (I'm using the included ATP-2 cartridge with a 205-DET stylus...:()

I give up. It's every owner for his (or her) self.:arrow:
 
ec1st said:
I just got the reply from my second e-mail to AT Tech support in which I specifically asked for cartridge mounting specifics.

Basically:

[1] Turntable not made "here".:dunno:

[2] I ...Tech Guy ... know nothing about manufacturing.:dunno:

[3] Buy a better cartridge. (I'm using the included ATP-2 cartridge with a 205-DET stylus...:()

I give up. It's every owner for his (or her) self.:arrow:
Click to expand...

Oh man, that's an awful response from them. Well, at least you tried. It's too bad they don't offer more support for the pl120. It's a good deck. I just think AT thinks the customer base for it is wannabe DJs who don't bother with things like cart alignment. Bad call on their part.
 
FWIW the standard offset angle for tonearms is the angle of the headshell and the most common overhang for run of the mill Japanese tonearms is 15mm. Using other alignments (Baerwald, Stevenson or the custom EJTM nullpoints) will usually require resetting the angle and overhang for perfect alignment. To be honest if you are getting more clarity, openness etc when using one alignment method over another it suggests an issue with the method you are using to align to the protractor as the actual differences in distortion are minimal :scratch2: Having said that, if you're getting good results using a particular gauge then I'd stick with it!
 
HI, all

Longtime vinyl spinner and 1st post here... Reading all the above is in tune with exactly what I'm doing with my 1200 and V15 Vx right now, and I ask the following general question:

Are all these different alignment setups affecting only sound quality, or is there a record wear issue as well?

2nd question: is there an effective way, without using wild measurement or scope tools, to measure VTA other than just visually observing for a level tonarm tube?

Thanks, Mike
 
1. enjoythemusic is not Baerwald. It's proprietary null points chosen by Steve Rochlin.

2. The offset angles are different, but Technics is either 21.6 or 22 degrees dependent on which series tt, so your measurement was off, and was probably off for the AT, as well.

3. No protractor will provide a square mounting in the headshell except for one with null points that coincide with the manufacturers. Most Japanese turntables are CLOSE to Stevenson, but not exactly. So the cartridge will still be turned slightly. Keeping the cartridge square is only a requirement when using the tt mfr's points.

4. In a tt where arm dimensions are not known, a protractor is the only reliable way to align a cartridge. The extent of the angulation when using any protractor is of no concern as long as the cartridge is parallel to the lines at both points.

5. You are actually not limited to the null points of existing protractors. These are just the results of previous experimentation to find the best overall sound quality and compromise in distortion over the play of an lp. Nothing stops you from printing out an existing protractor, marking your own points on it and experimenting. The whole point is that cartridge mounting not be random, because then chances are you'll have distortion all over the place. And without knowing dimensions, using the Technics gauge on the AT is tantamount to random mounting IMO.
 
hakaplan said:
1. enjoythemusic is not Baerwald. It's proprietary null points chosen by Steve Rochlin.
Click to expand...

I stand corrected. That's what I get for just "eyeballing" something.

I have to agree with Howard on the use of a protractor when the arm dimensions aren't known, as is the case with the pl120. Whichever one you use depends on which one sounds best to you.

As a previous poster said, the difference in distortion isn't really that great from one set of nulls to another. It really depends on other factors, as well. For instance, the type of cartridge can also impact the set of nulls you use. Something like the DL-103 can have issues with inner-groove distortion, so a set of nulls that minimizes distortion toward the spindle, like Stevenson, might be preferred.

For me, it came down to the fact that most Japanese manufacturers designed their tables with null points that were close to the Stevenson nulls. So that's what I've gone with. And it sounds just fine to my ears.
 
i want to revive this thread do to the fact that i just found it.

just out of curiosity, what are the PL120 users setting their VTA to?
 
I don't have one anymore, but for every cart I used on it, I had to set the VTA all the way down, i.e. the tonearm base as low as possible, AND use a double mat to get correct VTA.
 
That is probably okay. What you want to do is get the cart body as close to perfectly parallel to an LP as possible, and then you can tweak it a little by ear if needed.

The numbers on the PL120 for VTA, tracking force, and anti-skate are meaningless and don't equate to the same numbers on other PL120s either. You need to use other methods to determine each setting. Of course, you can use the numbers on your table to keep track of what settings work with what cart, etc, but don't expect them to transfer to someone else's PL120.
 
You must log in or register to reply here.
Back
Top Bottom