Incatech Claymore mark II

Many still remember the Claymore integrated amp in the late 1980s which was designed by Colin Wonfor. Tony Lonorgan and Lt Cdr Data both rate the amp highly. I have always been curious of what the Claymore sounds like.

I had the chance to buy a Claymore mark II version in new condition. It was one of the last batch made by Colin Wonfor before the company was closed down. Sadly one channel was distorted heavily on arrival. So I had to return it to the seller. The admicable seller who is genuine and he refunded me in full.

Before I returned the amp, I opened up the amp to see what the circuit looked like and also tried to find the fault. One channel was fine but one of the output transistors in the right channel was faulty (green one marked J118) , causing an over voltage of 60V to the black transistor (K413). I had a quick search in the net for the obsolete transistor but had no luck.

The build quality of the board was average, I found some solder flowed along the tracks and some components' physical dimensions were too big, so a few of them had to cramp together. The speaker outputs are very cheap 4mm plastic sockets. There was a few secondary windings on the toroidal transformer, one winding didn't have protective sheath, so the enamelled copper could be seen, although this is not dangerours, this practice is not seen very often for audio amps. The MM and MC phono stage used OP27 op amps.

It is a pity I didn't have the chance to listen to this amp, but if anyone has owned this mark II Claymore, I'd like to hear your opinion and its history.

Regards
Hon

 

Never heard the claymore II but had a one for many years ...recently sold on ebay The sound was damn good for the parts and construction.....mostly off the shelf components cheap maplinsque switches and sockets. So the design was a real hum dinger. I was going to extensivly mod mine until the wife decided we had too much hifi so for domestic harmony on to ebay it went.....cost around £390 in 1985ish sold 2005 for £105 not bad !!

 

They are discontinued mosfet parts numbers - but not impossible to source

 

Graham

As an amateur repairer, the mosfets are not easy for me to source. I searched through the net, although I may have found one site which sells them, usually there is a minimum charge which could cost as much as 20 to 30 pounds.

This is the problem I found with older transistor amps, it is hard to find spare parts or sometimes, audio manufacturers hide the part number so it is nearly impossible to identify the part. In the world of valve, it is much easier since there are fewer common small signal or output valve types and many small outfits sell them individually.

Regards
Hon

 

This is pushing the limits of my knowledge, but it may be possible to substitute more modern audio mosfets like toshiba or hitachi.

looks good quality....toroidal transformer

big psu diodes.

op27 as you say, very good opamp

It looks typcial of small british amps in that it has nice thick pcb and tracks, and simple design, too, largely why british amps have the best soudn quality notwithstanding the build which is not so typcial

looking at the circuit, I am guessing, but its the hitachi applications note design, similar to a maplin mosfet and the musical fidelity a2, as well as probably many others I don't know about.

Its a pity you can't get hold of Colin Wonfor, Doug Self on his amp site makes a reference to one of his designs/articles, needless to say he thinks its rubbish, but Doug self is a pure engineer, not a listener.
well well....