Dinky little 2-valve Chinese pre-amp

[Yorkie]

Search me - I'm on the fringe Nick.

I've reached an age at my kids are older than many of my chums!

At 45 he's his own master and doesn't consult me about his whimsical impulse buys, any more than does his older brother, who's 50.

If it's not to his liking, I guess he'll bin it.

(I blame the parents).

[Mark Hennessy]

To some extent, the Sony is more sophisticated that the average turntable - at the very least it has to have some means of switching between the two cartridges for each side of the record, so given that, it's not so impossible that they decided to put in a preamplifier at the same time. Either that, or the cartridges are ceramic, so won't need the usual RIAA equalisation. Google wasn't terribly forthcoming about that particular model.

It is strange when you think that inserting a "thing" that can only add noise and distortion is considered to be an upgrade. I can't think of many other walks of life where this is commonplace. If I sold an engine tweak that increased you fuel consumption in return for no increase in horsepower or torque, I wouldn't expect to sell too many. Hi-fi is hi-fi's own worst enemy.

[Refugee]

It just works as a head phone amplifier or will match a ceramic cartridge to a line in on a transistor amplifier but not a lot else.
I have a set of these that will pull a reasonable volume all be it badly tone corrected from a magnetic cartridge.

http://golbornevintageradio.co.uk/forum/...p?tid=3798&pid=38942#pid38942

They do sound good and there is no shortage of volume. One hummed out a little tune that told me it was time to try the new style capacitor re-stuff and it now sounds even better especially with the volume high enough to shake the floor.

[Yorkie]

To some extent, the Sony is more sophisticated that the average turntable - at the very least it has to have some means of switching between the two cartridges for each side of the record, so given that, it's not so impossible that they decided to put in a preamplifier at the same time. Either that, or the cartridges are ceramic, so won't need the usual RIAA equalisation. Google wasn't terribly forthcoming about that particular model.

Not sure whether the output from the cartridges is insufficient to drive his amplifier and he thought this little pre-amp would uplift the signal sufficiently, but for what it's worth, I've attached the mind boggling circuit of the Optonica RP114. It's certainly a well engineered and very complex bit of kit and I think they're still quite sought after. Top end stuff I imagine, given that it was produced more than 40 years ago.

[Nick]

... I've attached the mind boggling circuit of the Optonica RP114. It's certainly a well engineered and very complex bit of kit and I think they're still quite sought after. Top end stuff I imagine, given that it was produced more than 40 years ago

Actually, it was released in 1983, so 31 years ago - still a decent amount of time!

The microprocessor, an NEC uPD650C, is a CMOS 4-bit processor that was basically suitable for running washing machines and stuff like that - the clock ran at only 100kHz with 2Kbytes of ROM and only 48 bytes (96 4-bit "nibbles") of RAM. The same CPU was also used in early Roland machines...

[Mark Hennessy]

OK, so the cartridges are switched by a relay, with just additional transistors for muting. No preamp. I would assume that these are magnetic cartridges, given the general level of sophistication, so he's going to need a phono preamp that takes the nominal 5mV from the deck and lifts it up to around a volt, applying RIAA correction on the way.

This preamp won't do that.

I'm not really clear exactly what this preamp will do, frankly. It's an ornament. Nothing wrong with that - it's very pretty. I wouldn't put any of my audio through it though.

[Yorkie]

Thanks for reading my post and for your interesting response Nick.

[Joe]

I'm not really clear exactly what this preamp will do, frankly. It's an ornament. Nothing wrong with that - it's very pretty. I wouldn't put any of my audio through it though.

I think the function is quite clear: to separate the ignorant from their money. It certainly strikes me as being little more than a toy or novelty item. It may be OK to feed into an EL84 from something with a line-level input but I'd certainly make such a thing from scratch. This looks a more practical thing.

Still, if people THINK it improves the sound, and such things are highly subjective (said the man with a µA741 in his radiogram!), good luck to them.

- Joe

[AlanBeckett]

That looks promising Joe, and I suspect you'd be hard pressed to beat the price unless you had a lot of the bits already.
You'd have to add your own blue LEDs for maximum effect

Alan.

[Nick]

You'd have to add your own blue LEDs for maximum effect

As it happens, the state-of-the-art in sub-illuminated hollow-state hardware is to use RGB LEDs and to generate a mood-controlled visual colour bath...

No, really! It is!