Subwoofer in stereo set up

I used a Naim sub with my Superuniti, and it worked pretty well. Be prepared for lots of trial and error to get the room positioning and settings right. You can use either the sub-out or pre-out with a long (and rather expensive) low level interconnect, or use the high level connection from the terminals on your speaker, which can be done with very cheap cable. If you struggle to get good results, you could consider using DSP to tailor the sub to your room, but you would need to use the low level connection for this.

I don't use a SU (I use a 272 & 300DR) but I use a B&W ASW610XP with a pair of Spendor SP2s.

In my case I use the low level connection from the 272 to a miniDSP 2x4 that does both the crossover and digital room correction.  I use short Chord C-Line cables to connect the DSP.  It only needs a much cheaper RCA cable to connect the DSP to the sub, in general you don't need an expensive cable for that link.  I used REW and a miniDSP UMIK-1 to do the setup, it actually makes the set-up reasonably easy.  

I use a Velodyne sub and N-Sats with my SU. This sub come with microphone and set up software which makes a seamless integration more achievable and I'm very happy with it.

There are a couple of long recent threads on subs if you search this forum.

Thanks for the replies and I have now seen the thread which was interesting. I have been tweaking away with the 610 this evening with the LPF set to about 65 and the volume at 1/4. Its positioned to the right of the right channel PMC near the corner / bay window area. 

Ive seen some comments on bass traps and some technical information in the other thread. Mrs T may have an issue with Bass Traps in the front living room so that really isn't an option. I have noticed intitially an overall improvement to the sound using my ears as the guide although on some heavy metal music I don't think the sub is moving quickly enough. I listen to lots of music from dance / rock / heavy metal to folk. 

The PMC sub uses 2 6 1/2 inch drivers but the new twenty 5.sub is rather expensive. Does anyone have any experience using their subs with smaller PMC speakers? 

At the research stage with this at the minute so any advice / opinions really appreciated...

thanks

For a B&W 610, it needs to be about 1.5m closer to the listener than the main speakers to allow for it's group delay (about 2.5ms to 3.5ms).  It's this that's causing the 'slow' effect not the sub itself.  The problem is that you haven't taken the time domain into account with your crossover settings.

Also, don't put the sub in the corner of the room that's will increase the coupling to the main room resonance modes.

Others with more technical expertise than me have offered good advice above so my contribution will be simple observation...  when I bought B&W 802s I thought 'Ah, no more need of a sub'.  A few months later with the REL Storm sitting there doing nothing, I connected it 'just to see' (to the low level out of 552 pre).  It is so tempting to wind up the volume and crossover frequency of the sub so that you can 'hear it working', but don't do this.  A sub works well when you can't hear it, or to be more precise, when the settings are such that it blends quietly into your audio system...  not an easy setup to establish, but well worth spending the time (maybe days) to accomplish.

My only other comment would be about using a pioneer A/V amp to drive my front speakers... unlike Naim, Pioneer is not celebrated for its amplification quality, so concentrate on a setup that employs the SU amp.  I have to confess that after creating an expensive A/V system a while back, I eventually made the break and separated A/V from pure stereo audio systems.  The two systems sit together in my lounge, so the 'single speaker' fraternity would not approve (I use B&W wall mounted A/V front &  sides and B&W 802's for the stereo system).  Priority is given to the Naim system over a Yamaha system when it comes to upgrade investment, of course.

This probably doesn't help you right now, but if I've planted a seed of thought that questions the priority of A/V verses stereo in your mind then I'm pleased 

Roger 

Thanks all, I will try moving the sub around as suggested . I have no problem spending time in improving the sound. Might of been my explanation but I'm not using the Pioneer AV amp to run the PMC fronts. When using the AV I'm using the Naim to power the fronts. When listening to audio the Pioneer is off and using the Naim only with sub connected to Naim. 

So Huge with correct set up do you think the 610 is a good match to the rest of my equipment / room. I was thinking I needed to invest more in the powered sub to match the quality of the Naim / PMC. I'm also waiting on a Planar 6 with Ania to be delivered...

thanks

Hi MrT,

In terms of quality, the 610 isn't that far behind the SU and PMC Twenty5.21s, probably not quite a match, but very close.  I'd say the 610XP would be the B&W at same level as your components - I'm happy with one of those in a 272/300DR/Spendor SP2 system, so you'll be fine with a 'plain' 610.  The ear is much less discriminating of low bass sounds, so you don't need a sub to have as good an overall sound quality as the rest of the system.  It just needs to be responsive to transients and not produce too much in the way of distortion harmonics (both reasons why sealed subs like yours are better than reflex ported ones).

Tony is right, the sub should blend in seamlessly so you don't really hear it, you should just get a better sense of warmth, scale, weight and solidity to the sound.  Ideally you shouldn't really notice it's presence, but you should notice it's absence when you switch it off!

I have a velodyne with 02/200 and ovator 400 

if adds a 3d element to the sound rather than just low bass- switch it off and it feels like 1/2 the music has gone!

Huge posted:

For a B&W 610, it needs to be about 1.5m closer to the listener than the main speakers to allow for it's group delay (about 2.5ms to 3.5ms).  ...

@Huge: So just to be sure that I understand, this principle will apply to all subwoofers although the exact delay may differ between different models? Consequently they either all need to be placed closer than the main speakers to the listener or in theory a delay could be put into the main speakers. Am I thinking correctly? 

Yes, you're thinking correctly.

However, I wouldn't recommend putting an electronic delay in the path to the main speakers as that will compromise the sound quality in the midrange, where the ear / brain combination is most affected by small degradations in sound quality, and the extra processing will degrade the sound quality to some degree.  I think it's best to move the sub closer to the listening position and use the speed of sound from the mains to the listening position to compensate for the delay in the sub.

The delay isn't a reflection of poor design, it's an inevitable effect of the sub having to have a low pass filter in it's amplifier, and of some other aspects of the physics and engineering necessary to get the extra LF response a sub needs.

But also don't forget that this only applies to music systems:  In cinema (5.1 / 7.1) systems the sub is very often only used as a LFE (Low Frequency Effects) channel device, so time integration with the main speakers just isn't as critical (the main speaker and LFE signals aren't correlated - hence a few ms delay isn't an issue and cinema sound processors often allow digital delays to be added to compensate anyway).

Huge posted:

Yes, you're thinking correctly.

However, I wouldn't recommend putting an electronic delay in the path to the main speakers as that will compromise the sound quality in the midrange, where the ear / brain combination is most affected by small degradations in sound quality, and the extra processing will degrade the sound quality to some degree.  I think it's best to move the sub closer to the listening position and use the speed of sound from the mains to the listening position to compensate for the delay in the sub.

The delay isn't a reflection of poor design, it's an inevitable effect of the sub having to have a low pass filter in it's amplifier, and of some other aspects of the physics and engineering necessary to get the extra LF response a sub needs.

But also don't forget that this only applies to music systems:  In cinema (5.1 / 7.1) systems the sub is very often only used as a LFE (Low Frequency Effects) channel device, so time integration with the main speakers just isn't as critical (the main speaker and LFE signals aren't correlated - hence a few ms delay isn't an issue and cinema sound processors often allow digital delays to be added to compensate anyway).

Thanks for the confirmation. Other than hanging a subwoofer from the ceiling, which isn't going to happen, I've zero options to place a subwoofer in a suitable location either in front or behind our listening position so I'll stop spinning my wheels exploring this. It was only me playing anyway as the system sounds good as it is already. Putting an electronic delay in the main speakers was just a theoretical point and not a serious proposal so no worries on that point.

I always wondered why subwoofers in music systems seem to be treated differently but now understand, thanks for the explanation. 

Oops, I meant to say "I always wondered why subwoofers in home cinema systems seem to be treated differently ..." - sorry the edit window just timed out.

More fiddling complete, think I'm getting nearer what i think it should sound like. I have moved the PMC's back a bit and the sub forward and changed the angle its firing into the room and brought away from the corner. The B&W manual states

"Set the LOW-PASS FREQ control to match the -6dB low frequency cut-off frequency of the satellite speakers. Note: Both -3dB and -6dB figures can be found in the specification of each B&W speaker model. If the satellite speaker manufacturer quotes only a -3dB frequency, the optimum setting for the LOW-PASS FREQ control should be between 0.6 and 0.9 times that figure. The more gradual the low frequency roll-off of the satellite speakers, the lower the frequency should be set."

I cannot seem to find the low frequency cut off for the PMC, any ideas what the LPF on the sub should be set to for PMC 25.21? At the moment I am just using my ears to work it out!

thanks

MrT posted:

More fiddling complete, think I'm getting nearer what i think it should sound like. I have moved the PMC's back a bit and the sub forward and changed the angle its firing into the room and brought away from the corner. The B&W manual states

"Set the LOW-PASS FREQ control to match the -6dB low frequency cut-off frequency of the satellite speakers. Note: Both -3dB and -6dB figures can be found in the specification of each B&W speaker model. If the satellite speaker manufacturer quotes only a -3dB frequency, the optimum setting for the LOW-PASS FREQ control should be between 0.6 and 0.9 times that figure. The more gradual the low frequency roll-off of the satellite speakers, the lower the frequency should be set."

I cannot seem to find the low frequency cut off for the PMC, any ideas what the LPF on the sub should be set to for PMC 25.21? At the moment I am just using my ears to work it out!

thanks

Unfortunately it also depends on the location of the speakers within the room.

This thread should be read in combination with 2-1-system-vs-2-0-system-for-music?

I use pmc 20.21 with velodyne dd10+ it is awesome .... svs ultra 13 should also be good. Your pmc's will be fantastic with a good sub .... you need a model with full dsp and sealed ....they are not cheap.  

You don't need the DSP to be built into the sub - you can use a miniDSP 2x4 or a DSPeaker Anti-Mode DSP in the low level connection to the sub.

These also have the advantage of acting as a line driver, so taking load off the preamp.