For over 10-years. I have never ever heard anybody complain or regret about anything that they sent in that has been modifed by Jim at Audio Upgrades. Is it worth the cost and are the improvements worth doing? That is something only you can decide. If you realy like your 414 but just need or want it to be a notch better that it might be worthwhile to you. But don't expect to get back a completely different mic afterwards.

Thanks Audiogaff, It seems he eliminates the transformer and changes some caps. I'm not quite sure if this would be enough of an improvement to an already decent mic. Although, it supposedly ends up with about 5 more db of output which masks the noise floor alittle. I'm looking to make these work for a larger variety of situations.

Jim Williams did a wonderful job on my UM70. I would contact him

I have a friend that has a 414 that Jim did. It sounds great! He does great work. i have another friend that has a console that he rebuilt. The thing smokes!