I think everyone is overstating something that isn't really the case.
I track with semi-open back phones ALL THE TIME...there are NO bleed issues.
Maybe
some phones bleed badly, but I've not had any issues with my Fostex T50RP phones.
Also...most of today's headphones (like some of the Sony/AKG phones) fit very loosely, so you get as much “bleed” from the front as you do from the back side of some semi-open...but the level is SO LOW in either case, that you would have to CRANK the headphones and place them right up against the mic for it to be even picked up.
The real reason to use closed-back headphones isn't because of "bleed" concerns out of the phones, but for
isolation for the listener from instruments/voices in the room, that way you can still hear the cue mix clearly even if there is loud music in the room...which is not as easy with semi-open back.
But if you do a lot of single tracks and/or where you are the only one tracking...you can work easily with semi-open phones and you also get a lot of the natural room sound instead of that closed in sound.
A lot of folks like that...which is why some people take one side off their ear when using closed-back phones. With semi-open phones you don't ever need to do that. Singers will really like the semi-open as they can then hear their own natural voice much better instead of just what is coming from the cans within the mix.
Oh by the way...
the Fostex T50RP are absolutely fantastic sound-wise and have a low price compared to some of their competition. They offer some of the widest, most well balanced bandwidth I’ve ever heard in phones (that don’t cost crazy prices)…and...they don’t have any frequency spikes or harshness like some of the Sony phones. Some folks maybe like that midrange spike as it makes things pop out…but they sound like shit, IMO.
I have 3 pairs of the T50RP.
I also have a whole bunch of
the Koss Pro4AA closed back phones that provide some of the best isolation when that is needed...they really clamp on tight and are not flimsy and lightweight like some phones. Good for drummers and very decent sound quality. The Pro4AA were pro studio staples for many years.
So…think about what you really want out of a phone and how you will use them before you decided on any one pair or type.