I feeling good today, finally finished this thing, and I'm pleased with it
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After I finished my latest Lenco turntable project I figured I needed another phono stage cos I only had that stock cheapie stage that Tandy’s (That’s Radio Shack to our Transatlantic Cousins) used to stock in 1939 and CPC/Farnell still do – it’s horrid.
I looked long and hard, considered many things, favourite was almost a Pro-ject valve box with adjustable impedance settings but in the end I settled for an outfit I’d never heard of selling audio kits out of Hong Kong.
I’m not really sure what appealed to me about their stuff, save it seemed to be a helluva lot cheaper than equivalents on the market – if it were any good. And that was the question I decided to take a chance on – is it any good - and promptly despatched £306 including VAT, delivery, and a contribution to the Hong Kong poodle fancier’s society and awaited delivery.
About ten days later a parcel arrived very well wrapped in packaging that consisted a large deal of what looks like their local giveaway newspaper. I had also ordered two low voltage power supply boards for other projects of mine – a variable low current bench supply and a 2.5A PSU for my MOSFET Amp Camp build.
Those 2 PSU’s both worked straight off though both had parts missing on arrival, including a rather expensive voltage regulator. The supplier sent these missing parts without fuss free of charge though it took another ten days for them to arrive.
Back to the phono stage, for my loot I received: A dual supply PSU PCB and all parts, 2 DC rails, one for valve heater and the other 260V for the HT line. Both worked perfectly on completion, I let them warm up then adjusted voltage regulator pots to achieve desired voltages.
Plus a toroidal transformer; the valve phono stage kit (PCB & parts & valves – 12AX7 x 4), a large choke for the PSU and a metal case to put it all in. This is not a small phono stage, it takes up as much room as a regular hi-fi component such as an amplifier or tuner.
So, it took me 4 months on and off (I don’t like to rush things) but today, June 14th, I finished it. And it worked straight off - knock me down with a feather.
I hooked it up to my turntable with the Denon DL110 high output moving coil cartridge in it, set the phono stage for Moving Magnet (high output MC) and listened. I didn’t know what to expect.
Well, it’s good.
In fact I’m pretty much big smiley face happy. For that money I had expected
something but maybe not this good. I know this is a cliché but I’m hearing stuff from records I haven’t heard before. Particularly high sounding percussion.
Taste’s ‘On The Boards’ sounded particularly good. And I’ve been playing stuff all day through it, Pink Floyd’s ‘Animals’ was another high point.
I note from the circuit diagram that a pair of DIP switches fitted to the PCB adjust cartridge matching impedance through five resistors but there’s actually no guide to give common settings so it’s pretty much trial and error. I intend to construct a little box with 5 switches and 5 resistors, same value as circuit, and take measurements for different combos, this may help.
The 6th switch on the bank of DIP switches is to select between MM & MC cartridges but looking at the cct diag all this switch does is take the first valve in each channel out of circuit, presumably losing some gain.
Since taking the pics I’ve now put the lid on and it only gets a little warm.
Tomorrow I’m going to fit my Denon DL103 MC cartridge to the turntable used with this phono stage, fit extra weight as well to account for arm mass loading, set the phono stage to MC setting and try it, should be interesting.
The supplier, Analog Metric, as they call themselves, ommited a few parts from every kit (3 psu’s and a phono stage) (2 capacitors, 22nF 400V, from phono stage) but they did always post them to me when I pointed out their shortcomings via e-mail. Which is partly the reason why it’s taken me 4 months to put this together, hee-hee.
In their defence, they do give a phone number and they replied to all my questions by email. They definitely seem honourable, if not a little forgetful.
All in all, I know it’s not strictly a self-build, just a kit, but I’m very happy with it.
This experience does, however, still makes me very inquisitive about listening to as much audio equipment as possible – I am curious, as they say (yep, even after all these years).
…and to end – right now listening to side two of John Martyn’s ‘Solid Air’. Oh yes.
Some hastily snapped pix: