Online Parts International


Pre-amp Circuits for turntable MM or MC reproduction Apologies for the lack of updates over the last few weeks, our scribe has been off ill for a few weeks. Here’s to a new session of articles and hopefully a little bit of invigoration to our framework. The true value of Vinyl It’s amazing how times change – […]



Where to get vintage gear spares? Over the last 6 months I have received quite a few mails from desperate individuals wishing to restore their old radios, tube and semiconductor, integrated amplifiers, turntables and tape decks. Belts and power supplies and many semiconductors have equivalents but we get stuck with Germanium, decals, knobs and switches with most […]

M-Audio Fast Track Duo


The A/D Converter – pushing vinyl to digital The common and garden DAC can be picked up cheaply at most electronic stores, ready to run straight from your CD player through optical (Toslink) or coax and used to drive your analogue only system. Although these little units are cheap by comparison to high end products being portable […]



Where to find transistor equivalents? Restoring old gear can be a nightmare when it comes to some of the more obscure transistor types, and a pretty expensive exercise as well. Transistor equivalents for substitution is often a necessity when repairing vintage gear. This applies equally well to silicon devices and not just Germanium. Years back we were […]



Is vintage audio better than modern releases?  (post 2000) This reminds me of the first argument I had regarding the merits of mechanical VU meters over LED. Yeah, we like vintage stuff, especially with those big VU meters. Hell, I was looking at the specs of the Pioneer SX-1980 the other evening and thought  what a beast […]



Hybrid Amps: Some more circuits Using the first article to get our creative juices flowing I found some more well written well designed amplifiers using tubes and semiconductors. The design link below shows various permutations to feed a high voltage swing with little distortion to an emitter follower output stage.  This circuit, titled Hi-End Hybrid Amplifier 100W […]



Tube and Semiconductor Combos – the best of both worlds An interesting project on the web is that of a 6SN7 Mosfet audio amplifier capable of delivering 50W per channel. The article, written by Simon Brown is called Amplifier War and Peace – An Hybrid Amp I am not a big believer in that tube amplifiers are so […]



Local suppliers – South Africa As an addendum to our previous article “Alternatives to Tube  Output Transformers” we thought it pertinent to add a bit of local flavour,  Mars Amps in Paarl to the mix.  No, I have not met the gent but Karel Mars is a well known tube guru in the country and lends his […]

The Tube Digital MPA II from ART Pro Audio


The ART Digital MPA II – Solid state and tube preamplifier This was my first microphone preamplifier and admittedly it was a grudge purchase. I was looking for the Behringer 2 channel 12AX7 preamplifier to do some mods, higher voltage plate and RIAA preamplifier.  At the price it’s a steal, then just over R1200.00 for Mic200 and […]

What's a tube


Radio Tubes or Valves Take your pick, tube or valve? All irrelevant – ones Americanism (tube) and the other English as in UK (valve). We have a plate (American) and anode (South African and English). Cathodes are directly or indirectly heated (indirect = heater to cathode) which emits electrons which is attracted to the positively charged plate. […]

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