Regarding Tonearm

A Plexiglas Top Plate for the Headshell

Recorded on March 26th, 2016

photo of tonearm and cartridge

I took the brass plate off the top of the headshell and moved it underneath, sandwiched between the wood and the cartridge. I did that because the top of the cart (which is rather narrow) was digging into the wood of the arm, and I figured the surface the cart presses against will be more rigid if the pressure is distributed across a harder material over a bigger area.

On top now is a futuristic-looking piece of Plexiglas I scored, cut and drilled. Now that I’ve learned how easy that process is, I’m gonna be cutting and drilling plastic all the time.

In the process of ham-fistedly moving the cartridge around, I of course broke one of the tonearm wires. It’s bothering me to have to go to bed, but it’s too late at night to re-solder it now. I’ll get to it in the morning. At least I had the presence of mind to pull the stylus off first and set it aside.

Baerwald, the Conrad Hoffman Arc Template Generator, Wine, WineBottler, and Perfect Alignment

Recorded on March 24th, 2016

screenshot of Conrad Hoffman arc template generator software

Things have reached a new level of crazy in this house.

I had been using 1/4” of underhang on the DIY tonearm, with the AT120Eb mounted parallel to the arm, but with yesterday’s listening tests, I could hear that the cart was way out of alignment on the first couple of tracks on most albums. I could see it, too, but initially chose to ignore it, thinking that the trade-off in reduced side-force on the stylus would be worth it. It wasn’t.

Thus began what we call “hotbrain”, where I would do rapid-fire research on the iPhone and append every promising page URL to one entry in Drafts. That draft got quite long by the end of the hotbrain.

First was research into whether a 12” tonearm really needed an offset cartridge, or if straight would be good enough. I found a very religious, heated thread about “Tonearm without off-set” on Audiogon, where I learned that:

The sonic benefits of highly accurate alignment are huge. Search this forum for “Mint” or “MintLP” protractor for a wealth of information and testimonials across a wide range of tonearms and cartridges. You’d be shortchanging yourself not to have the best possible alignment, which won’t be feasible without a properly angled headshell.

This led to a hunt for the Mint LP protractor, a rather expensive custom-generator protractor they mail you after getting your turntable and tonearm model numbers.

Ah, but then this post about the Mint on the Steve Hoffman boards:

I own a Mint but prefer to use an arc protractor generated by Conrad Hoffman’s software, which is what I was using before I purchased the Mint.

Now I was fully converted to abandoning underhang in favor of using overhang + Baerwald alignment. The only problem was the highly-regarded – and free – Conrad Hoffman custom arc generator only ran on Windows. All I have are Macs.

This is where the crazy starts. I didn’t want to deal with downloading a copy of Windows and then a trial of VMWare to install the Conrad Hoffman software, so I was actually this close to signing up for a free trial of a Microsoft Azure hosted virtual machine. But then I read about the hurdles you have to go through to install third-party apps on such a service, and kept looking.

I thought later, “What’s the simplest thing that could work?”, and re-discovered Wine/WineBottler, a way to run some Windows programs on a Mac without installing Windows. I tried it, ran the Conrad Hoffman generator, and was surprised when it ran!

Only thing to figure out was what I wanted my spindle-to-pivot distance to be, since that’s the only parameter you enter about your own system. If I wasn’t doing underhang anymore, I had to come up with a suitable overhang for a roughly 12” straight arm. I found a post mentioning one of the Nanook 219 iterations, and someone said they designed theirs to have 14mm of overhang, and their arm was a similar length to mine. That seemed good enough, so I moved the arm pivot, measured the spindle-to-pivot distance as 308mm, and plugged it into the generator. Conrad’s readme file said that if you didn’t want to make a research project out of it, to just go with the DIN setting and Löfgren A (Baerwald). Those inner- and outer-groove measurements looked close enough when I measured a real LP.

I held my breath and clicked “Print Arc Template” and was relieved to see our wireless printer listed in the Windows print dialog. I clicked “Print” and heard printing noises starting up in the next room. I had to print one more copy after correcting for the Y-axis scale. I put it on the turntable, temporarily taped down the platter (per the instructions), lined everything up, and pretty easily got the cart aligned with the arc and the guides. I moved the stylus over a real LP and could see that the stylus was actually very closely aligned with the grooves all way way through the arc. Never got that close before.

I tightened it back in the headshell, put on Minute By Minute by the Doobie Brothers, and was carried away by the sound of perfect alignment all the way through the album side. It was involving and suspenseful, like a live performance that I didn’t know the outcome of. Every voice and instrument perfectly defined and weightless. I heard ambience cues that I never noticed before, and at the end of each song, lots of details that were masked previously. I’m a believer.

If you suspect you need alignment help, go for the Conrad Hoffman custom arc generator. And don’t be scared off if you have a Mac!

The Tonearm Is Stained

Recorded on March 23rd, 2016

photo of DIY tonearm

Five coats of PolyShade later, the tonearm is back in business. I think I’ll need to twist the cartridge relative to the arm by a few degrees, but that will be for tomorrow. The AT120Eb is mounted with 1/4” underhang and parallel to the straight arm, which means it’s going to be the most out of tangent at the beginning of a record. When I play one, I can hear the image lock in by about the middle of the second track. That must be where the tracking error starts to decrease below some soundstage threshold. The rest of the album side is rock solid. At times it sounds positively holographic.

I had to switch to a lighter top weight/washer plate on top of the headshell, because the first test tonight sounded too dark. It was good, but it was a little too much like the cartridge was swimming in molasses. Once I put the thinner plate on, the sound got its airiness back. I must have added quite a bit of mass with all the varnish, so something had to give for it to balance out.

I also changed the unipivot bearing to be the glass scriber tool. It acts more like a gimballed bearing, but without the chatter, I think. It sounds focused and deep, in any case.

Cosmetically, it needs a proper finger lift. The nylon wire ties look pretty awful.

Two Coats of PolyShade on the Tonearm

Recorded on March 20th, 2016

photo of tonearm and associated pieces

Even though this tonearm is a proof of concept, I’m taking it as far as I can before making a new one out of cocobolo. This weekend, I bought a can of Minwax PolyShade (American Chestnut), and some ultra flexible 320-grit 3M sandpaper. The goal here is to put as many coats as the tonearm needs to give it a better “transmission layer” in the form of a poly/stain shell. I don’t know if it’ll work, but I’m inspired here by a message in this old 12” DIY tonearm thread on Lenco Heaven:

First I tried listening to this contraption in its “pure” form, with no sealing or finish applied to the wood. Well, it was predictably horrible. Then the rod was sealed with shellac, and a few further thin layers of it were applied. Shellac was chosen because of its ease of application, quick drying and hardness of the surface film.

After 2-3 layers the sound started “opening up”. It was better than raw wood, but still “tolerable” rather than “good”. 5 layers — aha, it’s singing again! In the end, I put something like 10 layers of shellac and a couple of very thin wax layers on this stick.

How does it sound now? Well, it has completely dried up and settled, and to my ears it’s at least equal to the original aluminium tube “Sorta-fon”. I was surprised that something made out of cheap and very common wood can do so well. The “transmission layer” of shellac really changes it.

I’ve never stained or sealed wood before, so I have no idea what I’m doing. I’m using a very light touch with the 3M sandpaper between layers, and since each coat takes six hours to dry, it’ll take days to get to the point where I can put the final wax on it. I’ve never seen anything like the 3M 320-grit ultra-flexible paper. It feels like sandpaper from the future.

I read a lot about how steel wool is the greatest thing ever for getting a smooth finish on wood, but the more I looked into it, the more warnings I saw about how steel wool sheds. It’s probably great if you’re refinishing a dining room table, but I don’t want any metal bits dislodging from the arm and getting into the cartridge or falling into the LP grooves. If Home Depot had had synthetic steel wool, I would have bought some. Instead, I’ll have to get some Norton 0000 synthetic steel wool from Amazon.

More later as I add on layers of PolyShade. I’m beside myself with impatience because I also bought a new “bearing” in the form of a tungsten carbide glass scriber tool (shown in the photo above). It seems like it fits the hex head of the bolt in the tonearm well, but I won’t know until I’m done with all these varnish layers.

The DIY Tonearm Actually Works

Recorded on March 16th, 2016

Not much more to say about this, other than sorry for the shaky video. And that I shall be consumed this weekend with ways to make a DIY tonearm lifter. There will be Delrin involved!

The Return of the DIY Tonearm

Recorded on March 13th, 2016

photo of DIY tonearm

I got the bug again and bought an Audio-Technica AT120Eb to go with the DIY tonearm I made last year. I had given up on the arm because I didn’t want to move the Denon DL-110 from the Dual 1219 stock arm and all I had otherwise was an old used Stanton 681EEE cart of unknown lineage. I was actually afraid to play records with it because the stylus was in such bad shape, but I tested it on the wooden arm with a few LPs I didn’t care about. I knew the Stanton was hiding what the DIY arm could do. It sounded dull and unbalanced. Tonight I installed the AT120Eb and was blown away.

Everything about this tonearm was purposefully un-optimized because I wanted it to be a proof of concept. But even with the cheap/temporary choices and materials used (unvarnished cedar arm, a vise holding the Parker pen refill, a zip tie for a finger-lift, wiring cannibalized from an old FireWire cable, and a Craftsman wrench socket acting as a crude counterweight), this arm completely overwhelms the stock Dual arm (where the Denon cart still lives). I’m now a unipivot believer. Cymbals and vocals are focused and smooth, mistracking is gone, and there’s an air above everything where before it was suffocated. This setup sounds more like a Lenco L75 with an expensive arm than I thought was possible.

photo of DIY tonearm

I’m positive that all the improvements are not just because of the AT cart. It’s regarded as a great tracker, maybe even better than the Denon, but the huge correction in time alignment is something the cartridge can’t be responsible for by itself. The arm is just getting too many things right that the old arm couldn’t.

The only thing I think it’s missing for now is in the low end. It’s not as strong as with the Dual arm, but I think that once I shellac it or varnish it a bunch of times, it will firm up. It’s amazing that the soft cedar wood is able to sound decent at all. With some tweaks and with some break-in hours on the cartridge, it can only improve. There will be many more details to come, but for now, this project is a complete success. Everyone should try it. I don’t know why I didn’t do this sooner.

photo of DIY tonearm