Quote:
Originally Posted by Techman
I'm gathering that you're not so enamoured with it yourself from what you've said in a previous post. I think what we have to remember is that it had to be made down to a price to be affordable. If it had been made like a Dynatron LF59 with an industrial grade steel plate chassis, seam welded on all the corners that you could park an British army tank on, then it just wouldn't have sold to the target market. It is what it is and I think it's very good for what it is and for the price it was at the time.
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Well, I agree with you that it was designed down to a price and for a particular market, and I suppose that's fair enough. To expand a bit on my experience - I bought the Stern-Clyne kit to partner the Mullard Type C tape preamplifier that I was building (excellent circuit, pretty well up with the semi-pros), so performance mattered, especially with a tape pre-amp where so much design effort had gone in to eliminating hum. I went to Tottenham Ct Rd to buy the components for both circuits and, being more interested in the tape preamp, decided to get the kit version 5-10 to save me some time. Stern-Clyne's shop there had a built demo model which was exhibiting a low but intrusive hum, and I tackled the salesman on this. He assured me that the hum was simply the result of the connections between the 5-10 and the other source equipment, and wasn't "native". With hindsight, this was obviously a well-rehearsed sales patter to get around an awkward, basic flaw. I was in a hurry at the time and bought one. When I built it, it had exactly the same hum I had heard in the shop - even with the input grounded. That's what convinces me that there was a basic design flaw with these kits. I tried and checked everything, and eventually discovered that the hum could be reduced by connecting leads between various parts of the chassis (I didn't know enough about grounding good-practice back then as a teenager to analyse the earth-paths, and was in a hurry to complete the system). I ended up strapping thick cable across the chassis (and I mean thick - the stuff used for equipotential bonding in bathrooms/kitchens). This reduced the hum to something like what I'd expect from a 5-10. I often wished afterwards that I had bought the parts and built it exactly to the Mullard design. So, I was just concerned that the OP might have the same designed-in problem as I had, and might spend time and money looking for non-existent faulty components when the fault lay elsewhere.