Questions for 1075 amp owners

[bleeding ears]

Hi guys, just a few quick questions on the 1075 amp.

1) Is it acceptable to use a combination of 4 ohm and 8 ohm speakers with this amp? I have 8 ohm fronts and centre and 4 ohm rears.

2) Does the 1075 amp get very hot after a good workout (high volume) with 4 ohm speakers all round ? I could end up with 4 ohm speakers all round.

3) Anyone bi amping their fronts with the 1075 and how does it compare to using say a 1080 amp ? ( I use a rb 990bx for fronts, which is pretty much the same as a 1080, I think)

Just pondering the advantages of the 1075 amp over my current setup.

Any 1075 owners have experience with any of the above ?

Thanks Pete

[gianni]

Hi guys, just a few quick questions on the 1075 amp.

1) Is it acceptable to use a combination of 4 ohm and 8 ohm speakers with this amp? I have 8 ohm fronts and centre and 4 ohm rears.

Yes you can. It is easier on the amp than running all 4 ohm speakers. However, even running all 4 ohm speakers is no problem for the 1075. In fact even lesser Rotel models such as the receivers can do this. I believe the THX Select spec allows for mixed impedance speakers (although 4 ohm front and 8 ohm rears) to make the load receiver friendly.

2) Does the 1075 amp get very hot after a good workout (high volume) with 4 ohm speakers all round ? I could end up with 4 ohm speakers all round.

Like any amp the harder you drive it and the tougher the load, the warmer it gets. The 1075 does not get unusually warm given decent ventilation.

3) Anyone bi amping their fronts with the 1075 and how does it compare to using say a 1080 amp ? ( I use a rb 990bx for fronts, which is pretty much the same as a 1080, I think)

On this one, I have no idea.

[mjb]

1. yes.
2. no, although subjective.
3. a 1080 is more authoritative (despite the 1075 having a THX cert).

I upgraded from a 1075/1080 combo to a 1077, and honestly, the 1077 is amazing. It doesn't care about loads, runs very cool, is incredibly small and efficient, and its got 7 channels. If you're planning an upgrade, a 1077 is definitely one to try.

[bleeding ears]

gianni, thanks for the reply, I thought the 1075 would be ok, but just wanted some reassurance.

mjb, did you try the 1075 biamped against the 1080 ?

With 4 ohm front speakers biamped, the 1075 should give about 400 watts to each speaker. The 1080 with 4 ohm speakers would give only about what ?
300 watts per speaker?

I assume you were bi amping the fronts with the 1077 and using the other channels for centre and rears ?

Pete

[csuzor]

I have a 1075 biamping 703 fronts, they dip to less than 4ohm at some frequencies. The difference with biamping was obvious, the high frequencies could break free and sound more natural, and the very low frequencies were better controlled. I have not compared to 1080 single amp.

My 1075 gets very hot.

[Martinf]

FWIW, My -1075 is running to 8 ohm speakers and rarely breaks sweat at all.
b.t.w. I didn't think that you could "bridge" the 1075 in the way one can with the stereo Rotel amps.

As for the RMB-1077 which uses pulse-density modulation (PDM), it is no good for hi-resolution music (e.g. DVD-Audio), as it is severely bandwidth limited, whereas the -1075 goes all the way up to 100kHz.

[mjb]

10-80KHz vs. 15-100KHz is not exactly what I'd call "severely bandwidth limited"! But, whether it's good enough for for hi-res music is I suppose a matter of taste.

@ Pete: I'm not a fan of passive bi-amping, so I've never tried it with either amp. Sorry.

[Martinf]

When you look at spectral noise -- even just above 20kHz -- the 1077 doesn't look good.

But the -1075 is pretty clean all the way out 100KHz.

[hugexpat]

1075 bi-amp vs 1080

Hello

I run thru a RSX 1055 one 1075 bi-amping my fronts.
In line with his post, I was wondering whether a 1080 would do better?

Has anyone made this comparison?
Thank you for answering
Happy New Year

Hugues