Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums > LAB Lounge

Crown Itech or QSC PL380 for TH-118

<< < (2/3) > >>

Chris Van Duker:
I'm a fairly small operator, and I've got four TH118s (among other cabinets). I've decided to standardize on the IT8000 for everything, with the idea that I can run mono if I have to. I've got three so far, and I'm looking to eventually add three more.

I haven't had any reliability problems so far, including a week of solid use at Burning Man. I've run them at 208v and 120v. If you run them at 120v, be sure you've got solid circuits -- the power supply regulation means that current draw goes up when voltage sags. When I've had sub-optimal power, I've popped breakers both on the back of the amp, and on a far-too-distant distro. (This was on dance music -- rock might not be such a problem.)

Tim McCulloch:

--- Quote from: Mario Roman on February 05, 2011, 01:28:08 PM ---Since I'm using the TH118's with the new SM96 from Danley, I know that either amp is never going to have to work very hard to keep a balanced sound in the system for what we do. Thus it really comes down to how good the amp sounds running subs, the feature set and reliability. As far as features, I much prefer the Itech for its FIR filters, limiting options, and world power capability. From what I've read on the web as well as PSW, most people seem to prefer the Itech in this application. Most of the opinions seem to be that the subs sound tighter/punchier with the Itech.

Thus is comes down to my most important factor which is reliability. Most of the failures I've read about are from 2007-2009. Not much after that. It would seem that Crown has finally worked things out. So I guess the whole point of this thread it to get some opinions from current Itech users what their more recent experiences have been. Do they seem  to finally be reliable or are there still a bunch of problems but no one is posting anymore because the subject has been beat to death. Honestly if I knew that the Itechs now had the reliability of the QSC it'd be a no brainer.


--- End quote ---

We've got around 50 I-Tech 6000 and 8000.  We've sent 3 back to Crown for warranty service and none of them involved catastrophic failure.

If you go back to the old FUD forums (around 2008) you'll find me researching power for our line array purchase.  I made several calls to much larger players (Dirk Schubert & Dave Shadoan among others) and asked them to respond to this:  "any I-Tech that is currently operating and has been without fault for the last 6 months is no more likely to fail than any other amp in your inventory."  The answer from everyone still using I-Techs was affirmative, and the early adopters that bailed (understandably) were all pretty negative.

Our experience has been positive.  That said, QSC builds quality products and is more "forthcoming" when things go wrong.  I don't think you'd regret purchasing either model.

Have fun, good luck.

Tim Mc

Ivan Beaver:

--- Quote from: hibbasc1 on February 05, 2011, 11:59:43 AM ---According to my calculations, the TH-118 will reach ~ 141.5 db with 2500w (PL380 stereo).  With 4000w (Itech 8000 in stereo) you will get ~ 2 db more out out the speaker (143.5 db) but if you are intending to push any speaker to it's limit where 2 db makes a difference, you need more speakers not just a bigger amp. 


--- End quote ---
As Mac said you have to use your full real name.

My math gets a different number.  2500 watts is a 33.9dB gain not 33.5 as your math might indicate.

I assume you are adding 33.5 to the sensitivity of 108dB. 

The problem is that the sensitivity is for 2.83v and the cabinet is a4 ohm cabinet.  So at 4 ohms that is 2 watts, so the 2500 watt gain over 2 watts is 30.9. 

So add that to 108 and you have 138.9-go ahead and call it 139dB.

When looking at sensitivities you have to also look at the impedance and how the cabinet was measured.  Since an amplifier does not "put out" watts, only voltage (watts is the end result of a voltage across a particular load), that is the reason we use 2.83V as the drive signal for all cabinets-irregardless of impedance.

The ohm ratings are only nominal to a standard impedance.  You really have to look at the impedance graph to see what you would consider the cabinet to be-impedance wise.

Scott Hibbard:

Yes - I was using the 108 db sensitivty number (sorry I didn't mention that as my starting point). 

P.S. Mac - Apologies for the full name oversight.  I had full name on the old forum but hastily overlooked it when registering here. 


Mario Roman:
Thanks everyone for the help. I'm going to cancel my QSC order tomorrow and get the ITech 8000. They can be had on ebay for substantially less than the QSC. They're factory "Pre-owned" certified and come with a 1 year warranty. Next I'll be bugging you for limiter settings.... :D



[0] Message Index

[#] Next page

[*] Previous page

Go to full version