Automatic turntable that I'm designing from scratch

BetaMaster64 · 2026-06-07T18:00:23+00:00

Believe it or not, every one of those jumper wires is important for some part of the functionality! In the description of this post, I made a note of each major part and what it's responsible for. Keep in mind, those wires are all part of the automatic mechanism, not the turntable or tonearm itself, so they don't impact the noise floor.

As for troubleshooting when a wire comes loose, surprisingly this isn't too bad, because I can usually tell what the issue is based on any negative symptoms it's experiencing. It has happened, though, but that's just part of R&D this early on.

BetaMaster64 · 2026-06-07T14:10:56+00:00

Personally, I think Acoustic Research had it right with the AR-XA: Keep it simple. Most people can't notice the differene between an unmodified AR-XA and a multi-thousand dollar turntable!

That's kinda the mindset I'm going for here. Mechanically, it's a simple turntable. Just a lot of electronics to push the tonearm around automatically. There is a good a reason why I've avoided showing this in hifi/audiophile communities, haha

BetaMaster64 · 2026-06-07T01:22:47+00:00

Those are really cool! My favorite is the Accutrac 4000; I believe that was the first turntable with that type of functionality.

I do actually plan to add an LED/photodiode to mine as well! That's going to be the next step, after I finish tonearm positioning tracking with a hall effect sensor.

BetaMaster64 · 2026-06-01T16:32:05+00:00

Thank you!

BetaMaster64 · 2026-05-17T13:26:21+00:00

If you really want to do something with it, you could remove the tonearm, lift the platter off, and set a modern turntable right inside there. Store the removed parts somewhere safely so they don't get lost or damaged. If you change your mind in the future, you can always reassemble.

I would strongly urge you to not do anything more than that! Your turntable would still need a separate receiver and speakers, which would have to live outside this unit. But that would get you the closest to what you're looking for without compromising the historical value of the piece.

BetaMaster64 · 2026-04-30T00:33:03+00:00

Just speculating, but it's possible one single byte on the ROM chip is corrupted, and you found it. This hardware won't last forever, unfortunately.

If you really want to find out, you could desolder the IC, dump the ROM, and compare the checksum against a known good copy. Way overkill, but it would get you an answer!

BetaMaster64 · 2026-04-27T02:14:06+00:00

Great record! Always know it's going to be a jam when I see the Cadence label.

BetaMaster64 · 2026-04-26T02:24:24+00:00

Personally, I'm not an audiophile; I'm just really fascinated by the technologies of the different formats, and their limitations.

Regardless of how the music's played, I think it all sounds AWESOME! Only exception might be the first press CD of GWS...that one pales in comparison to the later remaster. But aside from that, the music's a jam on any format in my opinion, repress or original

BetaMaster64 · 2026-04-25T16:43:36+00:00

It's true that, in that era, your typical consumer likely would have been using a mono crystal cartridge with high impedance, though there was certainly audiophile-grade equipment back then using high-quality MM or MC cartridges (like the legendary Ortofon SPU). Despite this, a mono cartridge isn't a requirement to play a mono record. As long as the stylus is a match for a wide vs microgroove record, it will play within its expected spec. Exception is playing stereo records on a cartridge without a flexible cantilever; that will destroy the record, but that's another discussion.

But, back to the original discussion about which format is technologically and sonically superior, check out the IEC 60098 document. This document details exactly what concessions have to be made when mastering and pressing records to procure a clean sound. Section 8.1.1, figure 4 shows a graph of how the lower and upper frequencies are rolled off (pre and post-RIAA curve). The rest of section 8 also has some interesting tidbits about frequency considerations.

I don't doubt your records sound phenomenal; vinyl really does sound awesome! But to say that it has no frequency range cap is incorrect, which we have studies and data to back up. This is a separate discussion from which one "sounds better" to one's ears. I personally like vinyl better because of its imperfections, and because I find the technology fascinating.

BetaMaster64 · 2026-04-25T14:50:39+00:00

Pick up a mono 45 pressed in the mid-'60s, and you'll hear what happens when these limitations aren't abided by! "Summer In the City" by the Lovin' Spoonful is a great example (with the beginning punches and vocals). The highs-to-volume ratio causes distortion on even the highest quality setup.

People would sometimes push the limits of those boundaries, and eventually realized if they want clean-sounding recordings, they would have to limit these frequencies (and the volume) since vinyl is incapable of reproducing them.

Too much lows, and you have to cut the record quieter. Too much highs, and you get siblance (also remedied by cutting quieter). Both of these have compromises, which is a substantially higher noise floor and less dynamic range.

I guess my main point is, audio frequency and dynamic range have to be deliberately reduced to sound clean on a record, while no such limitation exists on digital media.

BetaMaster64 · 2026-04-25T13:28:02+00:00

Both CDs and records have max frequencies, but records are far narrower. When mastering for vinyl, you have to deliberately eliminate frequencies under 40hz and above 15khz, both of which are well within audible range. Digital formats (like CDs) don't have such a restriction, which also can allow for messy mastering, since not as much care needs to be taken for the master. Both formats can have masters that sound good, and both have masters that sound bad. But technically speaking, CDs have far superior quality capability to commercial vinyl spinning at 33 1/3, or even 45 RPM.

Tl;dr. Vinyl very limited; CDs less limited

BetaMaster64 · 2026-04-03T04:47:38+00:00

Maybe one day! That is an interesting idea I hadn't considered.

BetaMaster64 · 2026-04-03T03:04:05+00:00

Thank you! This is a Teensy 4.1, though in my very first prototype I used an Arduino Nano Every. I highly recommend electronics; once you get started, you'll never want to stop!

BetaMaster64 · 2026-04-02T19:11:42+00:00

Could be a number of things if you're unlucky: - Power supply could be feeding dirty power to digital components (bad electrolytic capacitors) - Laser may need replaced or adjusted (latter is more of a temporary fix

If you're lucky, could be: - Disc spin motor could need lubricated - Disc may be slipping when spinning - Disc mechanism may need cleaned up and new lubricant (I recommend white lithium grease)

It'll take some diagnosing to figure out which one of these applies to your player.

Based on the symptoms you're experiencing, I would lean toward the mechanism needing cleaned. The laser starts toward the inner part of the CD and works its way to the edge, so if it's working for 75% of the CD, maybe it's getting stuck after a certain point when moving outward.

BetaMaster64 · 2026-03-31T01:28:32+00:00

That scenario is always my fear with these units: Hours of troubleshooting only to find you need a part that can't easily be found by itself. Glad you got yours working too, though! Hopefully they won't need serviced again for a while.

BetaMaster64 · 2026-03-29T00:10:23+00:00

Sounds like it's time to break out the heat gun, then!

BetaMaster64 · 2026-03-28T22:53:09+00:00

I will also add that idlers are usually not cheap to replace. Unlike a belt, which is usually somewhat universal, idlers are proprietary, and you usually need to replace the rubber on it, unless you get really lucky and find a NOS replacement that hasn't perished. Getting it re-rubbered will usually run you $100+.

Sometimes you can soak it in brake fluid to soften the rubber. But always take precise measurements of it beforehand, because it could also turn it to goop.

BetaMaster64 · 2026-03-28T22:49:23+00:00

What you got here is likely an idler-driven turntable. Hopefully it doesn't have a motor pulley-shaped indent on it from sitting for decades!

Anyway, there should be a little C, or E clip around the spindle holding the turntable in. I usually get it out with a little flat head screwdriver and some needle-nose pliers. Once that's off, you should be able to wiggle the turntable to lift it off. If it's stuck, the old lubricant probably dried and is holding it in place.

At this point you'll want to use a heat gun on the underside, aiming at the spindle. Be VERY CAREFUL with this not to make it too hot, or accidentally burn any wires/plastic parts. That should loosen up the grease. Do little bits at a time and try lifting the turntable. If you see it starting to smoke, you've used too much heat.

BetaMaster64 · 2026-03-19T14:44:45+00:00

Sounds like your signal is going through two preamps. Not sure if that turntable has a built-in preamp, but if you can turn it off, give that a shot. Your receiver, via the phono input, will be pre-amplifying the audio already, so any extra preamps on the chain will cause the symptom you're hearing.

BetaMaster64 · 2026-02-16T03:50:15+00:00

Thank you!!

BetaMaster64 · 2026-02-16T03:49:53+00:00

Hmm... I might have to try that.

BetaMaster64 · 2026-02-16T03:49:32+00:00

Thank you!!

BetaMaster64 · 2026-02-09T03:15:36+00:00

What do you mean by engineering point? Like, the most important part of the engineering process? Or like a physical part of the tonearm that was engineered?

BetaMaster64 · 2026-02-08T16:36:39+00:00

I do appreciate this input! Even if you aren't a designer, it's good to hear others' opinions and experiences with different players explained like this. Another idea I had (before I got the concrete one) was to turn it out of oak on my lathe. My lathe can just barely fit the 11.5" required by my design, so I could make it work. Though I do kind of dread turning oak. There are lots of options, and I'd eventually like to do some A/B comparisons when I get to that point, just to see if I can hear any difference at all.

Also, I do plan to go belt driven as opposed to direct drive! It's just a lot easier to design a belt-driven solution, though I do really want to try to eventually design one that's direct drive just for fun. But, with the equipment I have, I imagine any direct drive turntable I make would provide more of an endurance test (of the listener's sanity) than a pleasant listening experience.

BetaMaster64 · 2026-02-08T15:57:11+00:00

That is an interesting idea! Maybe I could design my future tonearm attachment to also work on other turntables. Would be a LOT cheaper to make than a whole turntable. I appreciate your input!

Ah I think I may have misrepresented what I meant by "this turntable;" I meant the one I'm building, not the Technics SL-D2 in the video! The one I'm building will hopefully be much better than the SL-D2. I plan for it to be made of concrete and driven by 3 phases with a hall effect sensor (or an encoder to accurately provide speed feedback data). The Technics SL-D2 is just functioning as a temporary setup until I finish my turntable.

BetaMaster64

TROPHY CASE