Velleman K4700 in Quads? Ed pushes it to the limit!
Obviously the articles about building the Velleman K4700 protection-circuit in the Quad 405 were very inspiring ;-)
Hans was the first to propose an alternative location for the kit but Ed took it very seriously... He built the kit into the 303, the 405 and the 606 and he even developed a box to use the protection-circuit with any amplifier....
It is clear that Ed also will find a box of Antwerpse Handjes in the mail and he is hereby named a lifelong honorary member of Quad Spot ;-)
Do you work for Quad or Velleman, Ed?
Obviously there will be many questions on this subject, feel free to post them as a comment. To be continued....
Take a look and enjoy (click on the picture to enlarge):
In the 303
Note: in the 303 the protection-circuit is somewhat less usefull than it is in the 405. The 303 is a push-pull amp with an output capacitor, so as long as the capacitor won't fail there is no risk of having DC-current on the output, like in the 405, if one of the output-transistors breaks down. But there still is the advantage of the delayed power on/off. And with expensive speakers you never can be sure enough of course...
In the 405
Ed made a metal-adapter to fit the K4700 behind the transformer.
Note: as mentioned in earlier posts the 405 really NEEDS a better protection-circuit. I heard about several people who had their expensive speakers broken when one of the transistors gave it up. The original "clamp-circuit", even in the 405-2 does not react fast enough all the time.
In the 606
Ed even built a K4700 in the 606. This was not an obvious or easy job to do.
Update: An alternative location.
Ed mailed me some pictures of an alternative location for the Velleman in the 606. For Ed's explanations see the comments below.
In a separate box
This box can be used for any amplifier. But it should be switched on/off together with the power-amp, by a general swith or from the pre-amp.