Which xti's to buy?

[gilscales]

I went to the crown site to look at power consumption and was surprised to see this http://www.crownaudio.com/pdf/amps/139921.pdf
It looks to me that the best most flexible way to go is 2 of the 1000's as they put out about 400w into each channel in 4 ohms with the 1/8 power pink noise for 7.4a (14.8a total = one circuit) and I figure with a 4 ohm load I could run any combination of 8 BFM cabs each getting about 200w, I know that is not pushing the limits of the power handling for most of the cabs but I would think that 200w would be very close to as loud as the cab will play anyway would it not? ( future builds dr-250 deltalite 2 , wedgehorns, and t39 3012lf ) what do the current users of these cabs think?

[sine143]

Hmm, I opted for the 2000, because its "always easier to turn down than it is to turn up from max". the xti 2000 was also the most efficient. I run mono tops right now, but I plan on picking up a second amp for stereo tops, and more sub duty. Keep in mind that 2 titans on a channel will not be a for ohm load, more like a 5, so each cab will be seeing ~175 watts, with the amp CRANKED.;

To quote an answer to my thread of similar name: " a amp designed for 800 watts at 4 ohms will run 400 watts all day".

My personal choice for a dual amped system would be an xti 2000, and a 1000. with the xti limiters on (-3 db) , I'm cutting the 2000 down to around a 1000, but again, thats just the choice for me.

[gilscales]

Hmm, I opted for the 2000, because its "always easier to turn down than it is to turn up from max". the xti 2000 was also the most efficient. I run mono tops right now, but I plan on picking up a second amp for stereo tops, and more sub duty. Keep in mind that 2 titans on a channel will not be a for ohm load, more like a 5, so each cab will be seeing ~175 watts, with the amp CRANKED.;

To quote an answer to my thread of similar name: " a amp designed for 800 watts at 4 ohms will run 400 watts all day".

My personal choice for a dual amped system would be an xti 2000, and a 1000. with the xti limiters on (-3 db) , I'm cutting the 2000 down to around a 1000, but again, thats just the choice for me.

What struck me as odd is that the 2000 puts out less power for the same power draw, 400 for the 1000 at 7.4 amps and 310 for the 2000 at 7.5 amps, what is up with that? I don't understand that their charts show the 1000 putting out more power in most situations than the 2000 (scratching my head?) can anyone comment on this? http://www.crownaudio.com/pdf/amps/139921.pdf

[sine143]

I believe thats a chart of the efficiency of the amps. in this case, the xti 1000 would be losing more power to heat at 4 ohms (400 watts) than the 2000 ( 310 watts). This is one of the reasons the 2000 is more efficient.

I might be wrong though

[Ron K]

You should buy this instead and stop worrying about such an amateur amp.

http://www.crownaudio.com/pdf/legacy/be ... asheet.pdf

It's power dissipated as heat.Not necessarily wasted power because all the output produced creates heat similar to the regen current developed by a servo motor, but the amps design uses a regenerative circuit in the output topology to reuse that current.

Read the white paper about how it works in the "I" Class topology.http://www.crownaudio.com/pdf/amps/137234.pdf

When the speaker/motor coasts down after EFM forces movement there is a certain amount of current that the speaker/motor actually makes because for a short period of time it becomes a generator of current rather then a consumer of current.This current is placed back on the power supply rails as usable power.In servo motors this current is often dissipated across large resistors and in older amps it's dissipated buy the motor,wiring and amp output components as excess heat.

The biggest producer of these currents are subs due to the large motor assemblies.

[Sydney]

If speakers presented a pure resistive load it would be a different situation.
In a reactive system there are always lags. In a physical system with force and mass, or in an electrical system with voltage and current.
That Back EMF can as Ron pointed out can have a severe impact on an amp's output devices

Syd

[Haysus]

You should buy this instead and stop worrying about such an amateur amp.

http://www.crownaudio.com/pdf/legacy/be ... asheet.pdf

Thanks Ron. What a way to start my Monday morning.

[gilscales]

After sine143 and Ron k's post I understand now that my ignorance of electronics is worse than I thought!

[sine143]

dude.... dont worry. It took me like, 3 hours and a whiteboard to figure out why a 4ohm load to the amp puts out more watts hahahaha.... I had a whiteboard and everything. Sydney helped me out a lot, and then I remembered what parallel was all about and was like


The only reason I could tell you what that graph is all about is because it was given to me as a "look, the 2000 is more effiecient!" chart.

[Rockboy]

Any thoughts on the XLS 2500 vs Xti 2000 as far as cost vs features?

Robb

[dgrimm]

None, buy QSC PLX Series

[sine143]

As far as I knokw, the XLS series is not really optimal for BFM gear. They only have 24db Xover slopes, and the EQ is not good enough.

EDIT

DJgrimm, what is your experience with the PLXs?

As far as output is concerned, it looks like the plx2402 is similar to the xti2000, and its priced about 200 more. Do they have built in DSP?

[Rockboy]

I was checking out the two Crown series amps to see if I could downsize some weight.
I have a new QSC 2450 but no hard limit on the future Titans. I was thinking of selling
the QSC and buying a XTI 2000 for the lighter weight and DSP. Is this a good plan or
should I look to a seperate DSP and keep the QSC and put some wheels on the rack??

Thanks - Robb

[bzb]

Weight reduction was my primary goal. Onboard DSP is just a bonus, but it reduces another 5 lbs or so, and a rack space.

[Nick Pignetti]

Sine,

I've met dgrimm, he's running a qsc plx rack. He told me stories of crown amps failing on him which is why he switched brands. Long story short he feels the qsc are more reliable, and has not had any problems like he had with his crowns.

I love the xti amps, but as you probably know crown just put out a recall on several of them. You can go to crown's website and plug in the serial number on your xti to see if its affected by the recall.