Phil... wow, amazing feedback! Yes, the mkIV's seem bass shy at reasonable volumes against the FRD efficiency (almost as if they were tuned brighter than my mk1.5s), but can clearly crank out deep frequencies when turned up. Just checked and the serial numbers here are 007 and 008, so I'd guess these are very early models. I'm working tomorrow and don't really know the Zu guys, so if you'd have time to call and ask Sean, I'd be very appreciative!
I suppose I've liked the 300b mesh plate because I listen to so much music that isn't that well recorded and the rich and creamy character of these tubes hides some of that... 70s reggae made in the ghettos of Kingston just isn't audiophile grade. But I also have a strong collection of jazz, blues, R&B, and rock on vinyl as well, some of which are superb recordings. So for me it has been about finding a balance over the years of a system that's capable of being highly resolving, but also forgiving of poor recordings. It's a delicate dance. I'm certainly willing to try out some new tubes though ;)
Thanks again for all your help!
David
I suppose I've liked the 300b mesh plate because I listen to so much music that isn't that well recorded and the rich and creamy character of these tubes hides some of that... 70s reggae made in the ghettos of Kingston just isn't audiophile grade. But I also have a strong collection of jazz, blues, R&B, and rock on vinyl as well, some of which are superb recordings. So for me it has been about finding a balance over the years of a system that's capable of being highly resolving, but also forgiving of poor recordings. It's a delicate dance. I'm certainly willing to try out some new tubes though ;)
Thanks again for all your help!
David