Question about how to TUne PC Ultras

Re: Question about how to TUne PC Ultras

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.

Re: Question about how to TUne PC Ultras

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

Re: Not local Circuitry...

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.

Plugging the ports don't reduce the driver's excursion. It changes the tuning frequency of the enclosure and allows it to play lower while still using the air inside the enclosure as a spring or brake for the driver. I checked and the native tuning of the older PC Ultra is 20hz. Plug one port change the subsonic filter to 16hz. Take the sub for a spin through the movie scenes. Plug two ports and change the SSF to 12hz and watch the scenes again. With two ports plugged, you may change your noise from clanking to farting because the sub doesn't have enough port area for the amount of air being moved.

Yes, the driver may be damaged but it probably isn't. TC Sounds made some great drivers that can take abuse. With TC Sounds bankrupt, you won't be able to get a replacement driver.

Your settings mean nothing to me. It is room and equipment dependent so unless I have an exact copy of your room it is useless.

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

Re: Question about how to TUne PC Ultras

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?

Re: Question about how to TUne PC Ultras

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