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powerplaynow
02-18-2004, 08:35 PM
Alright. For those of you who've read enough posts asking how to bridge, etc; I'll save you the hassle of continuing. You can push the back button on your browser. For the rest of you, here's my situation:

My bi-amped system:

2 Peavey SP2G (8ohm model)
300W continuous, 600W program, 1200W pk

1 Peavey PV1200 amp
600W @ 2ohm, 450W @ 4ohm, 270W @ 8ohm
Briged 1200W @ 4ohm, 900W @ 8ohm

2 Peavey SP118 (8ohm model)
350W continuous, 700W program, 1400W peak

1 Peavey PV2000 amp
1000W @ 2ohm, 700W @ 4ohm, 400W @ 8ohm
Briged 2000W @ 4ohm, 1400W @ 8ohm

So what I've been doing is running the tops in stereo. I've tried the subs stereo. I quit doing that. Then I bridged and ran both subs out of channel 1 (channel 1 to sub1, channel 1 to sub2). If I understand correctly now, that didn't show my amp a 4ohm load, so I didn't really get any more power to my subs. So far, I haven't bridged and gone from channel 1 to sub1, and from sub1 to sub2.

So, what configuration would you suggest? The PV2000 has a built in X-over with high outs that I run into the PV1200 to power the high end. I'm considering forgeting the high outs and going from my mixer into my sub amp and also from my mixer to the high amp- that way, I'll put the full signal into the tops and get all I can out of them, ending up with even more bass. How's that for an idea?

I know that was long winded...if you're still with me, I owe ya big time. Thanks for your time and suggestions.

Brett

NickyB
02-19-2004, 09:02 AM
Brett -

Running both subs out of ch 1 IS NOT bridging. To run bridged-mono there should be a set of switches on the amp to get into bridged-mono mode. This will gang both the right and left channels to work as one channel with a higher output. Next, you need to use both of the 'RED' binding posts as your output. If the amp has neutrik connectors, you will have to rewire one of your speaker cables for bridged mono operation. Inside the plug, the pins are marked 1+, 1-, 2+ and 2-. Normal wiring is to use 1+ and 1-. For bridged mono operation, move the wire on the 1- connection to the 2+ connection.

My personal preference is to build an adapter to do this because once you change one speaker wire, you have to keep track of the one you changed. Using an adapter lets you keep your speaker cables intact for any wiring situation.

Nick

BigDog
02-19-2004, 09:30 AM
I may be misreading your post, but if you put both subs running out of channel one, your amp is seeing a 4 ohm load. It is not bridged, but it is 4 ohms is it not???

powerplaynow
02-19-2004, 10:15 AM
Thanks Nick, I was hoping you'd respond.

I have flipped the switch on back to throw the amp into bridged mode. However, the amp uses only 1/4" jacks. There are binding posts that I believe can be used with MDP plugs.

Does that clear things up any?

Given the specs above, once I get everything set up in bridged mode (and it sounds like I still need a little info to make sure I do that correctly), am I powering things correctly?

Thanks again,
Brett

Anthony Martorano
02-19-2004, 10:27 AM
You may also want to bridge the 1200 amp while running it to the SP2Gs. I have a pair of these, and the 270/channel just won't cut it with them. These are fantastic cabs, but you need to give them at least 400-450 watts to get them going. If you bridged the 1200, you would be running a mono system, but each cab would be getting 600 watts, which is a great match for the SP2Gs.

bjojade
02-19-2004, 10:27 AM
On the peavey amp, you can not use the 1/4" connectors in bridge mode. You must use the binding posts and connect across the red terminals.

NickyB
02-19-2004, 11:29 AM
Brett -

bjojade is correct....you MUST use the binding post outputs for bridged-mono mode. In normal stereo mode, the binding posts are paired black(-) and red(+) for each channel. When the amp is switched into bridged-mono mode, you need to use both red(+) posts as your single output.

Internally what happens in bridged mode, the left channel of the amp acts to amplify only the positive half of a low frequency output sine wave, the right channel amplifies the negative half of that low frequency sine wave....by connecting across the red-to-red binding posts, you get the entire signal amplified to a combined power level of both stereo channels max output.

If your speaker cables are 1/4" to 1/4", I'd personally switch one end to use dual banana plugs. Be mindful that there is a small tab on one side to indicate the negative(-) pole which normally get the black wire. Most people here prefer Neutrik/Speakon plugs that lock. I prefer the banana plugs for several reasons......one, they stack one behind the other for parallel connections; two they don't lock so if some clumsy person like me, trips on the speaker wire during setup, it merely unplugs and doesn't pull the speaker stack over or snap the connector.
On the other side, the Speakons do carry more current BUT I seldom find myself pushing my system to max current anyway....no need too if its designed properly.

NickyB

powerplaynow
02-19-2004, 11:44 AM
Perfect. That's a big help. I was wondering why nothing seemed to be changing. So I'll switch one of those to banana- I'll still be alright to run 1/4 inch out of sub1 and into sub2 though right? I won't need to do any modifications on the other end?

I'm not over/under powering the subs like this, am I? I'm still a little sketchy as to what I should be looking at with "continuous" and "program" ratings.

And lastly (I hope), would the extra power be worth it with the SP2Gs bridged- I'd prefer Stereo operation for the highs, unless you don't think theres a noticeable diference in sound going mono...I've never tried mono on the highs.

After all these years, and I'm still figuring out the best way to run my system... Thank a lot for your time and insight, I really appreciate it.

Brett

NickyB
02-19-2004, 01:30 PM
Brett -

If you've never worked on cables before, I recommend you purchase an adapter that is premade.
I carry two in my tool box that are banana-to-1/4" phone (Female) . This way you get to leave your existing cables alone in case you ever decide to go back to stereo mode across the board.

All my 12 ga. speaker cables are Banana-to-1/4" phono (Male). I have six 25 footers. but with the adapters in my toolbox, I can extend to 50 ft. without a problem.

Nick

short_circutz
02-19-2004, 06:24 PM
Before you cnsider bridging the amp into the 2 cabninets in parallel (which would be a 4 ohm load)...is the amp 2 ohm stable? when in bridged mode, each channel only sees half the impedance.

powerplaynow
02-19-2004, 07:34 PM
Travis-

I'm not exactly sure what you're asking, but the manual says this:

"...designed to drive 2ohm loads per channel, thus delivering awesome performance levels at 4ohm bridge mode."

However, it also states that "For bridge mode usage, the enclosure impendance must be 4 or 8 ohms--never below 4 ohms!"

I've never heard that running bridge mode only lets your amp see 1/2 the ohm load. Are you saying that, in bridged mode, my 2 8ohm subs would put a 2ohm load on my amp?

brian@btm
02-19-2004, 07:59 PM
Are you saying that, in bridged mode, my 2 8ohm subs would put a 2ohm load on my amp?

They are refering to the load of a 4ohm bridge is equal to what the amp would see in stereo 2ohm loads. You should not have any problems with most pro amps in a rack with good ventilation.

The advantage is getting the maximum wattage possible to two 8ohm speakers. The disadvantage is decreased thermal headroom and mono operation.