Any negative to these very high crossover slopes, 48db etc?
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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@clio09 I did not know anything about Roger until I bought some of his tubes, the best I ever had. I use Sound Labs speakers and before that Acoustats. I have been crossing between 100 and 125 Hz for 30 years. It requires a very steep slope to keep the sub out of the midrange. The reason so high is that full range speakers are very susceptible to Doppler Distortion. I chose 100 Hz because that is the point that I could not see the diaphragm move. Aside from lower distortion I get another 10 dB of headroom. ESLs will go extremely loud if they do not have to make low bass and they don't have to force an amp to drive a 30 ohm load. |
@mijostyn that is kind of my point for crossing over as high as possible, but Roger always told me the amp has a say in this so for the mains speakers if we can keep the amp from seeing difficult loads it will be happier and run more efficiently with less distortion. Case in point is a Music Reference RM-10 on a set of QUAD ESL speakers. While on it's own it does a fine job, in a active bi-amp arrangement with a 100 Hz LP and HP it relieves it of having to drive the high impedance in the bass. For the bass speakers Roger just advised me to get a decent solid state amp with good damping. |
Yes. The majority of the speakers were very capable of producing strong, impactful bass without using a sub. So, they were fed the full unrestricted signal. So my point is why on earth would you restrict and high pass filter using any of these speakers when they are perfectly capable on their own? For this reason you don't see any restrictive high pass filtering method being used. @mijostyn Not wishful thinking, just a fact. Very simply put... these speakers are allowed to perform as they were designed by the manufacturer without any unnecessary attempts to make them sound "even better" by choking them down and adding complexity. @mijostyn ... I believe ALL speaker manufacturers are looking to "sell speakers" not just REL.
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@clio09 Again, Roger is correct. Power and damping drive subs the best. But the real difficult aspect of ESLs is the very low impedance way up high. My tube amps have an output impedance of 1.75 ohms, but my speakers drop down to 1 ohm at 20 kHz. If you look at the system's amplitude curve, it starts rolling off at 12 kHz and by 20 kHz it is down 60 dB! I just got my DEQX Pre 8 digital preamp and the plan is to bi amp the transformers. I am going to use a Bricasti Design M25 to drive the high frequency transformer. The Bricasti has a very low output impedance and will easily take the speakers up to 20 kHz. It also has a huge power supply and will continue doubling down to 2 ohms. Sonically it reminds me of my old Krell KMA 100s. I ran those till they self destructed. Roger West recommended a crossover frequency of 5 kHz, so I will start there. In an interesting inversion the tube amp does a stunning job of driving the lower frequencies and would happily take the speakers down to 24 Hz, If I let it. Solid state amps suffer because of the high impedance, the MA 2s do not. @gdaddy1 That is true, the first motive of any company is to stay alive and to do that they have to sell product. The problem with REL is it seems to be the only motive. Anyone can shove drivers into a box and make up a marketing story. If you want really bad bass and a lot of distortion follow Rel's instructions. I have been using subwoofers since 1978 with electrostatic speakers and have been through every possible permutation. Commercial subwoofers are so bad I design and build my own. Randy Hooker made the best subs you could buy, brilliant design, but way too big for modern sensibilities. Mine are the best subwoofers you can't buy, but unlike Hooker's subs you need a lot of power to drive them. I took me 30 years and 3 trials to get them right. You can see pictures of them in unfinished form at the link below. They are finished in high gloss black polyester and clear coated. If you have questions about the design fire away. There will be a full pictorial of their construction in case anyone wants to have a go at it.
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