Tape reference level

Operating Level	Flux@1000Hz	Flux@700Hz
0dB	        180 nWb/m	185 nWb/m
+1dB	        200 nWb/m	
+2dB	        224 nWb/m	
+3dB    	250 nWb/m	260 nWb/m
+4dB    	280 nWb/m	G320 nWb/m
+5dB    	315 nWb/m	
+6dB    	355 nWb/m	370 nWb/m
+7dB    	400 nWb/m	
+8dB    	450 nWb/m	G510 nWb/m
+9dB    	500 nWb/m	

Magnetic        Flux level  
 flux Φ           LΦ 

520 nWb/m      +6.36 dB
370 nWb/m      +3.41 dB
320 nWb/m      +2.14 dB
250 nWb/m        0   dB   
220 nWb/m      −1.11 dB
200 nWb/m      −1.94 dB
185 nWb/m      −2.62 dB
150 nWb/m      −4.44 dB

1/4 track machines will respond different that 1/2 track machines.

The 1/2 track decks can use 370 nWb/M (+6dB) but the A2300 will not work well with that level. It needs to be no higher than 250 but more correct 200 if you want full bandwidth. Like a lot of guys are oing they get blinded except for one spec and that is flux density. This may enhance S/N ratio but also distortion goes up and bandwidth goes down.

So you are better off with a 200nWb/M tape for the A2300 at 7.5 IPS and can also be used on the quad Otari. The 25-2 is not going to like the levels above 250 nWb/M as it is designed and the A7300-2T is better off at 250 as well. If you want to run 370 nWb/M the Tascam 52, 62 and ATR units are more suited and have jumpers for those levels. Higher is not always better!

The track width of machines has a lot to do with how much flux you can throw at it. The 1/4 track decks like to have 200nWb/M and on a rare occasion maybe 250 but nothing higher. the 1/2 track machines is where you have many options and depending on the speed you might be able to throw a lot of signal at it. You know the other thing in upping the flux density- the tape has a fixed saturation point let just say +15. If you go and set up a deck for +6(370) instead or +3 (250) then what you risk is a saturation happening sooner as you then do not have +15 headroom but +9.