B&W 805 - Rotel amp 100watts or 500watts?

[Minivan]

Hi guys,

I've got a Rotel RSX-1056 receiver with 100watts in 2-channel mode. Is this good enough for the 805's considering they are rated at 50-120watts?

I could power them with a Rotel 1092 500watts power amp also. Is this overkill? Or would the extra power be beneficial?

Any comments welcome.

Cheers

[mjb]

IMO.... a quality 100w amp is more than enough for 805's, a 1092 with 500w is overkill for this speaker. However, prepare yourself for a barrage of opinions advocating a min of 500watts. :roll:

The best thing to do is try it and make your own choice based on your listening tests.

[stuofsci02]

I am running my 804S off a 130 wpc Chord Amplifier... Sounds great! You should be fine with 100 wpc.

[Isaac]

I also use an RSX-1056 with 805s's. I am using the digital processor in the receiver so I can cutoff at 80hz. Sounds amazing. :T

[Minivan]

Excellent. So I can probably sell the Rotel 1092 power amp and the 1056 should suffice for the 805's.

I will demo it with both if I can.

Although I've been doing A/B tests tonight of both amp just on my B&W 685's and don't think I can tell the difference.

[audioqueso]

Hmmm... I can't say if it's the quality or the quantity because I've never tried two amps of the same brand with different power outputs. Meaning... I was starting to write that There is a big different (especially in the lower frequency range) when I've used a receiver (110watts) vs high power amps (Parasound 200watt & 250watt amp, Rotel 200watt, McIntosh 150watt, Emotiva 200watt)... having the really improved on the lower range and smoothed out the upper range.
HOWEVER... it could be that the quality of the receiver just wasn't up to the quality of the dedicated amps. I've never tried a, let's say, 100watt Rotel amp vs a 200watt Rotel amp to see if the 805's really improve over 100 quality watts vs 200 quality watts.

Do you currently have the 1092 with you to compare with and without it?

[Minivan]

Yes, I have both amps setup for testing.

At first, I thought the 500watt power amp sounded better, more detail coming through - as well as plenty of raw power there if necessary. But when I switched back to just the Receiver, I wasn't sure if I could tell the difference on some audio tracks. Almost like I was trying to hear more detail with the power amp to justify keeping it, but in many cases I think I was getting more detail.

I'm not sure if the B&W's can give much more than they are with the Receiver anyway, but I don't have the 805s for a test.

Will do some more testing, perhaps at higher levels to see how they compare.

[audioqueso]

If you don't have the 805 for testing... with what are you testing the receiver and the amp?

[Minivan]

For now I've been testing the two amps on B&W 685. Not in the same league as the 805's I know, but thought I should do A/B test to see if there's any difference.

The jury is still out. Doing some more testing today.

Some speakers are hungry for more current, does this mean they perform better with amps with substantially more power than the speakers are rated at?

If so, why? If the sensitivity of the 805's is the same as the 685's that is.

[mjb]

Some speakers are hungry for more current, does this mean they perform better with amps with substantially more power than the speakers are rated at?

If so, why? If the sensitivity of the 805's is the same as the 685's that is.

10 watts from a 100 watt amp has the same current as 10 watts from a 500 watt amp (with the same speaker, or load).

Are B&W speakers insensitive? No, they're not. The 802D is 89dB/WM, the 805 88dB/WM. With 10 watts, both will be very loud.

However, consider, a low power amp will be operating closer to its max output during normal listening, almost straining (clipping) on peaks. A higher rated amp will be operating much further away from its max output, and therefore not as prone to clipping on the peaks - therefore it will sound better. Amp design plays a big part, and a quality amp should be paired with quality speakers.

A But to say B&W are current hungry, I don't totally buy it.

Feel free to slam my theory :lol:

[Nolan B]

I dont think B&Ws are current hungry. With regards to the 805s, i heard them powered by a 60 watt Rotel in a room that is roughly 10x15 and thought they were playing just fine at sound levels I woulnt go higher unless I was having a party.

500 Watts is total overkill....what are they rated at...like 120?

[KahunaCanuck]

I run my 805s with my KW500 now, which has 500 watts. I like it!

I do think a "better" amp with more power will control the lower end better, but that is not to say a lower powered quality amp can't sound good. I think unless you can try them both in the same environment with the same speakers it will be hard to tell.

Have fun deciding! :B

[BlueSander]

@minivan: if you're in fact considering selling your 1092, please PM, I'm in the market for one. (just got a set of N802 and looking for better amp). I drove my N803 with the 1075 which is rated at 125 watts. If sounds good but lacking in detail is visible to trained ears. The problem is much worse now with the 802. I have been looking at 1080 but I don't think it will have the power for my 802 (a pair of 1080 then maybe, 1090 is out of the question due to its size). 1095 is cheap and powerful but it's like getting something in 1090 size with the power of 1080.

[Horacio]

Minivan,
I suggest you try tubes with your 805 and see how you like them. I replaced a Rotel RB1080 (200 Wpc) with a McIntosh MC275 (75 Wpc) to drive my 804S and couldn't be happier. Getting better quality Watts might do you better than getting more quantity.

[Horacio]

Sorry for the afterthought: I meant auditioning 805S with a tubed amp. Many McIntosh dealers also carry B&W, for example. Diving into tubes has been a one way trip for me. Now getting a tubed preamp. Thrilling synergy with 804S!!

[BWzes03]

Also, keep in mind that there is a difference in 'sound color' from the amps. Your receiver is a class A/B system, while the RB-1092 is a class D amp. While I haven't heard any of the class D Rotel amps yet, I would suspect a difference in the sound color, not just the power increase and the level of ease.