Playing CD's through the gramaphone socket

[jdrysdale]

Just for curiosity's sake, could you play the line output from a cd player (or something like it) through the gramaphone socket on a valve radio (if not what would you need to do to do it). It would an interesting way to find out just how good (or bad) the sound quality of the radio is.

[Aerodyne]

I've done it successfully, despite the theoretical matching problems. I use a cheap portable CD player and take the output from the headphone socket because this works with the player's volume control. I made up a simple screened lead with a mini stereo jack on one end, to suit the player's output socket, and a pair of wander plugs on the other end. The min jack was internally bridged across the left-right channels. Results? surprisingly good from the headphone outlet, less so from the line out as this has no volume control and is in any case of the wrong impedance. Yes, it worked, but very hissy and poor.

Some will suggest small series resistors across the 'bridge' of the channels for safety (possible damage to the player) but I found no need for them. The player cost about £12.95 if my memory serves me correctly! Ideal for playing those old tracks remastered onto CD. Glenn Miller, Artie Shaw, Duke Ellington etc. played on a late 1930s radio sound great.

-Tony
p.s. Don't do this with an AC/DC set... only a fully transformer isolated receiver!

[jdrysdale]

I happen to have a 'gramaphone' player that I might try out first, I know there is a difference between the impedence of 'line' source and the gramaphone but I'm not sure yet how to compensate. Now to dig out a real vinyl record that hasn't being scratched to bits by little nieces and nephews.

As it happens I have VHF set which has a really good sound on FM (listening to bon jovi as I write).

[Hybrid tellies]

A few years ago when my music centre packed up I connected my cd player through the gram socket of the HMV 1124. To overcome the impedance problem I built one of those maplin pre amp kits, connected the two channels together though suitable resistors and powered it from a PP9 battery.
It worked really well and was a major talking point amongst my social circle

[paulsherwin]

Originally Posted by jdrysdale

I happen to have a 'gramaphone' player that I might try out first, I know there is a difference between the impedence of 'line' source and the gramaphone but I'm not sure yet how to compensate. Now to dig out a real vinyl record that hasn't being scratched to bits by little nieces and nephews.

As it happens I have VHF set which has a really good sound on FM (listening to bon jovi as I write).

The gram inputs on valve radios were intended to be driven by a crystal cartridge. These are high impedence high output devices. If you plug in a modern (last 35 years) magnetic cartridge, it won't do much.

You can plug in the headphone socket of a portable CD or MP3 player and it will work, but the level may be a bit low depending on the output. Just connect the two stereo channels together with resistors (1k-10k, not critical or even essential).

If the level is too low you can build a little preamp with a transistor or op-amp and either put it in a standalone case with a battery, or fit it inside the radio taking the power from the O/P valve cathode resistor. You could also experiment using any old audio transformers you have to raise the output impedence - the audio driver transformer from a scrap trannie should work well.

HTH, Paul

[Aerodyne]

The gram inputs on valve radios were intended to be driven by a crystal cartridge. These are high impedence high output devices. If you plug in a modern (last 35 years) magnetic cartridge, it won't do much.

AFAIK The very old (i.e. pre-war) add-on record players designed for radios 'Turn your radio into a radiogram' were in fact magnetic, high output; certainly the ones I've seen were, heavy as lead too. Dunno about their impedance but I presume low! I also tried, for the sake of completeness, using an output transformer to raise impedance from the headphone socket of my portable CD player but no discernable improvement was noted from what was already pretty good results with plenty of available power. (This was feeding into an Aerodyne TRF).
I, like Paul, very much doubt that any modern magnetic cartridge would have anywhere near adequate output to drive the amplifer in an old valve set. A pre-amp will be a necessity, I think.

Just for curiosity's sake, could you play the line output from a cd player (or something like it) through the gramaphone socket on a valve radio (if not what would you need to do to do it). It would an interesting way to find out just how good (or bad) the sound quality of the radio is.

Sure, but as I've said, it didn't work for me.
-Tony

[quantum]

I've taken the line output from a CD player and run it through the gram sockets of a set with reasonable results, so I suspect that you would have to 'suck it and see' to see if it would work for you...


Some sets used to have an input transformer on gram for the old magnetic type of cartridges that were around in the '30s and '40s, to ensure that the input impedence would be high enough, and also the occasional set would also have complex switching to bring in the triode stage of the FC valve to act as an extra AF stage on gram. However, with a modern magnetic cartridge even if the amplification was high enough it would sound horrible, as there wouldn't be any equalisation - the response would be 'tinny.'

[stephanie]

Back in the 1990s, in my less knowledgeable days, I had gotten my hands on a 1970/80s era hi-fi receiver someone had ditched.

It was an "Electrophonic/Morse" brand -- the off-brand type of pseudo component units (came with a gram and an 8-track deck that you'd plug in the back) that were in vogue in the era. Remember the fake woodgrain?

Anyway, I saw that it had a phono input, so I excitedly plugged in a modern gramo I had lying about -- with a magnetic cartridge.

All I heard was a whisper - a distorted one at that, with the volume slider flipped all the way up. At first I was afraid I had fried my precious little hi-fi, but then I remembered some discussion I had over-heard about pre-amps for turntables many years ago

I figured that this was probably one of those units that needed a "pre-amp" and instead opted for plugging my VCR into the phono inputs. Ahhhh magnetic versus ceramic cartridges!! D'oh!!

It served as my "home theater" system for a few years, together with a 13" black and white TV set.

Anyway, yes, I've fed the output of CD and tape machines into ceramic-gram inputs in receivers equipped with such. Haven't had any problems with sound quality or else.

[jdrysdale]

I think I'll have some fun playing with this over the weekend. A bit of Enimem blasting out at top volume,,,,well not blasting out exactly.

[avro]

I have been playing CDs through my Grundig 5088, 2035 (Wagner is a favourite) and my Saba Freudenstadt 16 Stereo for some years and have been satisfied with the results. A good CD player will offer better volume through a vintage set. The one I fancy is made by Tivoli and should fit in with a vintage 60's set well.

I use a mini to 5 pin DIN plug with the Saba and a mini to 3 pin DIN plug with the Grundigs (the latter were put together for me by Tim Pullin).

I have also used an Ipod instead of a CD player and this works great .

Since we moved to Germany in January I have been using the CD player through the gram socket even more than I did in England.

Avro

[Phil G4SPZ]

I've played CDs through the gram sockets of numerous classic radios of the 40s and 50s, and they all worked well using the line output from the CD player. My favourite CD is "The Great British Experience" which has all those favourites from my childhood, and sounds warm and mellow through a valve amplifier.

I have one Ferranti set which relies on the low impedance of a magnetic pick-up to mute the radio, so I wired a 4.7k resistor across the 3.5mm stereo jack plug which goes into the CD player. This adaptor seems to work fine on all my other valve radios, and most line-level outputs from tape recorders and other radios seem to work too.

Enjoy!

Phil Harris

[paulsherwin]

Originally Posted by G4SPZ

My favourite CD is "The Great British Experience" which has all those favourites from my childhood, and sounds warm and mellow through a valve amplifier.

I can also recommend this double CD, which is full of the sort of stuff that would be played on the Light Programme in the 50s and 60s.

Best regards, Paul