78rpm

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jwc1976
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78rpm

Post by jwc1976 » 30 Sep 2018 12:59

Can the Sony PS-LX300USB Turntable be made to go to the speed of 78 RPM?
Regards,
jwc1976

Coffee Phil
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Re: 78rpm

Post by Coffee Phil » 01 Oct 2018 04:08

Hi jwc1976,

I assume that you are looking to play standard groove 78 RPM records. To do this you should have a 2.5 - 3.0 mil stylus. I can’t see from pictures much on the cartridge of this Sony. There may be 78 styli available for the supplied cartridge but we can’t count on that. To be sure you can get an Lp stylus assembly re-tipped with a 3 mill stylus but that will be spendy considering the price of that Sony player. If the arm takes a standard 1/2” mount cartridge there are several options there with modest cost.

Assuming we can find a solution to stylus issue, we have the issue of getting the machine to turn at 78.26 RPM.
This machine seems to have an electronically controlled DC motor. That means it should be relatively easy. The questions are if the electronics are internal to the motor itself or are they accessible?

If we can get a schematic of the machine the job will be much easier.

Do you own this machine? If so, lets get the answers to the questions which I raised and there is a fair chance that we can bring this off.

If you are considering the purchase of this machine for 78s, I thing we can find an easier path.

Phil


jwc1976 wrote:Can the Sony PS-LX300USB Turntable be made to go to the speed of 78 RPM?
Regards,
jwc1976

yarvelling
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Re: 78rpm

Post by yarvelling » 27 Oct 2018 18:54

There are 78 styli available for this cartridge; it's a standard AT3600/AT91 cartridge. The issue will be to get the turntable to play at 78rpm..... I have seen one Youtube reviewer experiment with a turntable using the same base as this Sony, and he used the accessible 45rpm trim-pot from underneath the player to get it to spin near enough to 78rpm, but that sacrifices the 45 playback (unless you want a massive fiddle every time you go between 45 and 78 playback!).

AudioFeline
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Re: 78rpm

Post by AudioFeline » 03 Feb 2019 10:21

yarvelling wrote:
27 Oct 2018 18:54
There are 78 styli available for this cartridge; it's a standard AT3600/AT91 cartridge. The issue will be to get the turntable to play at 78rpm..... I have seen one Youtube reviewer experiment with a turntable using the same base as this Sony, and he used the accessible 45rpm trim-pot from underneath the player to get it to spin near enough to 78rpm, but that sacrifices the 45 playback (unless you want a massive fiddle every time you go between 45 and 78 playback!).
The most common mod of this type involves changing a resistor in the speed-control circuit. It could be either the 33 or the 45 circuit, most modder's will change the 45 circuit. A pot is a variable resistor, which is how the YouTuber referenced was able to change the speed.

45rprm playback does not need to be sacrificed with this modification. If the required resistor value for 78 is not known, a pot can be used to measure the resistance required to obtain 78rpm. Then a switch could be used to select either the original 45rpm resistor, or the newly-added resistor for 78rpm playback. It sounds like the YouTuber didn't do this, as it sounds like the video was created to demonstrate the concept, not as a how-to-do the mod.

WOF49
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Re: 78rpm

Post by WOF49 » 05 Feb 2019 05:44

I would suggest that it is simpler to have two turntables with one dedicated to spinning 78's. It will be a lot of work and expense to modify a TT not designed for 78 plus you will not have to switch the cartridge to go back to 45's or lp's. Should be able to find a decent vintage Garrard or if new is your style an Audio Technica that will serve you well.

AudioFeline
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Re: 78rpm

Post by AudioFeline » 05 Feb 2019 06:02

The direct-drive TT modification is not difficult if you know basic electronics. The resistor is usually easy to identify in the circuit (thanks VE for the downloads), and it's simple soldering. Candidate turntables can often be identified (and in some cases info on how to do it) by googling the turntable make/model and "modify 78".

WOF49
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Re: 78rpm

Post by WOF49 » 09 Feb 2019 01:20

After checking the specs of the Sony I certainly would still recommend a vintage TT. I think you would get a better TT even with some of the lower end machines. If the usb is the issue there are simple adapters for that. It would be helpful to know expectations and budget. Later.

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