Incorporating a sub-woofer

I've read the tutorial on multi-channel audio but what I'm attempting might be somewhat different. I am currently using 2 speakers set up in stereo and want to add just a subwoofer. Should I set up the sub on a separate channel or just integrate it with the 2 existing speakers and adjust the crossover accordingly? The stereo speakers are actually a little bit boomy even though they don't go below 20hz. I really just wanted the sub to handle the lowest and loudest ranks of the pedal division and not direct these ranks to the stereo speakers.

Thanks.

Everyone has an opinion of course, but I think in this case you'd be best off integrating the subwoofer with the two existing speakers, rather than fiddling with it on a separate channel. Many pedal ranks have a lot (think reeds, especially) of upper partial development, and you'll need the existing mid-upper range speakers to reproduce these properly.

If you use a powered sub which then has integrated outputs for a pair of speakers then you should simply output everything to the channel feeding the sub and its crossover will send upper frequencies onward to the speakers. You definitely want the sub to send upper freqs of the pedal stops on to the speakers and not send low freqs onward.

Thanks for the suggestions guys! Really appreciate it.

Mike,

I am considering changing my ageing stereo sound system to one with active speakers and a subwoofer.

As mentioned above, I want to send only the relevant frequencies to each speaker. I think part of the reason the MDA Salisbury makes my old speakers rattle is that they are not coping with the copious amounts of 32' flue output!

I quite liked the Genelec system. That has a subwoofer that does all the filtering - but it was about £1,800 for the subwoofer alone. It would expand to surround sound, though (4.1).

I have heard in this forum good reports of the Mackie HR824 speakers. However, if you are going to use a subwoofer then the HR624 model should be more cost effective and the subwoofer will replace any lost bass. I don't think the matching Mackie subwoofer is easily obtainable in the UK so I have been looking at the BK Electronics range (also mentioned elsewhere in this forum).

The HR624 has a filter to keep out the low frequencies and the BK Electronics XXLS400 has a filter to keep out the high frequencies - and the subwoofer is a more reasonable £417.33. I think that if I use my hardware mixer I will have all the necessary outputs to effectively run the same audio output to the both the stereo speakers and the subwoofer.

I looked at many makes and not all of them provided the necessary filters. You need to review the specs in some detail to see exactly what inputs, outputs, filters etc are required/provided. For instance, my mixer will produce a stereo output and the subwoofer is essentially a mono speaker. The BK Electronics XXLS400 can be specified with a stereo input that will merge the signals so I would not need another adapter.

It takes me a long time to make up my mind but the above is my current plan - subject to money still being available after upgrading to HW4 and Salisbury v2.

Regards,

Good point...HW4 and S'bury V.2 and 3 could have quite an impact on future plans!

Hello Mike,

For what it’s worth, I am using 2 Mackie HR824 MK1 with a Genelec 7060B Sub (the single most expensive bit of kit in my project). Audio from a Focusrite Saffire LE goes through the sub and into the HR’s. The audio quality is excellent.

Before I got the Sub the audio was still VERY good. The Sub just adds that subtle ‘umph’ on the low end, more of a feeling I guess, but adds somewhat to the realism. I did have to adjust the HR’s bass roll-off though after incorporating the sub as a little boominess crept in. After messing around with speaker placement and settings on the sub it has been well worth including the sub.

I was lucky enough to get 3 more HR824 MK1’s on ebay and am just waiting for another to pop up here in Australia. When I have six I will route the audio of all six through the Sub, and use the ‘Cyclic within octave, octaves and ranks cycled’ algorithm in Hauptwerk’s ‘Configure Audio Output Groups’ menu.

I was lucky enough to get 3 more HR824 MK1’s on ebay and am just waiting for another to pop up here in Australia. When I have six I will route the audio of all six through the Sub, and use the ‘Cyclic within octave, octaves and ranks cycled’ algorithm in Hauptwerk’s ‘Configure Audio Output Groups’ menu.

Each of the 6 HR824's needs an audio channel all to itself other wise the 'Cyclic' can't cycle.

Pax,

Thomas

Thank’s Thomas, I understand that. The Genelec 7060B has 6 IN/OUT and is probably well suited for my intentions. The Saffire has 6 OUT’s and these will go through the Genelec into each HR824. With 2 groups of 3 speakers, in stereo, using the ‘Cyclic within octaves, octaves and ranks cycled’ algorithm should yield excellent results.

An Auxillary mix-down sent to the sub also works well. Two situations I can think of when you might need this solution,
1. Some Subs don't have outputs to go on to other speakers - DefTech supcube III for example
2. You don't want to tie up two of the monitors to provide the upper frequencies for stops you are sending to the sub channel.
I use it for the second reason, I can use my six monitors in various ways and have more channels available for a multi channel setup. This way, not everything that needs a sub needs to be sent to the same channel.
If you do dedicate a pair of monitors to providing highs for the ranks routed to the sub, don't overlook the bass routing option as you load ranks. It allows most of the rank to go to another channel, so you don't end up with all of every 16 and 32 stop in the same channel.
John

[mdyde]

(Topic moved here.)

Thanks David. I did not know that was possible until now. You increased my knowledge base.

Pax,

Thomas

Some excellent points have been made already, but I will add a few more thoughts.

If one is using a single pair of speakers, for example among users of Hauptwerk Free or Basic Editions, it makes sense to blend a sub with the primary speakers using the crossover frequency and level adjustments typically found on the sub. A few subs will incorporate a high-pass filter to feed and amplifier for the satellite speakers. Some active monitors (eg., the Mackie HR824) have a built-in bass roll-off filter. Experimenting with these settings and room placement will generally help one achieve a good result.

When Hauptwerk AE users move to multi-channel audio, the picture gets a bit more complicated. With four channel setups, for example two in front and two reverb speakers in the rear, the configuration described above might be used for the front channels. A second subwoofer might be added for the rear speakers.

For six main channels, a user may wish to set up the speakers in a group of "octaves and ranks cycled". In this case, the best strategy for dealing with bass would be to setup a pair of outputs for bass and route only the bass pipes (say for example notes between 012-C and 035-B) to the bass channels. In this case, one will need a pair of full range speakers to use with the sub(s) to reproduce the upper harmonics of the bass pipes. An advantage of this approach is that the deep bass frequencies are never sent to the main speakers and this can greatly reduce distortion (harmonic, intermodulation, and doppler) from excessive cone excursion as well as amplifier clipping. It also eliminates the requirement for high-pass filters for the main speakers.

Another comment on subwoofers already covered in other threads is that reproducing 16' notes (32 Hz) is not too difficult, but achieving realistic 32' notes (16 Hz) is extremely challenging. That last octave gets to be very expensive. Three products that I would recommend are the DefTec Supercube Trinity Signature, DefTec Supercube Reference, and SVS PB13-Ultra.

Finally, the room itself will have a profound affect on bass reproduction. A room with at least one dimension greater than 32 feet, or half wavelength of a 32' pipe, is helpful. The worst room shape would be a cube (headphones recommended). A rectangular room which has dimensions conforming to the "golden mean" would be much better. With a 12' ceiling height the room would need to be 19 x 32 feet. The best rooms will have non-parallel walls. "Bass traps" can also help mitigate response anomalies. A second subwoofer can help one achieve a smoother overall bass response by "averaging out" nodes/anti-nodes caused by room boundary reflections. Hauptweerk's pipe-by-pipe level controls are also very handy.

Joe