ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 ... 6   Go Down

Author Topic: Amplifier questions.....  (Read 10460 times)

Jesse Gregorio

  • Newbie
  • *
  • Offline Offline
  • Posts: 34
Amplifier questions.....
« 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.
Logged

Tim McCulloch

  • SR Forums
  • Hero Member
  • *
  • Offline Offline
  • Posts: 21873
  • Wichita, Kansas USA
Re: Amplifier questions.....
« Reply #1 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.
Logged
"Practicing an art, no matter how well or badly, is a way to make your soul grow, for heaven's sake. Sing in the shower. Dance to the radio. Tell stories. Write a poem to a friend, even a lousy poem. Do it as well as you possible can. You will get an enormous reward. You will have created something."  - Kurt Vonnegut

Jesse Gregorio

  • Newbie
  • *
  • Offline Offline
  • Posts: 34
Re: Amplifier questions.....
« Reply #2 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.
Logged

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6236
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Amplifier questions.....
« Reply #3 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.

Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Jesse Gregorio

  • Newbie
  • *
  • Offline Offline
  • Posts: 34
Re: Amplifier questions.....
« Reply #4 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.
Logged

Scott Holtzman

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6236
  • Ghost AV - Avon Lake, OH
    • Ghost Audio Visual Systems, LLC
Re: Amplifier questions.....
« Reply #5 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. 



Logged
Scott AKA "Skyking" Holtzman

Ghost Audio Visual Solutions, LLC
Cleveland OH
www.ghostav.rocks

Jesse Gregorio

  • Newbie
  • *
  • Offline Offline
  • Posts: 34
Re: Amplifier questions.....
« Reply #6 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.

« Last Edit: May 10, 2017, 05:42:15 am by Jesse Gregorio »
Logged

Jean-Pierre Coetzee

  • Classic LAB
  • Hero Member
  • *
  • Offline Offline
  • Posts: 862
  • Gauteng, South Africa
Re: Amplifier questions.....
« Reply #7 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.
Logged
Audio Technician
Word & Life Church

"If you want "loud", then run a piece of sheet metal through a table saw------

If you want "watts"-then plug in a toaster"
- Ivan Beaver

Debbie Dunkley

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 5479
  • Central North Carolina
Re: Amplifier questions.....
« Reply #8 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.

Logged
A young child says to his mother, "Mom, when I grow up I'm going to be a musician." She replies, "Well honey, you know you can't do both."

Steve Ferreira

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 376
Re: Amplifier questions.....
« Reply #9 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.
Logged

ProSoundWeb Community

Re: Amplifier questions.....
« Reply #9 on: May 10, 2017, 12:29:41 pm »


Pages: [1] 2 3 ... 6   Go Up
 



Page created in 0.13 seconds with 23 queries.