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#72436 - 12/04/06 09:16 PM 1070 and difficult loads
Jay_S Offline
Deputy Gunslinger

Registered: 12/03/06
Posts: 1
Good evening all,

I own a pair of 4 ohm 86 db "efficient" magnepan MMGs, and need to purchase a new amp. The 1070 certainly has huge bang for the buck appeal, but I'm concerned about its ability to drive these speakers at levels I'm used to. I currently have an Acurus A250 with a dying/dead left channel. I love the headroom afforded by this much power and regret having to replace it.

This is all in a spare bedroom that I have converted into a small front projection home theater. Right now all audio is stereo, but I want to transition into surround and multi-channel audio. However, I think that 7.1 may be unneccessary given my room size (10x12 ft). 5.1 should be plenty.

* Can I use 4 channels of the 1070 to biamp? * I have outboard electronic crossovers, but if this could be done internaly - all the better. If this is not a current option, it seems like an easy option to add in software. Give users the ability to have either 7.1 full range or 5.1 with the L/R mains biamped using internal crossovers.

But back to my main question: how's the 1070 on difficult loads?


#72437 - 12/27/06 03:10 PM Re: 1070 and difficult loads
Cybermynd Offline

Registered: 11/21/06
Posts: 45
Loc: Regina, Canada
I don't think you could classify 4ohms as particularly difficult. The 1070 has a 4/8 switch and I suspect you get closer to 100wpc with 4 ohms. My speakers are 6 ohm and the 1070 is set to 8 but I haven't had a chance to drive them into nosebleed levels... yet. Some of it would depend on offloading the low frequency signals to a sub and then setting the Xovers appropriately. If set the main speakers to cross over at 80Hz or something most of the 1070 amplifier power would be driving upper frequencies and wouldn't need the stump pulling power that pumping out 35Hz would require.
I think my Wharfdales are only 93db efficient and in my 12 x 20 listening room it seems to get pretty loud although I haven't got my db meter yet... ;-)
1070, Arcam CD73T, Pioneer DV46-AV, Project Xpression-Grado Red-NAD PP2, Monster HT1600, Wharfedale 8.3 Diamond, Mirage OM200 sub, Omnisat Micros x 5, homemade speaker cables, Dell Axim 51v remote

#72438 - 12/27/06 05:46 PM Re: 1070 and difficult loads
gonk Offline

Registered: 03/21/01
Posts: 14054
Loc: Memphis, TN USA
Receivers are not generally good at 4 ohm loads - few are even rated for 4 ohms. The MMG's are popular speakers, so it's very likely that somebody around here has run them with the 1070 or with the older 1050 (which had comparable power output).

You cannot bi-amp using the 1070's internal amps. The 1070's internal crossovers are designed solely for bass management, and trying to incorporate something into the software that would let folks try to replicate speaker crossover networks for active bi-amping would be a really nasty can of worms to open (way too many variables). The best bet for bi-amping is to do it externally - send the left and right pre-amp outputs to your outboard crossovers and from there to four channels of amplification.
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