Originally Posted by scanido
Thanks for the quick response. Wondering if you also got confirmation on how the other channels would function in this AUX/XXL arrangement.
Currently I have my MX150 setup the conventional way (Mains 50Hz, Center 63Hz and all other rear channels including Sub at 80hz). I'm using a Balanced splitter on my two F113's from the Subout so it would be interesting to hear how my setup performs with the AUX inputs utilized instead. I ran it this way because the Subout channel would output all the channels' frequencies below their respective xover point, including the .1 sub channel. So in my conventional config, the main channels frequencies below 50hz would be sent to the sub, center channel below 63Hz sent to sub, rears 80hz etc, lastly .1 channel sent to sub entirely.
When utilizing the AUX channels and mains as XXL at say 50Hz xover, do you know if the other channels will function similarly to the setup mentioned above? For example, If the rear channels are setup as 80hz xover in this new config, will the 50hz-80hz frequencies be sent to the AUX (subs) or to the mains/AUX pairing? In the case of the latter, the mains would actually reproduce the 50-80hz range for the rear channels.
In any case, lots of experimentation is required as the documentation from Mcinstosh is lacking in this. Having to re-run Room Perfect is a definite pain!
The way I understand it is when setting speakers as xxl, they receive all crossed bass energy from other speakers plus .1 LFE. However, when using the AUX1/2 subs, all the xxl main's bass energy below the cross over point set in the AUX 1/2 settings is routed to the sub, so you are really not stressing your main if you have the cross's set appropriately. And again, it's a sloped cross, not a brick wall cross
The net effect is the subs are playing the bass energy and LFE at the crossover point (in my case, 50 hz, starting at 62hz I believe with the slope. It is recommended that the subs be close to the associated mains for optimal performance.
The tricky thing is you have to get the sub levels "correct", and its basically trial and error. But from what I can see, the 151 is not applying any level offsets to the aux subs, so if they are too low, for example, Room Perfect may cut the speakers too much to "match" the levels of the subs - in my case I was getting cuts of -14.5 db for my rears, which was too much - the range should be plus or minibus 12 db for optimal performance according to McIntosh. So I raised each sub even using the fathom gain control and a sound meter ( in my case about 3 or 4 db higher than the mains), ran room perfect again (minimum to get to 90%), saved the filterrs, and checked the offsets (you want to check the Bypass offset levels). If all the levels are less than + or - 12 db, you are good, and can add more room and focus positions.
For my fathoms, this put the gain controls around 9:30 or 10 o'clock...
To check the levels, I ran a sub test tone from spears and munsil 2nd edition, for the the left channel and then the right. Raise the master volume so you get a reasonable reading of the left main only (turn off the sub), then turn off the left main and turn on the left aux sub and measure. Initially, I tried making them equal, then the sub 3 db lower, and once I realized the the logic of what was happening, I went the other way and raised the subs 3 or 4 db above the mains and have not more the -9 db cuts.
So once the subs are in range, then room perfect and trim or pad the offsets for the speakers within the safe range...
Hope this helps - McIntosh doesn't make it easy in this regard...Edited by thrang - 5/22/13 at 12:34pm