The trouble with the Maplin kits was the price (to high) and when teted, they got mixed reviews (I guess to much corner cutting on the components)
I remember the mains transformers getting stupidly hot.
The mains transformers were simply not up to running a stereo pair.
They take 80 watts idle power consumption per channel and you can tell just by looking at that transformer that it's going to be on the ragged edge delivering 160 watts before you even start! Add to that the radiated heat from the valve anodes and it does get unacceptably hot.
As a pair of monoblocks, however, they are not bad. The mains transformers buzz a little more than I would like, mainly, I suspect, because they did away with a choke input filter.
The amps themselves are fine, though. They have been in use as my main amps pretty much continuously since I built them in '96/97 and are still on the original valves, still sound good and measure well.
The only thing that lets them down, IMHO, is the LF response. Partly, perhaps, because the output transformers are not as generously rated as they could be and partly down to the cathode bias arrangement, which "pumps up" as the amp is driven into class B trying to drive LF, biasing the output valves further off. Suffice it to say that if you like punchy bass when it's turned up loud these might not be the amps for you. They can sound little wooly on some material. I will eventually change mine to a fixed bias setup or add an op-amp bias servo so I can ground the cathodes, and see what that brings. Of course the ideal arrangement would probably be to filter out the LF and use a solid state amp for that, and let the valves handle the midrange where they excel.
I am thinking of getting one of the US kits for myself given the excellent price.
It would be interesting to see what they're like.
Kevin
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Topic: Amplfier wire route (Read 7810 times)