amp for powered sub

Discussion in 'Archived Threads 2001-2004' started by Kevin Beck, Jan 7, 2001.

  1. Kevin Beck

    Kevin Beck Stunt Coordinator

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    Hey guys,...Trying to find the best combination for the sonosubs I'm building. I have seen most of the sonotubes, I have read up on, use rack type amps. I am going to build these with onboard amps. Looking for experienced addvice on this subject.
    Thanks in advance again,...Kevin,...>>>--->
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Neil Joseph
    In other words, you will be moutning the internal amp on one of the endcaps (presumeably the top endcap if the driver is on the bottom). I am building a box right now for my present sub so my situation is different as I can mount the amp at the back. I can't remember the model (haven't bought it yet) but it is 350W RMS that has all the controls on it and it just mounts in the cutout at the back with mounting screws.
    What are the specs you are using for your sub and what is the volume and dimensions of your tube?
    orangeman
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    Neil's H.T. Site
    (plus large selection of H.T.Links and movie images)
     
  3. Dustin Haug

    Dustin Haug Agent

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  4. John E Janowitz

    John E Janowitz Second Unit

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    You may want to check out our amplifiers page. We have 5 different plate amplifiers now. The biggest is the AMP350 that is the same as the Apex Sr amplifier. This is similar to the Adire AVA250, but with more power. The AMP350 does have a 6dB bass boost at 30Hz, however by changing one resistor you can move the boost to a lower point, or totally remove it.
    For example, changing R26 from, 18K ohm to 100K ohm will remove the boost totally and give flat output to 12.5Hz. Values in between will give varried amounts of boost between the 12.5Hz and 30Hz range. I plan to put up the graphs of this soon.
    Another simple mod is to change C16 from .12uF to .22uF. This increases the slope of the LP filter from 12dB to 18dB. This can help with integration between the subwoofer and main speakers.
    For $225 this is a nice little amplifier. Here's an email I am quoting from John Koval:
    "There was a discussion recently about plate amps vs. regular Amps.
    So I put one of the APEX Senior amps on the bench. Here's what I found.
    @120v (variac regulated)and 20hz continuous sine wave the amp put out 250W+ @8ohm and 380W+ @ 4ohms.
    The clipping was quite clean with what appeared to be a little 60hz on the top. The main difference between it and any other amp I've seen is no reserve at 250W as with most amps. However, if it were rated at 235W then it
    would look petty typical and very good at 4ohms.
    Now I did not do any pulse or distortion tests but I would conclude that unless you are a believer in all the audio VooDoo this would be a fine amp especially for sub within the ratings specified.
    John Koval"
    For the money, the power is very good, especially into 4ohm. The ease of changing the bass boost and LP filter slope by changing only 2 components makes it a very good value for DIY.
    Now, regarding these amplifiers and sonosubs, the only difficulty is mounting them. Mounting amplifiers horizontally on the bottom or top endcaps is not highly recommended. Mounting the amplifier with the heat sink fins vertically really aids in convection cooling. Maybe Tom Vodhanel can give some suggestions for mounting amps on the sonosubs.
    John
     
  5. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    >>>. Maybe Tom Vodhanel can give some suggestions for mounting amps on the sonosubs.
    John
     
  6. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    I have the Adire AVA250 and recommend it. I'm going to mount it on the side of a sonosub I'm building (Adire Tempest, 24" diameter tube). I just finished fabricating an enclosure out of scrap 3/4" MDF. It has 4 sides, two of which are cut with curves (24" dia) so it will fit nicely on the side of my sub. The driver leads will pass through a small hole in the tube, which I will seal with caulk. Thus, there is no need to seal my amp enclosure. Some day I'm going to figure out how to post pictures.
     
  7. chris hunigan

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    John, Tom, Hank, or anyone,
    I have narrowed my choices down to the Adire AVA250 or Stryke AMP350. Now should I save the extra money to go with the AVA250 or go with extra power and give it a shot for the AMP350?
    I am going to power either amp for dual 12" drivers in a 2 cu ft enclosure (for each driver, so a total of 4 cu ft). So either amp should provide enough power, but is it reall worth it to jump to the Stryke AMP350?
    I noticed that its at least a 1-1.5 dB difference between the AVA250 and AMP350......
    cree
     
  8. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Chris, the Adire amp already has the nasty 6 dB 30 Hz boost removed. If you don't want to remove the filter board and replace a resistor (thus probably voiding the warranty) on the Apex amp, buy the AVA250. We checked out the AVA250 on a 6.5 ft3 ported Tempest in Austin, and it had plenty of oomph and sounded good. My 2 centavos.
     
  9. Kevin Beck

    Kevin Beck Stunt Coordinator

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    Hey guys, I have heard you all talk about this 6db boost at 30hz before. Is this a real problem, or is it splitting hairs? I'm new to this, so don't punch too hard,... [​IMG]
    100 more watts seems to be alot, if a small change is all thats in order to get rid of it. I realize, easier said than done, but also wouldn't the increase in performance pay off? Again, I'm a newbie,...
    Thanks Kevin,...>>>--->
     
  10. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Hi Kevin. As someone has pointed out, a big boost at 30 Hz is not so good, as room modes tend to add a boost in that range, so you may very well end up with a serious "boomy" sound in-room, and could have some really big peaks at certain seating locations. I understand the concern over wattage, and for a sub amp, I don't take a strong stand. I'll be happy with my AVA250, because I did listen to it powering a Tempest and it sounded very good and put out lots of volume (didn't have my RS SPL meter, so don't have measurements - maybe someone will post some).
     
  11. Kevin Beck

    Kevin Beck Stunt Coordinator

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    Hank,...
    I have already planned to do the same thing. Its a very simple way to get the amp mounted to the tube, and still have it look good. I'm sure you will do the same, and just turn the amp to the wall. The things are round, so I'm sure it doesn't make a beans worth diffence whitch way its facing.
    Kevin,...>>>--->
     
  12. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Kevin, we're thinking alike. When my Parts Express order gets here, I'll cover the tube with the thin carpeting I ordered, then mount the box with screws from inside the tube.
     
  13. Kimmo Jaskari

    Kimmo Jaskari Screenwriter

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    I'm also looking for an amp to use in my "in my head" subwoofer project (which I hope to transfer out of my head out into the real world soon enough).
    SVS makes use of a German made amp, the Detonation amp from RCM Akustik. Looking at its specs I'm not sure I understand why, exactly... Tom, care to comment if you're following this thread?
    The larger model, the 110, gives out 150 watts at 4 ohms which doesn't seem like a whole lot to me, but maybe I'm getting watt happy from reading too many amp specs. [​IMG]
    It does seem to have nice features; you can set bass boost at 30 Hz to 0, 3 or 6 dB, it has a subsonic filter, etc.
    Also, since it's German, I would be on the RIGHT side of the Atlantic ocean for a change. [​IMG]
    ------------------
    /Kimmo [​IMG]

    "Don't tell me; we're about to go over a huge waterfall?"
    "Yep."
    "Sharp rocks at the bottom?"
    "Most likely."
    "Bring it on."

     
  14. Chris Sherman

    Chris Sherman Second Unit

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    Does anyone know a distributor for the RCM Akustik amps in the US? Can you buy these here?
     
  15. Kimmo Jaskari

    Kimmo Jaskari Screenwriter

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    Used to be one, but he closed up shop some time ago. I remember reading it left SVS in somewhat of a lurch since they were about to use these for the powered line (if my memory serves...)
    Maybe you should try SVS and ask if they are willing to sell you one, they must be importing these in fair numbers considering how the subs are selling like hotcakes [​IMG]
    ------------------
    /Kimmo [​IMG]

    "Don't tell me; we're about to go over a huge waterfall?"
    "Yep."
    "Sharp rocks at the bottom?"
    "Most likely."
    "Bring it on."

     

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