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Need a power amp for b&w nautilus 804

post #1 of 17
Thread Starter 
I recently switched to a linn majik dsm as my integrated amp and digital streamer. Huge upgrade from my prior setups(arcam, marantz and anthem) for music.

However I feel the mdsm internal amps can run out of steam at moderately high volumes. Linn allows the internal amps (50wpc 8ohm) to be disabled for better sound so I'm thinking of getting separate power amps. Budget is at most 5k but ideally more like 3k.

Ones I am consider are below. Unfortunately I can't audition any of the below at home with the n804.

Linn akurate 4200 (bi amp)
Bryston 4bsst2
Nuforce 9 (not se) pair
Wyred 4 sound 500 monos
Mcintosh mc302

Would love to hear if anyone had any experience with any of the above amps and the older 800 series. My speakers are almost 8 years old and keeps sounding better to me. Until the linn I had no idea they could sound so good! Now i want to try to get the best out of them.
post #2 of 17
I have the Bryston. t's a very cool amp, and drives my WATT Puppies. I certainly wouldn't spend any more money on an amp to drive 804s. I also have B&W 801s, but drive them an Adcom GFA 555 MK II. It's plenty. What is the sensitivity of 804s?
post #3 of 17
Quote:
Originally Posted by akhter View Post

I recently switched to a linn majik dsm as my integrated amp and digital streamer. Huge upgrade from my prior setups(arcam, marantz and anthem) for music.
However I feel the mdsm internal amps can run out of steam at moderately high volumes. Linn allows the internal amps (50wpc 8ohm) to be disabled for better sound so I'm thinking of getting separate power amps. Budget is at most 5k but ideally more like 3k.

The B&W 804 are 90 dB/W speakers (fairly efficient) with a max power rating on the order of 200 watts.

Your existing amps put out 17 dBW so peaks on the order 110 dB SPL (a reasonable goal for lifelike reproduction) are outside your capabilities in a reasonable room with a reasonable listening distance.

You could probably significantly increase your system's capabilities for clean sound by adding a competent powered subwoofer. This would have significant other benefits such as an increase in clean sound at lower volumes and an increase in bass extension at any loudness.

The Bryston amplifier with about 200 wpc is only 6 dB louder than what you already have, so its audible benefits are likely to be relatively small, and of course would only be audible if you crank 'er up

If you want your system to play say twice as loud cleanly, a 500 wpc amp would be indicated. I think that for short peaks, you could use this amount of power without damaging your speakers.
post #4 of 17
The Bryston 4B SST2 is nominally at 300WPC into 8 ohms, but that's a conservative rating. My example tests 330WPC. I don't know how to calculate the predicted SPL with that power level, but I don't think you'll crank it in a reasonably-sized room and be able to tolerate it for very long driving 804s. I agree that those speakers would benefit from a powered sub.
post #5 of 17
Thread Starter 
My b&w n804 (old model) are 89 db/w but I don't know how to calculate anything from that. Wyred4spund gets me to 500wpc for about 2k which is tempting.
post #6 of 17
Quote:
Originally Posted by akhter View Post

My b&w n804 (old model) are 89 db/w but I don't know how to calculate anything from that. Wyred4sound gets me to 500wpc for about 2k which is tempting.

Estimating SPLs from power and speaker sensitivity is based on adding the sensitivity of the speaker in dB/watt to the power output of the power amp in watts expressed in dB.

Watts are converted to dB using the standard equation which is 10 times the Logarithm of the power. So, a power amp that puts out 1 watt is 0 dB, a 10 watter is 10 dB, and a 100 watter is 20 dB. 500 watts is 27 dB. So you add 89 to 27 and you get 116 dB SPL 1 meter from your speaker.

There are 2 speakers so you add 3 dB to get 119 dB at some imaginary point that is a meter from each speaker and on-axis to both. From there to actual SPL at your listening room is as much magic as science, but it is for sure less than 119 dB. Hey, it is an estimate.

I'm not a fan of Class D power amps because they are sensitive to the speaker load at high frequencies. I am a fan of Crown and QSC.
post #7 of 17
Quote:
Originally Posted by Jon Middleton View Post

The Bryston 4B SST2 is nominally at 300WPC into 8 ohms, but that's a conservative rating. My example tests 330WPC.
The difference between 300 and 330W is 0.4dB
post #8 of 17
Thanks, Arny. So, my estimated SPL for the WP 5.s with the Bryston is ~118dB, while for the 801/Adcom 555 MK II system it's only 110dB. Even 110dB is pretty loud.
post #9 of 17
91dB for the WP5 (from SP) and 300W (24.8dBW) is 115.8dB at 1m, but you won't be listening at 1m, more like 4m. 4m will give a free space loss of 12dB, but in a real room, probably half that, say 109dB at the LP
post #10 of 17
Quote:
Originally Posted by A9X-308 View Post

91dB for the WP5 (from SP) and 300W (24.8dBW) is 115.8dB at 1m, but you won't be listening at 1m, more like 4m. 4m will give a free space loss of 12dB, but in a real room, probably half that, say 109dB at the LP

Yep, in that neighborhood. The figure I saw was 93dB/W/m:

http://www.stereophile.com/content/wilson-audio-wattpuppy-system-5-loudspeaker-specifications

330W gives 25.1, which is where I got the 118dB. But I see on the next page of the review SP says they calculated 91dB/W/m. Doesn't matter much, my hearing is bad enough already that I won't listen beyond a comfortable level. I have another question. I run an M&K V125 sub in that system. How does that change SPL?
Edited by Jon Middleton - 7/28/12 at 11:43pm
post #11 of 17
Quote:
Originally Posted by Jon Middleton View Post

Yep, in that neighborhood. The figure I saw was 93dB/W/m:
http://www.stereophile.com/content/wilson-audio-wattpuppy-system-5-loudspeaker-specifications
330W gives 25.1, which is where I got the 118dB. But I see on the next page of the review SP says they calculated 91dB/W/m. Doesn't matter much, my hearing is bad enough already that I won't listen beyond a comfortable level. I have another question. I run an M&K V125 sub in that system. How does that change SPL?

A good sub generally increases the system's SPL capability, sometimes very significantly.
post #12 of 17
Actually, I use the 3B-SST2, and I think it has plenty of power for your system. I think it actually sounds a little bit better than the 4B, but the difference is small. It is certainly an excellent amplifier.

Another excellent power amplifier is the Vincent SP331MK, which is only $2500 and would be very nice.

I use the NHT B12D subwoofer, and I recommend it highly.

It is VERY VERY clean and has power to spare.
Edited by commsysman - 7/30/12 at 5:32am
post #13 of 17
Thread Starter 
Quote:
Originally Posted by commsysman View Post

Actually, I use the 3B-SST2, and I think it has plenty of power for your system. I think it actually sounds a little bit better than the 4B, but the difference is small. It is certainly an excellent amplifier.

Another excellent power amplifier is the Vincent SP331MK, which is only $2500 and would be very nice.

I use the NHT B12D subwoofer, and I recommend it highly.

It is VERY VERY clean and has power to spare.

What speakers are you using with the 3b? The bryston dealer recommended the 4b for my speakers. Unfortunately a sub is not an option for me for various reasons.
post #14 of 17
You won't hear a difference between the 3B and 4B unless you clip the 3B. They will sound identical below clipping. Depending on your room and how loud you like music, the 3B could well be plenty with the 804s. I turned up my 200WPC Adcom the other day way up, and it didn't clip driving my 801s (87dB/W/m) to a very high SPL. I don't have a meter, but my dog left the room.wink.gif I chose the 4B because it wasn't that much more than the 3B, but is twice as powerful.
post #15 of 17
A power amp that costs more than the speakers (c$4.5k now vs. $3.5k in 2001) let alone the whole pre- and power combo goes against common sense and general wisdom. I don't necessarily dispute 50W is a bit under-powered but 300W is way overkill. Apart from brand adulation and pride of ownership I can't justify it over say a pair of Emo if you need more power. A 150WPC amp was more than enough for my N803s (now using 175W mono). Your Bryston dealer must be loving you. biggrin.gif
post #16 of 17
Hi,

I have been through exactly what you are doing now (albeit with not as nice speakers; B&W 683s instead) and I went from the internals in my DSI (same thing as a DSM just renamed unless you have the HDMI one) to a second hand 4200 bi amping. Massive improvement, although I didnt demo anything else as I wanted a box to match my DSI. Since then I have tested the 4200 against Cyrus Mono X200s and the Linn was miles better. Oddly enough I have just sold my amp (trading it for a 2200 plus money, I sold by 683s and bought B&W XT8s which cannot be bi amped) otherwise I would be trying to sell mine to you! I have also heard the Classe amps go well with B&W being t more or less he same company and all!

On the 4200 note, especially with your speakers being power hungry, make sure you get one with Dynamik if you are looking second hand, they can struggle without it.

Tom

Sent from my ASUS Transformer Pad TF300T using Tapatalk 2
post #17 of 17
Thread Starter 
I do have the hdmi dsm with dynamik from factory. Pretty happy with the sound so will not add any amp next few months.

Tried a dynamiked 2200 and the bass seemed tighter but it was very subtle. Want to try some other brand amp. Maybe nuforce or Bryston next.
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