electrohippy

Re: bi-amping, I set the system up as follows: I didn't have enough speaker cable to run both a standard stereo to one speaker and a bi-amp setup to the other, so I went off my previous test results of one side pushed from a dual stereo setup (board settings were not changed between tests) I went from the left out on the board to a vintage Furman TX-3 active crossover. I set the input on the crossover to unity. I set the XO point at 1500 Hz. I started with the output levels for high and low at 5 just to be on the safe side I then went highs out to one side of my Carvin FET-400 amp that's supposed to do 100W per side into 8 ohms, and speaker out to the high side on the speaker cabinet Lows went into one side of a Crest amp, which is supposed to be 400W per side into 8 ohms, and speaker out to the low side of the speaker cabinet. I followed the same test setup as before for the speaker and meters (speakers and meter were not moved between tests) CONCLUSION: About 10-15 dB louder, and could have been more so, but the Crest amp was underpowered for the situation. I had to turn the output on the XO lows to 10, and the highs to 7 to get a good balance. I turned the highs all the way up just as a test, and it was much louder, no distortion or clipping, but a poor high/low mix. I then did a hybrid bi-amp and bridged thing, set up as above but with the Crest bridged (properly, per the manual, I should add). That tripped the safety on the crest amp after a few loops of the reference track (I use Golden Brown by The Stranglers as my ref track), even with the clip light staying off. It was quieter than stereo mode anyway, and I guess... at least the Crest protected itself...? FINAL CONCLUSION: I need to get a bigger amp than the Crest for larger outdoor shows, but I will be bi-amping the system with the Carvin in there on the highs in the future no matter what. The change was phenomenal!

OK so i tried out a couple of things and was surprised what I learned. Re: bridging: I set up a test system as follows: First Crest amp set up in stereo mode delivering one side to one of my speakers Second Crest amp set up bridged delivering both sides to one of my speakers Set speakers at equal distance and position from a dB meter Connected one side of my Yamaha mixing board to each amp, and set output and inputs identical all around, and both amps set to just below clipping played the same mono source out through each amp, looped a 15 second section watched the dB meter and noted the highest level through the loop went back and forth between them several times and checked, also swapped the channels and even which amp was bridged, so there's no way it's false! CONCLUSION: The bridged amp setup was actually QUIETER than the dual stereo setup! This seems counterintuitive to me, what gives? Anyone want to chime in?

Thanks for the reply! @DeepEnd, So let me aks you, maybe I'm reading this incorrectly. Besides the quote about "...effectively quadrupling..." here's more quoted from the section on bridging from the manual (the user manual was written to cover several related amps, and these amps are CKS 800-2 amps): "For CKS Series amplifiers, the recommended minimum nominal load impedance in bridged mono mode is 8 ohms, the equivalent to driving both channels at 4 ohms. [For models CKS 800-2, 1200-2 and 1600-2, the recommended minimum nominal load impedance in the bridged mono mode is 4 ohms, equivalent to driving both channels at 2 ohms]. So since my load is an 8 ohm load, then this should be, per their example, " the equivalent to driving both channels at 4 ohms." So is it true then that, since the specs sheet actually show the amp produces 600W into 4 ohms both channels driven, that it will in fact be 1200W into 8 ohms if bridged?? Or is it just double the 8 ohm rating like you said, at 800W? Or is it actually just 600W bridged into 8 ohms??? AAACK! Really wish they had given the actual bridged specs in the literature, but it's in neither the user manual nor the spec sheet I've found online. Tried contacting Peavey and they were basically like "amp is too old... bye." Thanks again for all the help folks!

Thanks so much for the great reply! Lots of extremely useful info in there!!! In my first post, I quoted several specs from the manuals of both the amplifiers and the speakers. It was probably TL/DR, so to restate: Amp = 400W RMS per side into 8 ohms Amp manual doesn't give numbers, but states the obvious, that bridging results in "...effectively quadrupling the power..." Speakers = 8 ohms, 500W RMS, 1000W program, 2000W peak Plan under consideration was to use one bridged amp per speaker, so 1600W RMS into 500W RMS 8 ohm speaker QUESTION: Just how dangerous it is to run a speaker rated at 500W RMS with an amp rated at 1600W RMS? Or is it, considering the peak handling of the speaker is 2000W? Related question: What steps can be taken to mitigate the danger if it is in fact dangerous? The powered speaker is a cheap American Audio from the mid 2000s (I think 2006). The buzz is continual even without signal, likely relating to a bad cap on the power supply. I plan to use the speaker to practice a recap and board reflow, and if I fail, it's no big deal, speakers are old and cheap. I have Deoxit, but thanks for clearly explaining why that matters and how to use it! I make my own cables mostly, have never made a speaker cable smaller than 12 gauge, and use only Neutrik Speakon connectors. I would never use a guitar cord for speakers, but thanks for drawing attention to that detail in case someone else is reading this. THANK YOU!!

So I'm still wondering, how dangerous would it be to bridge one Crest amp at 1600W into full range on these speakers? They are actually rated at 2000W peak. Am I just asking to blow them up, or will it be relatively safe?

So I'm still wondering, how dangerous would it be to bridge one Crest amp at 1600W into full range on these speakers? They are actually rated at 2000W peak. Am I just asking to blow them up, or will it be relatively safe?

OK so reporting back, the 400W per side amp was not enough, or just barely enough, for the show. Had to reduce bass guitar and kick levels to prevent clipping at the amp, which was OK, but reduced the quality of the experience. I didn't have time to make a 4 pole speakon cable to bi-amp with the 400W on lows and 100W on highs, but I'm guessing that would have been just enough to be right for the situation. Still would have been barely enough I'm guessing, but even without it, it did work out ok (barely). I would have benefitted from more amp power before clipping for sure!

OK so reporting back, the 400W per side amp was not enough, or just barely enough, for the show. Had to reduce bass guitar and kick levels to prevent clipping at the amp, which was OK, but reduced the quality of the experience. I didn't have time to make a 4 pole speakon cable to bi-amp with the 400W on lows and 100W on highs, but I'm guessing that would have been just enough to be right for the situation. Still would have been barely enough I'm guessing, but even without it, it did work out ok (barely). I would have benefitted from more amp power before clipping for sure!

Thanks for the reply. Anyone else have an opinion, since this is pro audio gear in a live music setting, not hifi?

can't delete accidental post!

REPOSTED FROM THE WRONG SECTION! (This is a duplicate thread because I posted it in the wrong section and it never got moved to the right one) Hello good people of Harmony Central, I come to you with an question that needs clarity. Apologies for the TL/DR post but I want to include all the info I think matters! I got an outside gig with a country band playing for about 150 people next week. When I pulled my powered 15s out, one has serious buzz after being stored poorly during the pandemic. They are old and cheap so it's not worth it to have a pro fix it with a reflow or recap, and I don't have time before the show to do it myself, so I've been looking over my gear for something I can use. I'm trying not to shell out $ to rent since I have some other gear to try and make it work, just need guidance. I have two Peavey Impulse 1015's. They can be bi-amped or full range. Per the spec sheet, they are rated at 500W RMS full range, or 500W low , 60W high (RMS) if bi amped. They put out 100 dB at 1W @ 1M full range. I have two Crest Audio CKS800-2 Amps. They spec out at 400W RMS per side into 8 ohms, or 1600W bridged. My understanding is that amplifier RMS rating is best between 160% and 250% of the RMS rating of the speaker, in this case between 800W and 1250W. So the problem here is that in stereo mode, one amp would push only 80% per side (too low), and two in bridged mode 320% per side (too high). Which is likely to be the safer (for the speakers) option while still providing enough sound reinforcement for 150 people, too high or too low? This is a family-friendly picnic event, not a rock concert, so I'll probably be shooting for around 85-90 dB about 30 feet out from the band where I'll mix from, but of course that depends on how loud the organizers want it and how cooperative the band is. I'm guessing that the 400W per side would be just fine with care, but I'd like to get opinions since I've mostly worked with powered speakers in the past. I also have a Yamaha P2500S amp, spec'd at 250W RMS per side into 8 and a Carvin FET400 at 100W per side into 8. Should I throw one of these in the mix, like say bi-amp lows at 400W per side with a Crest and the highs at 100W per side with the Carvin? I have a Furman TX-3 crossover, too. How would you guys run this configuration with the amps I have? THANKS IN ADVANCE!!!

A clean up and re-flow and/or re-cap is no big deal I agree... just no time really. Show is this Sunday and I'm busy all this week on another project so I can't do it myself. It's a long haul to a repair shop I trust, and the speakers are old and low quality so not really worth paying someone for the repair. I could rent but I'd rather not spend money on this if I don't have to because it's not exactly a high paying gig. Since I have all this other gear, I figured I'd just make it work if possible. Any help and/or opinions about what I actually plan to do would be greatly appreciated. THANK YOU!!

Hello good people of Harmony Central, I come to you with an question that needs clarity. Apologies for the TL/DR post but I want to include all the info I think matters! I got an outside gig with a country band playing for about 150 people next week. When I pulled my powered 15s out, one has serious buzz after being stored poorly during the pandemic. I've been looking over my old gear for something I can use. I have two Peavey Impulse 1015's. They can be bi-amped or full range. Per the spec sheet, they are rated at 500W RMS full range, or 500W low , 60W high (RMS) if bi amped. They put out 100 dB at 1W @ 1M full range. I have two Crest Audio CKS800-2 Amps. They spec out at 400W RMS per side into 8 ohms, or 1600W bridged. My understanding is that amplifier RMS rating is best between 160% and 250% of the RMS rating of the speaker, in this case between 800W and 1250W. So the problem here is that in stereo mode, one amp would push only 80% per side (too low), and two in bridged mode 320% per side (too high). Which is likely to be the safer (for the speakers) option while still providing enough sound reinforcement for 150 people, too high or too low? This is a family-friendly picnic event, not a rock concert, so I'll probably be shooting for around 85-90 dB about 30 feet out from the band where I'll mix from, but of course that depends on how loud the organizers want it and how cooperative the band is. I'm guessing that the 400W per side would be just fine with care, but I'd like to get opinions since I've mostly worked with powered speakers in the past. I also have a Yamaha P2500S amp, spec'd at 250W RMS per side into 8 and a Carvin FET400 at 100W per side into 8. Should I throw one of these in the mix, like say bi-amp lows at 400W per side with a Crest and the highs at 100W per side with the Carvin? I have a Furman TX-3 crossover, too. How would you guys run this configuration with the amps I have? THANKS IN ADVANCE!!!