Sub with "Large" floorstanders - good or bad idea?

Mr Incredible

Distinguished Member
Apologies in advance for the Sunday afternoon ramble!

Some of you may recollect a number of my posts in which I extolled, some may say gloated (!), the in-room response I was getting from my B&W 604s3's, excepting for a huge room suck-out as you can see.

604s3.jpg


Bi-amped 3805
Recently I purchased a Denon POA-T10 power amp to work in tandem with my 3805's amps to bi-amp the front. Other than running auto setup for levels and distances, I haven't re-run any frequency plots in the Room Eq Wizard. The set up has been working very well and the only niggle I have is that the older power amp does not appear to have specifically a 12v switch that I can hook up to the receiver to be automatically turned off and on. As a result I have accidentally left it on all night, doing no harm except to my electricity bill and carbon emissions.

Multiple "sources"
Being a relative n00b to home cinema and not knowing which interconnect would provide the best results, I plumbed in my 2900 with Coax, Optical and of course 5.1 analogue for DVD-A/SACD. I assigned "DVD" to Coax, CD to Opt1 and CDR/Tape to EXT-In so it is easy to flick between and compare. At Christmas Father Christmas brought me a Pinnacle Showcenter for streaming music, films etc off my PC. Also as a comparator I have the same source on the Showcenter and DVD/CD and often do comparisons between all variants.

Large vs Small with and without (EQ'd) sub for music.
Still on this apparently never ending journey to perfection, and notwithstanding I have just got a new toy to play with, I've also been dabbling with the 3805 in different configurations in terms of Large vs Small speaker set up, and with and without the EQ'd sub in the equation for listening to music. Hence my recent "discovery" of the Blue Man Group's materials. Although it is clear that a sub is needed for movie material, I was not sure whether I was squeezing the best out of my set up as far as music was concerned, even multi-channel music at that.

Familiar material
It is only over time and with knowledge of your favourite material that one can really sit down, close ones eyes and listen to nuances in what you hear. So with that in mind I have been re-visiting Pink Floyds' "Wish You Were Here", track 1, Shine on you Crazy Diamond. There are some really low notes a couple of minutes into the track; low, powerful and yet controlled and understated. Although I have the 2 track Cd version I also have the multi-track DTS version which I think has some good LFE reinforcement in places. So it is that which I have been listening to now for over a week, including a DTS streamed via the Showcenter.

Subjective results
Whatever combination of Large vs Small speaker setup, with and without the sub and with or without LFE + Mains, it became clear to me that although the 604s3s can low, they go low with no EQ in place. As a result the lower end appeared to be quite loose and a tad boomy, but obviously not as boomy as an un-EQ'd sub. Even with the speakers set to small and an 80Hz XO, I was not entirely sure I was getting the best I could. But to be honest as I had EQ'd the sub to the best level I could get, and everything else appears to be working as designed I'm not sure what else I could do.

The "Floyd"
Last night I again sat down to listen the Floyd but decided I'd break out the DVD for some more Coax/Opt/Ext-In comparisons (I need to get out more!). Just as an aside the Denon 2900 analogue output is sublime and with the Denon in Pure Direct mode on EXT-In for all 5.1 channels, the sound far surpasses that which is produced via a digital link using the 3805 to process the source. I digress.

So I put on the DTS source in the 2900 and sat back to enjoy another few re-runs of track 1. :eek:

All of a sudden when reaching the low notes which are equally felt as they are heard, they were produced with such a startling clarity, control and power that I couldn't believe I had missed that result before. But wait a minute, I hadn't actually changed any settings on the amp, so why was I hearing a completely different and improved rendition?

Oops :blush:
Well, although I have on a number of nights inadvertently left my power amp on, it also appears I am capable of doing the exact opposite: not turning it on. :suicide:

B&W 604S3 Bass Crossover
Intrigued with this finding I've been thinking about why this should be the case. I wondered about the material itself and whether there had been too much missing on the bass driver (my power amp drives the bass units only) when the power amp was off. But on investigation the 604S3's speakers are driven as follows: tweeter and midrange off the upper terminals and the bass drivers off the lower terminals. There is a 450Hz crossover for the bass drivers. So I cannot believe there was so much content between say 100 and 500Hz which would have been missing and which would have such a startling effect on the apparent ease of sub performance together with an apparent improvement in sub SQ.

Conclusions?
So is it fair to say that when one has a capable sub in place, that even with a crossover set at 80Hz, is it wise to have floorstanders which are apparently capable of colouring the sub well below the crossover level? Would it be better to have speakers which roll off at a higher level XO?

Secondly, as I already extract the main pre-outs to feed may power amps, and the fact that the bass drivers of the speakers run through a 450Hz crossover, would it be viable or desirable to run the L&R pre-outs through a BFD so as to get the same level of control which I apparently have achieved with my sub?

Sorry about the length of the post, but perhaps it's made for an entertaining read if nothing else!!
:smashin:
 

Member 96948

Distinguished Member
Let me get this right. You noticed an improvement without the bass content from the main speakers, correct?

Russell
 

mattkhan

Distinguished Member
Malice said:
So is it fair to say that when one has a capable sub in place, that even with a crossover set at 80Hz, is it wise to have floorstanders which are apparently capable of colouring the sub well below the crossover level? Would it be better to have speakers which roll off at a higher level XO?
I have been pondering this myself recently as my room provides a big peak (+15dB or so IIRC) between 45-55Hz and my measurements show my B&W602S2 are still kicking out an awful lot around that area and then rolling off quite hard from that point (as ISTR they are quoted as rolling off around 55Hz or so). I need/want to get some smaller speakers in across the front anyway so I could do with some home demo action with some smaller speakers to see if it really sounds that much better.

Cheers
Matt
 

Mr Incredible

Distinguished Member
What I am thinking of doing as an itial trial is to copy the BFD filters into another preset for both channels and then use the BFD to EQ the input into the Power amp. As the bass drivers are rolling off at 450Hz I don't think the BFD will cause too many issues with Signal to Noise ratios (i.e. hiss?) as it would do at 2kHz and above.
 

Member 96948

Distinguished Member
The speakers and sub still have a lot of output below and above the crossover repectively, even when they're set to small/80Hz crossover. My GB1s which are a lot smaller than your 604s, still register plenty of output down into the 30 something Hz and are definitely set to small.

Amongst other factors phase can vary with frequency, it's not unrealistic to expect cancellations to occur if the speakers are being asked to reproduce a larger portion of the subs spectrum by being set to large. In effect, you're trying to integrate 3 subs, two of which don't have don't have (currently) the abilty to be equalised. Tricky. By turning off the bass of the main speakers, I feel you may have proved this point to yourself with the better quality results you noted.

For it to work, I suppose you'd have to adopt the stereophiles route of turning the subs crossover to whatever suits the mains thereby minimising the duplication of signal. As you have full bass management, you know you can do better than that.

My hunch is that the power amp might be better utilised powering the fronts alone. Leave the 3805 to just handle the center and surrounds, for which there will now be power aplenty, and set the speakers to small. You'll still get the dynamic impact of all of those cones, but eveything will be getting an easier ride. As you've already noted that the sub alone gives the best bass, I feel it may be worth trying this out as you already have everything necassary.

Russell

PS. Good post BTW. Nice to have a query to discuss that can't be solved with a forum search.;)
 

Timbo21

Well-known Member
So,if you got big floorstanders, do you need a sub?hmm

I think a good, well setup sub can always bring something to the party.

It's more a matter of whether it can be succesfully integrated, or what is needed to successfully integrate it.

One thing for sure is you will need a decent sub. Let's face it, hooking a smallish sub up won't do the trick for decent floorstanders. And if you are a hifi buff, and don't want your stereo going through an all-in-one av reciever, then you've either got to run the floorstanders as they are, and engage the subs xover and fiddle with eq/xover/phase/level to get a successful outcome, or use an external xover, which is what our Nimby does (IIRC).

I would agree with Russell, and forget bi-amping, and run your fronts directly from the power amp. I also found I wasn't that keen on running my speakers as smalls with the 3805, but I think that's more about the quality of the 3805's bass management, since I run them now on small with a Primare processor, which sounds much better than using them as large.

I don't really know if any of the above is relevant, but anyway :rolleyes:

T.
 

Mr Incredible

Distinguished Member
Cheers Russell.

Amongst other factors phase can vary with frequency, it's not unrealistic to expect cancellations to occur if the speakers are being asked to reproduce a larger portion of the subs spectrum by being set to large. In effect, you're trying to integrate 3 subs, two of which don't have don't have (currently) the abilty to be equalised. Tricky. By turning off the bass of the main speakers, I feel you may have proved this point to yourself with the better quality results you noted.

Until you pointed out the change in phase with frequency, the penny hadn't dropped with me. But now that you have it's totally understandable. Although I had set speakers to Large in my various combinations, it was clear that there was too much interaction below the XO and so the speakers soon found themselves back at small. However, perhaps with the positioning of the speakers in the room and room modes, that I am still in effect having to manage the integration of 3 subs albeit it with the mains speakers rolling off from the 80Hz XO.

For it to work, I suppose you'd have to adopt the stereophiles route of turning the subs crossover to whatever suits the mains thereby minimising the duplication of signal. As you have full bass management, you know you can do better than that.

I had fleetingly thought about running wih the speakers set to Large and using a set of high level connections on the sub for the power amp portion and EQ that before running through the subs XO. But then I remembered your advice in another thread about "Do I need a sub" and reminded me that LFE is not sent to speakers even when set to Large, so I'd lose out. A non starter really. So I was then back to toying with EQing the power amp portion for the bass drivers. Why I'm keen/confident about this, but ignoring any phase issues, is that my sub sounded just as woolly before I got on the correct filter settings with some advice from the HTS guys. I think like you a "flat" response curve was flat in both name and sound. Awful! A house curve was needed, but once done I love my sub in its new position (hence the re-EQ exercise).

Although I did not re-do a sweep with mains and sub after finding the correct house curve, I thought it would be worth re-showing the response of mains and the "flat" sub together:-

BW604S3.jpg



My hunch is that the power amp might be better utilised powering the fronts alone. Leave the 3805 to just handle the center and surrounds, for which there will now be power aplenty, and set the speakers to small. You'll still get the dynamic impact of all of those cones, but eveything will be getting an easier ride. As you've already noted that the sub alone gives the best bass, I feel it may be worth trying this out as you already have everything necassary.

Russell

As noted Russell, I had put my speakers back to small. Perhaps I should have made that point in my initial ramble!

For now perhaps being the inveterate tinkering engineer that I am, I am more inclined to attempt to get my mains under control, for as much as reverting to the POA-T10 just for fronts would work, I feel I'll still have the same underlying problem: i.e. floorstanders that are apparently just too good to integrate well!! If that's not a contradictory statement!

PS. Good post BTW. Nice to have a query to discuss that can't be solved with a forum search.;)

Well, I hope it's been of use to others who also may be struggling with "integration" issues!

Bob

EDIT: Other thoughts quickly:

Put bungs in the speakers
Swap with my sons 602s3's for a while
Raise the XO to 120Hz for music.
 

Timbo21

Well-known Member
Raise the XO to 120Hz for music.

Bob, you can try xover at 120hz, but I find that the bass tends to get a bit disjointed when using 100hz, or above. I think THX realy hit the button with 80hz, but you can often get a better response using 100/120hz.
 

Mr Incredible

Distinguished Member
Update:

Penny #2 dropped tonight when I again sat and listened to my 2900's DAC's via the 5.1 analogue route.........

There's no bass management on the 3805 for analogue sources!! I wonder if I have the right bass management settings set in the DVD? Must check tomorrow!!
 

Mr Incredible

Distinguished Member
Update #2 - DVD settings.

The recommended settings for the speaker configuration for multi-channel DVD-A and DTS sources is to have the filter setting to "OFF", which puts all speakers to LARGE and Subwoofer to YES in the DVD set up. :suicide:

Putting the filter ON and setting the speakers to small resulted in a quite subdued output which had lost some of its impact.

Anyone got any vaseline? I appear to be disappearing up my own ****side at the moment!

Who said HC is fun? :)
 

TopMeTom

Banned
Update #2 - DVD settings.

The recommended settings for the speaker configuration for multi-channel DVD-A and DTS sources is to have the filter setting to "OFF", which puts all speakers to LARGE and Subwoofer to YES in the DVD set up. :suicide:

Putting the filter ON and setting the speakers to small resulted in a quite subdued output which had lost some of its impact.

Anyone got any vaseline? I appear to be disappearing up my own ****side at the moment!

Who said HC is fun? :)

Ah Bob,

That is a great line, vaseline, hehehe
 

Timbo21

Well-known Member
Putting the filter ON and setting the speakers to small resulted in a quite subdued output which had lost some of its impact.

SACD will have to be converted from DSD to PCM to enable small speakers. I also find that puting speakers to small greatly diminishes SACD with the Arcam DV139. The DV139 converts DSD to PCM anyway, but using small speakers just seems to diminish dynamics.

T.

ps. This is not a comment on small vs. large, but just really how good/bad the process of bass management is in some players.
 

Mr Incredible

Distinguished Member
With hindsight I realise my thread title is ambiguous. I meant to imply that with physcially large floorstanders, and even with the receiver set to "small", that the output of the large speakers below 80Hz XO appears to be a tad too much with room mode to be able to get good control.

Your confirmation Tim that you have had the same issue WRT to the DVD player's Large v Small settings all the more is reinforcing my view that meaty front floorstanders are perhaps not a good idea when coupled with a capable sub.

BTW I put the bungs in all my B&W speakers, and it really didn't apepar to make amy difference that I could pick up!

A 120Hz XO was not much success either.

So perhaps a temporary swap with my son's 602S3 may be needed. He'll be grinning with a set of 604s in his bedoom for a while!!
 

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