Question about how to TUne PC Ultras

Discussion in 'Speakers' started by Matt Krapf, Jan 9, 2009.

  1. Matt Krapf

    Matt Krapf Stunt Coordinator

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    Hi all. Anyone here also have a PC Ultra in a big room?
    Mine is ... or was Bulletproof on everything, and shook my guests in places they didn't know they chould vibrate. [​IMG]

    ...and shook a few can lights loose from the ceiling.


    But recently, I've started catching it POP ing. !!! This alarms me.

    I need to dialogue with someone knowledgeable who can help me do a few things.

    a) determine if there's damage from the pops. (I doubt it because it's still awesome and not producing bad sound...but what do I know?)

    b) actually figure out my settings. I've set it on low-ish settings and left it for 2 years. Probably time to tune it to the room.

    Anyone got some time to email or IM about it?

    Thanks folks,

    Matt

    Matthew.Krapf@gmail.com
     
  2. SHS

    SHS Stunt Coordinator

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    It could possibly be from from voltage spikes from other devices on the circuit. Do you notice it at any specific time or event?

    I notice mine "pops" when the overhead light is switched on. I moved it to another circuit and no more issues.
     
  3. Robert_J

    Robert_J Lead Actor

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    You tune the Ultra by plugging/unplugging the ports and changing the SSF on the amp. You calibrate by changing the level / phase / crossover / PEQ settings.

    a) What do the 'pops' sound like? Fart noise or air swooshing? Or is it a metal on metal clank? Metal on metal is a scary sound so you would know. Metal on metal is also the most dangerous to your sub. That is when the voice coil former slams into the magnet's back plate. Do that enough and you destroy your driver and sometimes take your amp with it.

    b) SVSound - FAQs to set the levels. If you want to properly use the PEQ, then you need sine wave test tones and Microsoft Excel in addition to your SPL meter.

    And if you have had it for 2 years, then you have the older model. Please don't destroy it! Those are some great underhung drivers. FedEx lost one that I sold. As sub enthusiasts, both myself and the buyer were very upset.

    -Robert
     
  4. Matt Krapf

    Matt Krapf Stunt Coordinator

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    the "pops" do sound like something's bottoming out.
    The last Vivid time I recall was while watching the Sonic Gun scene in the new HULK on BluRay.

    There are evidently SOME transient hits that even the Ultra -- on less than aggressive settings -- can absorb well.

    I believe another new CLAP/POP was the car bomb which killed the Judge (Black Lady) in The Dark Knight. Yes. that definitely was one.

    It seems that newer movies are able to induce this, more. Like the amplitude of the Sub hits is made to be more powerful.

    Case in Point. Not more than a few days after the Dark Knight demo'd that Car Bomb vulnerability, I rewatched my "Ultra Demo"...the Matrix.

    The entire Lobby Scene, through the Helicopter crash... No Problem!

    So, I have to ask...is my tuning off? Should I be plugging ports to reduce the driver throws a little? Is the Driver already damaged? Can I even believe it could be damaged, given it's vaunted reputation, and my admittedly paranoid light input settings?


    If anyone would entertain this further, I'd love to put up a Pic of the exact settings on the Amp I've had since day-1, and...where I've dialed them down to, in fear of the Pop/Claps.

    May I? Would you and/or others care to keep kiccking this around with me for a bit?

    Thanks,

    Matt


    PS...I'd love to SPL Meter and graph the room. Just don't know how. Willing to sport for the tools and time to learn tho. Thanks again.
     
  5. Robert_J

    Robert_J Lead Actor

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    Yes, newer movies are putting low frequency transients that stress even the best subs. I know the Dark Knight explosion very well since I watched it on Saturday night. It even stressed my subs and they are dual 15's with much more capability than your Ultra.

    Do you have an analog Radio Shack SPL meter? If so, download a sine wave generator application (there are dozens of free ones on the 'net). Generate a CD of tones that match the frequencies on this spreadsheet. 1 track per tone / each tone 3 seconds. I like to start with track 1 = the highest frequency and go down. Turn off all speakers except the sub. Play the tone around 60hz and set the volume so it reads 75db on the meter. Start with track 1. Play it. Write down what the meter shows. Track 2. Write down what the meter shows. Repeat until you have measured each tone. Plug those numbers into the spreadsheet. Now look at the graph. This spreadsheet is designed for the Behringer Feedback Destroyer but will work with your PEQ if you only use 1 filter. Play with the filter and flatten out the largest peak you have. Then transfer the software filter settings to your amp. Re-measure.

    -Robert
     
  6. SHS

    SHS Stunt Coordinator

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    Yikes...mine never had noises like that at max excursion levels. I can see why you are so concerned. Mine was more like a little "pop" when a switch was moved from off or on in the room. I chalked it up to a voltage spike on that circuit as we seem to have some rather dirty power here in FL as well as a problem with corrosion in some panels.

    I have tuned my Ultra using none, 1 and 2 ports plugged and settled for the 1port plugged route. It seemed to give me the best response on music and HT. From what I am reading you seem to have a different driver in yours than I do in my PB-Ultra 13. Maybe the cylinder design vs box design is an issue. Gurus like Robert will have to answer those mysteries.

    BTW (sorry this is off thread ) how is your IB project going Robert?
     
  7. Robert_J

    Robert_J Lead Actor

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    SHS, your Ultra 13 uses larger driver with more excursion than the older TV12 driver. That TV12 driver is based the old Audiomobile car audio driver. In fact, the TV12 driver I used to have had an Audiomobile sticker under the magnet boot.

    Weather is slowing things down. When it warms up it starts to rain. When it is clear it is freezing cold. Family issues are also getting in the way. I have about 3 hours of work left on the manifolds and have to finish building the 4th driver. That takes 20 minutes. I just haven't finished it because I will use the raw frame to determine where to drill the driver mounting holes.

    -Robert
     

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