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Author Topic: CROWN I TECH 8000 for subs ?  (Read 6233 times)

Randy Frierson

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CROWN I TECH 8000 for subs ?
« on: June 05, 2010, 06:21:20 pm »

So i haven't been keeping up with the crown I tech amps..On Ebay there are some I tech 8000's for $1,799 each and i'm in eed of sub amps...You Crown guys what do you think? Are they fixed and how do they do on subs, i guess i would run at 4 ohms as seems as no benefit to running at 2 ohms....

PS  If anyone has a Lab FP13000 for sale or rent i'm in need

thanks   Randy

randy@concertsystemsusa.com
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Tim McCulloch

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Re: CROWN I TECH 8000 for subs ?
« Reply #1 on: June 05, 2010, 07:25:01 pm »

Hi Randy-

We use ITech 8000 on JBL VT4880 subs and are very happy with the results @ 4 ohms.  I suggest you use a cable run to each sub, rather than jumping the speakers together.

Have fun, good luck.

Tim Mc
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Randy Frierson

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Re: CROWN I TECH 8000 for subs ?
« Reply #2 on: June 05, 2010, 07:35:16 pm »

thanks   R
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Mark Lonow

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Re: CROWN I TECH 8000 for subs ?
« Reply #3 on: June 06, 2010, 06:17:57 am »

was surprised the iteck did not make ur last sho0t out

its time for a nother sub amp shoOtout  wit:

iteck 8000/hd
plm20000Q lab
K10/20 powersoft

compared to the D12 and L8

maby ma5002 on hand as the control

let me know how it goes Very Happy

$/watt used iteck or even macros  hard to beat
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Randy Frierson

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Re: CROWN I TECH 8000 for subs ?
« Reply #4 on: June 06, 2010, 01:07:26 pm »

i was just wondering because they are on ebay cheap..I don't like a amp that is not optimized to run at 2 ohms...I'm only looking as my order from FFA is stuck in customs and i need sub amps for this weekend....decided to get the 2nd best brand and get a Lab FP13000...thanks  Randy

www.fullfataudio.com  
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Silas Pradetto

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Re: CROWN I TECH 8000 for subs ?
« Reply #5 on: June 06, 2010, 10:14:09 pm »

Randy, I don't like amps not optimized to run at 2 ohms either. But put it this way--most amps are quite current limited at 4 ohms already. This is obvious since power should exactly double into double the load, if voltage is constant, and power rarely doubles from an 8 ohm load to a 4 ohm load in most amps. But in Itechs, it is very close to double. The current limit doesn't hit until 2 ohm loads, but it can still sustain big power for 20ms or so into 2 ohms, a period which is good for most kick drum hits or other impulse signals.

I'm not defending Itechs in any diehard way, just inviting you to look at them differently. They do fine into 2 ohms loads, I do it all the time.
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John Roberts {JR}

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Re: CROWN I TECH 8000 for subs ?
« Reply #6 on: June 06, 2010, 11:31:37 pm »

Silas Pradetto wrote on Sun, 06 June 2010 21:14

Randy, I don't like amps not optimized to run at 2 ohms either. But put it this way--most amps are quite current limited at 4 ohms already. This is obvious since power should exactly double into double the load, if voltage is constant, and power rarely doubles from an 8 ohm load to a 4 ohm load in most amps. But in Itechs, it is very close to double. The current limit doesn't hit until 2 ohm loads, but it can still sustain big power for 20ms or so into 2 ohms, a period which is good for most kick drum hits or other impulse signals.

I'm not defending Itechs in any diehard way, just inviting you to look at them differently. They do fine into 2 ohms loads, I do it all the time.


The divergence from perfect doubling when you halve the load impedance, is not  caused by current limiting. It could be but it typically isn't.

Just like your lights dim when you draw too much power from the wall, there are several internal paths inside the power amp that have losses related to the average output current being passed, like simple low value resistors So everything from the output power devices to the power supply transformer windings will drop voltage in series related to the current output, that doesn't make it to the output load.

These losses appear more significant at 2 ohms since amplifier output power is a function of the voltage squared, so linear voltage losses make for nonlinear power output reduction.

Some class D amps have power characteristics that show evidence of simple current limiting at 2 ohms, while the relationship you describe for most power amps is simple resistive (and device saturation voltage)  losses inside the amp.  

JR
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Ken Freeman

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Re: CROWN I TECH 8000 for subs ?
« Reply #7 on: June 08, 2010, 02:21:57 am »

Hey Randy.

I think these are a good fit, but a 2.7 ohms.  Run them at 208 and put three cones on a side.  In the case of VT 4880's, that is three boxes per 2 channel amp.  Both the cones and amps are very happy.  We have done this a bunch of times and it is a happy pairing.

As I trust nothing, I am a more a 4 ohm guy.  I bought Itech 6000's, but 50% more.

ken
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Jason Phair

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Re: CROWN I TECH 8000 for subs ?
« Reply #8 on: June 08, 2010, 08:42:42 pm »

I'm a 2-ohm guy, but that's because I spent a few years hauling around Crest 9001's!  Laughing
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Jason Phair

Randy Frierson

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Re: CROWN I TECH 8000 for subs ?
« Reply #9 on: June 08, 2010, 11:23:58 pm »

thanks, there are some screaming b stock deals, but i decided on the Lab FP 13000...This is because i can't count..i have all of my new FFA amps coming in but misread the calandar and left myself short for a run of shows...that was an exspensive misread....thanks for the input   Randy
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