AP4 Power Amplifier

AP4 70 Watts/Channel Class A

There was one last Lecson power amplifier, the AP4. This was a massive Class A monobloc with a Class A output of 70 watts and a much higher output in Class AB.  Think of it as a Krell before its time.  This was a fantastic amplifier and at one time I had six of them in a tri-amped active crossover system.


Gone is the old cylindrical form factor-there’s now room for a large toroidal transformer and reservoir capacitors.




Stan Curtis writes, “The AP4 was one fantastic amplifier at the time; it was in a different class (no pun intended) from virtually all the competition.  




They could drive anything (+/- 90 amps peak current rating) and, if my memory serves me well the full power output (not all Class A) was over 150 watts into 8 ohms and over 250 watts into 4 ohms.  They sounded smooth and transparent.  



I loved them but you know what ? I haven’t got a pair. I had three pairs and never sold them so I guess they were stolen from me by various enthusiasts.




I think they came out in late 1979.  A batch of about 50 pairs was laid down but after 5 or 6 pairs had been sold the company ceased trading and I bought the remainder when I bought Lecson assets.”



Note the massive heat sinks, large power supply capacitors, and toroidal transformer.





Two are known to currently exist and have recently undergone restoration.  According to their owner, they “are amongst the best amps I have ever listened to and in a different league to the AP3 mkII.   They promised so much and delivered much more.  


Remarkably the only issue with the electronics was a fuse.  Stan pointed me in the right direction to avoid a heart attack on switch on.”

Leave a Reply