burfcontrol

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About burfcontrol

  1. Thank you. .. I'm still trying to wrap my brain around the 1/8th power pink noise concept as it relates to peak power in sine-waves.. or whatever you said. It doesn't matter, Crown is my preferred amp. JBL is my preferred cab.
  2. The claim made was that the amp's clip indicator led will start to flicker at about 1/8th rated power. I personally think this is garbage and that the amp will start to clip as soon as the signal peaks cause the amp to exceed its 'max power'.. but I know that I don't really know how any of this stuff works.. (really I'm sure it has more to do with the current exceeding max current).. In other words, this guy is saying that with an XTi 4000 bridged powering a 4 ohm cabinet, the amp will begin to clip as soon as it starts to make 400 watts of power???? Please tell me this guy has absolutely no idea what he is talking about and that I don't have to go research everything and relearn / rebuild what I believe about amplifiers in general. The way I have always thought about power is this: program power is the amount of power being created by RMS voltage where the peaks are causing instantaneous peak power... or something close to that. In which case, the XTi won't clip unless the power exceeds some 6400 watts at 4 ohms. (sounds extreme but.. this is a simplified sine-wave example) Who is more correct??? Me or that guy elsewhere? I have a sort of unimportant question about the meters. I personally LOVE the XTi amps for all applications. I have several and love them for SUB DUTY and everything else. with the location of the meters internally, is it possible to grossly underpower a sub at a low frequency and cause some strange "clunking" sound in the speaker without actually clipping the amp? (or without the meters picking up on the clip?) I have imagined a situation (based on a bunch of amplifier design ignorance and knowing that there are intended amps for intended speakers--- underpowering grossly is not proper use of an amp in my own personal opinion) .. here is what I was "imagining" the signal goes into the amp.. In other words, are the meters actually monitoring the actual speaker poles???? or are they monitoring everything up to just before the input side of the transformer? is it possible an input voltage is under the level at which it would "clip" yet because of the amount of time the low frequency was above or below "0 V" the power supply to the output of the overall amplifier became "depleted" causing a "knocking sound" in the sub??? because, not only with XTi's, I believe I heard this by grossly underpowering a sub.. I could be totally wrong, but I feel like I have heard the knock at low volume (reletively low compared to the relatively very high volume I have heard the same sub operate at problem free for hours at a different venue)--- we're talking operating a sub which can handle 4 or 5 times the power that the amp is rated for.
  3. thank you for your extremely fast reply! I will not worry.. more worried about the board than anything- I have extra fuses. that and I'm running the "B" rig until I figure out what is going on. I love my XTi4000's. they rule. they sound spectacular.
  4. Hello Everybody. I use 4 XTi amps for mains as well as a couple others for monitors. How bad is it if the power for the entire venue goes out during a set? This has been bothering me since it occured a couple days ago. I'd say the levels were set such that the -10 lights were intermittantly coming on so it was a decently loud mix when this happened. All power was lost at once-- the board, everything. My hopes are that the current spike had to evenly distribute accross all gear which diminished it. My other concern is -- usually, at the end of a show, I let the amps run their fans until the fans return to their normal speed. they weren't blowing hot air or nothing but it was a hot day when this happend. I feel like someone attacked my sound system when they cut off the power. I make sure each amp gets its own 20 amp circuit. Not a single GFI blew during the cutoff. Are these amps designed to withstand one of these? I am worried to say the least. I'm planning on using the "B" rig until I figure out what is going on with the power at the venue. Thanks, Bill
  5. I found that the XTi's sound great--- even for subs in bridge mono at 4 ohms. I know its running the amps hot but it sure sounds great. If you think of it like this, you'll see why I like the XTi's. Keep in mind, I typically never ride my faders up past -10 and its already too loud. For me the XTi's are a brilliant choice. If -3dB is half the power, then even in bridge-mono at 4 ohms, I'm never exceeding the current levels for a 4-ohms-per-channel draw and I always have enough headroom to really move the subs. If you are careful with your faders, level setting, and you use some sort of protection for your system (clip limiters or a driverack limiter) then I'd say go with the brand new amps. I've read so many bad things about the XTi's in forums and I can tell you from using them that I just don't see it at all.... I have seen some of the better amps deployed where subs were getting less than favorable power however and I can tell first-hand that if you have the $'s to get enough XTi's to bridge your amps and put the recommended power on them that they will sound better. XTi's are great. *I am definitely not knocking the MacrotEchs or convincing people not to buy them. I'd probably want MacroTechs if I were building my own venue or something and had an electrical contractor put enough circuits in so I wouldn't ever have to worry about tripping a breaker.. I'd also make sure I had enough of them so that I was putting the right enough power on my speakers-- they'd sound amazing. I've heard a couple of MA5002's knock my socks of. I've heard just a single MA5002 driving two subs though and in my opinion I liked a pair of XTi4000's in bridge mono a LOT better. Heck, I've even heard a single MA5002 knock my socks off with a different pair of subs. It all boils down to carefully paying attention to the specs of your speakers. Those specs are more important than a couple hundred dollars. That said, I'd still probably rather have brand new XTi's than used macrotechs. XTi's are REALLY nice-- especially when used appropriately. I really like XTi's even though I wish they were I-class but really, that would just be too good to be true. I'm personally "hoping" that I've reached the point in my life where I can graduate to some of the bigger-badder amps from here on out.... like ITechs maybe.
  6. The SRX 715's have continuous power rating of 800 watts and a peak power rating of 3200. It is a 8 ohm cabinet. So you want an amp that will put 1600 watts onto each cabinet. the XTi 4000 doesn't make enough power to drive SRX speakers in dual/stereo mode but it is a great amp. I use XTi's all the time, they are truely amazing amps and sound great. What you need to do is use the amp in bridge-mono mode. This will give you 3200 W at 4 ohms and if you daisy chain the speakers by running a regular speakon (NL2) from one speaker to the other, you will get a total of 3200 W of power which will be divided by 2 (1600 W onto each cabinet). Most stores only have the NL2 speakon connector so you might end up having to use a single banana-plug to hook up the amp to just one of the speakers. it is VERY important to note that in this system you MUST ALWAYS run BOTH speakers. if not, you will have WAY too much power to run just one speaker. A simple test each time you run your system is all you need to do: put the volume at a very low volume level-- ( like -60dB ) and listen to make sure sound is coming out of both speakers before you turn it up. You've actually got a lot of power there so you always want to be careful not to push any of your channels too hard.. those speakers are very nice. but I highly recommend using the amp in bridge-mono. Its only a 4 ohm load when you run 2 srx715's in parallel so if I were you, I would also use the amp's clip limiter at -3dB just to be safe. I doubt you'll ever need more power than -3dB on that setup. A better setup for your 715's would be if you had TWO crown xti 2000 amps. you could run each one in bridge-mono to get your 1600 Watts into each speaker. that way the amp would be seeing 8-ohms. The reason why this is better is simply because either way you need to bridge your amp to get the power right. And when you bridge your amp, you are essentially doubling the voltage which causes double the current. So at any given point in time, each channel in the amp could be delivering twice the current for the specified load. In other words, if you have an 8 ohm speaker on your amp in bridge mono, the amp channels are going to be supplying the "current" equivalent to a 4 ohm load (since its double the voltage on an 8 ohm load which is equal to the same amount of current as 'half the voltage' on a 4 ohm load). so bridge your amp-- use the clip limiter at -3dB -- and if you are confident in your ability to follow technical instructions and are good with cables, you can convert your banana plugs to (NL4) speakon connectors. That way you can run the amp in bridge mono right off your amps channel-1-speakon connector. If you do this, you have to find a way to "mark" your speakon cable so you don't reverse it and put the NL2 end into the amp and the NL4 end into the speaker (which should leave you with an open circuit I believe-- could be wrong). It shows you how to connect it up in the manual but its basically putting (negative) onto the 1+ and (positive) onto the 2+ of the cable. I could have that reversed so you need to check the manual. I was able to find the NL4 connectors for $8 a piece at a local music store but if you are looking for help on this, a forum like this might be your only way unless you call crown. In my case, nobody in town knew what it was besides one other sound guy but I didn't get a chance to talk to that guy until after I already had the cables working.
  7. After watching the ITech drop-test video, I'm sold. I wish I got 2 ITech's instead of 4 XTi amps. after reading tons of posts about bridging XTi's, I am so worried about running them at 2 ohms per side, I think its going to shed several years off of my life just thinking about it. Watching these drop tests by the way was probably the hardest thing I've ever done. I'm glad you guys do these tests-- it shows you have a much higher standard.. but on the other hand, I can't stand seeing such a wonderful creation get abused like that. Its like watching Mike Tyson punch an infant without a boxing glove on his fist-- and then the infant just keeps sucking the passifier. I truly hope the XTi's can hold up under the work load until I can budget a couple of these bad boys. These drop testers by the way. what the heck did they do to deserve such a great job? I've NEVER had a job that awesome. If I saw them drop testing an amp-- even if the test was sanctioned by the president.. I'd be *beep*ED. I would be FURIOUS! I would suddenly develop turrets syndrome or something and have some words for them "WHAT THE HECK DID YOU DO THAT FOR @##@$(*&^$#$% !!!!!!!!!!!!!" just kidding.. lucky guys. cool music playing through the amp too while it plunged for impact and SMASHED into the floor and kept playing.. (saddens my heart)
  8. You can run a whole system in mono with a single crown XTi4000. I think its kind of funny however but definitely possible. Since you have two speakers and will probably run them in parallel, and they are all 4 ohms, you will be running the amp pretty hot at 2ohms. * check to see what the power requirement is because if the speakers are small enough, you could theoretically run the tops in series.. as well as the bottoms with some wiring magic. This would make them 8 ohms for tops and 8 ohms for bottoms.. the amp wouldn't be working as hard or making nearly as much power but there are some low power speakers that do exist. in parallel however (this is caused by daisy-chaining your speakers) you will be getting a total of 1600 watts per channel off the amp. This means that each speaker will be getting 800 watts share of the power. This is definitely not an 'ideal' situation but if your speakers only need 800 watts, they will sound good at the expense of working that amp very hard which I've found out from crown will have the same effect it has by working any device to its maximum output: shorter overall life. I can vouch for the crown designs though: I know of at least one amp that has been working at 2 ohms per side now for 5 years straight in a permanent install and its a crown! they don't drive it at full volume but it still sounds incredible. Now, if each speaker only needs 300 watts to sound good, just wire them up in series and you wont be pushing anything and can crank it all day and night every day. to do series, you would have to find a way to create a current loop through both tops and bottoms. (two loops).. basically, the negative terminal from the amp goes to the negative terminal of the first speaker. then the positive terminal of the first speaker needs a wire to the negative terminal of the second speaker. then the positive terminal of the second speaker goes to the positive terminal of the same amp channels positive terminal.. thats one complete loop. do that for your tops on one channel and your bottoms of the other and you're running those amps at 8 ohms. I have NEVER seen this done but I know it works fine. you might have to have wires running all over the place to accomplish this unless your speakers have NL4 speakon connectors. or if you know what you are doing, you could rewire all the speaker jacks and you'd have to be sure to always hook them up the same way. I don't recommend doing this yourself. Find someone familiar with electronics.
  9. If you look at the ohm vs frequency plots for subs, the minimum ohms is typically what the cabinet is rated for. I was looking at a 4ohm cabinet plot. the minimum was 4ohms for that cab and it was considered to be a 4ohm cabinet. the frequencies were interesting for where it was minimum. I think somewhere around 75 to 85 Hz or something it was 4 ohms.. but below 75 Hz, the ohms increased and also above 85 it increased. the higher the frequency, the higher the resistance of course. I'm pretty sure the 4ohm load that the amp will see will coorespond to the "loudest" parts of the frequency response curve for your cabinet.
  10. Eventually, My intention is to get an ITech or a MacroTech - something that can drive both subs at 4000 watts per channel into 4 ohms dual. But I've got to make it a while before I can do that. For now, I am running 4 XTI 4000's in bridge mono. All 4 cabs are 4 ohms but only 2 are subs. Hopefully, if I don't push the amps too hard, They'll do a great job until I can upgrade.
  11. Thanks for Responding!! 1.4V <---> +4dB I'm terrible at looking for stuff on websites.. Especially Crownaudio. (too many cool things on here) .. I get distracted way too easily on here. I think I've started searching for this info several times and then started reading something else. I just picked up some xti's!!!! Can't wait until they get here. And I found some NL4 connectors so I'm going to get some bananna-plug to speakon cables at length to save some dough and then wire up the NL4's for bridge mono! What a great feature on these amps. I love it.
  12. This is the greatest thing I've ever read: Bottm line is make sure you have it right or bad thing WILL occure. ha ha.. so true. Get it right or a bad thing WILL occur!!!!!!!!!!!!!!!!! ha haa that is great
  13. WOE! BE CAREFUL what advice you take on here man!!! someone just warned you not to over power two srx715's in parallel with a bridged xti4000. Not true, that is a PERFECT match. Each 715 is 8 ohms and wants to see 1600 Watts Rms on them.. So with the both of them wired in parrallel, the amp will see 4 ohms and can supply a total of 3200 watts-- BUT where the advice went wrong is the fact that since they are parallel, the power is divided equally to both loads since they have equal resistance: 1600 Watts per cabinet!!! Proof, the reason why it is a 4 ohm load is because their are two 8 ohm loads drawing current off the voltage.. the amp can only supply enough current to make 3200 Watts total.. since the current is divided equally accross both loads, they both get half the power.. and half the total current supplied by the amp. the voltage however is the same accross both of them-- well so is the current-- but the current is equal and equal to half of the sum which comes out of the amp! power is tricky like that. Now if you wanted stereo, then the xti4000 is not enough power. not even close since each of its channels can only supply 650 watts rms into 8 ohms per speaker. but bridged into 8 ohms, the amp can do 2400 proving that when you bridge the amp, the sum is greater than both parts. but since they are parellel, its a total of 4 ohms. if you put them in series, it would be 16 ohms.. so your only choice with that amp is to do a mono parrallel wiring for a perfect match. I didn't read the rest of the post. but I said "WOE" because you DEFINITELY do NOT want to throttle back the amp's gain knobs half-way.. then you would have absolutely no headroom and wouldn't get much out of the speakers.. in bridged mode, I'm pretty sure that half power on the gains is severely reducing the total power. I could be wrong, but either way, you're looking at a lot less than what you want. Another thing I found in that post you might want to be careful of entertaining is the notion that you should run your amps at the "rms value of the speaker"? ? ? technically, the rms value of the speaker doesn't exist since the rms value of the speaker is technically the rms value of whatever signal you have running through it by any given amplifier. JBL does pink noise tests on their speakers and builds them for a physical beating (thats where they bench for their peak power handling capability). RMS for jbl is roughly "half" of peak which is what they refer to as "program power". Continuous power ratings are for continuous signal.. there are lots of gray areas in here if you ask me but I know those speakers want 1600 RMS on them if you want to hear them "sing". Sure you can run them with an amp whos rms power rating is equal to the speakers "continuous" rating, however, your peaks will only approach less than half of the speakers rated "peak" capacity. basically, thats no headroom in your amp.. you're not going to move the cones.. there are many more factors involved in designing speakers.. they probably use joules and work calculations and magnetic flux and force and fields and all kinds of crap to discover what kind of coil resistance, how many windings.. trust me, it gets ugly when you look at the math. there aren't just ohms and volts and watts and amps.. there are coulombs, farads, henry's.. etc. etc.. so when they design these speakers, they are designed to require a certain amount of EMF to pull the cones to actually make sound. if you want to hear what the speaker is designed to sound like and hear the full 20 to 20khz response of those puppies at the rated SPL, you need an amplifier that has power on reserve! now I don't recommend it, but if you really wanted to, you could do some RMS to Peak calculations for watts and estimate what your peaks are going to be with any given amp on your cabinets.. if your peaks come in under the JBL's rated peak power capacity, you're probably safe if you use a limiter.. but thats just my own humble opinion and I don't think you really need more than the program power. you probably won't benefit much -- but in the future, the more years you run sound, its good to know.
  14. ah.. i was going to recommend something but.. crown was so fast and I type so slow.