BillFitzmaurice.info

Hi guys...

So its my fault for not reading the specs prior, but long story short I advised some friends to buy a XTi 2000 for some t48s. The problem is, I didn't realize the limiters only worked in -3db intervals.

Correct me if I'm wrong, but with an amp rated 800w @ 4 ohms, -3db is 400w.

400w at 4 ohms is 40 volts.

However, since 2 titans per side is a 5 ohm load, 40 volts in a 5 ohm load appears to be 320w.

The math I did to conclude this could certainly be wrong, but it makes perfect sense to conclude that with the higher impedance of the titans (and thus less wattage from the amp) I am not able to get the full potential with the crown DSP.

I was just assuming the limiters would be far more intuitive than this. 320w is robbing 130w from the titans RMS rating. There doesn't appear to be any way to custom the threshold in system architect.

If you guys don't think there is any way around this I think I will advise them to return it. Any advise?

P.S. we use four t48s, so our only option is 2 per side. No bridging.

so your titans are being robbed of 130 watts. oh no.... 1 db less bass. I'm not too broken up about it myself.

Do not trust the limiter settings as accurate. Just as with any limiter measure the amp output voltage with a 100Hz sine wave input and no speakers, then set the limiters to whatever setting gives as close to without exceeding the voltage limits for the subs. And forget about 'losing watts', even if you lose 2dB that's hardly audible, whereas blown drivers are totally inaudible.

Bill Fitzmaurice wrote:Do not trust the limiter settings as accurate. Just as with any limiter measure the amp output voltage with a 100Hz sine wave input and no speakers, then set the limiters to whatever setting gives as close to without exceeding the voltage limits for the subs. And forget about 'losing watts', even if you lose 2dB that's hardly audible, whereas blown drivers are totally inaudible.

I've been playing with the voltmeter connected to my amp running the two T30's with a four ohm load on one side. I easily get voltage to drive these, and each side is rated at 600 watts per side into 4 ohms, so I've got room on the amp for two more on the other side. I use a Behringer DCX 2496 for the limiter, but I still like to see what actually getting to the boxes with the voltmeter.

Donny

Bill Fitzmaurice wrote:Just as with any limiter measure the amp output voltage with a 100Hz sine wave input and no speakers, then set the limiters to whatever setting gives as close to without exceeding the voltage limits for the subs.

Would you put an 8ohm resistor across the terminals, or just use a multimeter on the terminals?

With a solid-state amp(not a tube amp) you can turn up the volume without any speakers hooked up. This is quite handy when it comes to testting by putting the volt meter on the speaker outputs on the amp...less hurt on the ears.

Looks like you guys were right. I planned on pulling out the meter anyway, and it turned out I actually had to limit at the -6 db mark somehow, which amounted to a limit of 44 volts into 5 ohms which was closer to a satisfying 400w.

Just curious, but did everyone elses xti come with the fan turned off from the factory? I had to search kind of hard online to find out how to turn the thing on. Seems like a lot of less knowledgeable people might have fried their piece because of that.

Did the fan come on after playing for a while. Mine came preset to auto.

la malta wrote:Looks like you guys were right. I planned on pulling out the meter anyway, and it turned out I actually had to limit at the -6 db mark somehow, which amounted to a limit of 44 volts into 5 ohms which was closer to a satisfying 400w.

Just curious, but did everyone elses xti come with the fan turned off from the factory? I had to search kind of hard online to find out how to turn the thing on. Seems like a lot of less knowledgeable people might have fried their piece because of that.

Was this an xti2000?

Yes. Fan was either off or set to "auto lo" right out the box. But if memory serves I'd say it was just off.

Hi everyone,

Just wanted to ask, since the OP had to limit the XTi 2000 a bit under its max, is there really any point in having an amp larger than that to drive 4 T48s? Seems a lot of people use the XTi 4000 to do just that? I mean, if you need to limit the 2000 model, will you get any musical headroom when going with a bigger amp, or just more headroom for the amp it self?

I´m looking on which amps and so to buy right now, and I can get a rather good deal on the XTi 4000, but would the 2000 suffice? My rig will be 2 T48s and 2 DR280s, all kappalite loaded.
If going the XTi route, I shouldnt need any other DSP right? Maybe an EQ? All you guys running with just the XTi´s, are you happy with that? Feels like the DSP specs of for example the DCX 2496 are better, mostly the delay (100 times more delay possible in the DCX!) and the slope of the filters.
If one runs say 2 or even 3 XTi´s togheter in a stereo 2/3way system, is it possible to easily controll them all at the same time from a laptop?

Sorry for the threadsteal, but here comes one more question:P
If I should go for amps with a separate DSP, do you recommend the DCX 2496 or the Driverack PA+? Again, looks like the Behringer has better specs and more flexibility, and under half the cost. Are people happy with both of them? Would there really be any difference in soundquality?

The DCX 2496 and EP 4000 looks like a really nice combo if considering the price, and that does of course matter.

Robin_Larsson wrote: If I should go for amps with a separate DSP, do you recommend the DCX 2496 or the Driverack PA+? Again, looks like the Behringer has better specs and more flexibility, and under half the cost. Are people happy with both of them? Would there really be any difference in soundquality?

The DCX 2496 and EP 4000 looks like a really nice combo if considering the price, and that does of course matter.

The 2496/EP4000 offer a high value, if portability is no object. Using it with success in several systems, all permanent.
Both the PA+ and the DCX2496 are nice to use and well built, both units have extensive support online. Major difference is the delay as you noted.

Robin_Larsson wrote:Hi everyone,

Just wanted to ask, since the OP had to limit the XTi 2000 a bit under its max, is there really any point in having an amp larger than that to drive 4 T48s? Seems a lot of people use the XTi 4000 to do just that? I mean, if you need to limit the 2000 model, will you get any musical headroom when going with a bigger amp, or just more headroom for the amp it self?

I´m looking on which amps and so to buy right now, and I can get a rather good deal on the XTi 4000, but would the 2000 suffice? My rig will be 2 T48s and 2 DR280s, all kappalite loaded.
If going the XTi route, I shouldnt need any other DSP right? Maybe an EQ? All you guys running with just the XTi´s, are you happy with that? Feels like the DSP specs of for example the DCX 2496 are better, mostly the delay (100 times more delay possible in the DCX!) and the slope of the filters.
If one runs say 2 or even 3 XTi´s togheter in a stereo 2/3way system, is it possible to easily controll them all at the same time from a laptop?

Sorry for the threadsteal, but here comes one more question:P
If I should go for amps with a separate DSP, do you recommend the DCX 2496 or the Driverack PA+? Again, looks like the Behringer has better specs and more flexibility, and under half the cost. Are people happy with both of them? Would there really be any difference in soundquality?

The DCX 2496 and EP 4000 looks like a really nice combo if considering the price, and that does of course matter.

$ for $, lb for lb and rackspaces for rackspaces, you cant beat an xti 4000