Sounds like something in your growing conditions are causing this.
Too hot, too dry, air conditioning, etc.etc. Where are you you in the USA and what are your growing conditions, temps, pots, sunlight. potting mix, watering routine etc. etc.

I am in central texas. I have them in a west window on a table about 5 feet away from window. About 70s in my home not to exceed 75. I grow in bark mixed with shipping peanuts. my water routine is about every week with a feed every other watering half strength. the leaves stay a nice green color and have new growth. this is not happening to all of my orchids......i maintaing same care for most of my phals with the exception of a few that dry out faster.

How long have they been in bloom?
When my spikes are done (2-6 months for phals?) they usually brown from the top down and eventually die back.

Bob

these spikes are doing this when it holds up to 10 perfect blooms that show no sign of aging. i will usually loose the older blooms first and then so on when my blooms fall off thats when the spike turns brown. on these i never lost any blooms the spike just turned brown and all wrinkle dry appearance.

No help here...

Can you think of any other environmental change? A/C now on, home improvement project, painting, etc...

Good luck,

Bob