Originally Posted by Alan P
See my link to AustinJerry's awesome guide a couple posts up. I wish I would have had that guide when I got my MiniDSP a couple years ago.
It's the clipping that's getting me I think. Just have to measure my pre-out voltage and I should be good to go.
OK, so last night I measured my AVRs output voltage on the sub pre-outs...something very strange is going on I think. I need to confirm with AustinJerry, but this can't be right.
Following Jerry's MiniDSP guide here
, the idea is to get your output voltage at .9v or lower so as not to clip the 2x4 unbalanced MiniDSP inputs (limited to .9v for Rev. A and 2.0v for Rev. B, easily changed with a jumper).
I didn't measure .9v until both sub trims were set to -12db (the lower limit on my Denon 4520)!
I also checked to see where the sub trim would have to be if I switched the jumper for 2.0v input...that was at a sub trim of -6.5db where I saw 1.9v. I know that Jerry also has a 4520 and he got .9v at -4.5db. Now, I'm not sure if it matters at all where the sub trim is set in the AVR, but -12 seems a bit excessive....and I just don't like running things at the "max" setting of anything. I could swap the jumper and use -6.5 sub trim, but not sure if it will make any difference.
Anyways, after setting both sub trims to -12 and adjusting gain on the subs to get back to the SPL level I was at before (went from about 12:00 on the gain knob to about 3:00) I did some more compression sweeps (although I can't show them to you because my laptop crashed while saving the file
). I gained a little bit more headroom, got up to 112db without significant compression. I should be able to get more from the T-18s, but I'll be damned if I know what to try next.
I might try moving them around some, but the back of the room really is the only place these beasts can live. FYI, I have
tried a few other locations (one front/one rear, both front, one rear/one sidewall) and the both in the rear of the room has always provided the best response. They are currently in the back corners, I may try moving them away from the corners again and see what I get.
I believe Alan has listened to his setup for the better part of 6mo without tinkering.
I did, and I was happy! Damn you for trying the MiniDSP again and being successful.