Question Power amplifier for B&W 683s2 using Denon X3400H

gazza01

Standard Member
I have had these speakers for a few months, I heard them at a show and bought a pair second hand, my room is not very big 4m x 5m, I listen across the shortest length, they are in the corners of the room pulled out 250mm from the walls, I can not put them anywhere else as it is my living room and they are a good sized speaker and my wife is already a bit miffed about their size. The Denon is an AV amp and quite warm sounding, in surround they sound great but with stereo I like a cleaner sound, without using Audyssey they sound very warm without too much punch, the Audyssey helps quite a bit but I would like a cleaner sound with more definition, I used to have an Audiolab 8000p amp but unfortunately sold it before getting these speakers, I would like to keep the speakers and find a power amp to help get the sound I am after, after suggestions. I don’t hate the sound, I generally enjoy it but think it could be better.
 

Ugg10

Distinguished Member
Rotel and B&W are often paired together, possibly because they are now part of the same group, but this may not apply to the older models. The rotel RB power amps can be picked up quite cheaply second hand and have good power supplies and most of the older ones can be bridged to use as mono blocks (only 8 ohm speakers though) at the flick of a switch (and connecting the speakers correctly). I had a pair of RB850's used with B&W CDM1SE's mono blocked (150W each) and this was a really nice set up.

The gem in the older series tends to be the 100w/channel into 8Ohm (200w/4ohm and 300W/8ohm bridged) RB870BX with its fully dual mono design (one circuit board per channel), large toroidal transformer and 20,000uF per channel but can tend to demand a price premium (but still a reasonable £150ish).

Rotels tend to be fairly neutral and generally have good power supplies so can handle dynamic swings pretty well.

You could also look at the RMB1066 (around £200-300 second hand) that gives you 6 channels of 60Wx6 or you can bridge the channels for 150Wx3 (8 ohm only) so you have the option to use this for your whole surround sound setup or just the fronts.

Finally, if you can get your hands on a RB1070 or even a RB1080 then this would provide a good bit of umph for the B&W's. (the later RB15xx series are quire a bit more expensive)

HOWEVER ....... generally the power amp has a lesser effect on sound tone/quality than the preamp section of the music chain, so if you are still using the Denon for your stereo sources then this may be what is causing your issues. You can look to get an integrated with HT bypass and then connect your stereo sources to that thereby removing the Denon form the chain. This is the usual way of adding stereo sources to the front speakers for stereo listening.
 
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Orobas

Active Member
Very much agree with Ugg10 on this one.. Rotel is an ideal partner for B&W and given their sound characteristics .. get's my thumbs up
 

gazza01

Standard Member
Rotel and B&W are often paired together, possibly because they are now part of the same group, but this may not apply to the older models. The rotel RB power amps can be picked up quite cheaply second hand and have good power supplies and most of the older ones can be bridged to use as mono blocks (only 8 ohm speakers though) at the flick of a switch (and connecting the speakers correctly). I had a pair of RB850's used with B&W CDM1SE's mono blocked (150W each) and this was a really nice set up.

The gem in the older series tends to be the 100w/channel into 8Ohm (200w/4ohm and 300W/8ohm bridged) RB870BX with its fully dual mono design (one circuit board per channel), large toroidal transformer and 20,000uF per channel but can tend to demand a price premium (but still a reasonable £150ish).

Rotels tend to be fairly neutral and generally have good power supplies so can handle dynamic swings pretty well.

You could also look at the RMB1066 (around £200-300 second hand) that gives you 6 channels of 60Wx6 or you can bridge the channels for 150Wx3 (8 ohm only) so you have the option to use this for your whole surround sound setup or just the fronts.

Finally, if you can get your hands on a RB1070 or even a RB1080 then this would provide a good bit of umph for the B&W's. (the later RB15xx series are quire a bit more expensive)

HOWEVER ....... generally the power amp has a lesser effect on sound tone/quality than the preamp section of the music chain, so if you are still using the Denon for your stereo sources then this may be what is causing your issues. You can look to get an integrated with HT bypass and then connect your stereo sources to that thereby removing the Denon form the chain. This is the usual way of adding stereo sources to the front speakers for stereo listening.
Thanks for the informative reply, I will keep my eye open for the amps in the normal places, the HT bypass could be more like the better answer, although I am unaware of this option, I will have a google.
 

Ugg10

Distinguished Member
Another to look out for would be the Quad 606/707/909, these are all derivatives of the Quad Current Dumping topology and are rated at 140w per channel and have power in reserve.

The 606 is typically around £400, the 707 doesn't come up often and the 8909 being the newest is usually around £500 mark (all second hand).
 

Orobas

Active Member
Quads are quite a bit more coloured than rotels though Ugg10 .. not quite as neutral.
 

Ugg10

Distinguished Member
Agree but mainly in their Preamp’s, less so in the power amps, I think these are the best of the bunch and will drive most speakers well.

Rotel and Audiolab are probably the best of the bunch for neutrality.

Be useful for the OP to give a budget and new/second hand direction.
 

Orobas

Active Member
I'd concur with just the addition of one other.. the Cambridge Audio 851W power amp.. this thing is a beast of gem... sonically wow but erring very warm tonally and at some £800 more than the 909 is a heart clutching proposition... I'd usually point at the roksan but they do not partner well with B&W .. they show too many weaknesses with the b&w's
 

gazza01

Standard Member
To be honest, I have not really thought about a budget, I was after advice on if it would improve the sound, it would have to be second hand and ideally around £200, I was unaware that the pre amp would have such a significant effect on the sound, so I am unsure of which route to take.
 

Orobas

Active Member
At that budget.. i'd say you'd have to stick with the rotel option... i am not sure, and hoping Ugg10 might be able to shed some light on this.. if a NAD power amp would be suitable for one of their higher end stuff 2nd hand as they tend to be cheaper than rotel.. say their... 214 which you can pick up for around £180 these days
 

Ugg10

Distinguished Member
I’ve only had experience with a Nad preamp (1240) which I fed the rb850s with. It had a very good phono stage but tone wise it boosted the bass but lacked control, all a bit flabby especially compared to a the Rotel RSP1066 which was a surprisingly good stereo preamp/dac or my passive preamp (mpatch v2). Not sure about the power amps but the 216 (iirc the model number) got decent reviews.

£200 would get you a good condition 870bx if one comes up or possibly an 8000p that you used to have.
 

Orobas

Active Member
I’ve only had experience with a Nad preamp (1240) which I fed the rb850s with. It had a very good phono stage but tone wise it boosted the bass but lacked control, all a bit flabby especially compared to a the Rotel RSP1066 which was a surprisingly good stereo preamp/dac or my passive preamp (mpatch v2). Not sure about the power amps but the 216 (iirc the model number) got decent reviews.

£200 would get you a good condition 870bx if one comes up or possibly an 8000p that you used to have.
Thanks Ugg10 .. never been too sure what to make of the Nads! it was just the price that made me think of them. but thanks for the heads up. helps me out for sure for future :)

just looked up the 216 and yeah i think we can leave the nad out of the equation.. described as a clunker.. bright and bass heavy
 

Ugg10

Distinguished Member
This would probably do the job if you are close enough to collect. RB980BX, 120w per channel into 8 ohms, 20000uF per channel.


Review - http://www.rotel.com/sites/default/files/RB-980BX HPreview 92.pdf
 

gazza01

Standard Member
I’ve only had experience with a Nad preamp (1240) which I fed the rb850s with. It had a very good phono stage but tone wise it boosted the bass but lacked control, all a bit flabby especially compared to a the Rotel RSP1066 which was a surprisingly good stereo preamp/dac or my passive preamp (mpatch v2). Not sure about the power amps but the 216 (iirc the model number) got decent reviews.

£200 would get you a good condition 870bx if one comes up or possibly an 8000p that you used to have.
Yes the 870bx or 8000p seem like good choices but I am now concerned that my Denon AVR will have too much influence on the sound? I’m guessing the only way to be sure is to buy one try it, or would I be better with a 8000s or something similar but worried it could be a little under powered?
 

Ugg10

Distinguished Member
There is a couple of “cheats” that can be done.

Ideally you would have the surround sources (satellite, dvd, blueray, tv etc) connected to the avr and the rear, centre and sub running off that. To the front pre-outs you connect an integrated stereo amp via the ht bypass input. Into the stereo integrated you then connect stereo sources (cd, tuner, cassette, turntable streamer, dac etc.). In surround mode you set the integrated to the bypass input which turns it into a power amp, re run the room eq / surround setup and use it normally as an avr. For stereo turn off the avr and use the integrated with the stereo inputs.

Unfortunately stereo amps with ht bypass tend to be the upper end models so are expensive.

However, with non ht bypass integrated you can either get a speaker switch (two in one out) to switch the input to the front speakers between the avr and integrated, or set up as above and return the volume control to the same point (where set up/calibrated) when using the avr, easier if you have a digital volume display in either dB or numbers.

The rotel ra03 is a bit of a sweet spot in the newer integrated or the ra1060/1062 would be good if you can find one at the right price.

This option open things up a bit but will depend on what sources you use.
 
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gazza01

Standard Member
Thanks for the suggestions, I will consider my options, I realise that the speakers are likely too big for my room but am sure it can be remedied partly by a neutral amplifier.
 

Ugg10

Distinguished Member
You can always play around with bunging up the port with rolled up socks to try and tame the bass. Originally iirc they came with foam port bungs for this.
 

gazza01

Standard Member
HeHe, I do have the original bungs, I initially needed them, but since moving the speakers it appears I dont need them, but could be worth another look.
 

b1g1an

Well-known Member
Yes the 870bx or 8000p seem like good choices but I am now concerned that my Denon AVR will have too much influence on the sound? I’m guessing the only way to be sure is to buy one try it, or would I be better with a 8000s or something similar but worried it could be a little under powered?
I've just added a power amp to my 3500 and the results are excellent, although it's a 5 channel bought because the amp was struggling running 7 speakers, the change in 2 channel music run in Direct mode is amazing. My R300s have really come to life, much bigger soundstage, more detail... More musical!

Others have reported the same adding power amps to Denon AVRs with power hungry speakers even though popular opinion is it's the pre amps are most at fault as stated above.
 

gazza01

Standard Member
I've just added a power amp to my 3500 and the results are excellent, although it's a 5 channel bought because the amp was struggling running 7 speakers, the change in 2 channel music run in Direct mode is amazing. My R300s have really come to life, much bigger soundstage, more detail... More musical!

Others have reported the same adding power amps to Denon AVRs with power hungry speakers even though popular opinion is it's the pre amps are most at fault as stated above.
Hi which power amp are you using?
 

gazza01

Standard Member
I am a fair bit happier with the sound of my system at the moment, I pulled the speakers further out from the corner around 70mm, probably the furthest I can get them out the corner without them looking silly and upsetting my wife any further, I re ran the Audyssey set up and it improved the sound, I have found I prefer listening with the Audyssey MultEQ xt32 on but without the dynamic EQ on, the bass is controlled without any boom and better imaging, I still will likely add an amp of some sort to try to improve the dynamics.
 
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