Poweramp question - please help

[jazzyvee]

When i asked our sound engineer about running my power amp in bridge mode he said words to the effect of "good idea if you want to make it easier to blow your speakers."

 

[wraub]

<snip> BYou would be better off with an XLS 1500 given the enclosure and desire to expand in the future. Just run the Bag End off one side.

Riis

This. I got a 4 Ohm cab back when I had to schlep it on the subway, and I only use one side of my power amp.
In a different city with a car now, really wish I'd gotten an 8 Ohm box so I could double up.

My current config sees 400w into the cab, 2 8 Ohm boxes would get 350w each.

 

[BassmanPaul]

I’ve been using stereo power amps since the early Eighties. i’ve yet to feel the need to bridge any of them. As I see it, for the average player, what is the use of having 700W available if you’re only going to ever need 300?

My current rig I run in parallel mono with one cab per channel. In that configuration I have about 500W available for each cabinet.

 

[DWBass]

I’ve been using stereo power amps since the early Eighties. i’ve yet to feel the need to bridge any of them. As I see it, for the average player, what is the use of having 700W available if you’re only going to ever need 300?

My current rig I run in parallel mono with one cab per channel. In that configuration I have about 500W available for each cabinet.

This. I run my rig in parallel mode. My amp pushes 250w per channel @ 8ohms. Plenty for my 2 GK Neo112's and trust me, I can get plenty loud. If I need more volume, I run the 2 GK's off one side and my 4ohm Eden 212 off the other. 500w per channel at 4ohms. I don't need any more than that.

 

[Downunderwonder]

More watts is almost never the simple fix to a lack of volume.

 

[Al Kraft]

The only amp I ever ran bridged was the SWR SM400S. That amp really comes alive bridged, but at 8 Ohms is only in the 400 Watt range so it wasn't exactly a ticking time bomb, but clearly a lethal weapon that needs to be used carefully.

As a general rule I think bridging is usually a riskier solution/appraoch than having the right tool for the job, and especially if you are packing way too Watts for the speaker(s).

 

[Korladis]

I have one 8 ohm 15" Bag End cabinet. I'm looking for a power amp (as I plan I just using a power amp + a Sansamp unit). I noticed in the specs it gives output wattage in stereo and in bridged mono mode. I noticed a lot of times it will say something like; 1000 watts bridged mono @ 4 ohms.

Well what if the cabinet is 8 ohms? Can you not run the amp then in "bridged mono"? To me, I understand it that if you are going to use bridged mono mode then the cabinet or total cabinet load has to be 4 ohms.

Can anybody clear this up? Here's just one of the spec sheets I'm referring to;

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Okay... so, why? I mean, yes, you can do it. But what's the point of putting 700 watts into a single 15" cab that handles 300 watts? You would already be fairly close to the thermal limits of the cab just with one channel.

It's not obsession. It's trying to get the most bang for your buck. If I (or anyone) can save money by getting an amp where if you run it bridged mono you get more power - that's what I'm going to do. If money was not a factor then of course I was just get the 1.21 gigawatt model.

I can see how it might look that way, but it's really not. In fact it's not really a good idea at all. Even if money was no object, your cab's power handling is the limiting factor here. If your cab handles 300 watts, with 700 watts you'll be in danger of frying it. You can't put two pints of beer into a one pint glass. Except in this case, it's power, and a cab, and instead of spilling, the speaker breaks. There is pretty much no point to bridging in this case. Your cab can't take infinite power without damage.

I looked up a Bag End 15 and the one I looked at was only rated for 300 watts. I don't know if its the exact same model as yours. But that sounds typical for a many higher end 1x15s

If so, I'd be looking for something that puts out around 280 - 350 watts or so into one channel of an 8 ohm load so you can use the other channed to power 2 - 8 ohm cabs in the future.

Any of the amps on that page have the potential to fry that cab in bridged mode if the volume gets set wrong.

Indeed. This is silly.

 

[Thir13teen]

Thanks for everyone's input. Now armed with your information & the fact that I confirmed my cabinet is 8 ohms - I'm getting a QSC GX3.

 

[Al Kraft]

In my experience the QSC amps are an excellent value providing both solid performance and high quality at a great price. I think both you and your cabinet(s) will be very pleased with your decision.