Josh, I think your quesion is a good one. Also, the the link to the madisound post will soon cease to exist. The madisound discussion string is only 3-4 weeks long, and the archives only go back about two months. I will therefore paste this issue here. I think it is a good topic for others. The initial quesion posited was one concerning the possible advantages of a dual woofer design using two W18's.
Dennis responded to most of this. I think I have some fair comments to offer also.
a) Its sensitivity (with BSC) becomes too low and, unless the amp is very very strong, will miss some of the action in the 100-300 region, leading to leaner and more forward sound.
There aren't direct correlations between more woofers, and a rich sound. I auditioned a British metal cone TMM a few years ago that sounded very lean too. As Dennis mentioned the sound is directly dependent upon the frequency response shape. I agree with his comments. Just because a speaker only has one midwoofer doesn't necessarily mean that it will sound lean in the 100-300hz range.
b) It becomes a bit edgy when pusched, and does not like heavy dynamics and +90db.
It depends on the driver loading and the type of music played. I find that heavy women's vocals will cause the 1801 tweeter to surrender far before the woofer. If the tweeter is crossed low (relatively speaking) then adding a woofer won't yield any advantage in the power handling realm.
I'll also add that your hearing won't last long if you listen continuously at that level.
c) Its detailed nature can be a curse if the amp is too weak and the sound is too loud.
This is true no matter what the response curve is. Unfortunately a high resolution speaker can't transform into a low respolution speaker when exposed to poor source material. It is impossible for a cone to change from metal to paper when exposed to poor source equipment and/or poor recordings. Ya' can't have your cake and eat it too. The older Journey, REO Speewagon, Iron Maiden etc etc are really grungy recordings. I believe this stuff sounds much better on some nice soft cones.
I'll also add that the perception of detail results from clear reproduction of music HARMONICS. The FUNDAMENTAL tone provides a sense of impact, but the harmonics provide a sense of detail. A downward frequency response slope, or a soft cone that gets muddy as the hz rise will both have nice authority, but lack in perceived resolution. An upward frequency response slope or a very stiff cone will sound detailed as the hz rise. Hence the upward slope with the stiff metal cone will exacerbate the tendencey to sound bright/detailed.
Beyond the scope of that quesion is Josh's direct quesion regarding an MTM or dual woofer 1801 - aka 3601. Do I plan to make one.
The short answer is "no". Some explanation follows.
1. After completing the 1801, nobody has complained about lack of power handling with the 1801. All seem quite pleased with the sound pressure the 1801 creates.
2. A dual woofer design with the MTM would still place the same load on the tweeter. The 1801 crossover limits are already pushed to quite an extreme with a metal cone and a 3/4" non-ferro tweeter. Ideal distribution of the power load would move the crossover point higher and redistribute the load away from the tweeter and toward the woofer.
3. A dual woofer W18 speaker would see the 2.83 volt sensitivity rating would increase, but the nominal impedance would drop to 4 ohms and the low dcr would drop to about 3.2 ohms. While this might be fine for commercial guys, most folks don't have amplifiers biased towards driving such low loads. I think that Todd griffin puchased an Aragon, but he is one of the few guys with a current oriented amplifier. Most amps like a nominal load of about 8 ohms. The key to identifying the current orientation of an amplifer is in the power ratings. If the 4 ohm wattage rating is DOUBLE the 8 ohm wattage rating, then the amp is mean to drive the 4 ohm load. If not, the ability of the amplifier to drive a low load is quesitonable. A decent guy (Sean) mentioned to me a few days ago that Bryston amps sometimes have difficult with low loads. I found this a little strange, but certainly possible.
4. The MTM - I really wanted to hear something special with MTM speakers, but I don't. Joe D' has performed some monumental science in this venue. It is good and very valid science. I just don't hear it.
5. A dual woofer cabient would just be big. I have built some 50 liter test cabinets. I think a single 8" with a dome midrange would be better, but am not sure what direction this will take. It isn't really on my list of things to do.
6. The perceived need for an MTM comes from exposure to 99% of the midwoofers on the market. There are a few exceptions to these standard woofers. A few woofers have a linear throw that is a solid 2x the standard found in 99% of the other midwoofers. These long throw woofers include the 7" scanspeak units found in the Proac 2.5 and Merlin VSM. There is also the Accuton C95 found in the Kharma CE 3.1, and... well, the W18 that I use. Exposure to the other 99% of midwoofers certainly could leave the impression that 2 woofers are needed for good sound pressure.
I hope my response is adequate.
