I wanted to thank you for your post! I have a pair of Mk IV's that I am going to get updated TODAY!! I felt a little silly using these after buying used a pair of Von Schweikert 4.5's yesterday. I will get these modified and give them a serious listen. Can one also get the same level of results modifying the pas 3 preamp? I used to collect many vintage pieces but always heard that modifying these amps could give performance equal to the lower level Conrad Johnson products (MV 50 etc.) Thank you again for these posts and I will hold my head high!
Re: the pas 3 preamp, I have never been impressed by the dynaco preamps, even when upgraded. I think mr. van alstine makes a better dynaco-derived preamp, check him out www.avahifi.com
re: Joe curcio´s mods...I have no doubt that mr. curcios mods make the dynaco mkIV a better amplifier, improving measured performance and perhaps reliability. BUT I like the amp´s sound, thay is why I bought one...and all those mods curcio mods MUST change the basic sound of the amp, since many change, organically, the circuit desgin of the amp. Cosequently I stayed with upgrades that improved reliability and sound while staying within the original ciruit design.
Part of the fun of vintage amps if working on them...for me progressive modification works better than all-at-once rebuilds, try a particular mods and see if you like it better than before, and on and on until you get what you want.
I have yet to burn mine out, using it almost ten years and it was old when I got it. problems in other components (these are, after all, vintage units) can stress the power tranny ya know. with all vintage stuff there is a risk of failure of components but I have not seen anything to indicate that dynaco MK IVs are more prone to failure than any other vintage amp, in fact the opposite seems to be true, they are perhaps more rugged. YMMV JMTC ETC regards, T