Originally Posted by KJSmitty
This is something I really don't agree with, or better yet don't understand. Does Audyssey, YPAO and or Pio configuration programs all say regardless of what it comes up with set speakers to small and a specific crossover - IE basically ignore what the program is/are sensing/reading? One would come to the conclusion that with all the advancements and refinements within these configuration programs if you were meant to set speakers to small regardless, it would recognize the sub and just default to all speakers being set to small... This is honestly a question I have had..?
"Headroom" is one thing but most don't listen that loud to worry about it. The reason I bring this up is I just recently added two DIY Rythmik 1510 kits to my HT. Basically two beefed up F15HPs. My mains and surrounds are all identical large powered towers that YPAO sets to large and 40Hz. Prior to having the subs I ran all four of the large drivers as independent subs via RCA and set the towers as Small and 60Hz. Basically would perform a 5 or so position YPAO run and then tweak the "size" and crossovers etc. With the towers now speaker wire only and the sub-out RCA runs going to the Rythmiks, I let YPAO do its thing as well as experimented and played around with my own ideas - meter and all.... The best overall soundstage came from the 100% YPAO config - of which had the four towers set to "large" and 40Hz. I would not have thought this would be the case yet came to the same conclussion as JT78681 above - I'm just going to leave it as configured by YPAO and listen for a bit...
The only risk of setting the front speakers to large is how AVR handles the low frequency signals on FL/FR. If they do redirect it to sub channel, that is a correct implementation. However, some earlier AVRs (like Denon) has a mode that the same signal of FL/FR is duplicated also in the subwoofer channel. As you can imagine, this is very much a CYA (cover your..) method for lesser quality sound system. Maybe YPAO or Audyssey can do a smarter thing that they actually know how to use the natural roll-off of front speakers as a crossover point and only send the signals below the roll-off points of LARGE front speakers to subwoofers. But this type of setting crossover point is very problematic because speaker designers do not use in room response (in order to do know the phase relation between two drivers) to do their crossover design. They use close-mic or pseudo anechoic response to do that. In room response is not reliable for phase information.
Of course this definition of LARGE has been altered by each manufacturers to mean different things. I am a strong proponent of using 80hz as crossover point because the phase shift of the front speakers is low at 80hz and also relatively flat down to 80hz. The distance reported back from the YPAO or Audyssey is a good sanity check to see if the measurement is good (not noise ridden). Now when these programs use the natural roll-off points as the crossover point, it needs to recongize if the front speakers are ported or sealed (4th order roll-off vs 2nd order roll-off) meaning a 180 degrees vs 90 degrees phase shift. There is no feedback from Audyssey to tell the user if it has recognized the front speakers as ported or sealed.
Another reason to set crossover higher than the natural roll-off point is most front speakers have higher Q response (sealed and ported are alike although ported is particular more so) which is necessary to make front speakers to sound "LARGE" when playing them as full range speakers. But that is a undesirable design trade-off. And the simple solution to this problem is set the crossover point higher to filter out this undesirable characteristic. I still remember my early prototype demo to a consultant came to my house and listened to my Harbeth LS3/5A and DirectServo combination. I gave him without subwoofer (but LS3/5A full range) and with subwoofer (LS3/5A filtered at 80hz). I was just playing "Jazz at the Pawnshop" and after he listened to the subwoofer ON, he immediately told me "you changed the frequency response" of LS 3/5A. I explained him I need to do that because I cannot stand the "cardboard" type of midbass coming from LS 3/5A (all because it has a high Q roll-off). With the subwoofer and set crossover high, I killed two birds with one stone. So instead of saying "you change the frequency response of LS 3/5A", he should have said "you correct the problem of LS3/5A".
-Edited by Rythmik - 4/10/13 at 10:00am