Thread: PLZ pre-preamp
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Old 20th February 2019, 06:16 PM
bikerhifinut bikerhifinut is offline
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Join Date: Jan 2006
Location: Penrith, Cumbria
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Default Re: PLZ pre-preamp

Originally Posted by Richard View Post
Hi Andy,

That little circuit looks easy to build. Have you heard one? One of my earliest projects was a single transistor (BC109?) head amp circuit in one of the hifi mags of the day powered by a PP3 batt. I tried it against the Ortofon MCA76 and it was lively and gave enough gain but was noisy (hiss) and rough sounding. So would that modern Jfet be good enough (showing my ignorance of modern devices here ) or would it just be another fun project capable of comparison maybe to the built in MC gain in some integrated amps?
No I haven't heard one richard. I forgot to ask a friend who has a stash of 2SK104 to flog me a couple last weekend, as i have a long term project on the go to build a hybrid silicon/valve MC stage.
It's actually an obsolete FET, but thats nothing unusual these days as most new stuff seems to be SMT stuff. I wouldnt like to speculate on its noise performance without the spec sheets etc as FET's can be noisier than BJT's. I know of at least one manufacturers solid state phono stages that use an FET front end and apparently the double FEts he uses are shockingly expensive but are of the few that are sufficiently low noise. Previously he used low noise BJT's for the commercial stuff.
I'd look upon it as a "fun" project Richard but you never know it might be up to snuff? I figure you could knock that circuit up using decent standard quality parts for around a fiver to a tenner excluding case and sockets assuming the 2SK104 is still available for a quid or so each. Last time I looked the prices varied enormously. There'll be an equivalent though and certainly if you can work with surface mount devices theres apparently quite a lot of stuff available.
I'm not constructing just now until the building works done here, hopefully June, but I'll be doing this circuit and I hope I can get some meaningful numbers out too when I put it on the scope.
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