PDA

View Full Version : Adding some bass?



Gibbo
2007-11-12, 06:04
please ignore me

htrd
2007-11-12, 10:41
You should be able to connect any sub with a high level (speaker level)
input to your amp. Effectively the output of your main amp is the input to
the amp in the sub.

Ive been using a http://www.bkelec.com/HiFi/Sub_Woofers/XLS200.htm in a
similar set up for 9 months now and am very pleased. On slimserver we are
lucky to be able to use the Inguz EQ plugin to correct for room effects.
Will you be able to run this? Being able to use some form of EQ to correct
for room effects is essential to get the best out of any sub.

iPhone
2007-11-12, 12:50
If one were looking for extended low accurate bass that seamlessly mates to main speakers for music listening (not Home Theater), a possible suggestion would be any active sub that operates by becoming active before the output to the mains. These subs have a huge advantage over LFE, passive, or add-on subs.

The first and main advantage is they completely remove the low base load from your main amplifier letting it concentrate on the highs, midrange, and upper base. They blend seamlessly into the system and sound like they are part of the mains. Volume is no longer an issue because they behave as the mains do because they are receiving the same signal sample as the mains just only the low end. It is basically like somebody added a lower base driver inside your main speakers. Thiel and Vandersteen 2Wq (the V2W is for HT LFE) active Sub-woofers are both good examples. The ability to change the Q should be a function of the subwoofer itself, not an item that affects the whole system. Why mess with the source signal when the device that needs to be adjusted can be tailored to the room?

Now for the downside, although these active subs work wonderfully with full range speakers, they were not designed to add base to satellites and most monitors. The reason is because satellites and most monitors do not have enough bass extension to reach the area most subs operate in. This issue causes a hole or at a minimum a deep valley in the bass performance between where the monitors run out of gas and the sub takes over. Which is why a sub will not fix the lack of bass authority in satellites or most monitors. Speakers used with active subs need to have reasonable response an octave below the crossover point to have realistic blending (filter theory 101). Having a sub with a high upper bass reach adds to the problem because the sub is now not operating in its bandpass and will be to weak (probably 6dB) and muddy. The primary problem being that the more bass extension the mains lack the wider (hence higher up in bass frequency) the required octave overlap becomes (one octave at 50Hz {25Hz down and 100Hz up} is a much smaller range then one octave at 200Hz {100Hz dn and 400Hz up}). As an example if one targets the crossover frequency at 50Hz, ones mains need to realistically go below 25Hz. 80Hz is my preferred cross-over point with active subwoofers. I have a choice of many full range speakers that start running out of bass gas below 40Hz and the sub never has any work load above 150Hz staying well away from the 200Hz mud zone and yields actual bass response down below 20Hz.

Gibbo
2007-11-12, 16:18
Cheers for the responses.

pretend I know nothing, as to be honest when it comes to this I don't really,

an active sub should have a speaker level in, that can connect to a speaker cable from the standard amp left and right outputs? how does this connect with the speakers that are also connected? series? parallel?

thanks again.

pfarrell
2007-11-12, 16:29
Gibbo wrote:
> an active sub should have a speaker level in, that can connect to a
> speaker cable from the standard amp left and right outputs? how does
> this connect with the speakers that are also connected? series?
> parallel?

Depends on the specifics of the sub. On my REL stadium, the speaker
level inputs are actually high impedance, so while the operate in
parallel, they really don't load down the amp.

Other subs take the speaker level input and filter it, and send a high
pass signal to the speakers. So they are essentially in series.



--
Pat Farrell
http://www.pfarrell.com/

Gibbo
2007-11-12, 16:36
Ok, so thing is I want to make my system a little more enjoyable for films, it doesn't really have that rumble that you sometimes need, I have kef Q3's and a C320bee NAD amp. What can I do? and in very simple terms, what would you plug and where? just want people opinions really, I know this is audiophile country, but i'm thinking cheap options, < £100.

is it possible?

htrd
2007-11-12, 17:18
Gibbo wrote:

> but i'm thinking cheap options, £100.
>
> is it possible?

At that price, hmm, you could pay someone to slam your front door in time to
the music.

Or, to stretch the budget a little:
http://www.avforums.com/forums/showthread.php?t=645977


I hope that helps

zanash
2007-11-13, 02:21
paradigm made a small sub £100 sub .....I have one I used while my floorstanders were breaking in as they produced no bass !.... but I've never been convinced that this works very well in all the systems I've heard subs used.

Gibbo
2007-11-13, 02:51
Cheers. really just trying to get an idea of what price would give me something of a comparable quality to the setup I have already.

Skunk
2007-11-13, 05:34
an active sub should have a speaker level in, that can connect to a speaker cable from the standard amp left and right outputs? how does this connect with the speakers that are also connected? series? parallel?


You can use the 'Tape Out' RCA connectors on the NAD to feed the sub a line level signal instead of speaker level, so long as the sub has left and right RCA inputs (not just a single LFE input which is meant to be feed by home theater receivers).

I would also look for a sub with a crossover frequency control in addition to volume control, which will help you blend the sound with your main speakers.

SatoriGFX
2007-11-13, 07:41
You can use the 'Tape Out' RCA connectors on the NAD to feed the sub a line level signal instead of speaker level, so long as the sub has left and right RCA inputs (not just a single LFE input which is meant to be feed by home theater receivers).

The "Tape Out" will be fixed in level meaning the sub volume will not change as you raise/lower the volume. Not exactly the best idea unless you have a slave you can hire to adjust the sub volume as you adjust the amp volume. If one wants to use a line level connection to their subwoofer, a "Pre Out" (or "Sub Out" if available) is the output you really want to use.

Having said that, I don't think it makes sense to use the Pre Out on the C320BEE. The Pre Out on that unit is connected to the power amp section via a jumper. It's meant to be used with an external processor like an EQ or what have you. So, you can't just disconnect it and connect a sub.

My recommendation is to find a sub with speaker level inputs.

honestguv
2007-11-13, 11:55
Ok, so thing is I want to make my system a little more enjoyable for films, it doesn't really have that rumble that you sometimes need, I have kef Q3's and a C320bee NAD amp. What can I do? and in very simple terms, what would you plug and where? just want people opinions really, I know this is audiophile country, but i'm thinking cheap options, < £100.
is it possible?
I think you maybe getting some odd advice.

A subwoofer needs only one amplifier but that amplifier needs to work hard (lots of Watts) to get the the big drive units to shift a lot of air. The amplifier only needs to be flat upto about 100 Hz or so rather than 20kHz and this helps a lot in getting lots of cheap Watts. Conclusion: active subwoofers make far more sense than passive subwoofers.

£100 is not really enough but for £150 you can buy an OK active subwoofer. For example:

http://www.behringer.com/B2092A/index.cfm?lang=eng

but there are others around this price and this is not particularly a recommendation for this speaker.

You can download the manual from the web page and it tells you how to connect the subwoofer for both stereo and multichannel use. Namely, run a cable from the preamplifier output of the NAD to the subwoofer input and a cable from the subwoofer output to the power amplifier input of the NAD.

Note that the subwoofer will filter the bass from the signal sent to the power amplifiers of your main speakers which will enable them to effectively play louder and cleaner. There is nothing getting in the way of how the NAD drives the KEFs, the volume control on the preamplifier works as normal although you will have to adjust a knob on the subwoofer to trim the level between the subwoofers when intially setting it up. You may also have to adjust one or two other things when initially setting up as discussed in the manual. Whatever, this is the "proper" way to do it.

pfarrell
2007-11-13, 12:05
honestguv wrote:
> I think you maybe getting some odd advice.
>
> £100 is not really enough but for £150 you can buy an OK active
> subwoofer.

I've held out of this thread because I agree that £100 is not enough to
get anything serious. But there are "PC speakers" with subs in that
range. Lots of thump for explosions.

> Whatever, this is the "proper" way to do it.

The proper way depends on the model. Some subs have high pass filters,
others do not.

For proper setup of any subwoofer, RTFM


--
Pat Farrell
http://www.pfarrell.com/

Skunk
2007-11-13, 14:19
The "Tape Out" will be fixed in level meaning the sub volume will not change as you raise/lower the volume.
Oops. I guess it's been awhile since I've had a tape output. I noticed the preamp jumpers or would've suggested that instead.



Not exactly the best idea unless you have a slave you can hire to adjust the sub volume as you adjust the amp volume.

With the variation in bass from album to album, I practically end up doing that anyway. No truly high end setup would be complete without an audio slave though.

iPhone
2007-11-13, 21:53
No truly high end setup would be complete without an audio slave though.

The audio slave does come in handy. I prefer to use mine for searching for the next CD I am going to listen to.

A proper subwoofer system that blends to become part of the mains as well as having an adjustment for matching the main speakers sensitivity and being about to adjust the Q of the system to the room, frees up the audio slave for other duties. Any active subwoofer that interacts with the mains in this fashion has proper bass response no matter what the source material and has the proper level of bass output no matter what volume level is chosen. The reason for this is that the subwoofer is now operating as if it were part of the mains. To over simplify the explanation of what is happening, the net sum of the resulting system is basically equivalent to your mains having another base driver inside of them with the appropriate crossover for the very low frequencies. And since it is an active subwoofer with its own amp, the low frequencies are totally removed from the stereo amp's workload.

The downside is that these systems usually need a separate amp and pre-amp so that the crossover can be placed between them. They will also work fine with the few integrated amps and A/V receivers that have jumpers on the back labeled pre-amp out and pre-amp in.

So if you like tight accurate bass at the proper level to what your listening to (both material and volume level) and donít want to mess with having to change the gain level every time you change CDs or volume, pay a little more (Vandersteen 2Wq $1295) for a sub that will give you endless pleasure as well as free up the audio slave (especially if that happens to be you)!

slimpy
2007-11-14, 02:24
The audio slave does come in handy. I prefer to use mine for searching for the next CD I am going to listen to.
Looking at your user name I'm sure you had your audio slave painted glossy white or black. Which one is it?
;-)

-s.

iPhone
2009-01-14, 14:15
Looking at your user name I'm sure you had your audio slave painted glossy white or black. Which one is it?
;-)

-s.

Actually, the 8GB brushed Aluminum! ;}

slimpy
2009-01-14, 16:42
Actually, the 8GB brushed Aluminum! ;}
Wow, impressive. Quick response.

Just kidding. Look at the date of the post you replied to.

-s.

turbot fiend
2009-01-16, 06:31
A good active subwoofer connected via RCA, set to roll off 5-10hz above the bottom end of smaller bookshelf speakers using the sub cross over, works wonders!

http://www.avtalk.co.uk/forum/index.php?t=msg&goto=258485&rid=13040&SQ=1225385344#msg_258485

A bit above a £150 budget, but I can thoroughly recommend the Velodyne SPL Ultra series, having just integrated one. The in built EQ function saves hours fiddling with set up for you own room's dimensions and responses, and it really does free up your main speakers and unerpin the sound. One doesnt really notice it until you switch it off, when one senses the music loses weight, timbre and scale at the bottom end registers. Bass attack and decay (which some call 'speed') are also deeply impressive and adds to it's overall musicality and realism.

Sub design and small physical size all belies the power of this little box of tricks.