Transferring music from a 78 record player to my PC

[tom_the_LD]

OK thanks for all your comments guys. I will try and post some pictures but I don't know how :D

 

How do I go about checking it with a meter?

Active or passive DI?

BTW Ynot - It was my grandad who bought the record player for £5 :D

 

Sorry if the questions are stupid, but hey, we all need to learn :D

 

Cheers

 

Tom

[JimWebber]

Paul,

 

I am willing to bow down to expertise here, but if the internal electronics aren't isolated from the incoming mains, then the although the speaker terminals have only got a few volts across them, they will still be floating at half the supply voltage. If one side of this was then tied down to the earth/ground at the mixer/whatever end, could this not cause problems?

 

As an aside, I got a very nasty shock from a "Partylite" kit supplied by a major electronics manufacturer - who I will not name, but if you believe Jimmy Perry and David Croft, they also ran holiday resorts.

 

This kit had no isolating transformer, and all the control electronics simply relied upon a large resistor to drop the mains voltage. There were warnings in the instructions that the microphone casing would be at high voltage! being a rather headstrong sixteen year old who knew it all, I didn't believe them. I measured the voltage across the terminals - less then a volt...

 

All went well, until I touched the metal case of the microphone and the metal case of the partylite. It was at that point I found out that the bridge rectifier was acting as a potential divider, and that the whole circuit was floating at 120V ie half the mains voltage!

 

I have since found out that this used to be a common way of arranging power supplies especially in TV and valve electronics.

 

I'm not saying that it cannot be connected, just that it can be more involved tehn just a couple of wires...

 

Jim

[tom_the_LD]

Here are some pictures! :D

 

http://i167.photobucket.com/albums/u121/tom_the_drummer/th_DSC00169.jpg

http://i167.photobucket.com/albums/u121/tom_the_drummer/th_DSC00172.jpg

http://i167.photobucket.com/albums/u121/tom_the_drummer/th_DSC00171.jpg

http://i167.photobucket.com/albums/u121/tom_the_drummer/th_DSC00173.jpg

http://i167.photobucket.com/albums/u121/tom_the_drummer/th_DSC00174.jpg

 

Hope these add light to the situation

 

I'm sorry they are so big - I didn't know how to downsize them!

 

Moderation: Links replaced with clickable thumbnails

[paulears]

but if the internal electronics aren't isolated from the incoming mains, then the although the speaker terminals have only got a few volts across them, they will still be floating at half the supply voltage.

Don't worry about questioning me - I'm always happy to be wrong. You are quite correct, It could be half rail, but we don't have enough details to check this one. We don't know much about the internals at all - the pics don't help much apart from showing the tx. a DI box seems the safest and most likely to succeed. Most of the designs (well at least the UK ones) had the pickup screen chassis connected, and frequently had external speaker sockets on the back panel - I'm not aware of any problems in this area as most designs had a speaker transformer to do the high to low impendance conversion.

[tom_the_LD]

So Paul, are you saying that my best bet would be to do the whole soldering from the speakers, to a 1/4" jack but then go into a DI? If so, active or passive DI?

[Ynot]

So Paul, are you saying that my best bet would be to do the whole soldering from the speakers, to a 1/4" jack but then go into a DI? If so, active or passive DI?

Tom - honestly, I really, really REALLY think that your best bet is to skip that £5 deck and invest (or get dad/grandad to) in a half-decent player with the outputs already presented for your use. That way it's just a case of plug it into your amp, then into your (hopefully half-decent) soundcard and record the 78's as MP3's, which you can then sort and burn to CD (after cleaning them up if necessary).

 

Messing about with the internal wiring of an old deck with indeterminate details is, to me, just asking for trouble.

[tom_the_LD]

See what you mean Ynot. I know maplins do a USB desk but I don't know if it does 78s, plus I think it is more than what dad/grandad is willing to spend. I think I shall ask around people I know to see if they have a 78 player with RCA outputs.

[themadhippy]

Before you go any further it maybe worth while checking the turntable motor,if its a 60hz motor then the speed is going to be out.

[bruce]

Off-the-wall idea - get a standard turntable, and play it at 45rpm, while recording into your computer. Then use your favourite editing software to speed it up (and upshift frequency) by a factor of 78/45...

[p.k.roberts]

Off-the-wall idea - get a standard turntable, and play it at 45rpm, while recording into your computer. Then use your favourite editing software to speed it up (and upshift frequency) by a factor of 78/45...

 

I think you might find the modern 'micro-groove' stylus sitting in the bottom of the coarser groove of the 78s, giving a lousy recording and an unhappy stylus.

[tonythetechie]

See what you mean Ynot. I know maplins do a USB desk but I don't know if it does 78s.

 

 

According to the blurb that's on the Maplin Website, it will play 78's at 33 then the software will sort out the correct speed.

 

Hope this Helps

 

Tony

[jamesperrett]

If you are aware of the dangers of messing with valve amps then read on... Is there an output transformer between the speaker and the amplifier and does it completely isolate the speaker from the rest of the electronics? If there is then there is no need to bother with DI boxes - just connect an output in parallel with the speaker and feed it to a line input. Don't disconnect the speaker as you will run the risk of damaging the output transformer if you do.

 

The point about mains frequency is also relevant - the record player will probably be running at the wrong speed in any European country.

 

I would be tempted to look around for something more appropriate which will run at the right speed and have a higher quality output - you don't want to go doing this again in a few years time.

 

Cheers

 

James.

[andy_s]

The point about mains frequency is also relevant - the record player will probably be running at the wrong speed in any European country.

 

 

Cheers

 

James.

 

 

how much difference would this make? a semitone higher? more? less? I only ask because concert pitch (A=440) has changed over the years anyway, and is still as I understand it not universally adhered to ... I believe I read somewhere that Russian "A" is different to western Europe's A - or is this an urban myth type thing?

[bruce]

Well if it's a synchronous motor, it'll run 20% faster, so your A440 becomes 528, which is just above c but below c-sharp...

[boswell]

Well if it's a synchronous motor, it'll run 20% faster, so your A440 becomes 528, which is just above c but below c-sharp...

 

According to the OP its 60hz kit running at 50hz, therefore 16.6667% slower whatever that is in musical terms :P