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Author Topic: Bridging Amps to Power Mains  (Read 9048 times)

Derek Van Winkle

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Bridging Amps to Power Mains
« on: August 05, 2011, 11:22:33 AM »

Is this a practical thing to do? I've never been a big fan of it, but I just got a project that has already purchased all the amps and enclosures. The only way to effectively power the system is to bridge the amps (Crest CPX 3s) down to 4 ohms and run the enclosures (Peavey ILS 1594s) two per amp.

Any thoughts?
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Charlie Zureki

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Re: Bridging Amps to Power Mains
« Reply #1 on: August 06, 2011, 08:00:26 AM »

Is this a practical thing to do? I've never been a big fan of it, but I just got a project that has already purchased all the amps and enclosures. The only way to effectively power the system is to bridge the amps (Crest CPX 3s) down to 4 ohms and run the enclosures (Peavey ILS 1594s) two per amp.

Any thoughts?

  Hello Derek,

   Most Amps will operate perfectly fine in the Bridged mode at 4 ohms, but, I am not a big fan of operating an Amplifier Bridged at 2 ohms. 

  Also.. many Amp models do not even have a spec for a 2ohm Bridged configuration....meaning they advise against this scheme.

   Good luck and have fun

   Hammer
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Marty McCann

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Re: Bridging Amps to Power Mains
« Reply #2 on: August 08, 2011, 12:42:15 PM »

Is this a practical thing to do? I've never been a big fan of it, but I just got a project that has already purchased all the amps and enclosures. The only way to effectively power the system is to bridge the amps (Crest CPX 3s) down to 4 ohms and run the enclosures (Peavey ILS 1594s) two per amp.

Any thoughts?


The Crest CPX is not rated at 4 Ohms Bridged.  It may work for you, but if hit hard it may trip its breaker. 
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Brad Weber

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Re: Bridging Amps to Power Mains
« Reply #3 on: August 08, 2011, 03:12:58 PM »

I believe he was addressing the old CPX 3.0, which was rated at 3,000W (EIA)  for a 4 Ohm load in bridge mode, and it driving two 8 Ohm speakers for a total 4 Ohm load.  However, I would verify that this is the "only way to effectively power the system" as running one speaker per channel would seem to result in less output but would be easier on the amp and more flexible.
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duane massey

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Re: Bridging Amps to Power Mains
« Reply #4 on: August 08, 2011, 04:32:21 PM »

Even searching the PV site I could not find any info on the ILS 1594s speaker, but did find the Sanctuary series equivalent. Same with Crest, neither site seems to support any discontinued products, unless I'm using incorrect model #'s.

That being said, I'm with Brad on this one, it seems that bridging would be significant overkill, but running dual channel would be a better solution.
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Duane Massey
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Brad Weber

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Re: Bridging Amps to Power Mains
« Reply #5 on: August 08, 2011, 06:54:54 PM »

Even searching the PV site I could not find any info on the ILS 1594s speaker, but did find the Sanctuary series equivalent. Same with Crest, neither site seems to support any discontinued products, unless I'm using incorrect model #'s.
ILS 1594: http://peavey.com/assets/literature/manuals/80304892.pdf

The CPX 3.0 is older and apparently not on Crest's site, however I found some older discussions that seemed to agree on the specs, http://www.sonicstate.com/news/2006/07/25/snamm06-3000-watts-of-amp-power/ and http://www.talkbass.com/forum/f15/crest-cpx-3-0-power-amp-465525/.

I have a feeling that with a 750W Continuous/1,500W Program rating for the speakers what may be happening is trying to get the Program power for each speaker or 3,000W at 4 Ohms for the two speakers in parallel.  However, that only applies if one actually needs the output that can provide and if less output is acceptable then one speaker per channel seems to make more sense.
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duane massey

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Re: Bridging Amps to Power Mains
« Reply #6 on: August 08, 2011, 07:48:55 PM »

Thanks, Brad. For some reason my searches on PV's site do not seem to be successful. I tried "ILS 1594" and came up empty. I blame Congress...
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Duane Massey
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Marty McCann

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Re: Bridging Amps to Power Mains
« Reply #7 on: August 09, 2011, 10:35:36 AM »

Thanks, Brad. For some reason my searches on PV's site do not seem to be successful. I tried "ILS 1594" and came up empty. I blame Congress...

The search by Text block is lacking.  Best searches for archived products is here:  http://www.peavey.com/support/searchmanuals/archived.cfm
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duane massey

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Re: Bridging Amps to Power Mains
« Reply #8 on: August 09, 2011, 04:19:39 PM »

Thanks, Marty, I'll try that next time.
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Duane Massey
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Derek Van Winkle

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Re: Bridging Amps to Power Mains
« Reply #9 on: August 13, 2011, 09:32:55 AM »

I have a feeling that with a 750W Continuous/1,500W Program rating for the speakers what may be happening is trying to get the Program power for each speaker or 3,000W at 4 Ohms for the two speakers in parallel.  However, that only applies if one actually needs the output that can provide and if less output is acceptable then one speaker per channel seems to make more sense.
[/quote]

I don't think the venue would ever see using 1500w per box but it would need more than 825w. So I'm stuck with bridging the amps.

On another note, do any of you sell discontinued equipment? Almost everything in this install that was already purchased has been discontinued...amps, speakers, mics, mixer...and it's all Peavey.
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Brad Weber

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Re: Bridging Amps to Power Mains
« Reply #10 on: August 13, 2011, 06:27:38 PM »

I don't think the venue would ever see using 1500w per box but it would need more than 825w. So I'm stuck with bridging the amps.
The difference between 825W and 1500W is 2.6dB with the theoretical 1m output for an ILS1594 speaker going from 124.2dB to 126.8dB.  Would less difference than that really matter?
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Derek Van Winkle

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Re: Bridging Amps to Power Mains
« Reply #11 on: August 13, 2011, 08:45:55 PM »

The difference between 825W and 1500W is 2.6dB with the theoretical 1m output for an ILS1594 speaker going from 124.2dB to 126.8dB.  Would less difference than that really matter?

Very valid point!

Thanks!
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Rory Buszka

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Re: Bridging Amps to Power Mains
« Reply #12 on: September 14, 2011, 09:43:00 PM »

Here's another thing to keep in mind: Bridging an amplifier increases the amount of distortion present in its output, because of tiny differences in the output stage of either channel of the amp (even within the same chassis). Distortion in the bass is less audible, so bridging is a better compromise for powering dedicated low-frequency speaker systems. However, amps are less stable in bridged mode than when driving separate loads from each channel, and can't deliver as much current into the load at high drive levels.

It sounds like the clear solution here is to run the amps in stereo.
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Andre Spur

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Re: Bridging Amps to Power Mains
« Reply #13 on: September 16, 2011, 07:45:32 AM »

Is this a practical thing to do? I've never been a big fan of it, but I just got a project that has already purchased all the amps and enclosures. The only way to effectively power the system is to bridge the amps (Crest CPX 3s) down to 4 ohms and run the enclosures (Peavey ILS 1594s) two per amp.

Any thoughts?

Bridged amps sounds better in dynamics if you do not struggle them with too low impedance loadings :-/
I always prefer bigger (especially in amplifiers) because bigger amp sounds better and has more headroom, later on the limiter the safe range can be fixed.
Some amps are already so big that do not need to bridging like this: http://www.pknc.com/3phase_eng.html
I think this level of power is more than enough even for the biggest speakers.
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Mac Kerr

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Posting Rules
« Reply #14 on: September 16, 2011, 08:24:37 AM »

Bridged amps

Please go to your profile and change the "Name" field to your real full name as required by the posting rules clearly displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
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Jean-Pierre Coetzee

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Re: Posting Rules
« Reply #15 on: October 07, 2011, 06:39:02 PM »

Please go to your profile and change the "Name" field to your real full name as required by the posting rules clearly displayed in the header at the top of the section, and in the Site Rules and Suggestions in the Forum Announcements section, and on the registration page when you registered.

Mac
Not to hijack the thread but is such an amp even possible, from what I see it's not released yet... Apart from that, 80A on a single phase circuit, good luck getting that without a distro...
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Re: Posting Rules
« Reply #15 on: October 07, 2011, 06:39:02 PM »


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