ProSoundWeb Community
Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Kurt Stephens on December 07, 2011, 12:39:09 AM
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
Kurt, for $2,000, you can get yourself into a used I-Tech amp pretty easily-- an IT-6000 would give you 3,000 watts per channel-- not a bad amount to work with at all. (Can be better, but oh well.) You may even find an IT-8000, which would give you 4,000 watts per channel. I picked up two of those back in June for $3500 total.
Ray
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
What Ray said.
-
Kurt, for $2,000, you can get yourself into a used I-Tech amp pretty easily-- an IT-6000 would give you 3,000 watts per channel-- not a bad amount to work with at all. (Can be better, but oh well.) You may even find an IT-8000, which would give you 4,000 watts per channel. I picked up two of those back in June for $3500 total.
Ray
That is a good suggestion. Thank you.
I will have to check and see if buying used is feasible. These are for an educational institution and they may not be interested in purchasing used on their credit cards.
If it boils down to it - and I cannot buy used - any comments on the Crest CC series on these 728's?
I continually hear mediocre things about the XTi series (although I've had good experiences with them in the past), especially on sub duty, and especially bridged. The unknown is if the Crest will be any better.
-
If weight is not a problem and you absolutely need a new amp then what do you guys think about RMX5050?
You can find it new on google product finder for $1550 and up.
From what I read here the XTI 4002 gets bad sounding results from every one connecting it to the 728 although I heard a few sales people recommend this combo, don't know why.
I own one 4002 and use it happily on 4 tops.
A pair of 6002 are supposed to do the job (Kevin from the crown forum recommends it) but I don't have first hand experience with it.
You can find allot of used gear that will fit your power needs and budget, such as QSC PL9.0 or a couple of Crest 8002 that would easily do the job, but your best bet is to get a used i-Tech like ray and tim said
-
I run 5 Crest CC amps (tri-amped) in my indoor system amp rack. CC1800 drives top horn @4 ohms stereo, then 2 CC2800's to drive the mid range (4 ohms bridged) and 2 CC2800's to drive the low end (4 ohms bridged). (System consists of 2 JBL715 cabs per side and 2 JBL SRX718 cabs per side) This puts 2800 watts per side into the mid range to drive 2 JBL SRX715 speakers and 2800 watts per side to drive 2 JBL SRX718 subs. Signal is processed through a DBX260 cross over-speaker management system, and limiters are set properly. (Limiters properly set is important)
This has worked out well for me in small to medium sized venues. (Small venues we only hook up 1 high/mid cab and 1 sub cab per side.) This gives me plenty of SPL to cover about 200 - 300 peeps.
The CC amps have been bullet proof. I've never had a problem. Crest is now owned by Peavey.
My experience with the CC Crests has been very positive.
-
It's hard to beat a used ITech for under $2000. If you stay on top of it you can get them for under $1500. I have a 6000 that I run on 718's which is plenty of amp for sub duty. I have run a 4000 on my 718's and that performed well also. I like the fact that you can monitor a system with a cheap laptop, network switch and powerful program like SA.
-
I've had great results with Peavey CS 4080HZ; been using 3 for sub duty in my house gig, and never a hiccup. Also great luck with RMX5050, not so much with Xti6000.
I am assuming you are buying one amp?
-
You can also look at some QSC PL's on ebay or gearsource !
2 x PL4.0 will be kick ass and they are usually sold around a 1000$ each. I think it would be a bit to much for your subs but perfect in your price level.
There is also sometimes the PLX3602 seen for sale at about 7-800$ the amps ...
Othmane
-
What are you using now? The itech 6 or 8k does sound nice on these BUT the handful of times ive used them it seems something weird always happens so personally im not sure I would trust them as my only sub amp unless you have a backup or at least something to get you through the night. What about wall power? do the venues you playing have good setups?
-
The CC amps have been bullet proof. My experience with the CC Crests has been very positive.
Noted +1 for the two CC4000's thanks.
what do you guys think about RMX5050?
From what I read here the XTI 4002 gets bad sounding results from every one connecting it to the 728
your best bet is to get a used i-Tech
Going with two new 5050's would be our of budget - would a single one though be a comparable option to the CC4000's?
It's hard to beat a used ITech
Seems to be a trend here - If I have the option to buy used I will definitely check the ITechs. Thanks.
I've had great results with Peavey CS 4080HZ; been using 3 for sub duty in my house gig, and never a hiccup. Also great luck with RMX5050, not so much with Xti6000.
I am assuming you are buying one amp?
Seems to be another trend here - and that is that the XTi is something I should avoid on these 728's.
I can buy one or two amps - as long as it is close to $2000 when its said and done. A new RMX5050 means I would buy one for the two subs.
You can also look at some QSC PL's on ebay or gearsource
Will check those out too if used gear is an option. Thanks.
-
What are you using now? The itech 6 or 8k does sound nice on these BUT the handful of times ive used them it seems something weird always happens so personally im not sure I would trust them as my only sub amp unless you have a backup or at least something to get you through the night. What about wall power? do the venues you playing have good setups?
These SRX728's are replacing two QSC HPR181i's that were just barely enough for the higher impact gigs on this college campus. We wanted some more SPL/headroom to work with (not to mention those HPR181's don't seem to extend as low as I would like).
There are no amps powering them now - this is a new purchase not a replacement.
In terms of power - there are two primary locations they would be used - one of them is outdoors and has a 100A distro underground. The other is in a smallish auditorium with three (that are accessible easily) 20A services.
-
Yah, that's one 5050 for both 728's.
-
You can also look at some QSC PL's on ebay or gearsource !
2 x PL4.0 will be kick ass and they are usually sold around a 1000$ each. I think it would be a bit to much for your subs but perfect in your price level.
There is also sometimes the PLX3602 seen for sale at about 7-800$ the amps ...
Othmane
PL 4.0 is not too much amp, in fact, is just OK but the subs will take more.
I have used SRX728 / PL 4.0 many times at large gigs with limiters set to keep amps out of clipping (fast limiter set during show, in fact) and never damaged a cone. If 4.0 can be had for $1000, that's a great price for a pro amp.
Currently, 4.0 is what Logic Systems here in STL uses for 728 power. The 728s normally go out with X-Array.
-
That is a good suggestion. Thank you.
I will have to check and see if buying used is feasible. These are for an educational institution and they may not be interested in purchasing used on their credit cards.
Check out EBay for B-stock iTechs. There's a 4000 on there now for $1699. I paid $1799 for my 8000. Great amp. No issues. SRX 712s over 718s; 2/channel.
-
PL 4.0 is not too much amp, in fact, is just OK but the subs will take more.
I have used SRX728 / PL 4.0 many times at large gigs with limiters set to keep amps out of clipping (fast limiter set during show, in fact) and never damaged a cone. If 4.0 can be had for $1000, that's a great price for a pro amp.
Currently, 4.0 is what Logic Systems here in STL uses for 728 power. The 728s normally go out with X-Array.
How doe's one PL9.0 compared with two PL4.0? there are a couple on eBay for $1250 each.
-
How doe's one PL9.0 compared with two PL4.0? there are a couple on eBay for $1250 each.
I have not used 9.0s in this application, but my gut feeling is a pair of 4.0s would be preferential to a single 9.0.
I imagine one 728 per PL 9.0 channel would be very good, similar to PL380. I have used 380s for this and it's a great setup.
-
PL 4.0 is not too much amp, in fact, is just OK but the subs will take more.
I have used SRX728 / PL 4.0 many times at large gigs with limiters set to keep amps out of clipping (fast limiter set during show, in fact) and never damaged a cone. If 4.0 can be had for $1000, that's a great price for a pro amp.
Currently, 4.0 is what Logic Systems here in STL uses for 728 power. The 728s normally go out with X-Array.
Hi doug
What limiters do you use and what type of setting you apply. Ijust got my second PL4.0. I use to have only 1 pl4 for my 2 728's. My process is either ashley analog xr crossover or DB PA.
Othane
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
Now that I have all the ITech amps I need for a while, let me point out that I've bought nine ITech 8K amps in the $1700-$2250 range. They are great amps for the SRX 728s (of which I currently have six and am looking to get two more).
Just post a WTB message in the marketplace. I picked up five IT8K and one IT6K amps that way.
BTW, before getting my first two IT8K amps, I used to power four 728s cabs with four bridged XTi 4000 amps. They were always clipping. I cannot tell you how much better the SRX 728s cabinets sound with the IT8K amps over the bridged XTi4K amps. Don't go the XTi route for the subs.
Cheers,
Randy Hyde
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
I've used a bunch of smaller bridged amps on my 728's and the only one I could personally recommend is a good old bridged Crest 8001. FWIW I've tried a CC series model that was equivalent to a CA9 and preferred the CA9...
Seriously consider a used iTech 8000. The general consensus around here is that is one of the few amps that make 728's happy. Some of us can also provide you with presets to help users from blowing them up.
-
Hi doug
What limiters do you use and what type of setting you apply. Ijust got my second PL4.0. I use to have only 1 pl4 for my 2 728's. My process is either ashley analog xr crossover or DB PA.
Othane
Othane -
Easiest route is to merely use a peak limiter to keep amps' clip lights from lighting.
Note that there may some more headroom after the light comes on, maybe not. To be sure, use a 'scope on the output and set peak limiter threshold accordingly.
With 4.0s you should be good to go. It should be difficult to damage the woofs since the 4.0 is well within 728 power limits.
After this, you can experiment with gentler limiting if you don't like the sound of the peak limiters. Or keep it out of limit :-)
4.0 has a clip limiter but I do not know how effective it is.
Where is DDT when you need it? ;-)
-
Update:
OK so I ended up going with a PL380 for the two SRX728's after some chat with a dealer.
Any comments on how well the PL380 will drive these two subs?
-
Update:
OK so I ended up going with a PL380 for the two SRX728's after some chat with a dealer.
Any comments on how well the PL380 will drive these two subs?
It will kick ass. Great choice.
-
It will kick ass. Great choice.
That is what I like to hear - can't wait to test it out. It seems like it should be a definite upgrade from the two HPR181i's we have - or for that matter the XTi's that I was initially considering to run these.
-
That is a great amp. How are you going to limit for thermal protection?
-
That is a great amp. How are you going to limit for thermal protection?
Processing will be done by a selection of dbx Driveracks that are already in place.
-
Processing will be done by a selection of dbx Driveracks that are already in place.
Do the Driverack's have RMS limiting capabilities?
-
Situation: $2000 to power a pair of SRX728s.
Obviously I's prefer to go with something more substantial like a Macrotech - but this is all I was given to work with. I am aware two XTi4002's aren't going to drive the 728's to their full potential.
Question: Two Crest CC4000's or two Crown XTi4002's? DSP is not needed (system uses driverack PX). Weight is not a factor. Does anyone have first hand experience with the CC series?
Am I missing a better potential option?
Thanks in advance.
Quite possibly the entity you buy the USED I-Tech from may have it as factory recertified. Besides, when people say they won't buy anything used, I tell them I bet they never took a trip in a brand new airplane and I bet they never drank any new water but they trust both of those...
-
It seems like most people power the SRX series cabinets way over their RMS ratings. I have always set my RMS limiters below the RMS ratings of my cabinets and my peak limiters at 2x the RMS ratings of the cabinets. If I'm not using my ITechs I will use my QSC 4050 HD in stereo so thermal issues are at a minimum. Are the limiters in the driveracks and units like the (DBX1066) going to protects your speakers from thermal damage?
EDIT:
Side note: One of my tech's roasted a 718 this past weekend because he did not check to see if the RMS limiters were engaged. This was using a ITech 6000 (1500 watts 8 ohms)When they are engaged they are set for 500 watts 8 ohms.
-
It seems like most people power the SRX series cabinets way over their RMS ratings. I have always set my RMS limiters below the RMS ratings of my cabinets and my peak limiters at 2x the RMS ratings of the cabinets. If I'm not using my ITechs I will use my QSC 4050 HD in stereo so thermal issues are at a minimum. Are the limiters in the driveracks and units like the (DBX1066) going to protects your speakers from thermal damage?
EDIT:
Side note: One of my tech's roasted a 718 this past weekend because he did not check to see if the RMS limiters were engaged. This was using a ITech 6000 (1500 watts 8 ohms)When they are engaged they are set for 500 watts 8 ohms.
Hi !
We are a lot here using srx rig ! I am completely lost with this rms limiters. My 728's are fired with 2 x PL4.0. Am I in trouble pushing them ? how can we set a limit with a regular analog crossover such dbx234xl or similar process ?
If I understand correctly : Peak Watts : 6400W and average is 4000W
So ohm law states : V= R*I or P = V*V / R and heat losses are P = R * I * I
So :
4000w * 4 ohm =16000 and sqrt(16000) = 126.5V and 4000/126.5 = 31A = To get Max output from an amp.
And at Peak power : 6400 * 4 ... = 160V and 160/4 = 40A.
For sure, there is cable and distance and also reactive contribution but let keep it negligeable.
My question here is : If from an outlet you can get at maximum 120V and 20A - How is it possible to reach Peak limitation under these specific conditions assuming that the impedance will remain around 4 ohms.
So if my understanding is okay, with this voltage and current limitation, how its possible to reach the drivers Watt limits ...
Please correct me if I am wrong !
Thank you,
Othmane
-
Hi !
We are a lot here using srx rig ! I am completely lost with this rms limiters. My 728's are fired with 2 x PL4.0. Am I in trouble pushing them ? how can we set a limit with a regular analog crossover such dbx234xl or similar process ?
If I understand correctly : Peak Watts : 6400W and average is 4000W
So ohm law states : V= R*I or P = V*V / R and heat losses are P = R * I * I
So :
4000w * 4 ohm =16000 and sqrt(16000) = 126.5V and 4000/126.5 = 31A = To get Max output from an amp.
And at Peak power : 6400 * 4 ... = 160V and 160/4 = 40A.
For sure, there is cable and distance and also reactive contribution but let keep it negligeable.
My question here is : If from an outlet you can get at maximum 120V and 20A - How is it possible to reach Peak limitation under these specific conditions assuming that the impedance will remain around 4 ohms.
So if my understanding is okay, with this voltage and current limitation, how its possible to reach the drivers Watt limits ...
Please correct me if I am wrong !
Thank you,
Othmane
The simple answer is that the outlet current is rated for SINEWAVE. We are talking about MUSIC power. There is a much higher crest factor.dynamic range with music than there is with sine wave. If you are playing sine waves at constant levels, then you would be correct-but most people do not play sine waves for extended periods of time. If they do-they buy a lot of recone kits.
-
Hi !
We are a lot here using srx rig ! I am completely lost with this rms limiters. My 728's are fired with 2 x PL4.0. Am I in trouble pushing them ? how can we set a limit with a regular analog crossover such dbx234xl or similar process ?
If I understand correctly : Peak Watts : 6400W and average is 4000W
So ohm law states : V= R*I or P = V*V / R and heat losses are P = R * I * I
So :
4000w * 4 ohm =16000 and sqrt(16000) = 126.5V and 4000/126.5 = 31A = To get Max output from an amp.
And at Peak power : 6400 * 4 ... = 160V and 160/4 = 40A.
For sure, there is cable and distance and also reactive contribution but let keep it negligeable.
My question here is : If from an outlet you can get at maximum 120V and 20A - How is it possible to reach Peak limitation under these specific conditions assuming that the impedance will remain around 4 ohms.
So if my understanding is okay, with this voltage and current limitation, how its possible to reach the drivers Watt limits ...
Please correct me if I am wrong !
Thank you,
Othmane
Read this (http://www.crownaudio.com/pdf/amps/137331.pdf).
-
Read this (http://www.crownaudio.com/pdf/amps/137331.pdf).
Hi Yosi,
Thank you ! but what is this have to do with my question ?
Crown is explaining how magnificent and brilliant they are by using two relatively old technologies...
PFC means Power factor Correction, its very normal that if you correct the power factor of a network you get extra kw. More you push the voltage up, less amp you need to achieve the same work. In the industry, 90% of power factor is a minimum to have. the lower the power factor is, higher inductive loads they are, and more capacitor you will have to use. This principle is used for the past 75 years.
The second point crown are explaining in their white paper is focusing on the SMPS, its fun to see that the amps is lighter because of magnet replacement but these smps are Harmonics injectors, the switching is not clean, so if we fluke the input of one these amps, we might have some surprises !
Othmane
-
Hi Yosi,
Thank you ! but what is this have to do with my question ?
Crown is explaining how magnificent and brilliant they are by using two relatively old technologies...
PFC means Power factor Correction, its very normal that if you correct the power factor of a network you get extra kw. More you push the voltage up, less amp you need to achieve the same work. In the industry, 90% of power factor is a minimum to have. the lower the power factor is, higher inductive loads they are, and more capacitor you will have to use. This principle is used for the past 75 years.
The second point crown are explaining in their white paper is focusing on the SMPS, its fun to see that the amps is lighter because of magnet replacement but these smps are Harmonics injectors, the switching is not clean, so if we fluke the input of one these amps, we might have some surprises !
Othmane
I thought you asked how is it possible to feed the 728s with up to 6400W during the peaks using 20A breaker (X120=2400W), I was referring to this part of the document:
"massive amounts of energy reserve into I-Tech’s switchmode power supply, With plenty of energy available to reproduce transient program material"
So when you get the transient peaks, the PSU relays on energy stored in on board capacitors instead of grid power alone.
Please correct me if I'm wrong.
-
I thought you asked how is it possible to feed the 728s with up to 6400W during the peaks using 20A breaker (X120=2400W), I was referring to this part of the document:
"massive amounts of energy reserve into I-Tech’s switchmode power supply, With plenty of energy available to reproduce transient program material"
So when you get the transient peaks, the PSU relays on energy stored in on board capacitors instead of grid power alone.
Please correct me if I'm wrong.
Hi Yosi,
My question was toward how its possible to blow a driver that can take 6400w peak with 20A outlet using a 4000W rated breaker.
For your question, the capacitor bank inside the amplifier is simply used to raise the voltage. I cannot state they are use like super capacitors because it is not needed to correct PF. I am also wondering what could the be the power factor of such Itech6000 or 8000
Othmane
-
Hi Yosi,
My question was toward how its possible to blow a driver that can take 6400w peak with 20A outlet using a 4000W rated breaker.
For your question, the capacitor bank inside the amplifier is simply used to raise the voltage. I cannot state they are use like super capacitors because it is not needed to correct PF. I am also wondering what could the be the power factor of such Itech6000 or 8000
Othmane
In the "old days" before Class D amps were common, amp power supplies had large filter capacitors that stored energy for peaks as well as filtration. That, combined with a reasonably robust output section gave amps "dynamic headroom" that could approach 3dB above rated output (without excess line draw).
Today with switching power supplies, we can "steal" a bit more current over part of the AC wave form, and do it so long as we don't average above "x" amount of current (trip breakers, etc). IIRC, the Crown white paper *does* explain some of this as well as why using PFC allows more peak current draw than might be otherwise possible.
Go back and re-read Ivan's post, he outlines why the above will work.
Tim Mc
-
In the "old days" before Class D amps were common, amp power supplies had large filter capacitors that stored energy for peaks as well as filtration. That, combined with a reasonably robust output section gave amps "dynamic headroom" that could approach 3dB above rated output (without excess line draw).
Today with switching power supplies, we can "steal" a bit more current over part of the AC wave form, and do it so long as we don't average above "x" amount of current (trip breakers, etc). IIRC, the Crown white paper *does* explain some of this as well as why using PFC allows more peak current draw than might be otherwise possible.
Go back and re-read Ivan's post, he outlines why the above will work.
Tim Mc
Good Tim , Yosi and Ivan ! So we are using caps as super caps, it doe's make sens to me like in electrical cars, we use super caps to store energy from Regen and we take this energy for acceleration !
I have read the paper several times and I do understand I-Tech fundamentals, Thank you :) Its a very interesting subject because it touch Power Qiuality witch is more and more important in our day to day gigs.
What about using other type of amps ? Doe's a bridge PL4.0 will act same as an Itech ?
Because the topic is in regards to amps, one of my costumers have 2 x 728 and 2 amps : 1xPL4.0 and 1xPLX3602. he is asking me if we can bridge each amp for each sub. My answer was yes as long as you keep your gain equal. Am I right ?
Othmane
-
Why would you want to bridge those amps? In stereo they are a good match for the 728. This way you could add another set of 728's if you need more low end and not have to purchase another amp.