B&W Sub clarity

[jayskumar]

Hi,

Since I have found this forum in Nov 2005, I have found it incredibly informative. I have just bought a B&W ASW-700 sub and a little puzzled. If I put the volume to the max, the sound of the becomes incredible unclear. I can see the bass driver moving (which isn't a problem) but I think I can actually hear the diaphram moving and popping. Is this normal? I bought the sub new and am a little concerned. I hope the unit isn't defective.

Thanks.

Jay

[Karma]

HI Jay,
From what you are describing, you are grossly overdriving the sub. Back off a lot on the subs level control and listen to some music that has some bass. Try to determine if the bass and the sound from your main speakers sounds balanced and realistic. Adjust the subs level control until it sounds realistic. Integrating the sound between the mains and the sub is the secret to great bass.

Subs have their limits and it sounds like you have reached yours. Take it easy. You could damage your sub. You don't have to blow the walls down.

Sparky

[jayskumar]

Hi Karma,

I haven't had time to play with the settings too much, but I was disappointed at how quickly the sub starts to lose it's clarity. At higher and higher levels, my speakers (CM-4's) don't lose their clarity like this sub does.

It's not that loud. It's louder than normal listening loud but not louder than dance party in my apartment loud.

Jay

[miner]

First of all, how is you sub connect - speaker level of LFE? Are you using the subs active crossover, and, if so, what do you have it set at? My personal parameters for sub (ASW800) settings:

1) LFE - 2 sub cables from preamp (RC-1070)
2) Volume at 12 o'clock position
3) active crossover on, set at 45 Hz (mains still get full range signal)
4) EQ set to 'B'

using with B&W N804 speakers and Rotel amp & pre.

[jayskumar]

Miner,

I am using the LFE connectiong (1 plug on the pre-amp, split at the sub). Active crossover on, set at 100 Hz (where my Rotel's filter is set at also). EQ is set to A. Volume is at the maximum. When I lower the volume to about 12 o'clock, the clarity is great. At the max volume the clarity is atrocious. Lot's of popping and lots of bad sounds coming from the unit.

Jay.

[Karma]

HI Jay,
Let me jump in here. My settings for my two ASW800 subs match miners. There is a question as to which main speakers are being used. Mine are 805S's. A low pass setting for the 805's of 45Hz makes sense since that is slightly below the 805's natural low frequency cut-off. I do not use the high pass filter. Miner may be using different mains and, thus, have a different overlap.

Jay, you are simply not giving us enough information to help. I don't know which main speakers you are using, how big your room is, how many subs you have, and what your expectations are. I can say this: Running your sub at full volume is silly and unnecessary. If this IS necessary, something else is wrong with your system. Also, most main speakers, even small ones, have significant bass below 100Hz so why are you using this setting? I can't suggest a setting since you have not told us what main speakers you are using. It makes no sense.

I suggest that you do a little research on subwoofers so you can make settings that have a chance of working. Have you read your owners manual?

You mention that you are using the LFE output and split at the sub. What do you mean? Do you have two subs? Your profile is blank so no help is available there.

Sparky

[jayskumar]

Karma,

I have a Rotel 1068/1075 combo driving a pair of B&W CM-4's. If you don't remember these were the stylish versions of the 600's (with a much brighter and cleaner sound). I bought an ASW700 subwoofer last week as I complete my home theatre system. It is connected from the Rotel via a subwoofer cable from the sub output to the subwoofer using a y-adapter so that I go from 1 plug in the pre-amp to two plugs in the subwoofer.

I have configured the pre-amp to set the front speakers (the CM-4s) to large and the subwoofer to max.

In this set up, the subwoofer has very poor clarity and I hear popping sounds.

I know that this isn't going to be my permanent set up, I just wanted to test the subwoofer out. I am surprized that the subwoofer can't maintain clarity at their maximum volume.

Jay

[junior77blue]

I have configured the pre-amp to set the front speakers (the CM-4s) to large and the subwoofer to max.
Jay

There could be something wrong with your system...but before we go there lets check a couple of things.

You say you have your pre-amp set to max? Don't do that...just yet, you need to calibrate your output with a test signal. If you want to leave your sub knob all the way up and adjust it from the preamp, that is fine. To calibrate it you need to play test tones and using a SPL meter adjust them so they are fairly the same or you can nudge it up a few dB but don't get too crazy. If you wanted crazy bass you bought the wrong sub.

Next, set your mains to a higher crossover, say 60-80Hz to start with. You can play around with this based on your preamp increment adjustments and what sounds best to you. Make sure you play them with out the sub and listen to them....the lower the better I say. But, without straining your mids too much.

Then place your subwoofer crossover at the same crossover level you have at your main speakers. This will again be 60-80Hz.

The sub is not made or designed to play the higher frequencies...nor would you want it to play 100Hz+ frequencies. Localization comes into play...and this is sommething you do not want.

Room placement also plays a significant role, but lets start with the basics first.

[Karma]

HI Jay,
I have to tell you that I almost got out of this thread out of frustration with you. Rather than ignoring you, I will try to help a little more.

First, you did not answer my question when I asked if you have read the owners manual for your sub. Why? If you don't have it, it is available on-line at B&W's website. I read it today. So, have you read it? It has some good starting advise.

You are making a fundamental error concerning how volume (gain) controls work. We don't have the time and space here to discuss the concept. I have pondered the issue all day and even asked my fellow engineers how educate you via this forum. We agreed that your understanding is so flawed that a forum is not the place for the necessary schooling. Face to face we could get things straight pretty quickly.

If the information in the manual does not get you going in the right direction, you really need to seek professional audio help. I would suggest asking someone who repairs stereos or perhaps a sales person.

One hint. With your setup you only need one connection to your sub, not two. Since you didn't indicate where you have the cables connected I can't tell you how to correct it. You only need one connection. It needs to go to the Line In connector. The second connection may be the cause of your problems. Read the manual!!!! Good luck.

Sparky

[miner]

Sparky,
Why only one connection needed? I have 2 from my pre to my sub - I am not running cables from sub back to amp so my mains (N804) get full range. Are you suggesting that both L & R channel get same low freq. signal?

OK, I see Jay's pre has a sub out on it so it should be getting L&R sub signal.

[jayskumar]

Sparky,

I apologize. I don't think I am being clear in my question. I have read the owners manual for the speakers and the pre-amp. The dealer actually recommeded using the Y-adapter to connect my sub. I use an interconnect from the sub 1 output on the preamp to the sub but I use a y connector on the sub side. I don't think my connections are bad or wrong.

When I lower the sub volume (to 1 o'clock on the volume dial) the system sounds great with the subtle but noticeable clear bass.

I set the sub setting to max on the Rotel because there are only way to pass the low frequencies to both the fronts and the sub.

What I was really surprized by, was the fact that the sub's distortion massively increases as the volume on the sub is raised. I don't realistically intend to listen to the sub at that volume, but I would have expected that the sound coming from the sub would stay pretty clean. If the sound is supposed to be that distorted at those volumes, why does B&W allow to you set the volume that high? Or is my sub broken?

[miner]

Jay,
Last night I had my sub set to max on output and DID NOT notice any unrealistic distortion. I may suggest that you have your dealer look at the sub for some form of component failure.

For some reason I feel your pre/pro settings may be wrong. I would set sub to 'Sub' with freq. no higher than 60Hz and set your mains (fronts) to large. I am not familiar with your pre/pro so I am just grasping at straws right now.

[jayskumar]

Miner,

With my speakers set to large, I have three options for sub: No, Yes, Max. When the speakers are set to large my processor does not send any signal to the sub in the "no" and "yes" setting. According to the Rotel forum, that is how my pre-amp works and that is normal (though I think odd). I have to either set the speakers to small or set the sub to max in order to get output to my sub.

If you aren't getting this unrealistic distortion, then maybe my sub is not working properly.

[miner]

So, with the 1068, fronts set to large sends full range signal to them and nothing to sub out? I would suggest then setting the mains to small, sub to yes and see how you like that combo. Still, get yor sub checked out. Hopefully you can take to dealer and hookup there for them to listen to while you are there.

[RobP]

Jay, correct me if I am wrong here but by reading your post it looks as if you have two crossovers working, one at the processor and one on the sub, run your crossover setting on the subwoofer to the "out" position, and let the processor do the filtering.

[Karma]

HI miner,
For movies, the LFE output from the surround processor is monaural, thus, you only need one cable connected to the Line In sub input. For music, you should run two cables to the Line Level L and R inputs from your preamp L and R outputs so they can summed together in the subs amplifier. That's assuming only one sub.

If you have two subs, such as in my system, you should run the LFE signal to both subs and for music run the preamps L output to the left sub and the R output to the right sub. I have a separate bass signal path for music or movies so I can make the distinction between the two cases thereby gaining more control over the bass.

I thought Jay was only dealing with his processor LFE output, thus my comment. That plus he did not identify which sub connectors he was using. If, by mistake, he used the Line In AND his Line Out connectors, he would have the LFE signal connected to both an input and an output with unpredictable results. I wanted to make sure this was not the case.

If you want to connect the LFE to Line In L and R it won't hurt anything but also does not gain you anything.

Clear as mud, huh?

Sparky

[jayskumar]

I have my sub connected from the LFE to the Line In L and R.

I went to the dealer on saturday to check out their other subs to see if the same sound occurs on the same music. It doesn't. When the sub volume is very high the sound became very muddy; not popping like mine. He thinks that the driver is running out of space to move. I would be surprized. I am going to take it in next saturday to check it out though.

Even if it pops at high volumes (volumes that I wouldn't really ever listen to, should I bother returning it or just deal with it? I think I should return it because it cost me a little under $1300. For that kind of money you expect your product to work as specified.

Thanks for your help everyone.

[Karma]

HI Jay,
It sounds like you have it hooked up right. That's good.

It should not pop unless the cone is bottoming out which it might be at full volume or if there is a problem with the built-in amp. I would take it to my dealer, if you can, and check it out beside another that is the same model. If it is still under warranty, a repair may be in order. If you send it in for repair, be sure to include a note telling the tech about the nature of the problem.

I must admit that not much of this makes sense to me. The sub may be defective. Good luck.

Sparky

[JKalman]

If I put the volume to the max, the sound of the becomes incredible unclear. I can see the bass driver moving (which isn't a problem) but I think I can actually hear the diaphram moving and popping.

<sarcasm on>Perhaps I can be of some assitance. Why not buy an air raid siren and hook it directly to your ear drum. This way you can be certain you go deaf in less than a few weeks.<sarcasm off> :twisted:

All kidding aside, I wouldn't turn the volume up too loud or you might go deaf! Good luck with getting your bass set up! :T

[JKalman]

One hint. With your setup you only need one connection to your sub, not two. Since you didn't indicate where you have the cables connected I can't tell you how to correct it. You only need one connection. It needs to go to the Line In connector. The second connection may be the cause of your problems. Read the manual!!!! Good luck.

This is exactly why I'm only going to read this thread after this post...

[shades]

Jeff,

I think he's leaving out the reason why some people split the connection at the sub with a splitter to L and R. Most people do it so they can get a gain of 6db or so when they connect the LFE signal from the pre/pro or receiver. I've done this before on different setups just to see the gain.

[Karma]

HI shades,
You are right about the 6dB of gain being a reason. But it should not be needed in any reasonable circumstances. Since Jay did not initially indicate where he was connected on the subs I was concerned that the second connection might go to the wrong place. Thus, using only a single input to the sub simplified the troubleshooting possibilities.

Why did you need the extra gain?

Sparky

[jayskumar]

Wait. Connecting from the sub 1 output to the Input R and L adds 6db of gain?

[Karma]

HI Jay,
Indeed it does. But you should not need to do it because the subs amplifier should have plenty of gain. But doing so will not hurt anything unless you are at the limits of the amplifier input voltage range. I don't think that is your case. But you might try unplugging either the left of right input and see what happens.

BTW, 6dB equals a doubling of the voltage. So if you have a signal of 1 volt, 6dB more would equal 2 volts. The same ratio works with gain relationships. If you have a 1 volt input signal to an amplifier at a gain of 0dB, increasing the gain of the amplifier by 6dB would result in an output of 2 volts.

Sparky

[shades]

Karma,
That's exactly what i was going to say.

I don't personally use this setup up anymore for reasons that Karma said.

[jayskumar]

When I get home tonight, I am going to take out the Y connector and connect from Sub 1 to just the left input. I don't have any gain set on the pre-amp. I will lower that to it's minimum and see if I still get the popping. Not sure what it will show, except maybe I can determine some threshold for the popping.

[jayskumar]

Last night, I took off the Y connection and just plugged the cable into the Input L. At the max volume I wasn't getting the popping and unlike the subs I tested at the dealer it staid incredibly clear. Though at the max sub volume, it wasn't very loud.

This means I am probably sending too much voltage to the sub? I have to find my college phsyics text book and re-learn basic circuits this weekend.

[gregj66]

I'll admit that I didn't read every single post and that I'm far from an audiofile, but I do own Rotel and B&W gear.

I have a 1066 / 1075 hooked up to two 603s3 L&R, a 602s3 centre and an ASW675. I use an Ultralink sub interconnect that has the built in 'Y' connected to both the L & R Line In inputs.

I had to set the volume to "8 o'clock" on the sub and -9 db on the 1066. Yes, I used a SPL meter. Crossover is at 60Hz, sub 'yes' and all speakers set to small.

Sounds great!