View Full Version : New amp for B&W 703's
Stewrt
10-11-2005, 04:17 AM
Find that my B&W 703's are a lil more bright and forward than I would like. Have them hooked up to a B&K Ref 200.2 via Audioquest CV6 and CV4's (Bi-wired) CV6's on base end. Using a Denon 3803 as my pre.
Have a question about MFG's recommended power handling as well. B&W says "50W – 200W into 8Ω on unclipped programme". Well what happens if I throw 250 or 300 into it? Was thinking like a Bryston 4B SST PRO, or 6B SST PRO 4B giving me 300 watts into 2 channels or 6B giving me 250 into 3 channels. Reason for the 3 channel option is that my mains kinda overpower my center sometimes during movies. Have the HTM7 as a center. It's only rated to 50 to 120 watts.
Dampening factor difference is 400 with the B&K and 500 with the Bryston.
I've been told that you can never throw enough power at a speaker, only under power it. So what is with rated handling #'s by mfgs?
Does anyone recogmend anything besides the Bryston? Tubes? or?? When I do this around X-mas I should have about $3000 to spare. (should I spend more on an amp than I did on the speakers?)
Thanks for any and all help and advice.
Stewrt
Feanor
10-11-2005, 05:24 AM
...
Have a question about MFG's recommended power handling as well. B&W says "50W – 200W into 8Ω on unclipped programme". Well what happens if I throw 250 or 300 into it?
....
I've been told that you can never throw enough power at a speaker, only under power it. So what is with rated handling #'s by mfgs?
...
It does not harm to use a amp with more, even much more, power than the makers "maximum" rating. The extra power can help to provide the full dynamics of the recording. But note you shouldn't expect to use the full output of the amp at typical volumes -- if you did throw 300 watts continuously at a speaker rated for 200 watts you would likely damage it; use your volume control judiciously.
A 300 watt amp will give you 3decibals more volume than a 150watt amp and 3 decibals is barely audible. And of course if the speaker cannot handle "long term" power at 300 watts which the B&W's cannot then you will not even get the 3decibals -- you won;t get anymore significant dynamics or dynamic headroom either.
More power also tends to mean more negative feedback and also means that chances are the amp will be running in class b more of the time.
In the 1970s and early 1980s good amplifiers (not receivers) it was considered that if an amp was 30 watts it was a genuine beast. Marketing has claimed more of the "let's base amps on watts than sound quality" since that time.
The B&W's don't need morethan 50 watts and B&W is probably only requiring that thinking some will use insufficient amps like receivers that have notoriously terrible power supplies.
Bryston in many quarters is already considered a bright power amplifier so your problems may actually get worse with Bryston. Note the Brystons are good but they are better suited IME with something other than B&W.
I would do a lot of research to figure out 4-5 amp cd player combinations with the B&W's that people like -- don't worry about watts get a quality amplifier that can handle impedence swings well (more important than watts). Try and stay away from lean sounding amps like Bryston -- Perhaps something considered a little richer or thicker sounding.
post on audioasylum.com as well.
topspeed
10-11-2005, 08:37 AM
Well Stew, I feel your pain. If you look at my profile, you'll find our rigs are very similar, although I run the progenitor to your 703's. In my rig, the problem wasn't an aggressive top end, it was a general flatness whereas the music was simply lifeless. I remedied this by adding a two channel amp.
Both NA and RGA are right about the watts, they are overrated. What you are looking for is current and the ability to deliver it quickly, this will manage the impedence swings. The 703's were designed with a different motor structure in an effort to make them easier to drive than my notoriously difficult CDMNT's, so finding the right amp should be an easier exercise than the one I endured. I'd recommend you follow RGA's advice and audition a ton of amps as I did. You'll have far more options with two channel amps, but if you listen to a lot of MCH hi-rez, I can see the benefit of buying a 3 channel. Keep in mind however, if you use a 2 channel, you'll be relieving the 3803's power supply the monster task of driving those 703's, so I wouldn't be at all surprised if in turn it had more than enough to properly drive the HTM. If your system is properly calibrated and the mains are still overpowering the center, it's probably in the mix and an additional channel of amplification won't change that.
If you are looking to warm up the sound a bit, I'd recommend amps from Rotel, Cary, BAT, Aragon, Parasound Halo (not HCA), ASL, Bel Canto, and PS Audio. You might also consider used amps from audiogon.com in which case you could also consider Threshold, Pass, ARC, CJ, or some of the bigger BAT's.
Good luck and enjoy your search. Hope this helps.
nightflier
10-11-2005, 12:53 PM
If you are looking to warm up the sound a bit, I'd recommend amps from Rotel, Cary, BAT, Aragon, Parasound Halo (not HCA), ASL, Bel Canto, and PS Audio.
While these are all great brands in their own respect, I don't think all of them are good options; in particular the Rotel, Aragon, Parasound or PS Audio will likely sound brighter or at the least similar to the B&K. I would suggest that maybe your receiver is responsible for the bright edge that you are trying to eliminate. Again, the Denon is a fantastic receiver, but it is a bit bright as well. Have you tried substituting a preamp? A nice Jolida or Cary preamp would do wonders, here.
Agree with Topspeed on the starting point for your audition list -- if it is for two channel then the tube amps mentioned from ASL may work nicely -- As well as Jolida (possibly one of their hybrid amps with tube pre and ss power. They come in pretty beefy versions and dont seem very expensive - best is to try the all tube version first and if it gets winded in the low bass and upper treble then look the hybrid.
http://www.divertech.com/antiquesl.html
Jolida http://www.jolida.com/catalogue/index.shtml
Some other Jolida and all prices http://www.vacuumtube.com/vacuum.htm
To give you some perspective of power needed I have heard the 705 with my OTO a 10 watt (and this figure is a little generous as it's probably closer to 6 watts per channel) drive the 705 very well. As well as a bryston Pre/power separates combo at least to levels that are normal. In a big room more power would be nbecessary but then the 705 should never be put in a big room anyway.
The Jolida/ASL amps have substantially more power the B&W is around 90db sensitive and they state a minumum 3 ohm impedence -- 30 watts would do the trick.
Two of the Jolida's that get the most attention are the 302B and the 1000A http://www.vacuumtube.com/JD%201000A.htm
Of course tubes need to be replaced -- so it is wise to consider which tubes an amp takes as some are less costly than others. EL34s and EL 84s range from $10.00 to $20.00 a pair. Preamp 12AX7 and 12AT7 around $7.00 to $10.00 Each. My amp is rated for 8000 hours on the tubes - not sure what they rate these ones for but they are basically like light bulbs. Preamp tubes could last you ten years or more while the power tubes with say an average of 10 hours a week listening could last you 4 years. Depends on how much you listen.
My dealer had the Jolida 1000A as a trade in and it is a massive amp weighing in at more than 50lbs. - kinda ugly though but they make nicer looking ones like the 302 and the 801 is really sexy. Have not heard the 801 but looks great and has enough watts http://www.vacuumtube.com/JD%20801A.htm
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