John Hunter of REL just has a different philosophy about how to use subwoofers. Not saying it's wrong, just different. As @tomic601 alluded to earlier I come from a different school of thought, one taught to me by Roger Modjeski (designer of the electronic crossover for the Beveridge 2SW) who finally convinced me to use subs (8" woofer in a 1/3 cubic foot sealed box x 4) with my QUAD ESL speakers. His recommended LP and HP cutoff was 100 Hz. Why? Simple, the speaker was designed with a 90 Hz bump and that crossover point eliminates the bump. Now the QUAD ESL will never make anyone's best bass from a speaker list, but without that bump the speaker would have significantly less bass output, so there is that to consider as well. On my box speakers which are Spendor 1/2e I use 70 - 80 Hz.
Subwoofer speed is in the room, not the box
First, if you like swarm, that’s fine, please start a thread somewhere else about how much you like swarm.
I want to talk about the impression that subs are fast or slow compared to planar or line sources.
The concern, and it’s correct, is that adding a subwoofer to say a Martin Logan or Magneplanar speaker will ruin the sound balance. That concern is absolutely a valid one and can happen with almost any speaker, not just speakers with tight dispersion control.
What usually happens is that the room, sub and main speakers aren’t integrating very well. Unfortunately for most audiophiles, it’s very hard to figure out exactly what is wrong without measurements or EQ capabilities in the subwoofer to help you.
So, there’s the myth of a small sub being "faster." It isn’t. It’s slower has worst distortion and lower output than a larger sub but what it does is it doesn’t go down deep enough to wake the dragons.
The biggest problems I’ve heard/seen have been excessively large peaks in the subwoofer range. Sometimes those peaks put out 20x more power into a room than the rest of the subwoofer. Think about that!! Your 1000 W sub is putting out 20,000 watts worth of power in some very narrow bands. Of course that will sound bad and muddied. The combination of sub and main speaker can also excessively accentuate the area where they meet, not to mention nulls.
A lot is made about nulls in the bass but honestly IMHO, those are the least of our worries. Of course too many of them can make the bass drop out, but in practicality is is the irregular bass response and the massive peaks that most prevent any good sub from functioning well in a room.
Bass traps are of course very useful tools to help tame peaks and nulls. They can enable EQ in ways you can’t do without it. If your main speakers are ported, plug them. Us the AM Acoustics room mode simulator to help you place your speakers and listening location.
Lastly, using a subwoofer to only fill in 20 Hz range is nonsense. Go big or go home. Use a sub at least at 60 Hz or higher. Use a single cap to create a high pass filter. Use EQ on the subwoofer at least. Get bass traps. Measure, for heaven’s sake measure and stop imagining you know a thing about your speaker or subwoofer’s response in the room because you don’t. Once that speaker arrives in the room it’s a completely different animal than it was in the showroom or in the spec sheet.
Lastly, if your room is excessively reflective, you don’t need a sub, you need more absorption. By lowering the mid-hi energy levels in a room the bass will appear like an old Spanish galleon at low tide.
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Making a large diameter stiff structure is so easy…. i listen to two vastly different engineering solutions to the same problem…. 3 x 8” vs a push pull titanium honecomb bespoke Scanspeak driver…. like i said prove that big 15” paper cone stays in pistonic in the bandpass…. send it to germany….laser scanner does not lie…..
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One should not confuse my argument as support for anything less than a systems engineering approach to the sub / room problem. The solutions i mention in a previous post include MUCH more than 3 x 8” drivers in a domestically attractive 90# box….. Obviously, i’m a Vandy owner and fan…. I’ve owned the big block gear, starting w Hartley … Infinity servo….Beveridge, etc ( i am…an old bastard… )carry on….and enjoy the music gents !,,,,,,
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@clio09 - Using a high crossover point to fix a low frequency bump is sound. I've done the same while making internal crossovers. It avoids extra EQ components. My recommendation is usually to ask users to plug any ports for kind of the same reasons. It makes integration a little easier. @tomic601 Don't use a laser scanner to prove what you can easily see in distortion. |
agreed that measurements and acoustic panels and traps are critical to a near perfect integration. i do believe that some subs give the impression of being faster than others in the same room. i tried several subs and came to the following conclusions- subwoofers need to have low audible enclosure resonance above your crossover region or they can blur the midrange clarity of the mains. subwoofers with parametric eq are excellent for taming peaks and to even the response between left and right subs, especially when one is near a corner. deep flat response down to 20hz makes a huge difference and makes them worth the effort. sealed subs are less efficient but have lower distortion in critical frequencies. some overlap between subs and mains is ok but not much. putting the subs inside the main speakers makes integration much easier. spread your mains wide if you have to! |
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