Integrating a sub into a 2-channel system

[Camverton]

Hi everyone.

I'm thinking about trying out a subwoofer, most likely one of the new SVS offerings that features built-in DSP, to round out the bottom end of my system.

Using a Creek Evo 100A amp with Tannoy XT6F speakers I currently get nicely tight low end to below the 38hz the speakers are rated for, but it's always nice to have an extra octave to spare. Now, I know that when using a sub with 'full-range' main speakers and a traditional amp (as opposed to an AVR processor), one usually crosses the sub's output over with the lowest end of the main speakers, i.e. unlike with an AVR set up, one doesn't (and usually can't) modify the output of the mains at all.

However, the Creek has rather nicely implemented switchable tone controls, and I was wondering if anyone had, with a similar set up, reduced the bass output of the mains using tone controls on their amp, allowing the sub's output to be crossed over at a higher frequency? My thinking is that it would relieve the mains of some of the bass duties, while leaving more of the LF heavy lifting to the sub. Obviously this would need to be achieved with the help of room measurement, but it would also mean that, with more of the bass range being delivered by the sub, one would be able to use the on-board DSP to manage potential room modes better.

Or would it be the case that traditional tone controls on amps are too blunt a tool to be effective in this case?

Thanks in advance for any thoughts on this

First of all, a sub can greatly enhance a stereo system if, and it’s a big if, it is integrated well. I don’t think I‘d attempt to use tone controls to integrate a sub; too gentle a slope and if you have good main speakers with good sounding bass as far as it goes then I think it is best to make use of that and use the sub to supplement the mains.

There are various ways of integrating the sub. One way is to use a crossover and miniDSP provide various options from fairly inexpensive up to the SHD for best audio quality. Such a unit has the advantage of being able to control phase, delay, slope and of course EQ. This could mean that one could get away with a less expensive sub without so much built in adjustment.

The other method, which I am using, is to run the mains fall range and adjust the sub so that it comes in below the mains and by adjusting phase helps to cancel the effect of any room modes. Further tuning can then be done by applying dirac or similar.

One question that crops up is whether all this can be done by ear rather than measuring. I reckon, having done it both ways, that you would either have to have the patient and hearing of a saint to get it right by ear. Much better, and way quicker, to use REW to check the effect of adjustments as you make them, followed perhaps by a final tweak of gain for personal choice.

If not using miniDSP or the like to crossover then I think it very worthwhile to invest in a sub with continuously variable gain and the modern subs controlled by an app will save a lot of getting up and down adjusting the setting on sub.

As for the sub I think the bigger the better, bearing in mind that room has to be found in a room for it. A larger sub working less hard seems. to be a better, albeit more expensive, way of doing things. SVS have a guide on their website suggesting which sub matches which speakers and suggested crossover points; quite how reliable this is and whether it is designed to upsell to a dearer model I don’t know. I have used an REL sub with 10” driver in the past and it was a waste of money, even in quite a small room.

Sorry about the ramble but hope it helps a little, it’s a big subject!

 

[Nifkin]

First of all, a sub can greatly enhance a stereo system if, and it’s a big if, it is integrated well. I don’t think I‘d attempt to use tone controls to integrate a sub; too gentle a slope and if you have good main speakers with good sounding bass as far as it goes then I think it is best to make use of that and use the sub to supplement the mains.

There are various ways of integrating the sub. One way is to use a crossover and miniDSP provide various options from fairly inexpensive up to the SHD for best audio quality. Such a unit has the advantage of being able to control phase, delay, slope and of course EQ. This could mean that one could get away with a less expensive sub without so much built in adjustment.

The other method, which I am using, is to run the mains fall range and adjust the sub so that it comes in below the mains and by adjusting phase helps to cancel the effect of any room modes. Further tuning can then be done by applying dirac or similar.

One question that crops up is whether all this can be done by ear rather than measuring. I reckon, having done it both ways, that you would either have to have the patient and hearing of a saint to get it right by ear. Much better, and way quicker, to use REW to check the effect of adjustments as you make them, followed perhaps by a final tweak of gain for personal choice.

If not using miniDSP or the like to crossover then I think it very worthwhile to invest in a sub with continuously variable gain and the modern subs controlled by an app will save a lot of getting up and down adjusting the setting on sub.

As for the sub I think the bigger the better, bearing in mind that room has to be found in a room for it. A larger sub working less hard seems. to be a better, albeit more expensive, way of doing things. SVS have a guide on their website suggesting which sub matches which speakers and suggested crossover points; quite how reliable this is and whether it is designed to upsell to a dearer model I don’t know. I have used an REL sub with 10” driver in the past and it was a waste of money, even in quite a small room.

Sorry about the ramble but hope it helps a little, it’s a big subject!

That's really helpful, thanks. You'll be pleased to hear that my silly idea of using the tone controls on my amp to high pass my main speakers has been well and truly abandoned, not least once I twigged that, by adjusting the tone controls on the amp, I would also adjust the signal being fed to the sub via the amp's pre-outs Even if this didn't happen, it would still be a very crude way of high-passing the mains: I'll be using them full range.

Totally get your points about working to get the integration right: this is why I've bought a calibration mic to use with REW, and have managed to get my hands on an ex-demo SVS 3000 Micro for a bargain price, which means I shouldn't lose too much if a sub doesn't work in my space and I decide to move it on.

I've seen the speaker guide on the SVS site, but I do suspect they're pushing their more expensive models with the recommendations, although the x-over and slope advice is consistent for each main speaker model regardless of the sub used, so it acts as a good starting point. I feel the the 3000 Micro model should work well for music in my 3.5m x 4.5m space, and that the DSP functions should get it as integrated as any sub could be: so if it doesn't work with this model in this space, then I think something larger is unlikely to do any better.