Purchasing new amps. Need tips

[MMirabent]

Hello all,

So first, a little back story. About five years ago, the highschool that I (then) attended received a large donation which was put towards a new sound system for our cafetorium. Five years later, our subwoofer amplifier is borked and our high-range amplifier is half-borked. I now work for my old high-school and am pricing some replacement amps. Obviously, I do not want to replace them with the same brand (Staner) as I cannot find any datasheets or manuals for these amps. The Staner website is entirely in Portugese, they used to have a US website which is now down. The sound consultant we called in actually had to call Brazil and find an engineer at Staner that spoke english.

So, what I need are suggestions for some hardy amps. I will be getting into a lift to look at the speakers and determine what they're rated for, but for now can anyone suggest some brands and product lines of power amps that would work well in a dusty environment?

Thanks in advance,
Marcos

 

[Les]

QSC or Crown would be the top two on my list.

Why is the environment so dusty? Can they be relocated? Any amp out there is going to need cleaning periodically; more often in a dirty environment. I wouldn't expect any amp to hang on long if it's constantly sucking in dirt.

 

[MMirabent]

Right, the problem is these amplifiers are in a road case in one of the dressing rooms backstage. These dressing rooms don't get cleaned unless its by the drama club. So they never get cleaned. Also, the crew that cleans the cafetorium floor uses electric leaf blowers to "sweep" the floor, so all of the dust and food scraps, old french fries, etc. are blown in the air and towards the stage. I've found this crap accumulated on top of our ceiling mounted projector. that's about 25 feet up. Relocation would be nice but unless I do it for free, it ain't happening. This is a small South Florida private school with no "theatre" budget to speak of. This purchase will have to be some sort of special exception.

I'm actually thinking of making a front cover for the road case that would force air through a filter so at least the amps would be breathing filtered air and maybe they'll last a bit longer.

 

[chausman]

Probably the best thing to do is make sure that someone in charge knows they need to be cleaned, or their nice new equipment won't make it long, and their going to have to have another "special exception".

 

[bishopthomas]

Can you give us more info? What are the speakers? What are the specs on the amps you're running now?

 

[bishopthomas]

I'm actually thinking of making a front cover for the road case that would force air through a filter so at least the amps would be breathing filtered air and maybe they'll last a bit longer.

Most amps from the major manufacturers have filters built in. Of course, someone will need to change these periodically...

 

[MMirabent]

Which is kinda weird because no one wants to take ownership of the space except the drama teacher who is currently on maternity leave :/ meanwhile everyone wants to use(read: abuse) the space but no one wants to pay up when it breaks except the people who need it most. But that's school politics, and I digress. This thread is about amplifiers.

</political tangent>

 

[museav]

Right, the problem is these amplifiers are in a road case in one of the dressing rooms backstage. These dressing rooms don't get cleaned unless its by the drama club. So they never get cleaned. Also, the crew that cleans the cafetorium floor uses electric leaf blowers to "sweep" the floor, so all of the dust and food scraps, old french fries, etc. are blown in the air and towards the stage. I've found this crap accumulated on top of our ceiling mounted projector. that's about 25 feet up. Relocation would be nice but unless I do it for free, it ain't happening. This is a small South Florida private school with no "theatre" budget to speak of. This purchase will have to be some sort of special exception.

I'm actually thinking of making a front cover for the road case that would force air through a filter so at least the amps would be breathing filtered air and maybe they'll last a bit longer.

Are the amps mounted in a road case or in a rack?

I'd be sure to check the airflow before doing anything, not all amps flow front to back, for example many QSC amps have the air intake on the rear and exhaust out the front. Mixing amps with front-to-rear and rear-to-front airflow near each other in the same rack is a good way to burn up the amps as they start circulating the air between them with the air then getting hotter and hotter.

It would really help to know the current amp models, the speaker models, anything you can share regarding how the system is wired, any information on any existing speaker processing, etc. It also sounds like a good time to document the system so nobody has to go through the same thing the next time there's a problem.

 

[MMirabent]

Are the amps mounted in a road case or in a rack?

I'd be sure to check the airflow before doing anything, not all amps flow front to back, for example many QSC amps have the air intake on the rear and exhaust out the front. Mixing amps with front-to-rear and rear-to-front airflow near each other in the same rack is a good way to burn up the amps as they start circulating the air between them with the air then getting hotter and hotter.

It would really help to know the current amp models, the speaker models, anything you can share regarding how the system is wired, any information on any existing speaker processing, etc. It also sounds like a good time to document the system so nobody has to go through the same thing the next time there's a problem.

So we've got a dbx DriveRack processor feeding into a Staner 1k2 amp for the highs (half-borked) a Staner 1k6 for the mids (not borked yet) and a Staner 5000 for the lows (fully borked) The amps are all rack mounted in a road case.

The 5000 was originally only using one channel for the subs with a spare channel, but the highs were moved to that spare when the 1k2 amp (half)died. Then the 5000 amp died.

The loudspeakers are Staner, that's all I know. I haven't been in a lift to actually inspect the speakers and get power ratings and possibly a model number, but I plan to soon.

I actually have a manual I was writing for the system. It's about half-finished. But what I can surmise is that there are two cables with 4 wires each that run to the speakers. One cable for left, one for right. each cable has a pair for highs and a pair for lows. There's a 20 input, 4 output snake head in the receiver rack. From that, we get left+right out from the mixer, a monitor feed and a DMX-512 feed. The left and right feed the DriveRack and and monitor feed goes to powered speakers over the stage. the DMX goes to some dimmer boxes with Altman 6x9's and Fresnel's for front light and crappy Chauvet LED fixtures for top light. These like to die, a lot, but that's for another thread.

The speakers themselves are fitted with Neutrik Speakon connectors. I'm guessing that 1+ and 1- are the highs and 2+ and 2- are the mids but I cant say for sure because the cables on the amp side are bare-ends and not labeled.
The amps are in a road case on wheels that has front and back covers. The back covers can't be put on because of the power, snake and speaker cables running from the back of that rack. The front covers don't get put on unless I'm there(>.<) and power comes from three independent circuits

On a side note, the amps all have their air intakes on the front.

 

[gafftaper]

Wait the DMX runs through the same snake as the audio? That's seriously messed up and likely the cause of your issues with the lights.

Sounds like you need to throw out your amps and speakers and get all knew gear. Odds are good that putting in some quality QSC/Crown amps will just blow the crappy speakers.

You could replace your speakers and amps with a set of Electro Voice ZXA5's (self powered) and skip the amps for them. They'll cost you around $1700 each but it's an amazing speaker and amp all in one. Heck you could add a powered sub too and never have to worry about the amps getting dusty because they are mounted in the speakers.

 

[MMirabent]

Wait the DMX runs through the same snake as the audio? That's seriously messed up and likely the cause of your issues with the lights.

Sounds like you need to throw out your amps and speakers and get all knew gear. Odds are good that putting in some quality QSC/Crown amps will just blow the crappy speakers.

You could replace your speakers and amps with a set of Electro Voice ZXA5's (self powered) and skip the amps for them. They'll cost you around $1700 each but it's an amazing speaker and amp all in one. Heck you could add a powered sub too and never have to worry about the amps getting dusty because they are mounted in the speakers.

Yeah, your telling me. We get constant flickering when the lights are all set to "off" on our "light board" but scrapping the current rig is, unfortunately out of my budget(haha, whats a budget??????) And if the subject of replacing the system ever comes up, I'll probably go with some powered speakers and eliminate the amp rack entirely. But alas, we dont have the money for a complete overhaul.

 

[MMirabent]

It would really help to know the current amp models

Forgot to mention. From what I can infer. The amps are rated for 1200 watts(1k2), 1600 watts(1k6) and 5000 watts. There is no information on the back of the amps of the power output, just power input requirements. The figures quoted above are from a reseller in Miami and there is no more information than the above. I'm assuming these are overall power output figures. Also, the sub was connected to one channel of the 5k amp. Not bridged, just using half of the amp. Just clarifying here. And again, thanks for your responses.

 

[venuetech]

Is "borked" a Portuguese word? Is the rack on the floor? if so can it be elevated some how so the low dust is not sucked in to the amps. With the rack raised you will get a higher grade of dust. i will echo QSC or Crown.
perhaps you could convince the cleaning staff that it would be best to use a hose to clean the floor. Or a broom or dust mop can be very effective.

 

[museav]

Okay, I found some specs for the amps:

1k2 - I found one source claiming 726W into 8 Ohms and 1210W into 4 Ohms but another source with more complete specifications says 220W per channel into 8 Ohms. Apparently rated down to 2 Ohm loads.

1k6 - The only source I found says 288W per channel into 8 Ohms. Apparently rated down to 2 Ohm loads.

SR5000 - One source saying 1,200W per channel into 8 Ohms and 2,000W per channel into 4 Ohms.

I noted one detail that may have something to do with your problem. The 1k2 and 1k6 amps will run on 110/120VAC but were apparently designed for 220VAC operation, thus they potentially have high current draws with 110VAC operation, as in 15A for the 1k2 and 20A for the 1k6. If they are driving 8 Ohm loads you may not get anywhere near those current draws but if you have something like all three amps on a single 15A or 20A circuit and you push them hard then that could be a problem.

You may also want to verify the mounting in the road case, whether the amps are run with one or both covers on and whether there is good airflow or if the amps end up getting no cool intake air or even sucking in their own hot exhaust.


I also looked at Staner's current speaker models and while they may not be what you have, I found only one model that could be bi-amped and it may point out why it would be important to know what you have as it is apparently rated at 1000W"RMS" and 4 Ohms for the low and 70-100W"RMS" into 8 Ohms for the high (the range for the HF depends on the crossover frequency used). They also have single 18" and dual 18" subs, both rated at 4 Ohms, 800W"RMS" for the single and 1600W"RMS" for the dual. So you may have a mix of 4 Ohm and 8 Ohm loads.

I see three possible approaches:

1. Puchase new amps to match the existing amps as closely as possible. That would probably require being more sure of the specifications for the current amps in order to determine what would be comparable.
2. Ignore the existing amps and select new amps that best match the speakers. This would require knowing more about the speakers and their ratings so that you have a good basis for any amplifier selection.
3. Dump the amps and speakers and start over with products for which you know the specifications and that you can assume will be better supported.

One thing to keep in mind is that if you get new amps they will most likely have a different sensitivity, gain, possibly connectivity, etc. than the existing amps. That would mean most likely having to verify the system gain structure and possibly retune the system. If things are close that may just be adjusting the amplifier attenuator settings but if there are significant differences it may also get into the DriveRack settings.


Not directly relevant but given your location and all the Staner products, I have to wonder if MAM - Miami Audio Music was involved since they seem to be about the only Staner dealers in the US.

 

[MMirabent]

Okay, I found some specs for the amps:

1k2 - I found one source claiming 726W into 8 Ohms and 1210W into 4 Ohms but another source with more complete specifications says 220W per channel into 8 Ohms. Apparently rated down to 2 Ohm loads.

1k6 - The only source I found says 288W per channel into 8 Ohms. Apparently rated down to 2 Ohm loads.

SR5000 - One source saying 1,200W per channel into 8 Ohms and 2,000W per channel into 4 Ohms.

I noted one detail that may have something to do with your problem. The 1k2 and 1k6 amps will run on 110/120VAC but were apparently designed for 220VAC operation, thus they potentially have high current draws with 110VAC operation, as in 15A for the 1k2 and 20A for the 1k6. If they are driving 8 Ohm loads you may not get anywhere near those current draws but if you have something like all three amps on a single 15A or 20A circuit and you push them hard then that could be a problem.

You may also want to verify the mounting in the road case, whether the amps are run with one or both covers on and whether there is good airflow or if the amps end up getting no cool intake air or even sucking in their own hot exhaust.

I also looked at Staner's current speaker models and while they may not be what you have, I found only one model that could be bi-amped and it may point out why it would be important to know what you have as it is apparently rated at 1000W"RMS" and 4 Ohms for the low and 70-100W"RMS" into 8 Ohms for the high (the range for the HF depends on the crossover frequency used). They also have single 18" and dual 18" subs, both rated at 4 Ohms, 800W"RMS" for the single and 1600W"RMS" for the dual. So you may have a mix of 4 Ohm and 8 Ohm loads.

I see three possible approaches:

[*]Puchase new amps to match the existing amps as closely as possible. That would probably require being more sure of the specifications for the current amps in order to determine what would be comparable.
[*]Ignore the existing amps and select new amps that best match the speakers. This would require knowing more about the speakers and their ratings so that you have a good basis for any amplifier selection.
[*]Dump the amps and speakers and start over with products for which you know the specifications and that you can assume will be better supported.


One thing to keep in mind is that if you get new amps they will most likely have a different sensitivity, gain, possibly connectivity, etc. than the existing amps. That would mean most likely having to verify the system gain structure and possibly retune the system. If things are close that may just be adjusting the amplifier attenuator settings but if there are significant differences it may also get into the DriveRack settings.

Not directly relevant but given your location and all the Staner products, I have to wonder if MAM - Miami Audio Music was involved since they seem to be about the only Staner dealers in the US.

Wow. Thanks a million. I'm pretty sure MAM was the distributor used as I found their website earlier and was quoting specs from them. I will probably go with new amps to suit the speakers and retune the DriveRack. Once I get up close and personal with the speakers that is. Thanks for all your help everyone.

P. S. For those wondering, borked isn't Portuguese as far as I know. Just a minced oath to keep me from saying some other choice words about these amps.

 

[pmolsonmus]

File in the FWIW dept. It would be good to know your room size and specs, but given what you're describing I'd definitely consider a new set up using powered speakers and second the notion of trying to separate the DMX from the audio snake.
I'll put in a plug for QSC's line. We just put K12s in a black box (1000 watts ea) and they rock! Can be safely flown and are <$800 each school price.
By the time you pay for quality amps for your current speakers (which BTW may be blown themselves - I'd definitely check, when amps are stressed, speaker cones go too) you're going to spend lots more.

Powered speakers get your amps out of the area, but there are still connections and "stuff" flying around them. Try to address this as well.

A DMX splitter and hundreds of feet of cable could be had for less than $500 and prevent some of the "if it fits that cable is ok to go here" situation in a school.

Good Luck

Phil

 

[museav]

I'll put in a plug for QSC's line. We just put K12s in a black box (1000 watts ea) and they rock! Can be safely flown and are <$800 each school price.
By the time you pay for quality amps for your current speakers (which BTW may be blown themselves - I'd definitely check, when amps are stressed, speaker cones go too) you're going to spend lots more.

Powered speakers get your amps out of the area, but there are still connections and "stuff" flying around them. Try to address this as well.

Powered speakers may be a very good option in some applications, however they are not necessarily 'plug and play' replacements for an existing unpowered speaker system, especially a flown system, and there are aspects that may have to be considered in deciding if they make sense or not. Powered speakers take getting power to the speakers, which for an installed system that was not designed for powered speakers may mean having to move existing power or run new power to the speaker locations. Powered speakers can also be heavier than their unpowered equivalents, which for flown speakers can mean verifying that the greater load can be supported. I have encountered situations where replacing an unpowered speaker system with powered speakers was structurally and/or financially impractical.

Similar regarding the K12, a nice speaker if, as for any speaker, the output, pattern, response, etc. are all appropriate for the application.

 

[pmolsonmus]

No disagreement with what Brad said (I can't think of a time when I disagreed with his advice).
My point (and Gafftaper's too) is to consider getting the amps out of the area (if possible) all of Brad's suggestion are questions to consider to check feasibility and appropriateness of the purchase.
Especially because it's in a cafetorium you may want to approach a student/class council for additional funds/ fundraising. My guess would be that LOTS of groups use the space and the sound system.

Best of luck

Phil

 

[MMirabent]

No disagreement with what Brad said (I can't think of a time when I disagreed with his advice).
My point (and Gafftaper's too) is to consider getting the amps out of the area (if possible) all of Brad's suggestion are questions to consider to check feasibility and appropriateness of the purchase.
Especially because it's in a cafetorium you may want to approach a student/class council for additional funds/ fundraising. My guess would be that LOTS of groups use the space and the sound system.

Best of luck

Phil

Thanks Phil, I will definitely look into moving the amps. Even if it means putting the roadcase on a table or shelf a few feet off the ground and away from the dirty floors.

EDIT: and yes. everyone and their mother uses this space but the Drama club traditionally ends up taking care of repairs. And because no one wants this added to their budget they're all reluctant to talk about it. Hopefully, we can convince the management that this is a space worth investing a little time and money into to make it right. This is a rather politically charged topic for the school.