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Title: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 02:19:22 am
To start off, I'm new here so hopefully I'm posting this in the right place. Please bear with me as I have a lot of questions mixed up in my head. I'm just looking for any 'real world' experience/help/opinion.

Anyway, this is my scenario:

I recently purchased (4) JBL STX 812m monitors and a Crown XTI 4002 to power them. I was planning on using the XTI for both mains and monitors. Would this be a good setup? I've searched the internet high and low to see if anyone was running something similar with little or no result. I know that I am 'underpowering' the 812's, but I've also read numerous forums on under/overpowering speakers with no real decisive results on the subject. In the end, I was planning on purchasing a used iTech 4000 to power the 812's and using the 4002 for sub duty.

Now, I've read a few forums saying that the XTI isn't highly recommended for sub duty as I was planning to purchase (2) SRX 818s'. Through anybody's real world experience, would it be advisable use the XTI to drive the two subs on a 4 ohm load, bridged? Or should I keep the XTI for the mains/monitors and use the iTech 4000 for the subs? On a side note, I also have an XLS 2500 at my disposal, or if it can help my situation, I'll keep it.

One of my other questions that I have is how reliable is a used iTech 4000? I've read that certain production years had problems with connections, bad boards, etc. I just want to be sure before I spend a chunk of money on something used. I've been burned before buying used sound equipment. However this is what I'm faced with due to my current budget.

Thanks in advance.
Title: Re: Amplifier questions.....
Post by: Tim McCulloch on May 10, 2017, 03:10:13 am
There are parts in original I-Techs that contain the rare element "Unobtanium".  Factory repairs are expensive and if the wrong thing is broke, irreparable.  You might get 20 years out of one or you might get 6 months.

I've powered mains from one side of an amp and a single monitor mix on 2 wedges from the other side, without incident but this was 30 years ago on a Peavey CS800.  I suspect you could do it with the XTi *002 series without technical issue.  Here's the limitation:  I don't think there is a JBL preset for the XTi that has mains settings for the left channel and monitor settings for the right channel (or vice-versa).  You might be able to "roll your own" but I suspect that's more than you're comfortable with at this time.

The original *000 Xti didn't have a great reputation as a subwoofer amp but whatever caused that was fixed in the *002 series.  We power SRX728 with bridged XTi6002 and have destroyed a couple of 18s, we've since gone back to stereo mode, saved an amplifier and ignore the occasional clip light.

Now, about single 18s:  seems like a good idea but if you do some reading here in the Lounge you'll find several folks who started out that way and ended up going with 2x18 subs.  If you're moving your gear in a car or SUV you're absolved, but if you have a van or trailer and the venues you play have the room, go 2x18.  Really.

That all said I think you should be looking at the SRX828p for a subwoofer.  A pair of STX818 MAPs for $2400 and a used IT4k will be $1000, probably.  You can buy a pair of SRX828p for just a little more (B Stock or store demo) and not worry about repairing an ITech.  Paying MAP, the 828p is <$2,000, or less than you'd pay for 2 STX818 without power.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 03:52:31 am
There are parts in original I-Techs that contain the rare element "Unobtanium".  Factory repairs are expensive and if the wrong thing is broke, irreparable.  You might get 20 years out of one or you might get 6 months.

I've powered mains from one side of an amp and a single monitor mix on 2 wedges from the other side, without incident but this was 30 years ago on a Peavey CS800.  I suspect you could do it with the XTi *002 series without technical issue.  Here's the limitation:  I don't think there is a JBL preset for the XTi that has mains settings for the left channel and monitor settings for the right channel (or vice-versa).  You might be able to "roll your own" but I suspect that's more than you're comfortable with at this time.

The original *000 Xti didn't have a great reputation as a subwoofer amp but whatever caused that was fixed in the *002 series.  We power SRX728 with bridged XTi6002 and have destroyed a couple of 18s, we've since gone back to stereo mode, saved an amplifier and ignore the occasional clip light.

Now, about single 18s:  seems like a good idea but if you do some reading here in the Lounge you'll find several folks who started out that way and ended up going with 2x18 subs.  If you're moving your gear in a car or SUV you're absolved, but if you have a van or trailer and the venues you play have the room, go 2x18.  Really.

That all said I think you should be looking at the SRX828p for a subwoofer.  A pair of STX818 MAPs for $2400 and a used IT4k will be $1000, probably.  You can buy a pair of SRX828p for just a little more (B Stock or store demo) and not worry about repairing an ITech.  Paying MAP, the 828p is <$2,000, or less than you'd pay for 2 STX818 without power.

Thanks for the quick reply....

Would 'underpowering' the 812's with the 4002 still be an issue? If so, what other amplifier would you suggest that is comparable other than a used iTech 4000?

On the other hand, if I were to use the 4002 for sub duty, it states in the owners manual, "Putting the amplifier in BRG SUBS (bridged subs) mode allows you to bridge the amplifier for use with a single 8 or 4 ohm subwoofer". Can you parallel TWO 8 ohm subs for the 4 ohm load with no adverse effect?

Thank you, but as for the recommendation for the 828p, my preference would have to be passive. I'm just trying to make the best with what I have. However, I am willing to cough up some cash for a used iTech 4000 or something comparable if need be.

Thanks again.
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 10, 2017, 03:57:40 am
Thanks for the quick reply....

Would 'underpowering' the 812's with the 4002 still be an issue? If so, what other amplifier would you suggest that is comparable other than a used iTech 4000?

On the other hand, if I were to use the 4002 for sub duty, it states in the owners manual, "Putting the amplifier in BRG SUBS (bridged subs) mode allows you to bridge the amplifier for use with a single 8 or 4 ohm subwoofer". Can you parallel TWO 8 ohm subs for the 4 ohm load with no adverse effect?

Thank you, but as for the recommendation for the 828p, my preference would have to be passive. I'm just trying to make the best with what I have. However, I am willing to cough up some cash for a used iTech 4000 or something comparable if need be.

Thanks again.

I am not sure you understand the statement.  If you are going to buy the 818's and the amp you are going to spend more money than the powered box and be disappointed in the results.

I don't get buying $1000 monitors either and then putting them on one mix.  I would have gone with a less expensive monitor rather than have a single monitor mix.

You are getting great advice, I would not be so quick to dismiss it.

Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 04:57:14 am
I am not sure you understand the statement.  If you are going to buy the 818's and the amp you are going to spend more money than the powered box and be disappointed in the results.

I don't get buying $1000 monitors either and then putting them on one mix.  I would have gone with a less expensive monitor rather than have a single monitor mix.

You are getting great advice, I would not be so quick to dismiss it.

I am sincerely sorry if I am offending anyone. Don't get me wrong, your advice is greatly appreciated.

As far as the sub suggestion goes, I have thought a lot about purchasing a powered sub/subs. The SRX 828s does seem to be the general consensus but I have to consider the logistics of transport/handling the cab by myself (can't see going up stairs carrying a 140 lb plus speaker with no ramp/elevator), available power at the venue, etc. I just figured that (2) SRX 818s's would meet my needs.

As for the monitor mix, a majority of the groups that I work with are small, usually 3-4 mics/3-4 di's at the most and are accustomed to a single monitor mix. The indoor venues that the performances are at only have approximately 100-200 people at the absolute most and can be handled with what I have. I've even seen/heard  (2)MRX 515's-(2)512's mains/monitors up to (4)VRX 932's-(2)712's mains/monitors do a pretty good job at most of these places just to give you an idea. Only on the outdoor events here have I seen SRX 725/722 for mains stacked on SRX 728's with multiple 712's for monitors which require heavy duty generators. Some of these indoor/partial outdoor venues are also have questionable power which limits powered speakers to a certain extent.

Being that I'm setting up and running sound by myself and sometimes playing bass at the same time, I'm looking for the 'best bang' for the buck while balancing portability with quality.

Again, I DO appreciate your advice.
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 10, 2017, 05:02:56 am
I am sincerely sorry if I am offending anyone. Don't get me wrong, your advice is greatly appreciated.

As far as the sub suggestion goes, I have thought a lot about purchasing a powered sub/subs. The SRX 828s does seem to be the general consensus but I have to consider the logistics of transport/handling the cab by myself (can't see going up stairs carrying a 140 lb plus speaker with no ramp/elevator), available power at the venue, etc. I just figured that (2) SRX 818s's would meet my needs.

As for the monitor mix, a majority of the groups that I work with are small, usually 3-4 mics/3-4 di's at the most and are accustomed to a single monitor mix. The indoor venues that the performances are at only have approximately 100-200 people at the absolute most and can be handled with what I have. I've even seen/heard  (2)MRX 515's-(2)512's mains/monitors up to (4)VRX 932's-(2)712's mains/monitors do a pretty good job at most of these places just to give you an idea. Only on the outdoor events here have I seen SRX 725/722 for mains stacked on SRX 728's with multiple 712's for monitors which require heavy duty generators. Some of these indoor/partial outdoor venues are also have questionable power which limits powered speakers to a certain extent.

Being that I'm setting up and running sound by myself and sometimes playing bass at the same time, I'm looking for the 'best bang' for the buck while balancing portability with quality.

Again, I DO appreciate your advice.

You can apply the same principal to single powered 18's also. 

For the gigs you are describing the logistics and consistency of powered boxes makes so much sense.   At the lounge level I am seeing young techs come up that have never even run a system with processing and amplification.  If you are under 25 and been in the business less than 5 years chances are you are mixing on an x32 and some type of powered box.  If anyone else has to run your system the powered boxes give you more protection.

It's interesting you mention 4 VRX's.  They get stupid loud and are sound fairly painful in the process.  All the worst attributes of a dash array. 



Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 05:38:57 am
You can apply the same principal to single powered 18's also. 

For the gigs you are describing the logistics and consistency of powered boxes makes so much sense.   At the lounge level I am seeing young techs come up that have never even run a system with processing and amplification.  If you are under 25 and been in the business less than 5 years chances are you are mixing on an x32 and some type of powered box.  If anyone else has to run your system the powered boxes give you more protection.

It's interesting you mention 4 VRX's.  They get stupid loud and are sound fairly painful in the process.  All the worst attributes of a dash array.

I'm sort of a "late bloomer" in the sound business. I was 'elected' to run sound for one of my first groups while playing bass. Nobody wanted to run the mixer due to lack of technical understanding (I'm an automotive technician by trade). It basically a crash course in live sound engineering. I feel I've come a long way from using a Soundcraft Gigrac to going digital and I admit, I still have more to learn. I've played at a lot of venues and found what I like/don't like and quickly chatted with various engineers with varying levels of experience. A majority of them are die hard 'passive fans' with some others that swear by powered units. I've read numerous forums debating which is better and I can honestly see the pros and cons of both. In finding what I like, I've discovered that I prefer going passive. I am still open to powered speakers/subs depending on what venue/group size I would need them for. I'll cross that bridge when I get there.

As far as the VRX set up, I wasn't able to hear the main mix as a I was performing. The VRX's were stacked on each side on a stand in an 'array'. However, the high's on the 712's were a little harsh to me. I did a comparison between the 712's and 812's at my work and found the 812's to be smoother. The 712's had great bass/treble at low level but got a little more harsh as I turned up the volume. The 812's sounded more smooth/balanced no matter what volume. I've had two of my friends who are strictly musicians (not sound techs) and three other people who are neither confirm this. Now for more bass which would obviously require a sub to round/out the response which led me here to Pro Sound web for opinions/advice on where to go.

Title: Re: Amplifier questions.....
Post by: Jean-Pierre Coetzee on May 10, 2017, 08:19:10 am
How about you give us some specifics about why you believe that a passive box would be better. You will likely be carrying less weight, the boxes have better protection built in and the manufacturer can more precisely  setup the DSP to match the box.

The only advantage I can think of in passive is that there isn't a single point of failure but having multiple points of failure doesn't mean that its less likely to fail.

In your situation you are running both mains from one amp channel so it remains a single point of failure.
Title: Re: Amplifier questions.....
Post by: Debbie Dunkley on May 10, 2017, 11:04:32 am
With respect:-
One of the reasons powered speakers have become so popular is because of folks like yourself who have limited knowledge or experience on how to deploy a PA system successfully and  to its full potential.
Powered speaker systems take most of the guess work out of the equation because the company has done pretty much everything for you.
I used to run a passive SRX system and I got great results but only because I researched and researched how to set DSP, which amps, wiring configurations I should use and I took advice from the knowledgeable folks on here.
My first powered system however -JBL PRX - took no thinking about - just plug and play and VOILA - great results.
Makes it easy when it comes to monitors too... just add as many as you want according to the amount of mixes available from the mixer - OR daisy chain if sharing mixes.

There are still a lot of folks at LAB level who prefer passive systems for some very good reasons but there is a lot more to getting a passive system 'right' than a powered one.

Title: Re: Amplifier questions.....
Post by: Steve Ferreira on May 10, 2017, 12:29:41 pm
I'm still debating on moving from a passive SRX700 rig to an active SRX800 rig. I'm trying to listen to a rig before I purchase. I will list some pros and cons:

SRX 700 (712, 725,728, Itech 8000 & XTI 4000)Pros: Sound great and does everything I need them to do. Light for what they are.
Cons: Racks of heavy amps, NL4 cables in various lengths and Power draw. More space required when moving to and from venue. Most times I'm running 2x Itechs 8000s and 4x XTI 4000s. Unless I have a panel with camlocks I need to get creative.

SRX 800 Pros: Self powered, cheaper then buying speakers and amps separate. Just have to worry about XLR and power. Factory presets with limiters.
Cons: Initial price yet still cheaper then passive. A little less power then my SRX700 rig but I doubt anyone will hear the difference.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 01:26:50 pm
With respect:-
One of the reasons powered speakers have become so popular is because of folks like yourself who have limited knowledge or experience on how to deploy a PA system successfully and  to its full potential.
Powered speaker systems take most of the guess work out of the equation because the company has done pretty much everything for you.
I used to run a passive SRX system and I got great results but only because I researched and researched how to set DSP, which amps, wiring configurations I should use and I took advice from the knowledgeable folks on here.
My first powered system however -JBL PRX - took no thinking about - just plug and play and VOILA - great results.
Makes it easy when it comes to monitors too... just add as many as you want according to the amount of mixes available from the mixer - OR daisy chain if sharing mixes.

There are still a lot of folks at LAB level who prefer passive systems for some very good reasons but there is a lot more to getting a passive system 'right' than a powered one.

How about you give us some specifics about why you believe that a passive box would be better. You will likely be carrying less weight, the boxes have better protection built in and the manufacturer can more precisely  setup the DSP to match the box.

The only advantage I can think of in passive is that there isn't a single point of failure but having multiple points of failure doesn't mean that its less likely to fail.

In your situation you are running both mains from one amp channel so it remains a single point of failure.

I can totally see what advantage powered speakers have as a simple plug and play solution which also seems to be the leading trend. Believe me, I was one click away from buying a totally powered system but at the last minute decided against it. Like you, with NO disrespect intended, the whole reason why I'm posting here is get some expertise on if what I have as far as amp wattage to speaker requirement will work or not for my current situation and not whether I should buy powered speakers. Although powered speakers now days have pretty much everything built in, I'd rather be able to control everything from one point vs. multiple points since I sometimes have to play bass as well as run sound. It would be hard for me to make adjustments to a particular powered speaker in the middle of a song or to run out and make an adjustment in between songs. Granted that there are wi-fi speakers such as the PRX/SRX?800 series I'd rather control everything from my mixer alone.

To me, whether to go passive or powered is almost like picking which car to drive to go somewhere. In the end the goal is the same, just different ways on getting there based on preference or needs. To reiterate, with NO disrespect intended, what can I avail of with my situation in my original post? I'm pretty much looking to keep my setup.

Thanks again for your input.
Title: Re: Amplifier questions.....
Post by: Michael Storey on May 10, 2017, 01:32:23 pm
At the end of the day, only you and your clients/bandmates can decide if the XTI 4002 powered STX 812's on monitor duty will work for you. I'd say you're slightly underpowered, but if you're happy with the volume level you achieve with that combo, then being a bit underpowered becomes irrelevant. If you find yourself constantly clipping the XTI 4002, you need a bit more amp. STX presets are available for the XTI series.

The XTI 6002 is a whole different beast compared to its XTI siblings. I found it to a be a solid subwoofer amp, and would be a great match for the SRX 818s, or your STX 812's for that matter. I don't see SRX 818s presets readily available for the XTI, but i'm sure they exist. Probably will require a call to JBL.

For the reasons Tim explained, I would not purchase a used IT4000. I do see a few second hand IT5000HD's out there for not much more money than a new XTI 6002, and presets are available for the SRX line.
Title: Re: Amplifier questions.....
Post by: Dave Guilford on May 10, 2017, 01:57:56 pm
Wow what a strange thread. 

Itech on subs.  No doubt.  Itech on any srx/stx will be very high quality low end.  Certainly even better than a powered srx818/828.

I've been through 4 used itech amps any never had a problem.  One has 12k hours on it, and one has 4K hours.  The rest between that. 

I'd also say that srx700 beats the srx800 and stx series. 

The dude wants to run monitors all on one mix?   Weird but ok.

I've bridged my xti6002 amps into srx728 and it gets plenty loud.  But the sound quality is considerably better when I bridge my itech 4000 into one.  Difference of 2000 watts - headroom mostly - but I way prefer the IT4k over the xti60002 on subs.

Good luck !
Title: Re: Amplifier questions.....
Post by: Debbie Dunkley on May 10, 2017, 02:01:31 pm
I can totally see what advantage powered speakers have as a simple plug and play solution which also seems to be the leading trend. Believe me, I was one click away from buying a totally powered system but at the last minute decided against it. Like you, with NO disrespect intended, the whole reason why I'm posting here is get some expertise on if what I have as far as amp wattage to speaker requirement will work or not for my current situation and not whether I should buy powered speakers. Although powered speakers now days have pretty much everything built in, I'd rather be able to control everything from one point vs. multiple points since I sometimes have to play bass as well as run sound. It would be hard for me to make adjustments to a particular powered speaker in the middle of a song or to run out and make an adjustment in between songs. Granted that there are wi-fi speakers such as the PRX/SRX?800 series I'd rather control everything from my mixer alone.

To me, whether to go passive or powered is almost like picking which car to drive to go somewhere. In the end the goal is the same, just different ways on getting there based on preference or needs. To reiterate, with NO disrespect intended, what can I avail of with my situation in my original post? I'm pretty much looking to keep my setup.

Thanks again for your input.

I understand completely.
However,  my post - although covering FOH and monitor powered options for the sake of giving a hopefully informative opinion for anyone reading my post -  was also about agreeing with Tim that getting powered versions of the SRX subs would still benefit you  for all the reasons mentioned here. Amps included, nothing else to think about and cheaper overall.

One more thing , you mentioned not being able to make adjustments to powered speakers as easily during or in between songs. Rarely have I ever had to make a change to powered speaker once up and running. Once sound checked, and my levels are set on the FOH speakers, all my adjustments happen as the console.
Title: Re: Amplifier questions.....
Post by: Steve Garris on May 10, 2017, 02:14:01 pm
I can totally see what advantage powered speakers have as a simple plug and play solution which also seems to be the leading trend. Believe me, I was one click away from buying a totally powered system but at the last minute decided against it. Like you, with NO disrespect intended, the whole reason why I'm posting here is get some expertise on if what I have as far as amp wattage to speaker requirement will work or not for my current situation and not whether I should buy powered speakers. Although powered speakers now days have pretty much everything built in, I'd rather be able to control everything from one point vs. multiple points since I sometimes have to play bass as well as run sound. It would be hard for me to make adjustments to a particular powered speaker in the middle of a song or to run out and make an adjustment in between songs. Granted that there are wi-fi speakers such as the PRX/SRX?800 series I'd rather control everything from my mixer alone.

To me, whether to go passive or powered is almost like picking which car to drive to go somewhere. In the end the goal is the same, just different ways on getting there based on preference or needs. To reiterate, with NO disrespect intended, what can I avail of with my situation in my original post? I'm pretty much looking to keep my setup.

Thanks again for your input.

You've got some great monitors with those STX812's. I would power them alone with your amp, and there's nothing wrong with having a single mix if that works for you.

Regarding the powered mains, as Debbie stated there would never be a time when you would need to control a speaker during a gig. These powered boxes are so well balanced, you will literally plug them in and go. Your main EQ, if you have one, will likely be flat. That's how good the new powered boxes sound. I have an SRX8xxp system, and once you find the initial sub to top level settings, you are done for good. You're getting great advise here on the powered vs passive boxes.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 02:23:39 pm
Debbie,
I appreciate your input. Thank you very much.

Steve,
I also appreciate and thank you for your input.

Dave,
I can totally agree that this thread has been a curvy road at best with a lot of varying replies. If it is necessary to upgrade to a used Itech or a new 6002 then I'll bite the bullet on it. But with Michaels reply as confirmation, I'll stick with the 4002. Kinda sketchy with the used Itech 4000 deal. If what I have can work, I'll stick with it for now.

As far as subs, I'm waiting to replenish my funds before going further at this point as other financial concerns have arisen.

I know that running monitors on one mix is somewhat uncommon, but that is what most of the performers I deal with are used to being that the groups are commonly no larger than a quartet.

Thank you for your input.

[/quote]
At the end of the day, only you and your clients/bandmates can decide if the XTI 4002 powered STX 812's on monitor duty will work for you. I'd say you're slightly underpowered, but if you're happy with the volume level you achieve with that combo, then being a bit underpowered becomes irrelevant. If you find yourself constantly clipping the XTI 4002, you need a bit more amp. STX presets are available for the XTI series.

The XTI 6002 is a whole different beast compared to its XTI siblings. I found it to a be a solid subwoofer amp, and would be a great match for the SRX 818s, or your STX 812's for that matter. I don't see SRX 818s presets readily available for the XTI, but i'm sure they exist. Probably will require a call to JBL.

For the reasons Tim explained, I would not purchase a used IT4000. I do see a few second hand IT5000HD's out there for not much more money than a new XTI 6002, and presets are available for the SRX line.

Michael,

Thank you very, very much. THAT, was basically the answer I was looking for.
Title: Re: Amplifier questions.....
Post by: TJ (Tom) Cornish on May 10, 2017, 02:39:00 pm
If you find yourself constantly clipping the XTI 4002, you need a bit more amp. STX presets are available for the XTI series.
If you find yourself constantly clipping the XTI 4002, you need to turn it down.  A larger amp will make virtually no usable output improvement (doubling amplifier power only adds a theoretical 3dB, which is probably less due to power compression), and will significantly increase your risk of damaging your speakers.

+1 to self-powered SRX 800p series boxes instead of any passive+amp combo.
Title: Re: Amplifier questions.....
Post by: Rob Spence on May 10, 2017, 04:35:38 pm
Just to mention a point from much earlier...
To the OP; you mentioned power availability in the venues. Passive with amp is not really different from active for the same volume levels.
I would not make my choice based on that.

My bar rig mains speakers are all active. No fussing to get a big power source for the amp rack.


Sent from my iPad using Tapatalk HD
Title: Re: Amplifier questions.....
Post by: Jamin Lynch on May 10, 2017, 04:41:20 pm
There are parts in original I-Techs that contain the rare element "Unobtanium".  Factory repairs are expensive and if the wrong thing is broke, irreparable.  You might get 20 years out of one or you might get 6 months.

I've powered mains from one side of an amp and a single monitor mix on 2 wedges from the other side, without incident but this was 30 years ago on a Peavey CS800.  I suspect you could do it with the XTi *002 series without technical issue.  Here's the limitation:  I don't think there is a JBL preset for the XTi that has mains settings for the left channel and monitor settings for the right channel (or vice-versa).  You might be able to "roll your own" but I suspect that's more than you're comfortable with at this time.

The original *000 Xti didn't have a great reputation as a subwoofer amp but whatever caused that was fixed in the *002 series.  We power SRX728 with bridged XTi6002 and have destroyed a couple of 18s, we've since gone back to stereo mode, saved an amplifier and ignore the occasional clip light.

Now, about single 18s:  seems like a good idea but if you do some reading here in the Lounge you'll find several folks who started out that way and ended up going with 2x18 subs.  If you're moving your gear in a car or SUV you're absolved, but if you have a van or trailer and the venues you play have the room, go 2x18.  Really.

That all said I think you should be looking at the SRX828p for a subwoofer.  A pair of STX818 MAPs for $2400 and a used IT4k will be $1000, probably.  You can buy a pair of SRX828p for just a little more (B Stock or store demo) and not worry about repairing an ITech.  Paying MAP, the 828p is <$2,000, or less than you'd pay for 2 STX818 without power.

Unobtanium.....LOL ;)
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 04:57:47 pm
Just to mention a point from much earlier...
To the OP; you mentioned power availability in the venues. Passive with amp is not really different from active for the same volume levels.
I would not make my choice based on that.

My bar rig mains speakers are all active. No fussing to get a big power source for the amp rack.

I agree to a certain extent, however (correct me if I'm wrong), with an active system (2 monitors, 2 mains with 2 subs), wouldn't that system require more power vs a passive system with just two amps? My other concerns would be outlet distribution for all of these units, questionable building electrical integrity and the added costs/routing for extension cords espcially outdoors.

Sent from my iPad using Tapatalk HD
Title: Re: Amplifier questions.....
Post by: TJ (Tom) Cornish on May 10, 2017, 05:05:24 pm
I agree to a certain extent, however (correct me if I'm wrong), with an active system (2 monitors, 2 mains with 2 subs), wouldn't that system require more power vs a passive system with just two amps? My other concerns would be outlet distribution for all of these units, questionable building electrical integrity and the added costs/routing for extension cords espcially outdoors.
Jesse, there isn't a material power consumption difference between active and passive.  Amps only draw what they are asked to produce - just because a "2000 watt" speaker says so on the marketing material doesn't mean it will draw that from the wall.  As it relates to "questionable building integrity", that issue exists either way.

There are people who prefer passive for cable management reasons, but in recent years the sound quality difference between a high-performance active system like the JBL SRX800P series and anything passive is so significant it outweighs (IMO) any small logistical disadvantages, not that there are that many.  And you don't have to carry around an amp rack.

The SRX800p series is cheaper, sounds MUCH better, and is much harder to destroy than the SRX passive series + generic amp.  If you already own amps it may make sense, but if you're starting from scratch, the performance difference of the self-powered speakers is not subtle.  The fact that the SRX-P series is cheaper just makes it silly to not go that way.
Title: Re: Amplifier questions.....
Post by: Stephen Kirby on May 10, 2017, 05:31:19 pm
Think of it this way, with a powered box you have the ideal coupling of amp and speaker.  Potentially the best efficiency.  Not that 25-50 of decent speaker cable dramatically affects anything but from an academic standpoint, powered boxes have greater inherent power efficiency.

The reality is that modern class D amps (either in racks or built into speaker cabinets) produce a great deal of sound for the amount of juice they pull out of the wall.  While the spec's might imply one thing, many of us are getting away with plugging a couple of 1500W (by the marketing literature) tops over 4+ 18" subs into a single 20A outlet.
Title: Re: Amplifier questions.....
Post by: Michael Storey on May 10, 2017, 05:43:44 pm
If you find yourself constantly clipping the XTI 4002, you need to turn it down.  A larger amp will make virtually no usable output improvement (doubling amplifier power only adds a theoretical 3dB, which is probably less due to power compression), and will significantly increase your risk of damaging your speakers.

+1 to self-powered SRX 800p series boxes instead of any passive+amp combo.

I agree, if you're constantly clipping ANY amp then you need to turn down.

But for arguments sake, if a larger amp makes virtually no impact as you say, should he just return the XTI 4002 and settle with a XTI 1002 and save some coin?

I guess what I'm saying is, being familiar with the equipment in question, I'm confident that by powering 2/ side STX 812m with a XTI 4002 he'd be leaving performance/headroom on the table. If he's doing small venue's and clubs (like I assume), then its a moot point. If he happens to be doing med-large outdoor shows with screamo bands or deaf rappers, he'd probably be clipping that XTI 4002 pretty often, and the XTI 6002 would probably be a better option. It's up to him to determine if the XTI 4002 is good enough.

This is all assuming that he follows the general ideology (as I do) that clip lights are bad, especially on full-range systems.

PS. +10000 to the self powered SRX 818SP recommendations. But he's made it clear that he prefers a passive setup and that's his prerogative, and his money. Hence, I didn't bother.

PPS. IMO the XTI feels closer to an iTech than its XTI brethren.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 05:52:54 pm
Jesse, there isn't a material power consumption difference between active and passive.  Amps only draw what they are asked to produce - just because a "2000 watt" speaker says so on the marketing material doesn't mean it will draw that from the wall.  As it relates to "questionable building integrity", that issue exists either way.

There are people who prefer passive for cable management reasons, but in recent years the sound quality difference between a high-performance active system like the JBL SRX800P series and anything passive is so significant it outweighs (IMO) any small logistical disadvantages, not that there are that many.  And you don't have to carry around an amp rack.

The SRX800p series is cheaper, sounds MUCH better, and is much harder to destroy than the SRX passive series + generic amp.  If you already own amps it may make sense, but if you're starting from scratch, the performance difference of the self-powered speakers is not subtle.  The fact that the SRX-P series is cheaper just makes it silly to not go that way.

Tom,

Although amplifiers (whether in a passive or active application) draw what they are asked to produce, would a totally active system (2 mains, 2 monitors, 2 subs for example) demand be too high for a 15A circuit? A lot of venues that I'm at have only 15A circuits. Up to now, that's all I've seen. I'm running what I have through a Furman P1800 AR which suits what I need. I do not see a need at this point and time to switch to powered speakers even though I've thought about it numerous times. I do agree that the SRX812p is a good speaker but I like the wedge/lower profile size etc. of the STX 812m because it suits my needs at this point in time. My ORIGNAL question has already been answered without need for further discussion on whether I should buy passive or powered speakers. Everyone has their own opinion and I'm glad to hear it but I also have my own which counts the most to me. I'm not suggesting everyone buy passive speakers for reasons x,y and z so I would appreciate the same in return.

I have already purchased my equipment based on my research/needs/preference and that should be respected.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 06:00:32 pm
I agree, if you're constantly clipping ANY amp then you need to turn down.

But for arguments sake, if a larger amp makes virtually no impact as you say, should he just return the XTI 4002 and settle with a XTI 1002 and save some coin?

I guess what I'm saying is, being familiar with the equipment in question, I'm confident that by powering 2/ side STX 812m with a XTI 4002 he'd be leaving performance/headroom on the table. If he's doing small venue's and clubs (like I assume), then its a moot point. If he happens to be doing med-large outdoor shows with screamo bands or deaf rappers, he'd probably be clipping that XTI 4002 pretty often, and the XTI 6002 would probably be a better option. It's up to him to determine if the XTI 4002 is good enough.

This is all assuming that he follows the general ideology (as I do) that clip lights are bad, especially on full-range systems.

PS. +10000 to the self powered SRX 818SP recommendations. But he's made it clear that he prefers a passive setup and that's his prerogative, and his money. Hence, I didn't bother.

PPS. IMO the XTI feels closer to an iTech than its XTI brethren.

Again, Michael,

Thank you for understanding/answering my ORIGINAL question. That is why I came here.

PS - I do understand that clip lights are bad and will try to avoid them at all costs.
Title: Re: Amplifier questions.....
Post by: TJ (Tom) Cornish on May 10, 2017, 06:24:51 pm
Quote

Everyone has their own opinion and I'm glad to hear it but I also have my own which counts the most to me. I'm not suggesting everyone buy passive speakers for reasons x,y and z so I would appreciate the same in return.

I have already purchased my equipment based on my research/needs/preference and that should be respected.
Jesse, you started off this thread saying "I bought all this stuff, is it a good system?"  And "I'm confused about a bunch of stuff."  That's a pretty interesting way to start out. Now you've apparently convinced yourself that you did indeed buy a good system that is perfect for your needs, though you still seem to misunderstand some of the questions you initially asked.

The quantity of self-powered speakers you mention will be fine on one circuit.

I'm sorry you didn't hear what you wanted to hear, but I'm glad you have decided that you are happy. Your gear will be fine, just keep the amp out of clipping.

Title: Re: Amplifier questions.....
Post by: Tim McCulloch on May 10, 2017, 06:31:10 pm
Your original question is kind of moot after you told us why you were headed in a particular direction.  The concrete reason is money, the emotional reason is about a perceived lack of control over the system.

I've been "that guy" with the control issues and after 35 years in this industry I'm plenty happy to let JBL/Crown/D&B/l'Acoustic/RCF do the heavy lifting/thinking for me.  Seriously.

It's easier to make good sound that it's ever been.  It's cheaper to buy "design family" loudspeaker systems than to configure your own that easily outperform equipment designed 10 years ago or even less.

I'm not a powered speaker pimp, in fact the company I manage has less than 10% of our system investments in powered speaker systems, but that's because we had a half million $$ invested in legacy ways of doing things and my boss wasn't keen on having to respend that $500k.

At your level of expertise and lacking a bunch of older gear you need to keep making money I think it's foolish to continue on the path you've begun.

I know that wasn't your question (which I believe I contributed pertinent answers to), but you are not required to make the mistakes of others if you can learn from our experiences.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 07:10:11 pm

I recently purchased (4) JBL STX 812m monitors and a Crown XTI 4002 to power them. I was planning on using the XTI for both mains and monitors. Would this be a good setup? I've searched the internet high and low to see if anyone was running something similar with little or no result. I know that I am 'underpowering' the 812's, but I've also read numerous forums on under/overpowering speakers with no real decisive results on the subject. In the end, I was planning on purchasing a used iTech 4000 to power the 812's and using the 4002 for sub duty.


That was my main/original question. Basically I was asking if it would be ok if I 'underpowered'  the STX 812m's with the XTI4002 which maybe I should've asked originally to lessen the confusion. After asking my question, everyone started in with powered speakers this and that which wasn't relevant to what I was asking. That in turn led me explaining why I chose passive over powered. As for this statement.....

Jesse, you started off this thread saying "I bought all this stuff, is it a good system?"  And "I'm confused about a bunch of stuff."  That's a pretty interesting way to start out. Now you've apparently convinced yourself that you did indeed buy a good system that is perfect for your needs, though you still seem to misunderstand some of the questions you initially asked.

....this is not accurate. With no convincing needed, I knew I bought a good system for my needs or I wouldn't have bought it at all. I thoroughly research what I buy beforehand by reading forums, reviews, listening to professional sound engineer advice and reading whatever other information that is easily available. As for misunderstanding the initial questions that I asked, I just had a simple question of whether the running the speakers underpowered would be an issue.

Michael had the best replies which answered my original question(s) completely.

Again, that's all I needed with no disrespect intended. I sincerely thank you all again for all of your input.
Title: Re: Amplifier questions.....
Post by: Michael Storey on May 10, 2017, 07:39:31 pm
Again, that's all I needed with no disrespect intended. I sincerely thank you all again for all of your input.

Stick around. Threads occasionally get weird, but everyone means well.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 10, 2017, 08:04:50 pm
Stick around. Threads occasionally get weird, but everyone means well.


Most definately :)
Title: Re: Amplifier questions.....
Post by: Jonathan Betts on May 10, 2017, 08:22:45 pm
We use ITech 4000 to power SRX 712m's and other SRX passive cabinets. This combo performs great for either monitor or mains duty. IMO, they sound and perform better than the SRX 812/815p boxes.


We have 8 original Itech 4000's and have never had any issues. Only a couple issues with a certain Itech 6000. Recently this amp went to Crown and was fixed for a reasonable fee. Crown support/repair has been excellent.
Title: Re: Amplifier questions.....
Post by: Stephen Kirby on May 10, 2017, 08:40:48 pm
I will say that I like the low profile of 712s and for the money they can carry a pretty loud stage.  The only other low profile monitor I have experience of are MicroWedges which I believe are considerably more expensive.
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 11, 2017, 12:33:36 am

Most definately :)

I just reread the thread and can't seem to find what you are using for main speakers that you intend to augment with the subs.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 12:59:38 am
I just reread the thread and can't seem to find what you are using for main speakers that you intend to augment with the subs.

First post, first paragraph, second line:

I was planning on using the XTI for both mains and monitors.
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 11, 2017, 01:04:53 am
First post, first paragraph, second line:

I was planning on using the XTI for both mains and monitors.

The XTI is the amplifier.  I asked what speakers you are using for mains that you will be augmenting with the subs.  Understand you have the 4 812's on monitor duty.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 01:23:35 am
The XTI is the amplifier.  I asked what speakers you are using for mains that you will be augmenting with the subs.  Understand you have the 4 812's on monitor duty.

I'm sorry for the confusion. This is my setup: Channel 1, 2-STX 812m's as mains (4 ohm load delivering approximately 600 watts to each speaker), Channel 2, 2-STX 812m's as monitors (again 4 ohm load delivering approximately 600 watts to each speaker). Although this is not how it should be set up on a 'professional level' (XTI 4002 for either mains OR monitors, not both at the same time), this is what currently suits my needs.
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 11, 2017, 02:06:49 am
I'm sorry for the confusion. This is my setup: Channel 1, 2-STX 812m's as mains (4 ohm load delivering approximately 600 watts to each speaker), Channel 2, 2-STX 812m's as monitors (again 4 ohm load delivering approximately 600 watts to each speaker). Although this is not how it should be set up on a 'professional level' (XTI 4002 for either mains OR monitors, not both at the same time), this is what currently suits my needs.

Ok got it.  Have you setup the DSP's and limiters in the amps?

Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 02:09:27 am
Ok got it.  Have you setup the DSP's and limiters in the amps?

Not yet. Any recommendations?
Title: Re: Amplifier questions.....
Post by: Scott Holtzman on May 11, 2017, 02:53:33 am
Not yet. Any recommendations?

Just what was mentioned, the factory provided presets for your speakers.

You don't need hard limiting since you are underpowering the speakers but using a limiter to compress just a little and proper a high pass will give you a bunch more headroom.  The subs will be a huge improvement too, the tops won't have to work as hard.
 
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 03:13:30 am
Just what was mentioned, the factory provided presets for your speakers.

You don't need hard limiting since you are underpowering the speakers but using a limiter to compress just a little and proper a high pass will give you a bunch more headroom.  The subs will be a huge improvement too, the tops won't have to work as hard.

Cool. Thank you.
Title: Re: Amplifier questions.....
Post by: Geert Friedhof on May 11, 2017, 07:41:33 am
I like the idea of passive monitors.

So what about this: Buy another XTI 4002. This will give you the option of running 2 monitors, 2 fronts, or 4 monitors and use the house PA. When one of the amps fails, or mains power is dodgy you can easily run from 1 amp. And when funds allow buy 2 SRX818P's which you use when needed.

Btw: you never mentioned which mixer you use.
Title: Re: Amplifier questions.....
Post by: TJ (Tom) Cornish on May 11, 2017, 08:42:19 am
I agree, if you're constantly clipping ANY amp then you need to turn down.

But for arguments sake, if a larger amp makes virtually no impact as you say, should he just return the XTI 4002 and settle with a XTI 1002 and save some coin?

I guess what I'm saying is, being familiar with the equipment in question, I'm confident that by powering 2/ side STX 812m with a XTI 4002 he'd be leaving performance/headroom on the table. If he's doing small venue's and clubs (like I assume), then its a moot point. If he happens to be doing med-large outdoor shows with screamo bands or deaf rappers, he'd probably be clipping that XTI 4002 pretty often, and the XTI 6002 would probably be a better option. It's up to him to determine if the XTI 4002 is good enough.

This is all assuming that he follows the general ideology (as I do) that clip lights are bad, especially on full-range systems.

PS. +10000 to the self powered SRX 818SP recommendations. But he's made it clear that he prefers a passive setup and that's his prerogative, and his money. Hence, I didn't bother.

PPS. IMO the XTI feels closer to an iTech than its XTI brethren.
Michael, the difference between an XTI4002 and XTI6002 is 3dB.  The apparent volume difference between a clipped XTI4002 and an unclipped XTI6002 is probably nonexistent; in fact, the clipped amp may seem louder.

The problem with the thinking that a larger amp will help is the presumption that those last couple dB make the difference between an unhappy client and a happy client, and that clipping will no longer occur.  I have not found that to be the case.  Instead, the usual result - especially with mismatched amps/speakers - is fast destruction of the speakers.

This can be minimized with significant time spent on limiting such that the amp is programmed to not send more power than the speaker can handle.  This is not a trivial balance to strike - limit too early and performance is left on the table.  Limit to late and the smoke comes out.  Program material factors into this as well - EDM music with sustained sine waves requires different limiting than an R&R kick drum. 

This is the killer feature of the latest crop of self-powered speakers.  JBL (and others) have spent significant time testing this, and using the sophisticated processing originally from the ITechHD line (LevelMax) have worked out peak and RMS limiting such that the boxes are really hard to kill.

This can be reasonably well achieved with the STX series and ITech HD amps, especially if they are bi-amped.  This is a very high cost though - an ITechHD4x3500 into a pair of STX812m boxes is around an $8000 solution; a pair of the similar SRX812p boxes is less than $2500.  The XTI series amps, even with presets, do not have all of the special sauce in them.

I'm sure Jesse's system will be fine as most likely monitor wedge quality is lost in stage volume issues, not to mention too few mixes, and the box form factor is indeed nice.
Title: Re: Amplifier questions.....
Post by: Tim McCulloch on May 11, 2017, 10:51:46 am
Michael, the difference between an XTI4002 and XTI6002 is 3dB.  The apparent volume difference between a clipped XTI4002 and an unclipped XTI6002 is probably nonexistent; in fact, the clipped amp may seem louder.

The problem with the thinking that a larger amp will help is the presumption that those last couple dB make the difference between an unhappy client and a happy client, and that clipping will no longer occur.  I have not found that to be the case.  Instead, the usual result - especially with mismatched amps/speakers - is fast destruction of the speakers.

This can be minimized with significant time spent on limiting such that the amp is programmed to not send more power than the speaker can handle.  This is not a trivial balance to strike - limit too early and performance is left on the table.  Limit to late and the smoke comes out.  Program material factors into this as well - EDM music with sustained sine waves requires different limiting than an R&R kick drum. 

This is the killer feature of the latest crop of self-powered speakers.  JBL (and others) have spent significant time testing this, and using the sophisticated processing originally from the ITechHD line (LevelMax) have worked out peak and RMS limiting such that the boxes are really hard to kill.

This can be reasonably well achieved with the STX series and ITech HD amps, especially if they are bi-amped.  This is a very high cost though - an ITechHD4x3500 into a pair of STX812m boxes is around an $8000 solution; a pair of the similar SRX812p boxes is less than $2500.  The XTI series amps, even with presets, do not have all of the special sauce in them.

I'm sure Jesse's system will be fine as most likely monitor wedge quality is lost in stage volume issues, not to mention too few mixes, and the box form factor is indeed nice.

^^^ THIS.  RIGHT.  HERE. ^^^
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 12:50:06 pm
I like the idea of passive monitors.

So what about this: Buy another XTI 4002. This will give you the option of running 2 monitors, 2 fronts, or 4 monitors and use the house PA. When one of the amps fails, or mains power is dodgy you can easily run from 1 amp. And when funds allow buy 2 SRX818P's which you use when needed.

Btw: you never mentioned which mixer you use.

I really like your idea. Thanks for the suggestion.

I primarily use a Allen and Heath Qu-16. My backup is an old Yamaha EMX-5016 (my original when I first started) which I hope to upgrade someday soon.
Title: Re: Amplifier questions.....
Post by: Nathan Riddle on May 11, 2017, 03:50:11 pm
I really like your idea. Thanks for the suggestion.

I primarily use a Allen and Heath Qu-16. My backup is an old Yamaha EMX-5016 (my original when I first started) which I hope to upgrade someday soon.

OT:
Grab an xair 18 for your backup. Works great when you can't have a FOH and will get you through in a pinch for if the QU16 goes down (I use the QU24).
Title: Re: Amplifier questions.....
Post by: Michael Storey on May 11, 2017, 03:57:25 pm
Michael, the difference between an XTI4002 and XTI6002 is 3dB.  The apparent volume difference between a clipped XTI4002 and an unclipped XTI6002 is probably nonexistent; in fact, the clipped amp may seem louder.

I agree that when looking at the numbers on paper there shouldn't be much of a difference between the two amps. But in practice, having personally tried a XTI4002 and XTI6002 on my old STX 828s subs, I found the apparent volume difference between a XTI4002 and XTI6002 just before clip was definitely noticeable, in favor of the 6002 of course.

The problem with the thinking that a larger amp will help is the presumption that those last couple dB make the difference between an unhappy client and a happy client, and that clipping will no longer occur.  I have not found that to be the case.  Instead, the usual result - especially with mismatched amps/speakers - is fast destruction of the speakers.

Would you agree the general consensus around here has been that (assuming the users program material has a typically high crest factor) it's best to use an amp that matches the program power rating of a loudspeaker? That's the way it's been on this forum for as long as I can remember, which dates back to a bit before Evan K. was blowing up Carvin speakers and whatnot (look at him now!). The XTI 6002 sits right in that sweet spot, but not over the top.

If you achieve the SPL levels needed with the underpowered 4002, but clip often, doesn't the last couple dB the 6002 affords you indeed become desirable? Again, this of course assumes one follows the ideology that you should keep your amps out of clipping.

This can be minimized with significant time spent on limiting such that the amp is programmed to not send more power than the speaker can handle.  This is not a trivial balance to strike - limit too early and performance is left on the table.  Limit to late and the smoke comes out.  Program material factors into this as well - EDM music with sustained sine waves requires different limiting than an R&R kick drum.

This is the killer feature of the latest crop of self-powered speakers.  JBL (and others) have spent significant time testing this, and using the sophisticated processing originally from the ITechHD line (LevelMax) have worked out peak and RMS limiting such that the boxes are really hard to kill.

This can be reasonably well achieved with the STX series and ITech HD amps, especially if they are bi-amped.  This is a very high cost though - an ITechHD4x3500 into a pair of STX812m boxes is around an $8000 solution; a pair of the similar SRX812p boxes is less than $2500.  The XTI series amps, even with presets, do not have all of the special sauce in them.

I'm sure Jesse's system will be fine as most likely monitor wedge quality is lost in stage volume issues, not to mention too few mixes, and the box form factor is indeed nice.

Great points.

I own a dozen SRX 800 series powered boxes, so it's safe to say I agree with you regarding their advantages. However, he made it pretty clear that he preferred passive subs. Yes, the powered SRX is the more logical choice IMHO, but he's free to do things the expensive way if he chooses to. Hence my suggestion of going with XTI6002 or even the IT5000hd to power a pair of SRX 818s. If he uses JBL presets for either amp, his limiting should be fairly dialed in, even on the XTI6002 (the XTI2 series limiters don't suck as much as the original XTI series).

Title: Re: Amplifier questions.....
Post by: TJ (Tom) Cornish on May 11, 2017, 04:23:33 pm
Would you agree the general consensus around here has been that (assuming the users program material has a typically high crest factor) it's best to use an amp that matches the program power rating of a loudspeaker? That's the way it's been on this forum for as long as I can remember, which dates back to a bit before Evan K. was blowing up Carvin speakers and whatnot (look at him now!). The XTI 6002 sits right in that sweet spot, but not over the top.
Yes, the general rule is to have program-power-ish-sized amps, but there are a lot of assumptions to this - a couple being the need (and ability) to keep the amp from clipping, and R&R or gentler program material.
If you achieve the SPL levels needed with the underpowered 4002, but clip often, doesn't the last couple dB the 6002 affords you indeed become desirable?
Sure in theory, but it's a knife edge. 

Get a friend to do a blind test with you.  Play music (not a sinewave) at a fairly loud level.  Move the fader up 2dB and back.  See if you can actually hear the difference.  You can probably hear the difference at 90dBA in an otherwise quiet and dampened room, but now throw in a non-optimal small venue with 100dBA+ stage volume and I'll bet you money you won't be able to tell the difference.  For this marginal at best volume improvement, your speaker now has to dissipate almost twice the heat (3dB would be twice the heat), which significantly increases the risk of damage.  You're on the wrong end of a long lever - lots of input change for minimal output change.

If I was starting from scratch (and had a moral objection to self-powered speakers) I would probably get an XTI6002 over the 4002 just because, but I think upgrading an existing system from a 4002 to a 6002 is a pretty tough sell.  In the OP's situation, a second 4002 to add more monitor mixes will be a much better upgrade than a single larger amp.

By the way, it's unclear if the impedance issue was ever covered here.  Forgive me if I missed this, but was the OP trying to run all 4 STX812m off one side of the amp and his mains off the other side of the same amp?  If so, that's way too much on the same amp.  At a minimum, one XTI should run the 4 monitors and a different amp the mains, and yet a different amp the subs.  Or much better yet, self-powered versions of these things.
Title: Re: Amplifier questions.....
Post by: Nathan Riddle on May 11, 2017, 04:33:26 pm
By the way, it's unclear if the impedance issue was ever covered here.  Forgive me if I missed this, but was the OP trying to run all 4 STX812m off one side of the amp and his mains off the other side of the same amp?  If so, that's way too much on the same amp.  At a minimum, one XTI should run the 4 monitors and a different amp the mains, and yet a different amp the subs.  Or much better yet, self-powered versions of these things.

2 STX boxes per channel on the amp.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 08:11:41 pm
OT:
Grab an xair 18 for your backup. Works great when you can't have a FOH and will get you through in a pinch for if the QU16 goes down (I use the QU24).

I was looking at that or maybe an Xrack. Another alternative I was considering is the QU-Pac.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 08:21:37 pm
At a minimum, one XTI should run the 4 monitors and a different amp the mains, and yet a different amp the subs.

Eventually, this would be the ideal setup that I would like to have, but my budget says otherwise at this time.
Title: Re: Amplifier questions.....
Post by: Debbie Dunkley on May 11, 2017, 08:22:38 pm
I was looking at that or maybe an Xrack. Another alternative I was considering is the QU-Pac.

I went with the QU Pac as my second mixer as I already owned and still own the QU16. This means I can share  scenes and shows between the 2 mixers in seconds, I could slot either into place quickly if the other failed at a show, the learning curve was very easy as I already knew the QU16 inside and out and if I do need 32 channels, along with my D- snake ( which I can use with either mixer), I have them using the QU Pac.
Lastly, I like the fact I can still mix from the QU Pac if wifi goes down.
I was tempted to go for one of the other rack options but paid little more and got much more benefit for my purposes. The SB wasn't out then but I still like having a screen on the QU Pac.
Title: Re: Amplifier questions.....
Post by: Jesse Gregorio on May 11, 2017, 08:34:16 pm
I went with the QU Pac as my second mixer as I already owned and still own the QU16. This means I can share  scenes and shows between the 2 mixers in seconds, I could slot either into place quickly if the other failed at a show, the learning curve was very easy as I already knew the QU16 inside and out and finally, if I do need 32 channels, along with my D- snake ( which I can use with either mixer), I have them using the QU Pac.
Lastly, I like the fact I can still mix from the QU Pac if wifi goes down.
I was tempted to go for one of the other rack options but paid little more and got much more benefit for my purposes. The SB wasn't out then but I still like having a screen on the QU Pac.

After reading your reply, it reinforced my thoughts in to considering the QU-Pac more than the xRack. It makes way better sense to go that route being that I'm already familiar with the QU-16. I love my QU-16.

Unfortunately these damn things called bills keep getting in the way..... :(
Title: Re: Amplifier questions.....
Post by: Steve Ferreira on May 12, 2017, 09:59:31 am
If the OP will be using the limiters and processing in the amp then just get the "bigger" amp. Better to have the extra power and not use it.