You know, we were just discussing weird and/or obsolete audio formats in the writers’ dungeon the other day. (By the way, have you ever bought anything on DAT or MiniDisc?) While vinyl is hardly weird or (nowadays) obsolete, the fact that this Bluetooth record player by [JGJMatt] is so modern makes it all the more fantastic.
Not since the Audio-Technica Sound Burger, or Crosley’s semi-recent imitation, have we seen such a portable unit. But that’s not even the most notable part — this thing runs inversely to normal record players. Translation: the record stands still while the the player spins, and it sends the audio over Bluetooth to headphones or a speaker.
Inside this portable player is an Arduino Nano driving a 5 VDC motor with a worm gear box. There really isn’t too much more to this build — mostly power, a needle cartridge, and a Bluetooth audio transmitter. There’s a TTP223 touch module on the lid that allows [JGJMatt] to turn it off with the wave of a hand.
[JGJMatt] says this is a prototype/work-in-progress, and welcomes input from the community. Right now the drive system is good and the Bluetooth is stable and able, but the tone arm has some room for improvement — in tests, it only played a small section of the record and skidded and skittered across the innermost and outermost parts. Now, [JGJMatt] is trying two-part arm approach where the first bit extends and locks into position, and then a second arm extending from there and moves around freely.
Commercial record players can do more than just play records. If you’ve got an old one that isn’t even good enough for a thrift store copy of a Starship record, you could turn it into a pottery wheel or a guitar tremolo.
WOW! K, now do a CD player the same way :)
500 RPM looks like a bit too much for this design…
If you use 10 arms, it’s only 50 rpm.
And that’s just a 1x speed CD-ROM :-)
brownie points if you can put an optical sensor on it to find the tracking marks on the record so you can automate the process of finding the song you actually want to play.
I thought about this a while ago to. Back in 2004-ish some college students used a scanner and matlab to reconstruct audio from records:
http://www.public.asu.edu/~mamccan1/visionfinal/doc/index.html
It was rough, but it makes me wonder what could be done with a Pi along with a camera with a macro lens in real time. maybe add in some AI noise reduction to add a modern touch to it too.
Very cool concept – though I wonder if the arm will ever really be able to keep the needle in the groove properly, its spinning and wants to unfold quite hard with own interia I would think, along with changing the balance point of the whole system some when its more or less folded up…
A counter balance that moves to match the distance of the arm, or just making it heavier so the rotating arm has less influence is probably going to help keep the player stable so the needle stays in the groove, and might be all that is really needed, love to see some more slow motion shots of its action.
I would think that you could add a spring or even a clever counterweight on the opposite side of the pivot which could counter the centripetal (are we still using that word or the other one?) force on the needle.
Well, it’s not exactly the same thing. Centrifugal force is still frowned on, and “the other one” is centripital ACCELERATION.
Also known in the trade as “Skate”, unless I forgot stuff again
I avoided that word set for a reason, as this debate does my head in, all the terms are accurate and understandable enough to be very clear, so they should all be correct!
With the varied force as the arm is more or less stretched out I’m not sure a spring could really be selected that will work for the whole record, at least not at all easily. Putting in one of those gear systems on the arm that locks the counter balance to the matching position of the arm perhaps? But without some slower footage of it working and failing its hard to know what is actually going wrong – maybe the arm just needs another pivot in it lightly sprung so it tries to remain in the right place but has that little bit of give before it can jump out of the groove.
The biggest problem is, that the force depends on r² and for a simple counterweight r gets smaller while r of the needle-arm gets bigger.
Perhaps a combination of a counterweight and a spring could solve this problem. You have a few degrees of freedom to optimize the function of force vs. extension angle, but it can probably only be optimized for one rotational speed.
For the counterweight you can vary the angle of the arm relative to the needle carrying arm and of course it’s mass.
With a spring you can vary it’s force and it’s pre-tension.
A major flaw of this design is the change of angle the cartridge makes. The cartridge might be orthagonal to the groove at the mid section, but this is not the case at the inner and outer sections. Probably why it has trouble tracking at those parts.
Looks to me like the way its supposed to close/open does keep the cartridge on the expected orientation – the arm is curved enough I assume it keeps the like well – probably better than the fixed arm record traditional players I would guess – but again really need to see it working or get the geometry for closer study
The angular error depends only on the radius of the circle the arm is pivoting on, unless there is some fancy articulation to correct the error, which is not the case here. This is smaller (i.e., greater error) than any arm that pivots from outside the edge of the record.
There is an ‘error’ in its position as its pivot moves round the circle to accommodate different radii, which can be corrected for if its actually audible by changing the speed of rotation very slightly to account for it – keeping the needles surface speed in the expected range despite lagging its pivot by more as the record plays..
But the OP seems concerned with the angle of the needle cartridge to the record grooves – and this design looks to me to keep that better than the traditional record player – looks like the needle is always going to be perfectly aligned on the grooves.
I see – the picture at the top is misleading. It shows the arm being one piece, which clearly didn’t work, since on the project page it shows a two-piece arm. However, in his description, the OP says that the inner arm “locks into place” and the outer one rotates freely, so that arm is still on a very short radius. I stand by my statement.
And by the way, the shape of an arm has no effect on the motion between its pivot and its end. It can be straight, or it can wind around in c curlicue; the only thing that matters is the distance between the two points. The moving end will always move in a circle whose radius is the distance between the pivot and the moving end.
With it looking two part (maybe in some images technically 3 part) what in my mind the curve was doing is making sure the the drag of the needle keeps it aligned with the groove, I haven’t read the source in that much detail, its a goofy project and I have things to get done…
As when its two/three part the length from the pivot which in this case is effectively the centre of the record is varied so its arc over the surface isn’t tightly constrained to any one of the many lever arms real pivot points but the combined position of them all, which look like they should sort out to match the record..
However looking at it again, but still at a glance, I really can’t figure out how its all supposed to be working, what is and isn’t supposed to be articulated… One of those rare cases where a good slower video clip of all the movement would be really informative, way more than most video clips vs the text that I usually hope accompanies them…
Again, from what the builder writes, “I now have two arms, the first one extends out and locks into place and then the second arm moves freely on the end of the first.” I will repeat the relevant part: the first one extends out and LOCKS INTO PLACE.
I really like the idea of keeping the record stationary and the record player itself moving. It also brings the concept of playing both sides. Perhaps it might be better to have a straight ridged arm that contains a long threaded rod, then mount the head perpendicular on a spring with a bearing and have the threaded rod follow the spring. Literally just mount two contacts either side and a limit switch at the ends. When the spring bends a motor turns and relieves the pressure and the spring will get rid of any vibration and allow the record groove to do the fine following freely.
Mid-1970s. Rabco SL-8.
We had that in the early 1980ies from Sony. Although I am not sure if they used point contacts or optical sensors. Though there were for sure optical sensors to detect the size of the record and the “breaks” between different songs for an auto-seek function (if they were sufficiently “visible”depending on the record.
this is extremely rad
Techmoan has covered similar commercial devices, ‘panopic’ was one of them I think.
Elaboration: they’ve demonstrated devices that look like a tall cylinder with a needle in the bottom. You put the device on a page of a book that has a record-style section and the device plays the audio from it. It was used for karaoke, you had the words and audio on one book page.
There was something (I thought I saw it here on HaD) that was like a little car that drove itself around in circles on your record. Seems like it didn’t have anything connecting it to the center hole, though.
I’ve been reading the posts on HaD for many years, I must say, I don’t recall that one, although I may have missed it.
It sounds like an interesting concept though, certainly bringing a whole new meaning to, line following. Thinking about it, that’s a pretty tricky thing to get right. I guess, the lazy way would be to do the old lawnmower attached to a tree via a rope design and have it wind around a central peg, effectively just driving in a straight line, then you’d only need to consider a bit of dampening and wiggle room on the head.
Perhaps this is what you were referring to?
https://m.youtube.com/watch?v=Qe5ib947Hjc
Yes! That was it. But also, another thing called RokBlock: https://www.youtube.com/watch?v=LPIJVdQkb1Q. But at least with the one you found, it LOOKS like a toy.
I remember the Techmoan video. Sound and tracking looked quite bad and the noise of the motor of the “car” was also quite loud. :-)
There was also a problem with speed. If you turn a disc around it’s center, the linear velocity changes with the radius. The little car had a constant linear velocity which was only correct in the middle of the record.
The best idea since ritz crackers and ice cube sandwiches!
What’s wrong with connecting a Bluetooth sender to the output of a normal record player , pretty logical and easy , special motors just to make the record turn
If you only ever use consumer devices you bought retail, why are you here?
Nah, that’s already been done plenty of times. Feel free to make one though.
> By the way, have you ever bought anything on DAT or MiniDisc?
Yes. What do I win?
I have owned many minidisc players including a 4 disc in dash and a 6 disc in trunk Sony set.
I had a Tascam Dat recorder as well. I still have a tape laying around.
Also, I have records and a reel-reel player/tapes.
Minidisc was awesome…but having cheap storage nowadays kinda took away the need…but way better than CDs…they didn’t get destroyed in the car like CDs did.
I first encountered MiniDiscs in my school theatre, where we had a portable recorder/player which was used for any sound effects or music required.
The sound quality was higher than the tape it replaced, and being able to (almost) instantly skip tracks made it a lot more useful than cassette. The machine had an all-important ‘pause between tracks’ function, so all owe had to do was hit the play button at the right point in the script and it all just worked.
The maker is going to need to measure the stylus downforce, there were tools made for this purpose years ago. Too little, and it will skitter out of groove as described, too much, and it will prematurely wear out the LP.
Also, measure contact angle of the stylus. It needs to be aligned properly in the groove to prevent the same issues as improper downforce. The way the arm is designed, I suspect that is the major issue.
A really cool example of thinking outside the box. What I would be a bit worried about is all of the additional coupling to the tone arm and needle from the rotating body.
Very cool! Reminds me of the record runner (https://recordrunner.jp/)
o, wow, i didn’t know they were in production again, and even with bluetooth!
Run the motor much slower, to avoid skidding and too much load on the record. Digitise the signal from the needle and buffer it. Speed up the buffered signal to the correct speed and play it.
I’m guessing an optical mouse wouldn’t have enough resolution.
But from experience I know a cheap 1.3/5MP web cam, with the focal range adjusted, does act as a very powerful microscope, with the right lighting, I wonder if it could read an LP in enough detail to reproduce intelligible sound.
Okay, I guess I was wrong about seeing it here; it was called RokBlok, and Techmoan did a review: https://www.youtube.com/watch?v=LPIJVdQkb1Q
Hm. Good old WordPress: posted reply to wrong article.
Use a photo sensor that sees 20 turns of the groove at a time, and you can reduce the rotation rate by a factor of 20. Don’t know why we’re still using destructive mechanical pickups on vinyl records, anyway.
With today’s technology even that would not matter. You need to play the record only one more time and digitize it. Then you can listen to it’s music forever.
Or you could leave out the middleman, and digitize it straight from the master tapes, and record it without compression on some kind of optical media.
Hmm…whatvare the wow and flutter specs?
If you need to ask, you won’t like it.
There are still some different levels possible: Bad, gross, or unbearable :)
The player would have problems keeping equal pressure on each side of the groove even if it managed to stay in the groove. Looks to be a novelty and perpetuate the myth that vinyl sounds bad.
Linear tracking is the ultimate for this and a Bluetooth transceiver the best wireless solution.
But it’s a novelty piece so it will entertain..
Linear tracking is superior. No straight or s shape tone arm can compete without angle compensation and complicated anti skating.
Still rocking my 30 or so minidisc portables, deck and a good hundred or so discs!
Looks like a good way to wear out your expensive vinyl. It is a toy a gimmick.
My thoughts exactly. Go buy a nice turntable and skip this foolishness.
Indeed, I certainly wouldn’t want to use this on any record I was intending to keep scratch free.
But all the same, it’s always nice to see innovation and creativity, every idea has to start somewhere.
This seems like an excellent way to implement DRM on vinyl – after all it’s gonna play (decently) once.
The tracking force from inertia alone is going to strip the groove dry, at least one stereo channel. Horrible.
Built in obsolescence on vinyl records, now that is a scary concept. Although there’s always the good old wax cylinder.
There’s a technology that was around for a short period called “Flexplay” which sealed DVDs in an airtight package, and once that seal was broken, the disc would degrade over the next couple of days so that it no longer played the movie.
Bluetooth leaves much to be desired for sound quality which kind of defeats the purpose of spending extra money on vinyl. Plus, if this thing is skipping and skating, keep it away from my vinyl.
I have always said that but look into all the specs for BT. Its a whole family of backwards compatible modes and at 5.0 there is a high def format now. The problem is you need 5.0 at both ends for it to work, and it’s hard to find out the details in a product description.
I still would rather plug my headphones in than have to plug the ‘phones into the charger or not have them usable.
If you want sound quality, you buy digital media. I would one expect to buy vinyl only for nostalgic reasons and perhaps for the haptic experience of the legacy records.
the geometry is all wrong,hence it only works in one segment of the disk.geared motor is going to make it rummble grumble.
instead have the arm wrap more than once around the player,with
a second pivot in a location yet to be found.
motor could be permanent magnet dc.
keeping the whole player confined to the blank center section,playing good,and still non precious is going to an iterative process
Two words: Linear Trackling
I applaud the engineering that went into this project. I can’t even think of how many challenges were encountered. However, is this a better mouse trap or merely just a different one?
Slow the rotation, buffer the audio, increase pitch of audio, profit.
The reason this has never become production type technology is that it is poor sound quality and destructive to the record. Similar systems have been tried multiple times over the years.
Sigh… you all are getting it wrong… this thing is perfect — what it is for is not for taking out and listening to your favorite records you collected… it’s for your FUTURE favorite records… what I mean is, the best MOST valuable RAREST records are the ones that only a handful (and I mean literally as some had less than a 100 produced) ever made… there is no catalog, cd compilation, MP3 audio, or even known existence of such a record. How do you know then if its valuable? … Well, if its not on a common record label and it sounds good, there’s a pretty good chance it has value.
If you are out at some flea market or tromping around an old neighborhood you are not going to want to haul around something that you have to plug in… just slip this into your pocket and go hunting … playing it once on this and then bringing it home to your 3″ thick platter turntable would pay itself off 10 times over with just 1 find.
SO only improvement – make it have a selector for 33 / 45 / and 78 – there is some very good Delta Blues and Jump you wouldn’t want to miss out on!
If you think anybody selling rare discs is going to let you anywhere near them with a contraption like this…
This reminds me of the Skiwee, a predecessor to the Jetski. The inventor spent time and money on hydraulics that nobody was asking for instead of a motorcycle on water… the Jetski. In short, focus on what people want. Change your perspective, the same goal could be achieved with an arm instead of a feral stylus. Or a turntable that will play both sides of the record without flipping it over;)