Axiom Home Page Forums General Discussion Advice from Axiom Owners Help - M60 & VTF-2 bass rollercoaster

Greetings all. This is a call to owners of the goods in the title of this thread - I know you're out there. Disclaimer - this is my first home theater so please forgive questions of the obvious.

I just received AVIA in the mail last night and had a chance to try to fine tune the sub placement, M60 placement and crossover settings. I'm finding I have some huge bass humps - over 10dB in some areas and the whole sub sweep varies roughly between 75dB to 95dB from top to bottom in some areas. I've got the volume set to output at 85dB, everything is crossed at 80Hz right now. Bumping up the M60s to 100 seemed to tame the humps a bit, but then I really seems to lose volumes below 60Hz. This really doesn't make sense to me. Do I just have the room from hell?

I'm really at a loss for how to attack the problem other than random configurations. I've tried Alan's infamous crawling technique, though the differences in locations were very subtle. I've realized I'm learning how to listen and what to listen for. I'd appreciate some input on how owners of similar gear have their's configured - crossovers and levels. I know my room is the critical factor, but I guess I'm looking for a rough starting point, I feel like I'm grasping at straws.

I have the M60's with a VTF-2 as well. I have the cross-over switch on the VTF-2 turned off and use only the crossover settings of my Rotel. I've set the crossover at 40 and 60, depending on what I am listening to. 80 is quite high to be matched with the M60's.

I'd also drop an email to Dr. Hsu. He's very good about getting back to people with setup issues.

Good luck...once you get it right, the M60ti/VTF-2 combo is SWEEET!

That's so true. Dr. Hsu, whom I've met it person (at CES 2003), seems to be one of the most accessible "subwoofer celebrities" in the audio business.

Thanks for the info. I've got the sub crossover off as well. I'd started at 80, well, because that's what everyone says to do.

If I recall the big bass hump comes in the 60-80Hz region so I thought if I lowered the crossover on the M60s I'd just make things worse.

At one point (pre AVIA - tuning by ear) I'd tried a lower crossover point for the M60s to address some localized bass (the sub is right by the couch) but I started over once I got AVIA and I could actually determine the output for a given frequency.

I've seem glimpses of greatness, I know once I get it dialed in it should be awesome.

I think if you lower the x-over universally, the M60s might handle the 60-80hz range more evenly than the sub. I'd try tweaking your x-over through the entire 60 - 80Hz range to see which point gives you the smoothest response. Just keep your level calibrations the same throughout the tests.

Toby,
As Peter mentions, you can crossover the M60s with a sub. I have my EP350 set to about the 50Hz mark or so (M60s set to large in the receiver options) and i've found a smooth integration with the main speakers (gain set around the 10 oclock mark).

Your other option is to set the M60s as 'small' in the receiver options and then turn up the crossover on the subwoofer all the way in order to allow the receiver's built in crossover (usually around 80Hz but some are changeable) to handle the switching duties.

Chess...the Hsu crossover is defeatable to allow the receiver's crossover to handle the duties. No need to crank it up on the Hsu.

Defeatable?
You mean if it is kicked a couple of times the crossover shuts off?

Does it have a switch? That would be quite a handy feature, and more appropriate.

First off, thank you all for the quick responses and input. This forum is an awesome resource thanks to the likes of yourselves.

Yep, as spiffnme mentioned, the VTF-2 crossover can be turned off via a switch so everything from the receiver is output by the sub. I'm running everything with an HK 525 so I can set the crossover point for each set of speakers independently. I know I'll need to do some tweaking, just looking for suggestions of the best road to go down so I can stop fiddlin and start enjoying!

Toby, I don't know that you can effectively do much tweaking, absent an equalizer to work on the bass frequencies. Bypass the VTF-2 crossover, set all speakers small on the 525 and cross all at 80hz. Unless your room is cubelike, the smoothest and strongest(so turn it down)response is with the sub in the tighter corner behind the speakers.