JM SW900 Subwoofer

Discussion in 'Speakers & Subwoofers' started by MikeDuke, Sep 27, 2004.

  1. MikeDuke

    MikeDuke Stunt Coordinator

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    [​IMG]
    Part I-about sub woofer
    This subwoofer is JM Lab’s Electra SW900. The retail price is $1750. It is a bass reflex design. It is set in a downward firing configuration. The driver itself is 13.18 inches. A 400-class A/B amplifier powers this subwoofer. I know that their web site says 250 watts, but trust me this has 400 watts of power. I know because my audio representative indicated to me that they were conservative with this number (250 watts), the amplifier is also auto on. The sub has 2 ports. The ports are 2.75 inches in diameter and are 8.26 inches in length. The cabinet is 100 liters. It has a crossover range from 40Hz-140Hz. Also, it has a variable phase control from 0-180 degrees. In addition it also contains a second level boost of 3db at 35Hz. This does not affect power handling. The rear connections consist of two filtered line input (s) (RCA)Direct input (s) for 5.1 (RCA).
    [​IMG]
    It has a weight of 44Kg or 97 pounds. Its dimensions are 19.21"tall 16.92"wide 24.21"deep. The driver is made of JM labs higher end material called a W cone. Other speaker designers like to emphasize that they do not use off the shelf parts and that their drivers cost hundreds of dollars. Well, JM labs is right up there with them. This is no $50 driver. It requires 2 hours to build by hand. . The following is a direct link to learn about the technologies used http://www.focal.tm.fr/gb/home/electra/tek.htm. The SW900 has a frequency response that is listed at 25Hz-180Hz at -3db and 20Hz at -6db (at least, 32Hz at –3dB in free space). The fit and finish of this sub woofer is really fantastic. It seems as though only the finest woods were used. To use the term “furniture grade” for the cabinet is not an understatement. One thing I like about the sub is that it is made all in house. They make the drivers. They make the cabinets. They make the crossover and amp. So for them to integrate everything together is much easier that someone who does not do everything themselves.

    Many other companies source out their drivers. Jm lab does not do this. Now, are there good, well know speaker companies who make good speakers but do not build their own drivers? Yes there are. But personally I like the fact that JM creates everything themselves. It even goes for this sub. Because they make the driver and cross over they can blend the two together perfectly.

    R&D is a part of speaker manufacturing. Each driver built by JM is designed to be in one particular speaker only. So, if a floor standing speaker and center channel both employ a 6-½ inch woofer they will not be the same. The design will be different for both applications. In addition the majority of speaker manufacturers fold the price of research and design into the final price of the speaker. JM lab doesn’t do this. They have a totally separate budget that is just for R&D. I happen to know that it is a substantial amount of money. What this means is that when you buy this subwoofer you are only paying for the materials and the cost of assembly. The cost for the design and development of the technologies used is not factored in to the price.
    [​IMG]
    Part II about room and set up
    The room is small I admit. But we all have some limitation. My room dimensions are L-12.5 feet W-9.5 feet, and from floor to ceiling is 8 feet. In my processor, I have the LFE channel set to -4db. I used my Krell internal test tone and set the subs level to 87db. I also have the 3db boost on the sub flipped on. The cross over cannot be defeated so I set it to its maximum and let my preamp handle everything, which in affect took the sub’s cross over out of the equation. All speakers except for the center channel were set to small. Due to room constraints the subwoofer is not located in a corner. It is located along one of the long walls about one third from the front of the room.

    My Equipment consists of the following
    1.Krell Showcase preamp
    2.1 Bryston 4b-ST for L/R
    3.1 Bryston 5b-ST for Center and surround
    4.1 pair JM labs 927Be for L/R (Limited run of 500 pair with beryllium tweeter)
    5.1 JM Labs CC-901 Center channel
    6.2 Polk RT-3 surround speakers
    7.1 JM labs SW900 Subwoofer
    8.1 Monster power HTPS-7000
    9.1 Monster power AVS-2000
    10.Cables by Transparent Audio
    11.Pioneer DV-47ai DVD player
    12.Sony 34XBR800


    Part III Testing with movies
    My previous subwoofer was an older definitive technology power field 15. As the name implies it had a 15-inch driver with a 200-watt amp. It was good at the time, but when I got the SW900 the difference in quality quickly showed it self. When listening to the Def tech, it could shake the room with no problem. But when I switched to the JM something happened. I heard and felt real bass for the first time. What I mean is with the def tech, what I thought was bass was just distortion. The overall sound is so tight. There must be very little distortion with this subwoofer. It took me a few days to get used to only hearing bass and not the other stuff as well. But also the total volume (SPL) and extension were enhanced also. I was getting more and better bass out of a smaller driver. When I watch dvd concerts the bass is so smooth, tight and balanced that I can not tell the subwoofer is on. The bass sounds like it is coming from the main speakers only. The volume has no problem filling my room. After the sub was broken in it was incredible. I was watching the animation scene in Kill Bill. This is after I had already beaten my room up with bass. In that scene, the bass was so loud at one point it caused my blinds to fall out of the ceiling. Wow! The overall sound of this sub is just fantastic. It has no “boom” at all. Bass is just tight. Sound tracks just sound so smooth with this sub. Also, I cannot detect any port chuffing. The bass just sounds mean and violent.

    All measurements were done with a radio shack digital SPL meter. All readings were done at the main listening position, which is at the far wall. All SPL levels are C weighted with no extra compensation. My pre amp has a starting volume of 0 for no sound. All numbers of volume are relative from that point. Volume for movies and tests were at 14 on my Krell.

    Below is a chart of my in room response. In a corner I am sure that the readings will be stronger. As hard as I tried I could not fix that dip at 63 Hz. I used the parametric EQ in my Krell showcase to try and get the flattest response.
    [​IMG]
    Do not pay attention to numbers below 22Hz.. My Avia disk does not go below that level. Besides that one dip, at 63 Hz the response, 80-25 Hz looks pretty good.
    I did a bandwith uniformity calculation. I took the subs average over the range 25-63Hz and put it over the maximum out put. The resulting number was between 98-99%


    For the movie measurements you could add 4-5db to get an accurate reading to compensate for the radio shack SPL meter. Keep in mind that this has only one driver. I think it is pretty impressive for having only the 13:18 inch driver and 400 watt amp. Now I don’t believe that these measurements represent the limit of the Sub. They just represent the limit of my room. I am sure that in a bigger room you could crank it up even more and get more SPL out of it. What I mean by that is this sub could be made to deliver more SPL if needed. I did not mean to say that just moving it to a bigger room will yeild more SPL. I just meant to say that this sub has the ablility to fill a larger room thatn mine with high amounts of SPL. My room is so small that this is all I and my room can handle. In a bigger room I have no doubt that it could be calibrated to handle more room volume. I have heard this in a much bigger room and it still was very powerfull. Sorry if any body was confused.

    All volume is at 14 on my Krell
    movies and scenes to do
    LOTR-FOTR
    open battle 95-100 db
    Sauron attacks 93-94 db
    Sonic wave 102 db
    ring drop 94 db
    Bilbo ring drop 96 db
    tree root 94-100 db
    Gandolf speaks at Elron 100-107 db
    Giant octopus 90-96 db
    troll 102-106 db
    bridge/balrog 102-111 db


    Fiding Nemo
    Daria taps 103-107 db
    whale 98-110 db

    Kill bill
    Anime Sequence (36:54-42:23) 96-104 db

    Star wars I
    Engine start 96-99 db
    Pod Race 98-103 db
    Saber battle 94-102 db

    Star wars II
    Coruscant Ship Passing (0:02:02) 111-114-115 db
    Coruscant Ship Exploding (0:03:23) 111 db
    Speeder Chase 101-106 db
    Asteroids 104-110 db
    From 110min-118min peaks from 98-110 db


    Jurassic Park III
    Plane crash and attack 92-96 db
    Dino fight 94-97 db

    Master & Commander
    Opening Salvo (0:09:03-0:09:09): 99-100 db
    Salvo Exchange (0:10:48-0:11:32): 98-100 db
    Double Blast (0:13:21): 101, 104 db
    Last Round (0:13:31): 104 db




    Open Range
    Opening Thunderclap (0:02:41): 94 db
    Shotgun Blast In Saloon (1:12:35): 94 db
    Handgun Fire (1:42:57): 88-96 db
    Shotgun Blast Through Wall (1:46:50): 95 db




    LOTR-ROTK
    Nazgul Flyover (0:43:26): 104 db
    Battering Ram Hits Door (1:46:45): 104 db
    Oliphant Stomping (2:04:20-2:04:23): 105 db
    Oliphant Stomping (2:04:54-2:04:57):106 db
    Nazgul Death Throes (2:09:37): 106 db
    Witch King Spike Ball Hits Ground (2:10:10): 100, 104 db
    Oliphant Howdah Sliding (2:13:21-2:13:24): 101 db
    Sauron Spots The Ring (2:29:05-2:29:27): 105-107 db
    Frodo's Beating Heart (2:40:33-2:40:57): 99-108 db


    So as you can see I am very satisfied with this sub. I find it a very capable subwoofer. As I said before, it sounds so smooth and tight to me. I think it is another option people should be aware of.

    For this review I used the movie scenes that Edward J M
    uses in his reviews. I used them because they are popular scenes. I followed his basic template of description, explanation, and measurements because it was just so logical.


    P.S I double checked the comensated SPL readings on the chart and found they were a little off. 22Hz should be 89db, 25Hz should be 94, 28Hz should be 98db, 45Hz should be 98db, 50Hz should be 98, 56Hz should be 96.5db. I found this out when I did the caluclations my self. I just want to try and give an accurate account. The movie SPl's are the same.

    Post Script:
    I think it is only fair that I also inform the people reading this review of some problems I have had. I have had 2 amps go bad on me. The first went bad over a year since I had it. I think there was a brown out that my protection just could not handle. So the amp was taken out and was fixed. It was reinstalled and worked fine. It was reinstalled about one month ago. This past weekend it went out again. Now this may be an anomaly unique to me and my crapy power in my area. I do not know. I am going to have the sub shipped back and fully checked out. I still love this sub; I hope this fixes the problem. I just thought it would be fair to inform you of this.

    The problem was identified as being just a bunch of blown fuses. A detailed explanation is listed on one of my posts on page 2.
     
  2. Ned

    Ned Supporting Actor

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    I would imagine people are missing this post. Lots of good info.
     
  3. Kiet

    Kiet Stunt Coordinator

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    Hi Mike,
    Nice post, I owned a JMLab SW900. And what you have just mentioned in the review, is exactly what I want to say. Guessed you have said it 100% correct. Nice info too. [​IMG]
    About the 3dB boost, I didn't turn it on because I am afraid it might add some bominess or distortion to the sound. I guess after reading your review. I might try to turn it on. [​IMG]

    By the way, how much did you pay for your sub, and the 927Be? Because I am thinking of getting the 907Be for music. [​IMG]

    Keep up the good work. Can't wait to see your review of the 927Be.
     
  4. Craig Chase

    Craig Chase Gear Guru
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    Hi Mike - Very nice write-up. You are having fun "working", yes ?

    Check your PM... a couple of thoughts....
     
  5. MikeDuke

    MikeDuke Stunt Coordinator

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    Thanks for the kind words. Both of you.
    Kiet, I got a good deal at my dealer. I payed about $1550 for the sub, $1750 retail, and $5300 for the 927, $6000 retail. Yea, the boost does not make it sound boomy at all. Give me time. I will put up a 927 review when I get the chance.
    Once again thanks.
     
  6. MikeDuke

    MikeDuke Stunt Coordinator

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    Craig

    Thanks for your info and yes I am having a boat load of fun.
     
  7. Craig Chase

    Craig Chase Gear Guru
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    Mike - You are welcome. If you want to make taking measurements easier and more fun, check out the TrueRTA and/or ETF software packages.

    The TrueRTA, with a Behringer ECM-8000 microphone, and an M-Audio Microphone pre-amp (they have models with phantom power supply and USB outputs for your computer) can make for a VERY nice measuring tool for about $300...

    The ETF is great, though more complicated... and is recommended if you are REALLY serious...

    TRUE RTA will also give you info on getting the microphone calibrated...

    Then you can take a LOT of easy to chart measurements...
     
  8. Kiet

    Kiet Stunt Coordinator

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    By the way, did you put the spike on the sub. I found putting spike gives the bass a little more touch of accuracy and focus in the bass
     
  9. MikeDuke

    MikeDuke Stunt Coordinator

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    Kiet. If you mean on the bottom of the bass plate then no I did not. Maybe if I get a chance I will try it.
    Thanks
     
  10. MikeDuke

    MikeDuke Stunt Coordinator

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    Would spikes make that much of a difference even though the sub fires down into the base plate?
     
  11. Kiet

    Kiet Stunt Coordinator

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    Yes, for me they sort of give me a better feel of the bass, especially for movie. It seems to spread out a little bit better with the spike. But that is just what I feel.
    I know other people in Hong Kong that actually buy better spikes and isolation plates because they notice the difference.
     
  12. MikeDuke

    MikeDuke Stunt Coordinator

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    I will have to check them out then
    Thanks for the tip.
     
  13. Kiet

    Kiet Stunt Coordinator

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    Hey Mike,
    I was just wondering have you ever heard an SVS subwoofer. There are certainly lots of myths and legends around this brand of sub on the forum.
    How does it compare with the JMLab?
     
  14. MikeDuke

    MikeDuke Stunt Coordinator

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    You know, I never heard a SVS sub so I can not directly compare them to the SW900. Personally, I am sure this will start the flaming, but my guess is that the SW900 could keep up with some of the subs from SVS in quality and output. The truth is that I would like to see some sort of comparison between the two. And if SVS out perfoms it oh well. There is always something that can play louder or lower. But as far as quality of bass, I think it would be a close race. As far as the word on the forums and reviews go, is that they are all very good. I do not want to pass judgment since I have not heard it. I am not that kind of guy. I am not the one to say one is better than the other. But I have heard the Wilson audio watch dog, martin logan descent, and dynaudio contour sub. To me, in the right room, the SW900 can hang with any one of them.
     
  15. Edward J M

    Edward J M Cinematographer

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    Gee, this stuff looks vaguely familiar.....
     
  16. MikeDuke

    MikeDuke Stunt Coordinator

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    yea well, your reviews are the standard I desided just to "borrow" the movies that you did. I hope you do not mind.
     
  17. Kiet

    Kiet Stunt Coordinator

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    Yes Mike,
    I agree with you. Stats sometimes can be deceiving, because something that plays loud does not necessarily means that it produce the better overall sound. Because sometimes, you can get too much bass which sounds very fake and artificial.
     
  18. MikeDuke

    MikeDuke Stunt Coordinator

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    Thanks Kiet. That is the point I was trying to make. My dealer taught me that. I was first into the numbers game. Then I started to listen very carefully. I found out that subs that may not have the most impressive numbers can still be pretty amazing. And be affordable.
    Mike D
     
  19. paul clipsel

    paul clipsel Stunt Coordinator

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  20. MikeDuke

    MikeDuke Stunt Coordinator

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    Thanks Paul. I appreciate that. I saw that review After I bought it. I just wish there were more reviews of the 900. It is a good review I agree. I agree with that reviewer %100.

    Thanks again
    Mike D
     

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