Help me decide on a Av12 enclosure&amp

Discussion in 'Home Theater Projects' started by Garret_O, Jul 2, 2003.

  1. Garret_O

    Garret_O Agent

    Joined:
    Sep 11, 2002
    Messages:
    26
    Likes Received:
    0
    Trophy Points:
    0
    Hey everyone. I've been doing some searching here in the DIY section in regards to the Av12 and enclosure options.

    I actually purchased two av12s in the first preorder and now have decided to build new enclosues for them.

    I do listen to music but I spend the most time watching movies. Right now the room is only 10x15x10. So, not that large. I will be moving within the next 5 years though and the space HAS to be larger.

    Anyway, from what I've been reading, a great option is the 2x15" pr with the av12. Thunder with 2x SA-PR15-1400?? This gives solid extension down to 20hz. Now, what are the disadvantages of this setup? Not as tight bass? Not as efficient? Well, right now I'm still running JL ported subs so it would have to be an improvement. But others have had good success with the av12 in sealed configurations. However, given that I'm into movies would the 2xpr option be a better configuration? I could build one sealed 2^3 for music and one 2xPr box for movies. THoughts?

    Now, as far as power, right now everything is in the main room and I don't have a closet to shove a pro amp in (noise). So I'm looking at the outlaw m200 amp and/or plate options. Here is the linkhttp://www.outlawaudio.com/products/200.html#
    Does anyone here have any thoughts on amps for these subs? Are there mods for the pro amps that will make them silent?
    I could always stay all-Stryke and try a AMP350 with bass boost removed, correct?

    I have done some searching and have gleaned some good information. I thought that I could get just a little more before moving forward.

    Thanks for any help,

    Garret
     
  2. Jake K

    Jake K Stunt Coordinator

    Joined:
    May 22, 2003
    Messages:
    132
    Likes Received:
    0
    Trophy Points:
    0
    Check out Rythmik Audio, I'm going to get one of their 380 watt plate amps to power my AV15 sub. They have all that other nifty stuff on them too. Only $140!
     
  3. TimForman

    TimForman Supporting Actor

    Joined:
    Dec 4, 2002
    Messages:
    847
    Likes Received:
    0
    Trophy Points:
    0
    I run a pro amp in my room and sure it has fan noise but once you start some music or a movie it's not noticable unless you play your stuff at
     
  4. John E Janowitz

    John E Janowitz Second Unit

    Joined:
    Oct 30, 2000
    Messages:
    445
    Likes Received:
    0
    Trophy Points:
    0
    Hi Garrett,

    If you compare the Thunder 12 box to a 3cf sealed sub, you will have much more output capability and extension with the Thunder 12. The sealed will have about 8dB less output at 20hz than the PR sub.

    The only negative thing about going this route is that many people feel there is too much low bass. I have heard this many times and so has Nick from Lambda. People tend to feel subs that are flat to the lowest frequencies sound "slow." If that is the case, tuning even lower will give a more sloped response that looks closer to the rolloff of a sealed enclosure.

    With regards to the fast/slow bass, it's been proven over and over again that subs with less low end output often sound "faster" and that is why many prefer sealed enclosures. As Tom Nousaine once said about a subwoofer regarded as fast, "the bass was so fast it got up and left the room"

    For mainly HT use, flat to below 20hz should be the way to go.

    John
     
  5. Garret_O

    Garret_O Agent

    Joined:
    Sep 11, 2002
    Messages:
    26
    Likes Received:
    0
    Trophy Points:
    0
    So John,

    Would you suggest moving up to 1800gram pr? I read somewhere that a heavier pr would give a slightly lower extension but reduce output slightly at 20Hz. Problem is, I don't know where they sell 15" pr @ 1800g.

    edit: I read another post by you inthis thread.

    Other thoughts on tuning the av12 even lower? I suppose a larger box is in order. More in line with the 12.3 Stryke box?

    Hmm.. I like the idea of low extension but I also understand the "quick-bass" idea. Granted, with 2 jl 12" with a output spike at 60hz in my current setup- I'm sure I'm not privy to "quick bass" [​IMG]

    John, are you running a av12 in a sealed 3ft^3? I might be fine with a 3ft^3 sealed in my small room.

    Any additional thoughts?
     
  6. John E Janowitz

    John E Janowitz Second Unit

    Joined:
    Oct 30, 2000
    Messages:
    445
    Likes Received:
    0
    Trophy Points:
    0
    Hi Garrett,

    Overall my best recommendation is the Thunder12.3 with the dual 1400gram Pr's. This will get you the best extension. If you feel that this gives too much low bass, then the Thunder12.2, 2 cubic foot enclosure may work better for you. Then go with 1800gram PR's. This will raise your F3 to about 23Hz and you won't get quite as much output below that.

    As for sealed, you could easily do this as well still with good results. I just really like PR systems though, or vented if the situation calls for it. Comparing the Thunder12.3 to the 3 cubic foot sealed, you get 9dB more output at 20hz with the same input power with the Thunder12. That is a lot of extra output for only the cost of the 2 PR's.

    John
     
  7. Brian_DR

    Brian_DR Extra

    Joined:
    Mar 19, 2003
    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    0
    Garret,

    The adjustable extension filter on our amps can alleviate room gain problems which commonly cause bass to sound slow or boomy. Room gain is related to where you put the sub and very much room dependent.

    BTW, for those who would like to try sealed box configuration, we will have optional Linkwitz transform (LT) module in a week. It basically corrects and extends frequency response at the same time. The customers will still have the adjustable filter (for compensating room gain and trading off max output vs max extension). So the possibility is enormous......

    Brian D.
    Rythmik Audio
     
  8. Garret_O

    Garret_O Agent

    Joined:
    Sep 11, 2002
    Messages:
    26
    Likes Received:
    0
    Trophy Points:
    0
    Hmm...

    Brian_DR, with your A350 and the Linkwitz transform (LT) module I could possibly use my existing cabinets and get good low-bass extension correct?

    ID 15"x15.75"x15.75"

    I will have to plug a port but I was thinking I could plug it with a new speaker terminal and build a quick external box for the amp.

    Any thoughts?

    I do like the dual PR option but if I could reuse the existing cabinets and get solid extension...near instant gratification.

    [​IMG]
     
  9. Jack Gilvey

    Jack Gilvey Producer

    Joined:
    Mar 13, 1999
    Messages:
    4,948
    Likes Received:
    0
    Trophy Points:
    0
     
  10. John E Janowitz

    John E Janowitz Second Unit

    Joined:
    Oct 30, 2000
    Messages:
    445
    Likes Received:
    0
    Trophy Points:
    0
    Yes, you can get extension with the LT method. Meaning that you can get the subwoofer to play flat down to a certain frequency. The disadvantage is that your output is severely limited compared to the PR enclosure. While the AV12 displaces 2.33L, each 15" PR can displace 4.15L. So the dual PR system with woofer would displace about 10.63L total. To get the same output at low frequencies with a sealed system would require 4-5 AV12's and much more power. That is assuming equal box size between the PR system and the multiple sealed system. In reality 3 AV12's each in the 15x15.75x15.75 enclosure with about 1000W total would pretty much equal the low end output of the 3cf dual PR system with dual 15" PR's and 350W.

    John
     
  11. Garret_O

    Garret_O Agent

    Joined:
    Sep 11, 2002
    Messages:
    26
    Likes Received:
    0
    Trophy Points:
    0
    John, you've convinced me, it seems like the dual PR option in a Thunder 12.3-type box is going to be the best option for the long run. This way I could sell my existing boxes to someone that is looking for a solid car subwoofer.

    Jack- I'll be awaiting your results!

    Brian_DR - Your plate amp seems like it would be a good fit with the av12, any comments here? Any clipping reported with the combination? I've been looking at pro amps but the fan noise is an issue for me (I don't have an enclosed rack) and I don't have the cash for a k2. Anyone have the
    A350 installed in an external box or does everyone mount it in the sub?

    Thanks again everyone.
     
  12. Allen Ross

    Allen Ross Supporting Actor

    Joined:
    Sep 30, 2002
    Messages:
    819
    Likes Received:
    0
    Trophy Points:
    0
    pick up an old Crown DC 300, there dead silent, no fans what so ever, rock solid and a huge part of audio history.

    I get a nice smile on my face when i turn mine on, with no transience none the less,

    its 150 X 2 @ 8 ohms so if you are driving a 4 ohm mono you should have plenty of power and thats an understatement [​IMG]
     
  13. Brian_DR

    Brian_DR Extra

    Joined:
    Mar 19, 2003
    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    0
    Garret,

    The clipping problem depends on how hard you push the sub and how you adjust the extension filter properly. For vented or PR configuration, one may also be concerned with the excessive excursion below resonance frequency. The computer simulation will show the largest excursion occurs at the frequency below resonance frequency, not above. Using the extension filter, one can cleverly limit the excursion below resonance frequency and at the same time reserve more power to use on pass-band signals. The adjustable filter is something that PA or dedicated amp does not have. To get most bang out of the sub, you may want to consider corner loading the sub. The extra boom can be largely resolved by setting extension filter higher. This way you can get good output and at the same time reduce the change of clipping.

    Brian D.
    Rythmik Audio
     
  14. Brian Bunge

    Brian Bunge Producer

    Joined:
    Sep 11, 2000
    Messages:
    3,716
    Likes Received:
    0
    Trophy Points:
    0
    I believe I'm the one that got Brian interested in the LT option for his amp. I've worked up a design that I will sell to my customers who want really small enclosures with deep extension but don't necessarily want ref. levels of bass. I guess you'd say this would be for the typical Velodyne buyer who'd like a finish other than black and doesn't want to spend a fortune.
     
  15. Brian_DR

    Brian_DR Extra

    Joined:
    Mar 19, 2003
    Messages:
    17
    Likes Received:
    0
    Trophy Points:
    0
    Brian,

    Thanks for bringing up the idea. It also goes well with my earlier plan - to bring out my own subwoofer drivers. For those who are looking for LT circuit but does not want to pay for a full unit, this is the most economical solution.I have my own recipe for good subwoofer drivers, ie, short-circuit ring to bring down flux modulation distortion.

    For those who are interested in LT circuit board, please check out the www.rythmikaudio.com. I have put out some preview results overnight. More detailed information will be added later. Please note all the graphs are based on measurements. I did all my speaker response measurement using near-field technique in my backyard. In-door near-field measurement does not provide correct results below 30hz due to wall reflection.

    Brian D.

    Rythmik Audio
     

Share This Page