Answered Best way to set subwoofer with amplifier without bass management

<aNiMa>

Standard Member
Dears,

So I just bought a Klipsch R-115sw and I'd like to find the best way to connect it to my current system (Cambridge cxa60 + Tannoy xt6f + chord mojo).
Now from my understanding the amplifier cxa60 doesn't have bass management but it does have the sub output.

(from the amplifier description: If you want to use a subwoofer as part of your speaker complement, the CXA60 doesn’t penalise you for it. Because we want to ensure there’s no unnecessary high frequency noise affecting the subwoofer, we’ve put the output filter at 3kHz. This is high enough to prevent any phase shift associated with the low pass filter affecting what happens below 200Hz. The result is a phase linear subwoofer output signal which is clean and musical.)

Questions:

1) how should I set the low pass dial? Just set to LFE and let the Cambridge do the job or set the crossover on the sub?

2) The problem is that I don't know how the Cambridge cxa60 deals with subwoofers since it doesn't provide me with a way to set the crossover. Did the cxa60 set the crossover at a specific value?

Cheers guys let me know! :)
 

BlueWizard

Distinguished Member
The Tannoy Revolution XT6F are rated at 38hz at -6db on the low end.

TANNOY Lifestyle - Revolution XT 6F

The Crossover Control on the Klipsch R-115SW seems to cover about 40hz to 250hz.

Powered Reference Subwoofers | Klipsch

The best you can do is set the Subwoofer Crossover to the Natural Roll-Off of the Front speakers.

At -3db (instead of -6db) I would speculate that the roll-off starts is in the range of 43hz to about 46hz (38hz + 5hz or 38hz + 8hz), so that is where you set the Subwoofer Crossover. Let's say roughly in the 40hz to 45hz range. That will give the smoothest blend with the front speakers.

You don't have a means of controlling the frequency response of the Front Speaker with a Stereo Amp, so the best you can do is try to blend them at the natural roll-off of the front speakres, allowing the Sub to fade in at the point where the Front are fading out.

You can overlap the Front and Sub, for example, set the Crossover to 80hz. That will create an artificial bump in the bass response in the overlap region, but some people like that. Give it a try, but for the smoothest most even and balanced blend of the two, the crossover should be in the roughly 40hz to 45hz range.

Steve/bluewizard
 

BlueWizard

Distinguished Member
PS: If the Cambridge does internally set a limit on the Subwoofer Output, it is very high, likely in the 200hz to 250hz range. Too high to be of use to anyone.

Steve/bluewizard
 

<aNiMa>

Standard Member
Thank you so much.
Now it all makes sense... That's why when I set to LFE, letting the cambridge manage the sub, it was so boomy. It was due to the fact that from around 40 to 200-250 hz my speakers and the sub were overlapping, weren't they?
Then I tried setting the low pass at 80 hz and again I felt it boomy though way less than lfe mode. I guess it was to blame on the overlap from around 40 to 80 hz, right?

Few questions:
1) -3dB and -6dB...and then 38hz + 5hz or 38hz + 8hz.... what does it mean? I'm sorry I'm quite noob :(
2) Before buying the sub, I thought the cxa60 could actually bass manage any sub...but yeah I was pretty wrong. And I guess for now the best solution I can follow is the natural front speakers roll-off crossover setting. In terms of sound quality is there a big difference between using the cxa60 and using a proper receiver? Would it be worth it for me to buy a receiver?
 

Timmy C

Distinguished Member
Are you new to using a sub? If not please ignore me but if you are, be sure not to set the sub volume control too high. It's probably something we were all guilty of to some degree with our first subs, particularly in the earlier days of surround sound home set ups and it usually sounds pretty awful!
 

<aNiMa>

Standard Member
Yeah it's actually my first real sub.
1) Now I'm actually torn between setting it at 40-45 hz (following the speaker natural roll off crossover setting rule) and around 60 hz (following the f3*1.5 rule, some people seem to suggest this rule over the other one). Any other thoughts on this choice?
I mostly listen to jazz and electronic music. I tend to prefer tight bass.
The sub manual suggests to set from 50 to 90 kz.
2) Any suggestions on how to set the volume gain? Just by ear and my personal preference?
 

Timmy C

Distinguished Member
I set mine by ear still using the old techniques that hifi magazines used to suggest. I play some sort of dance music track with a regular beat and deep bass, turn the sub up until it's obviously too loud then slowly turn it back to the point it appears no sound is actually coming from it at all. If all is good then you should find that although it's not obviously doing anything, switching it off altogether will make you realise it was adding to the sound. You can then experiment/tweak it a bit over time until you feel you have the balance just right.

As far as frequency goes I think that would need to be trial and error as no one can tell you what you like best. I would have thought your first suggestion (40-45) would be the way to go and would be what I would be trying first but what may sound best with one persons set up may not be the same as anothers. Sorry, I know this isn't helpful as such but the only way you'll get the best from it is to play around a bit. Good luck!
 

BlueWizard

Distinguished Member
....
Then I tried setting the low pass at 80 hz and again I felt it boomy though way less than lfe mode. I guess it was to blame on the overlap from around 40 to 80 hz, right?

Yes, likely it was boomy due to the overlap. Though as someone else pointed out, you also have to manage the Volume Control on the Sub. Much like the Crossover Control, you have some flexibility here, you can crank it up, but that's not going to give you the best blend.

I say start with the Sub turned down or off, then slowly bring it up until it seems fairly balanced with the Front Speakers. Then eventually you can adjust it to taste, more if you want more, or less if you want less.

Few questions:
1) -3dB and -6dB...and then 38hz + 5hz or 38hz + 8hz.... what does it mean? I'm sorry I'm quite noob :(

From observation, though not consistently true, I have discovered the the difference between the -3db (virtually flat) and the -6db (down a bit but still usable) tends to be in the range of 5hz to perhaps 8hz.

So if you have the -6db rating of a speaker, you can make a fair estimate of the -3db by adding either 5hz or 8hz. Or you can go the other way, if you only have the -3db response rating, then you can subtract 5hz to 8hz to get a best guess -6db rating.

To illustrate, if the speaker had been 38hz at -3db, would could guess that the -6db rating would be in the 30hz to 33hz range.

Of course there are acceptions, but as a best guess estimate, using something in the range of 5hz to 8hz usually gets you close.

For example, the 6.5" Wharfedale Diamond 220 has these specs -

Frequency response (+/-3dB): 45Hz ~ 20kHz
Bass extension (-6dB): 40Hz

A difference of 5hz.

Many manufacturers like Wharfedale give both -3db and -6db ratings. Some like Tannoy only give the -6db, others like DALI only give the -3db rating for the speaker.

In this case
2) Before buying the sub, I thought the cxa60 could actually bass manage any sub...but yeah I was pretty wrong. And I guess for now the best solution I can follow is the natural front speakers roll-off crossover setting. In terms of sound quality is there a big difference between using the cxa60 and using a proper receiver? Would it be worth it for me to buy a receiver?

Bass Management is extremely rare in a Stereo Amp and generally expensive, though there are a few. Bass Management is a AV Receiver is pretty much universal, but for a fixed amount of money, you are buying a lot of amps that you don't need which dilutes the value of each amp channel. That is, TWO Amps for £500 are worth more than SEVEN or NINE Amps for £500.

Certain speakers lend themselves better to integrating a Sub with Stereo, the Tannoy would be one of them. If the rated bass had been 30hz, there would have been no way to blend the Front and Sub because the Sub only goes down to 40hz. But since the Tannoy at -3db are in the roughly 40hz range, you should not have a problem blending them.

In some cases with a Pre-Amp/Power-Amp or with a Integrated Amp that has a break between the Pre-Amp Section and the Power-Amp section, a fixed crossover can be inserted to limit frequencies to the Front speakers. I don't think the Cambridge has this feature though, but some NAD and some Yamaha do.

If you look at the dial on the Klipsch Subwoofer, the difference in the position of the Crossover Control Dial between 40hz and 45hz is very small, so really just set it a bit above the 40hz mark and it should be fine.

klipsch-r115sw-backsm-jpg.855660


Steve/bluewizard
 

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