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Recommend a sub for music to match my 805's

stevos

Distinguished Member
Hi,

Could someone recommend a sub that would work well with my b&w 805's when it comes with music. It is also likely to be used with my av setup.

Not too sure about budget but would prefer something that comes up fairly often on the second hand market.

On a side note, what is the best way to connect a sub to a normal stereo amp (cyrus prex in my case)?

Regards
Steve.
 

asdonk

Active Member
the rel strata III maybe, can be connected high and low level
or a MJ Acoustics reference 1 both very musical subs
I know as I have had both subs, now a rel stadium II and a BK monlith
 

Nimby

Distinguished Member
The B&W ASW750 sounds superb with the 805s on film.
PS: I've noticed they have music as a background to films. ;)

If your stereo amp has pre-outs then connect a sub to those using a phono to phono cable.

If not, then use high level (speaker level) connections using mains flex. No need for proper speaker cables.

Place the subwoofer somewhere between your main/stereo speakers.

You may connect at the speaker terminals on your amp or connect to the terminals of your speakers. Whichever is most appropriate for your situation.

Maintain stereo and L&R.

Set the sub's own crossover to the twice the -3dB point of your speakers or 80Hz as a starting point.

Phase "0".

Gain to taste.

Enjoy! :)
 

HiFiRuss71

Distinguished Member
Set the sub's own crossover to the twice the -3dB point of your speakers or 80Hz as a starting point.
Purely out of interest, why twice?

Russell

PS. Is it just me, or are the colours of your avatar changing places?
 

Nimby

Distinguished Member
A change in frequency of one octave requires about twice (or half) the cone excursion of the starting frequency.

Most floorstanders roll off at around 40 Hz. So 80Hz is a good starting point to protect the speaker's bass driver from heavy LFE (film) bass.

Classical music and a bass guitar are usually limited to around 40Hz (except for organ music).

With smaller speakers one may have to push the crossover frequency higher.

Downside then is the sub's need to play higher frequencies and the greater likelihood of its location being audible.

Avatar? Changing colours??? ;)
 

HiFiRuss71

Distinguished Member
A change in frequency of one octave requires about twice (or half) the cone excursion of the starting frequency.
Ok. This I know and the coresponding reduction in power required by the speaker's amp.

Most floorstanders roll off at around 40 Hz. So 80Hz is a good starting point to protect the speaker's bass driver from heavy LFE (film) bass.
Classical music and a bass guitar are usually limited to around 40Hz (except for organ music).

With smaller speakers one may have to push the crossover frequency higher.

Downside then is the sub's need to play higher frequencies and the greater likelihood of its location being audible.
Yip. Know this also. I may have been confusing it with the final line of the OP's question, with regards to the best way of connectiing to his Cyrus stereo amp.

FWIW, a friend who reviews for TNT Audio (stereo purist website) has trouble understanding why I buy floorstanders, when I cross-over at 80Hz+. I've tried to explain that the best integration happens with at least an octave overlap either side of the cross-over frequency. There's no point having a carefully managed 24dB/octave slope when your speakers superimpose an additional 12 or 24dB/octave slope within the first octave of the crossover resulting in a lop-sided crossover to manage.

Then again, speakers like the SVS SBS-01s and any number of M&Ks are designed to roll-off at 80Hz (or higher) naturally. OK, they're sealed, giving lower rate of roll off, but I'm interested to hear what your thoughts are, with regards to this modus operandi.

Avatar? Changing colours??? ;)
Well, obviously, I'm wrong again but, I could swear the blue one was 2nd bottom a couple of days ago. Now be honest, my autistic side get's real hung up on irrelevant details like this.:)

Seasons greetings,

Russell
 

Nimby

Distinguished Member
Regardless of what it sounds like, an 80Hz crossover protects the bass drivers of the speakers when watching films. The 805 has a remarkable 40Hz response which suggests that it should be treated just like a floorstander and crossed over at around 80Hz for films.

Classical and acoustic music protects the bass drivers by being frequency limited to around 40Hz. Organ and electronic music are a completely different problem.

Most "audiophiles" won't want to attach their speakers to the crossover output terminals on a subwoofer. The sub's internal, high level crossover is likely to be a passive 6dB/octave using small, cheap components. Many subs don't even give you that option.

Pre-out sockets on a stereo amp are going to give you a fullrange signal. Sealed speakers will offer some protection from the air cushion in the box.
Reflex speakers won't.

So, for music, you have a number of choices:

Take the REL approach and play your speakers fullrange. With the sub just plodding along at the frequencies the speakers can't reach.
You will experience higher distortion from the speakers than a sub can probably manage with its hands behind its back. (unless you actually bought a REL) :devil:

Or use an active crossover between pre and power amps to roll off your speakers and your sub. Sub's own filter (or crossover) set to bypass.

The choices depend heavily on the actual speakers involved, the choice of music and the levels enjoyed. A basshead who likes deafening levels of bass on electronic music could still use the 805s if they rolled off the speakers with an active crossover. Perhaps in the future an 80Hz active filter to a Sub-out socket will become the norm on most stereo amps.

Interestingly(?) many pro-amps have high pass optional filters but whether any of them sound better than a Cyrus when driving 805s is open to discussion. :)

For films it is best to use an AV Receiver. Most DVDPs will automatically apply dynamic compression to protect the speakers if you downmix from DD5.1 to stereo. DTS will give your speakers a harder time with DVDs downmixed to stereo.
 

ttree sound

Active Member
Seasons greetings to all.

Everything I've read so far goes against every part of my setup. Yes, I use a Rel which has a crossover filter of 12db per octave I beleive. It is connected at high level from the stereo amps speaker outputs and I set the crossover at 22hz. This I have found gives me a perfectly seamless sound - no overlapping from the floorstanding speakers and solid tight profound deep bass with absolutely no boom, when the source produces low bass from the cd player or tuner.

The sound from my system is so perfect for me ears that I dont intent to change anything else for the forseable future. I dont waste time fiddling with any settings anymore but just enjoy the music and films to the full.

Am I missing anything, the thought of limiting my floorstanders to 80 hz or therabaouts scares me! My understanding of subs maybe skewed but I always thought that their job was to produce low bass certainly way below 30hz not bass up to 80hz. Yes I know this is the thx crossover recommended for films. Music bass is produced far more often than film bass, which for the duration of a film is a small percentage, wheras music may not be quite as low and strong as lfe effects in general but just as demanding at times.
 

Cable Monkey

Well-known Member
No you are not missing anything, you simply have a setup which suits your ears. There is nothing written in stone about how people set their systems up, you have to work with what you have. Film reproduction has created a different set of philosophies regarding speaker theory but the different ways of doing things are by no means exclusive. I have my sub (a 750) underpinning my 705's to good effect with music on a stereo system. Works for me!
 

ttree sound

Active Member
Cable Monkey, the 705s are standmounters though, so the crossover position is likeley to be much higher than what floorstanders would require?

What crossover setting do you use with your stereo setup?
 

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