I have been seeking as much info as possible about these subs and came across a site which posted a graph of frequency response for the LFM-2. It showed a peak of 104dB @ 70Hz to a trough of 96dB @ 42Hz, rising again to 101dB @ 27Hz and staying at 101dB all the way down to 21Hz. That low figure is impressive, but unimportant for acoustic instruments which don't often go below 42Hz (open low string on a bass fiddle). What this means, if these measurements are accurate, is that the LFM-2 is down 8dB at the most important level - not much different from my main speakers, and identical to my little Yamaha sub! (Of course, 40dB is the bottom of the Yamaha.)

Moreover, I downloaded the manual for the LFM series and found the following specs for the LFM-1: Frequency Response - 25Hz - 180Hz +/- 2dB, and for the LFM-2: Frequency Response - 25Hz - 180Hz +/- 2dB - that is, the same! ???

I have never heard any Outlaw (or Hsu) sub, so can only go by specs. These specs are not impressive for what I want - which is a level response down to 40Hz and then a gradual rolloff to, say, 30. Can anyone suggest a sub which meets those requirements?

I'd be curious to know how those measurements were taken, as room response can generate significant dips and peaks. Seeing as Outlaw rates the sub to be +/-2dB across its range under ideal conditions and without any details about the origin of the graph you saw, I would suspect that the graph included some uncorrected room effects.

According to the Outlaw site, the LFM-2 starts to roll off at 28Hz while the (now discontinued) LFM-1 went to 25Hz. I suspect that the "25Hz" figure for the LFM-2 is a cut/paste typo in the manual. The LFM-1 Plus will reach 25Hz in high output mode or 18Hz in max extension mode. A +/-2dB rating is actually more conservative than most manufacturers, as a +/-3dB rating is more common (lets to list a somewhat lower bottom figure).

As for being flat down to 40Hz, I've been told that the SMS-1 calibration sample in the Outlaw Guide to the SMS-1 was made using an LFM-1. The graph on page 24 shows a response corrected to (at least mostly) eliminate room response issues and looks pretty darn flat all the way down to 25Hz (15Hz below the point where you are seeking a level response).

In addition to the LFM-2 and LFM-1 Plus currently available from Outlaw, there are two subs expected to arrive in the next month or two. The LFM-1 Compact will use a 10" driver and will get down to 25Hz (click here for a press release), and the LFM-1 EX will use a 12" driver in a cabinet somewhat larger than the LFM-1/LFM-1 Plus used and will reach 22Hz with both ports open or 16Hz with one port plugged (see this press release ).

Thank you, Gonk, for your quick reply. You are of course correct to wonder about how these measurements were taken. I don't know how much of the article in question I can copy consistent with the copyright laws, so I am instead posting the URL where you can find it:

http://www.hometheaterhifi.com/volume_13_2/outlaw-lfm2-subwoofer-5-2006-part-2.html

I will certainly look into the two new subs you mention, for which I also thank you. Buying speakers, or any other audio equipment, online, with no opportunity to hear or compare it with comparable equipment, is really unsatisfactory, but obviously necessary - I know of only one high-end audio store in Tucson, a city with an MSA approaching a million people, and it does not allow home trials (except for a very short period and with a punitive restocking fee). Speakers, especially subs, are very heavy and therefore very expensive to ship, so "free" trials are scarcely free; buying several subs to compare, and then returning the losers, would be very costly indeed; and few people have switching facilities at home. But of course you know that, as does everyone in these forums (fora?). We must do the best we can, which is what I am trying to do.

Gonk, I have now looked at the press releases you cite, and I am really confused: the LFM-1 Compact joins the LFM-1 and LFM-2 at showing a frequency response of 25Hz - 180Hz +/- 2dB. That is, all 3 subwoofers, though differing in size and cost, have exactly the same specs! What am I missing? Or is this another "cut/paste typo"?

The Secrets review measurements were taken in-room. While the reviewer has clearly done a pretty solid job of setting up his bass traps, that's not necessarily a cure for all problems and is likely part of the reason that the measurements were +/-4dB between 20Hz and 75Hz. Your room response is likely to be quite different.

The LFM-2 does not go down to 25Hz (well, it probably will in most rooms - after all, it hit 20Hz pretty comfortably in the Secrets review - but it's not rated that way). The LFM-1 has been discontinued and the LFM-1 Compact appears to be taking its place in the line, so it's not surprising that the two have comparable frequency responses. Keep in mind, though, that frequency response alone does not define a subwoofer. The LFM-1 was rated at 115dB of output while the LFM-1 Compact is rated at 112dB - the smaller driver and cabinet are tuned to go as low, but at a cost of 3dB of output.