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 a mechanical 33rpm LP record player
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 Return to top of page · Post #: 1 · Written at 12:50:22 AM on 27 March 2013.
Elijah B's Gravatar
 Location: Melbourne, VIC
 Member since 28 February 2012
 Member #: 1098
 Postcount: 8

I'd like to be able to play 33rpm LP records on an entirely mechanical record player; that is, without any electrical components. I'd like to be able to play LPs where there is no electricity available.

I know that there were mechanical 78rpm players but I'd like to know if any were made for 33rpm, and if there were, what they might be called and where I might be able to find one.

I've thought about converting a 78 player to slow down to 33, but I am not sure about the styli used on such a player, and whether they are too coarse and may damage the LP.

Any thoughts would be welcome. Thanks.


 
 Return to top of page · Post #: 2 · Written at 5:14:21 AM on 27 March 2013.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 4375

Very few gramophones, if any at all, were made for LP records and there's a good chance of ruining any that get played on them as the steel needles are too harsh and the 'tonearms' are just too heavy.

While it's not as nostalgic as listening to old equipment the cheapest way of listening to records now is to purchase a turntable from JB HiFi which has a USB output to a computer.

One other way is to grab hold of one of literally hundreds of HMV radiograms from the 60s era which people would probably pay you to take away. Many of these are mechanically A1 and only require subtle electronic upgrades. At worst you'd be up for a new rubber band for the idler pulley and these can be bought from TV technicians. (The same rubber bands are made for older VCRs)


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Brad.

A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 3 · Written at 1:24:09 PM on 28 March 2013.
MonochromeTV's avatar
 Location: Melbourne, VIC
 Member since 20 September 2011
 Member #: 1009
 Postcount: 906

The idea of a all mechanical LP record player is interesting.

However, there are a couple of issues that would make it impratical. Firstly, assuming you are using a spring-loaded motor, the lower speed would likely cause wow & flutter. Secondly, even if you could devise a acoustical pick-up to suit LP recordings, you would not get the same frequency response as you would from a crystal/ceramic or magnetic pick-up.

In short, I suppose it could be done - but the end result would be some dreadful sounding music.


 
 Return to top of page · Post #: 4 · Written at 5:37:13 PM on 10 April 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

To add to the gloom...

Design of the 33rpm records is quite different to the 78s. They were originally called "microgroove" recordings, as the groove is very much narrower than the older records. This means that the movement of the needle in the groove is very much less than the needles in the old 78s. I used to be able to hear the music on a 78 by resting a finger-nail in the groove as it turned (when parents were not looking).

The microgroove simply doesn't have the width and depth to generate enough mechanical movement in the needle to produce a practically audible sound. 33rpms and 45s were designed on the assumption that every player would have an electronic amplifier.

Together with that, the older recordings were made of a hard material, bakelite or shellac or similar. Microgrooves are made with softer flexible plastics, which are just hard enough to transmit the vibrations accurately to a very light and sharp needle, but not hard enough to transmit the force needed to generate a usable accoustic vibration.

As a kid, I tried playing a 45rpm disk on an old accoustic gramophone that we had at home. I heard a faint sound of music, then noticed the needle was ploughing up little spirals of plastic as it scored the grooves like a wood-lathe. The disc was never the same again.

It would take some very skillful accoustic engineering to devise a totally mechanical player for 33rpms. You would probably need something like a doctor's stethoscope plugged into your ears to hear the music at a useful level - not really a social experience.

Maven


 
 Return to top of page · Post #: 5 · Written at 5:48:25 AM on 14 April 2013.
Wa2ise's Gravatar
 Location: Oradell, US
 Member since 2 April 2010
 Member #: 643
 Postcount: 618

There was this American toy record player for 45's (which I think also were microgroove), called a "Kenner Close And Play". Aside from a motor to turn the record, it was purely mechanical from the needle to a speaker like mechanism. I'm sure the records got trashed...


 
 Return to top of page · Post #: 6 · Written at 10:48:42 PM on 19 April 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

Yes- the mechanical principles for sound transmission are quite different.

In an electronic pickup, the signal is generated right in the cartridge that holds the vibrating needle in an electronic field. Therefore the more inertia in the arm, the more of the energy of the vibration is available for conversion to electrical energy in the cartridge. Hence the emphasis on counterbalancing the arm.

For mechanical transmission of the sound, the energy needs to be transferred to a diaphragm directly in contact with the needle. In old gramophones, some portables relied entirely on a diaphragm on the travelling end of the tone arm. The horn types had hollow arms that acted like brass trumpets to funnel the accoustic energy from the diaphragm, with some degree of accoustic resonance tuning, to the mouth of the horn.

Looks like that toy one had a light plastic diaphragm in the lid, which could not be very loud but might be more kind on the records than the old-style gramophone weighted stylus.

Maven


 
 Return to top of page · Post #: 7 · Written at 11:11:14 PM on 13 January 2014.
Sue's avatar
 Sue
 Location: Daylesford, VIC
 Member since 13 January 2011
 Member #: 809
 Postcount: 265

Mechanical repro was practical with pop 45s, then. These usually have "louder" grooves than 33rpm LPs, and were designed to sound OK on tinny portable radios.


 
 Return to top of page · Post #: 8 · Written at 11:39:17 PM on 13 January 2014.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 3972

I had missed this thread until now. As a kid my sister had a small mechanical record player toy in the style of the one pictured, though smaller overall. The discs were plastic and contained nursery rhymes. It was quite loud and, as with most loud musical toys, it eventually drove everybody nuts.

I remember how funny it sounded when the batteries were low. Imagine saying "three blind mice" straight after getting a dental block and you get the idea.


 
 Return to top of page · Post #: 9 · Written at 11:46:46 PM on 20 January 2014.
Chris Ronayne's avatar
 Location: Wauchope, NSW
 Member since 1 January 2013
 Member #: 1269
 Postcount: 576

I think it may actually be possible now, with the right adjustments and equipment.

I've been listening to some 33s and 45s on my El Cheapo 1990s Sharp 3-in-1 (tuner, tape deck and phono) unit, and it doesn't even require a speaker. I don't know why, but the needle vibrates so much on the record that the music itself is quite loud with just the platter spinning.

I'm listening to some old rock and country on it right now, with the volume on zero, so I don't keep my step-brother in the next room awake - and it's easily loud enough to hear from the other side of the room. The sound quality isn't the best, but considering that it's coming solely from the needle and not a speaker, is still quite good.

I can take a video/recording of it tomorrow if anyone's interested, though I'm not sure how well the cheap microphone on my camera will pick up the sound.

Chris.


 
 Return to top of page · Post #: 10 · Written at 10:48:42 PM on 22 January 2014.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

If the tone arm is transmitting enough audio energy for you to hear it across the room, that is an indicator of the inefficiency of the tone arm. The principle of an electronic pickup is that the vibration of the needle in the groove should transmit as little energy as possible to the tone arm, but should be resisted by the inertial mass of the tone arm, so as to impart maximum deflection force to the device at the head of the needle that transforms mechanical vibration into electrical current - either the electromagnetic coil or the peizoelectric transducer of a ceramic cartridge. Good quality tone arms are thus relatively heavy, but balanced by a counter-weight so there is not too much downward pressure on the needle in the groove, which would increase friction. Some use a further weight to to counter the unbalanced inertial effect of the groove contantly pushing the needle toward the centre of the disk. On a stereo disk, the groove is V-shaped and the outer wall of the V is one track, while the inner wall is the other track, thus producing deflection of a single needle on two separate axes at 90degrees to each other, that can be detected in the pickup coils oriented on those two axes. Inertia biases the signal toward the outer wall/track.

Another possible audio source is, if the vinyl record is a bit warped or too flexible, and not sitting very firmly on the platter, the record itself can be acting as a kind of mechanical diaphragm vibrating with the varying pressure of the needle as is travels across the indentations in the groove.

The needle itself is the least likely source of the audio energy, because it has such a small surface area to transmit audio frequency vibrations to the air.

Maven


 
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