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Author Topic: The Perfect Amp for LAB Subwoofer  (Read 11293 times)

Josh Billings

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The Perfect Amp for LAB Subwoofer
« on: January 27, 2008, 08:32:10 am »

What do you guys think of the Crest Pro 8200 for an amplifier for the LAB Subwoofers. I'd prefer to not spend $2,500 on 2 amps when i can get the QSC 4050HD and whatnot for pretty cheap, but i want to make sure i get the right fit for these boxes.

I want to make sure we can run them close to clipping (Maybe occasional clipping) and not burn up drivers. Reconing and replacing LAB drivers are just a pain in the ass.

I was also considering Crest CC4000s / Peavey CS4000s, QSC RMX4050HD or Crown XTI-4000s. I am really concentrating on the fact that it's a 800 watts a 3 ohms cabinet (I believe 2.7 is the minimum).

I also thought about the I-tech 8000 running in stereo with 2 boxes per channel, but i know these things lose power when the impedence drops below 4 ohms so i was kinda shying away from those.

It's just so tough to decide because so many specs are based on 1khz and sometimes the 20hz-20khz number is substantially lower and sometimes it isn't much lower at all (Would prefer one that doesn't lose a lot of power down low). Let me know what you guys think

I know the QSC PL6 PFC (2 cabs per channel) would be great, but i only have 20 amp circuits to deal with most of the time. I

-Josh Billings
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Kevin Pippen

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Re: The Perfect Amp for LAB Subwoofer
« Reply #1 on: January 27, 2008, 08:54:39 am »

Hi Josh,

Probably over budget here but you might want to check-out some of the digam powersoft amps... Anyways,...in addition to output, power requirements, and the normal specs I would consider a high damping factor for a sub duty amp...http://www.teamaai.net/kevin/2cents.gif

EDIT: My "dream" amp for sub duty would be one of the powersoft K series (damping factor >5000 20-200Hz)...Very Happy  

Kev
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Jesse Soden

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Re: The Perfect Amp for LAB Subwoofer
« Reply #2 on: January 27, 2008, 07:21:45 pm »

The first two LAB's that we built were powered by two QSC RMX 1850HD's. Yes, the dampening factor is not the best for that model, but they were cheap (our subs, venue's amps). We had absolutely no problems with blown drivers for over 3 years, even with excessive clipping. When we built our current system, we opted for PLX series amps, and decided to use the 3402 per two cabs. The dampening factor is greater than 500, which, for the buck, was acceptable. Running them in parallel input mode gives at least 1100W (figuring on 4 ohms for simplicity). Again, no relative issues, except when the drivers come loose in the cab (I don't want talk about it!). We've tried the 1602's in bridge mono, but I was not comfortable with the impedance of the cab being below the 4 ohm minimum rating of the amp in bridge mono. We also tried a few Crest amps, with destructive results. I never put an Oscilloscope on the amps output to see what happens at clip, but we started chewing drivers up left and right (tearing the surround). I do remember reading on this forum a few years back that Crown (can't remember the model) amps tend to do the same thing. I also remember discussion of running 4 cabs on a Power Light 9.0 with good success (that's 2000+W/sub!). So, after replacing a few drivers (at least they're fairly cheap!), we're back to the 3402's. I guess the crucial thing is to make darn sure that the amp in use has soft clipping. I've been told that Yorkville amps would be an excellent choice (higher dampening factor), but we don't like the weight (sucks getting older Sad ). I hope this helps!
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Pascal Pincosy

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Re: The Perfect Amp for LAB Subwoofer
« Reply #3 on: January 27, 2008, 08:45:42 pm »

Kevin Pippen wrote on Sun, 27 January 2008 13:54

EDIT: My "dream" amp for sub duty would be one of the powersoft K series (damping factor >5000 20-200Hz)...Very Happy

The Powersoft K series looks even better when you get it with the DSP module included. The limiting features are bar none. Between peak limiting with feedback from the amp portion, and the RMS limiting, again with feedback and clear metering (unlike the I-Tech) you can set, forget, and never blow a sub driver again.
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Al Limberg

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Re: The Perfect Amp for LAB Subwoofer
« Reply #4 on: January 27, 2008, 10:21:10 pm »

Looks to me like some folks should do a search on 'damping factor'.  Pay particular attention to JR's  (John Roberts) posts.

?;o)
Al
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Kevin Pippen

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Re: The Perfect Amp for LAB Subwoofer
« Reply #5 on: January 27, 2008, 11:29:12 pm »

Hello Al,

I have done some research and have made my conclusions that amplifiers with a high damping factors have greater control over the movement of the speaker cone and will deliver tighter bass...http://www.teamaai.net/kevin/2cents.gif

That's just me,...and of course everyone's entitled to their opinion...Smile

Kev


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Tim McCulloch

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Re: The Perfect Amp for LAB Subwoofer
« Reply #6 on: January 28, 2008, 12:52:43 am »

Kevin-

A DF of >25 at the end of the speaker cable is probably sufficient.  The claims made famous by Crown that high DF creates some kind of sonic superiority have been largely busted... A higher number is better, but only up to a point.

If you read John Robert's writings on the subject you'll understand why.

Have fun, good luck.

Tim Mc
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John Roberts {JR}

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Re: The Perfect Amp for LAB Subwoofer
« Reply #7 on: January 28, 2008, 10:36:12 am »

Everybody's entitled to their own opinions but the facts must be shared by us all..

Damping factor was worth comparing between old tube amps but modern solid state amps are arbitrarily good. If anything in SR applications you may need to pay attention to wire gauge on longer runs, as this will be more impedance than modern amplifier output stages.  

I think this is covered in Study hall.

JR
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Kevin Pippen

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Re: The Perfect Amp for LAB Subwoofer
« Reply #8 on: January 28, 2008, 10:51:20 am »

Hello John,

Roger-that and agreed!...Smile My insertion losses were less than .02 ohms on this budget install... That's #10 AWG in parrallel pairs...Very Happy

http://www.teamaai.net/kevin/Youth/BOOTH4.JPG

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Kev
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Evan Kirkendall

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Re: The Perfect Amp for LAB Subwoofer
« Reply #9 on: January 28, 2008, 11:52:21 am »

Josh Billings wrote on Sun, 27 January 2008 08:32


I know the QSC PL6 PFC (2 cabs per channel) would be great, but i only have 20 amp circuits to deal with most of the time.

-Josh Billings


You can run a PL6.0 on a single 20 amp circuit with no issues.


My favorite LAB sub amp is the PL9.0. Smile




Evan
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