SVS Amp Interface by Marchand Electronics

Discussion in 'Speakers' started by Richard Little, Oct 15, 2003.

  1. Richard Little

    Richard Little Stunt Coordinator

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    I am wondering if anybody knows what the -3dB points are for the SVS Amp Interface by Marchand Electronics. I have spoke with Tom V of SVS who said he believes that the -3dB points are about 2hz lower than the 15hz, 20hz, 25hz markings. I emailed Marchand Electronics direct who said that the -3dB points are nominally as marked (ie. 15, 20, and the 25 hertz). Does anybody know thru testing or experiment of any kind what the -3db points are?
     
  2. Joseph_ P

    Joseph_ P Stunt Coordinator

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    I've had the svs black box hooked up with my twin 16-46cs+'s
    i ran test tones thru it once (10hz-60hz) the black box seemed to act like a brick wall below the 15hz setting,
    i got nothing ,then at 15 hz you could feel the floor start to rattle. i took it out of the system and now the floor rattles at 10hz and up

    [​IMG]
    (i havnt tried any tones below 10hz)
    with just one sub it was nice to have the black box in the
    circuit to help prevent bottoming(i like to set em' hot!!)
    but with 2 of these monsters i feel i no longer need it.
    maybe i could give you a deal on it if your interested,
    i think iv'e had it about six months and it is in perfect
    condition. say 125.00 +shipping?.
     
  3. Richard Little

    Richard Little Stunt Coordinator

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    Ok, I can do paypal or a check. email me. Thanks
     
  4. dave alan

    dave alan Second Unit

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    If Dr. Phil told you the 3 dB down points, then I would put that in the bank.

    I know first hand and through some of his high end clients that he builds deadly accurate filters and crossovers.

    I would be surprised if he was off by 2 Hz.
     
  5. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    The -3dB points aren't exactly at 15/20/25hz...the filtering and slope was designed to my specs. The -3dB points vary slightly and it isn't a brickwall filter, although it is a relatively steep slope.

    Whether the -3dB point is 13,14 or 15hz...it isn't going to make a bit of audible difference. If it makes someone rest easier...just pretend they (the -3dB points) are at the indicated (15,20,25hz) frequencies...[​IMG]

    Tom V.
    SVS
     
  6. Richard Little

    Richard Little Stunt Coordinator

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    I believe Dr Phil is good at his work. I had a phone conversation with him a week ago and he spoke with a lot of confidence, sounded very knowledgeable, and generally like a good guy. My only concern with his answer is it was a bit on the... I don’t know how to put it in words. His reply to the question was
    Hi, The 3dB points are nominally as listed. The filters have a slightly elevated Q, I seem to remember, to enhance the bass.

    Hope this helps.
    Phil
    Maby he was a little and I'm glad he responded, I was just looking for something a little more definitive.
     
  7. Richard Little

    Richard Little Stunt Coordinator

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    When designing with UniBox, for each Hz lower I go it lowers the SPL by a dB and the max excursion point 1Hz, so 2Hz or 3Hz one way or the other makes a difference of 2dB or 3dB and moves the point at which the driver will bottom out 2Hz or 3Hz. I don’t want to give up SPL or increase the chance of bottoming out if I can "theoretically" avoid it by designing accordingly. The software model shows that the point of bottoming out is only 2Hz lower than the tuning point. If that is anywhere close to real world that doesn't give me a lot of wiggle room. I've asked here at HTF because I know that there are people here who have experimented before and have empirical data that they are willing to share with the far less knowledgeable folks such as myself and I do sincerely thank every one who has taken time to help me out.
     
  8. Tom Vodhanel

    Tom Vodhanel Cinematographer

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    Hi Richard,

    I understand completely. When looking at simulations(cough)...it can seem like something like this is going to make a big difference. In reality, the chances of a 1-2hz difference in the -3dB point causing your subwoofer to "bottom" when it wouldn't otherwise are damn slim though. In the end, if you'd feel more comfortable...there are user adjustable subsonic filters out there...and Marchand could probably even build you a inexpensive (
     
  9. Frank Carter

    Frank Carter Screenwriter

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    I don't know if you want it but I could email you a graph of my subs response with and without SVS' Marchand box in place.
     
  10. Richard Little

    Richard Little Stunt Coordinator

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    Tom, your box is the only one for me. I've looked at amps that have subsonic filters, DIY filters (and power supplies to power them), other pre-builts, designing the sub to have such a low bottoming out point that the filter wouldn't be necessary and other avenues in all price ranges including the $30 job by Phil, and your box probably offers the best bang for the buck (that sounds a little kinky[​IMG]) I’m just one of those people that likes to know all the details. If it takes and hour to get it 99% perfect, I'll gladly spend 3 weeks to get the extra 1%.

    Frank
    That would be great and thank you
    [email protected]
     
  11. Frank Carter

    Frank Carter Screenwriter

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    Hey Richard,
    These responses are were taken different levels, the blue is eq'd and the pink is not. My first eq filter is set at 25hz and the filter has a very narrow Q, so it's not affecting the response where I have the SS filter set to 15hz. You can notice the sharper roll off with the blue curve, my subs are tuned to 16.3hz so they'll naturally start to roll off around there.
    [​IMG]
     

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