Critique my (somewhat mid-sized) set-up please

[AJ Ta Misery]

I'm new to the boards (somewhat new to running sound as well) and I just wanted to get some opinions/feedback/advice on my sound set up.

 

I mainly run sound for hardcore, punk, and metal bands with the occassional hip hop and acoustic acts. Most of my venues are community center type buildings with little to no carpeting ... usually somewhere between 200-450 capacity. I mic the drums and vocals. Sometimes if a band has really weak guitar set ups, I'll mic their cabs and run them through the system. More often than not, the bands have Triple Recs/5150s and I don't need to worry about putting them through. I get keyboards/samplers/bass boosts from time-to-time as well. Anyhow, here's what I run...

 

SoundTech1604 mixer --->

Behringer Super X Crossover --->

QSC USA 900 (bridged mono STAGE LEFT) ---> Peavey SP2XT full range speaker (600 watts at 8 ohms) daisy chained into Ross full range 15" woofer speakers (300 watts)

QSC USA 900 (bridged mono STAGE RIGHT) ---> Peavey SP2XT full range speaker (600 watts at 8 ohms) daisy chained into Ross full range 15" woofer speakers (300 watts)

Crown 1200 (bridged mono STAGE LEFT) ---> Yamaha SW215 Club Sub Dual 15" subwoofer (400 watts at 4 ohms)

Crown 1200 (bridged mono STAGE RIGHT) ---> Yamaha SW215 Club Sub Dual 15" subwoofer (400 watts at 4 ohms)

 

I also run the Monitor Outs from the mixer into a QSC USA 900 and run a set of two Yamaha Club Series IV 10" Monitors. I'm about to purchase another set of 15" monitors. I will daisy chain the two Yamahas together with one of the 15"s I'm about to purchase for across the front (making 3 across the front) while taking the 4th monitor (the other 15" I'm about to purchase) as a drum monitor running as a separate channel.

 

Soon, I'll be purchasing another set of 18" subs and potentially daisy chaining them off of the other subs. Will this cause a problem with phasing? Also, would I be better off daisy chaining the two Yamaha Sub Club dual 15"s together one one power amp and then daisy chaining the two 18"s I'm about to purchase (in bridged mono, of course) on the other Crown 1200?

 

Also ... my mixer clips at really low levels for the mics. I'm pretty sure I have more than enough power and there's no way I should be clipping. The power amps never even come close to clipping while the mixer will clip at a very low level. Keyboards, CD players ... all of that stuff I can bump through the system very loud. Would a compressor somehow help with the volume of the vocals? Maybe I need a new mixer? If so, what would someone suggest (16 mic preamps is more than enough for me).

[Square]

If I read your post right, it sounds like you are mixing your mid high cabinets. I would recommend against that. Pick one type of mid high box and get more of that type of box if you need more sound. Different cabinets sound different and you will not be able to properly EQ a rig with mixed boxes. If you do need multiple mid high cabinets, you will need to research and buy a box that is designed to be used in multiples.

 

For the reasons stated above, I would recommend against buying 18's to go with your 15" subs. Either buy more 15's or sell the 15's and buy 18's. Also a dual driver box is typically wired in parrallel so it will present a 4 ohm load. You cannot daisy chain multiple 4 ohm boxes off of your amp in bridge mode. In fact, there are only a few amps in the world that will properly handle a 2 ohm bridged load (1 ohm per channel) and they are very old, very expensive and very, very heavy. The current way to handle multiple 4 ohm subs per side is to either get a big amp that can handle 2 subs per channel, or to get a bunch of identical small amps and bridge one on each sub.

 

As for your board clipping, what is clipping, the channel inputs, or the sub/master outputs? If it is the inputs clipping, then yes a compressor will help. You can:

- insert the comp on the vocal channels (1 comp per vocal)

- drop the input gain below the point of clipping on the screams

- use the comp to control the dynamics

- use the output gain on the comp to give you a decent minimum level

[Craig Vecchione]

You've got problems, present and future:

 

Present - You're running two USA900's mono-bridged into 4 -ohm loads. This amp is not recommended to be run bridged into lower than 8-ohms.

 

Future - Your subs are presently 4-ohms. You plan to add another pair, each possibly 4-ohms. As square wrote, each paired sub will be a 2-ohm load...way below what you should be running bridged even on a Crown (I'm assuming Micro-Tech?) 1200.

 

The same advice Square gave regarding mixing the mid-highs will apply to any future subs as well. It's generally not advised to mix and match. Could sound okay, could sound bad. Note that this means identical cabinets, not just matching driver sizes.

[AJ Ta Misery]

Alright ... note taken on matching the enclosures.

 

Question about suggesting that I don't bridge underneath 8 ohm loads. I believe you with no problem ... but I've read through the USA900 manuals front to back and I didn't see this anywhere in the writings. Basically, what I'm getting at is ... how do they expect me to know these things without telling me and is there a way to find out these things if its not included in the manual?

 

Could I run them daisy chained as stereo?

 

This thread is going well so far ...

[AJ Ta Misery]

And about the mixer ... for example: I'll have a keyboard running super loud and everything is going fine ... and then a vocalist will come into the mix and it will be clipping on the master output even though he is singing at a significantly lower level.

 

I've read through the Setting Level Controls primer from the Rane website and go through the process before every show. Let me know what I could potentially be doing wrong.

[AJ Ta Misery]

One more thing to keep in mind ... if my budget was higher (just like everyone else) ... I know what I'd get ideally. However, I'm pretty much limited to good deals that pop up on Craigslist and whatever shows up in my local Music Go Round. Therefore, I can't be too too picky. I'm gigging around with this set up for $150 a night ... and until I get out of the hole from piecing this together, the budget is even more limited than usual.

[Dookietwo]

Put the sp2's on one side of the stage and the ross's on the other. It may not look right but may sound better.

Dookietwo

[Dark Ice]

Question about suggesting that I don't bridge underneath 8 ohm loads. I believe you with no problem ... but I've read through the USA900 manuals front to back and I didn't see this anywhere in the writings. Basically, what I'm getting at is ... how do they expect me to know these things without telling me and is there a way to find out these things if its not included in the manual?

Its worded ambiguously (in my opinion) but it does say...

"Output voltages as high as 110 volts rms are available between the USA 1310's bridged terminals. Fully insulated CLASS ONE wiring must be used to connect the amplifier to the load, and the load must be rated up to 1200 watts (8 ohms)."

Whats confusing however is that on the same page it has a diagram of a speaker hooked up in bridge-mono with the text 16?, 8?, 4? on top of it.

 

But if you look at the specification at the back of the manual it clearly has no rating given for a 4 ohm load in bridge-mono.

 

I suppose they just expect you to know that putting lower loads on amplifiers is going to 'stress' them more, and generally if a ratings not given its not designed for that load. The manual really is from a different era than todays instruction manuals though

 

Steve.

http://www.qscaudio.com/pdfs/usausr.pdf

[Square]

 

... but I've read through the USA900 manuals front to back and I didn't see this anywhere in the writings. Basically, what I'm getting at is ... how do they expect me to know these things without telling me and is there a way to find out these things if its not included in the manual? Could I run them daisy chained as stereo? This thread is going well so far ...

 

 

According to the manual for the USA series that QSC has on it's web site there should be a sticker on the back of the amp under the output connectors that tells you "4 ohms minimum per channel, 8 ohms minimum impedence in bridge mono mode" it is on page 7 here:

 

[url=]http://www.qscaudio.com/pdfs/usausr.pdf[/url]

 

As for running your tops 1 box per channel, you can do that, but you will see fewer watts per box. You would need to put the amp into parallel mode with the dip switches, or use a "Y" cable to get the signal to both channel inputs.

 

As for why your board clips it's master outputs when the singer starts singing at a lower volume than the keyboard, your master Left/Right buss has a finite amout of headroom, if the keyboard is just under that and you add tha additional signal strength of the singer, it is possible to clip the master output even though the input is not clipping.

 

The bigger question I have for you is: What are your amps doing when the board clips? If your amps are not clipping when your board clips, then I think you would do well to setup your rig in your shop and work on the overall gain structure so that you can get the most out of your rig before your board clips.

[agedhorse]

Do not bridge the USA into 4 ohms... definately not rated for it.

 

The MA-1200 bridged into the Yamaha subs is an waful lot of power unless you are VERY careful.

[Craig Vecchione]

Alright ... note taken on matching the enclosures. Question about suggesting that I don't bridge underneath 8 ohm loads. I believe you with no problem ... but I've read through the USA900 manuals front to back and I didn't see this anywhere in the writings. Basically, what I'm getting at is ... how do they expect me to know these things without telling me and is there a way to find out these things if its not included in the manual? Could I run them daisy chained as stereo? This thread is going well so far ...

 

The specifications show the usable impedances. 8 and 16ohms. It is generally understood that you don't go lower than what's shown in the specs. A certain basic minimum knowledge has to be assumed when writing a user manual. It's possible to try to make them fool-proof....but someone always seems to come out with a better fool......

[AJ Ta Misery]

 

The MA-1200 bridged into the Yamaha subs is an waful lot of power unless you are VERY careful.

 

 

See, I was always under the impression that the problem was with UNDER powering the speakers ... not OVER powering them. However, I've been reading through a lot of online material and it seems to be a problem with both methods. Is it correct to say that it's proper to have approximately double the power in watts as you do speakers ... but not to go with more than double the watts?

[Square]

Yeah, 2X the speakers RMS rating is a good rule of thumb for power amp size.

 

As for a small amp hurting a speaker, it is true...BUT, it only applies when you are trying to get more sound out of the amp then it can produce...AND you do not have any limiters in place to prevent clipping...AND the signal becomes clipped at the amplifier stage with full amplification...AND said clipping creates extreme frequencies that would not be part of a normal signal (this is typical with clipped signals by the way)....THUS those clipped signals are sent to the drivers at full power from the small amp...THUS causing the driver motors to attempt movement beyond their design limits, and thus causing damage.

 

If you use a smaller amp, and never ask for more sound than the amp can produce, then you will not hurt the speaker, you will just be in a situation where the speaker could produce more sound with a bigger amp without damaging itself.

 

If you use a 1,000 watt amp on a 20 watt tweeter, you endanger the tweeter because the amp is big enough to induce enough electricity into the coil that the reaction with the magnet will cause the coil to exceed the excursion limits of that particular driver (makes the little cone move farther than it is designed to and damages it)

[AJ Ta Misery]

OK then ... give me a suggestion on this then ...

 

I have two QSC USA900s.

I have two Peavey SP2XTs at 600 watts a piece at 8 ohms

I have two Ross full range 15" enclosures at 300 watts a piece at 8 ohms

I have two Yamaha Club Series IV 10" Monitors at 200 watts a piece at 8 ohms

 

Alright ... so what do you think the best way to handle all of this would be? The only thing I'm thinking is to run the power amps in Bridged Mono and just run one of the Peavey's off of each power amp. That would be supplying 900 watts to a 600 watt speaker. However, this leaves me without any power amps for my Ross' ... and I'd like to maybe configure the monitors in there somehow.

 

I could also run the power amps in Stereo. Giving one power amp to the Peaveys exclusively and giving the other power amp to the Ross' & Yamahas daisy chained together.

 

I don't really understand parallel mode ... would this somehow benefit me or get me more power to these speakers? I mean, I know how to turn parallel mode on ... but that's about the extent of it.

[AJ Ta Misery]

Thanks for the clarification on power. I'm just paranoid about blowing {censored} because I actually blew those Peavey SP2XTs by only giving them a 400 W (2 x 200) power amp and miking drums. This was before I understood crossovers and subs. Live and learn.

[Craig Vecchione]

 

See, I was always under the impression that the problem was with UNDER powering the speakers ... not OVER powering them. However, I've been reading through a lot of online material and it seems to be a problem with both methods. Is it correct to say that it's proper to have approximately double the power in watts as you do speakers ... but not to go with more than double the watts?

 

 

 

Putting less power than a speaker can handle will never damage it.

 

 

Is the Crown an Xs1200, Micro-Tech 1200 or Macro-Tech 1200?

[Craig Vecchione]

 

I don't really understand parallel mode ... would this somehow benefit me or get me more power to these speakers? I mean, I know how to turn parallel mode on ... but that's about the extent of it.

 

 

Parallel mode usually means that as in bridged mode, one input is used to feed both amps, but the amplifier's outputs remain discrete...no connection. In bridged mode the two amps are actually connected at the outputs...+ of one to the - of the other

[Not Serial]

whoa craig. i have several amps that are + + in bridged mode. i have NONE that are + -

[AJ Ta Misery]

Macro Tech.

 

So parallel mode is for linking amps together? Would this be of any benefit to get maximum wattage from my arrangement of speakers I have listed above?

[Unalaska]

Your at a wierd crossroads right now with the gear. The next step will take more money than you may want to spend but it's needed.

 

Speakers: Gotta stop the mix & match, not good for sound at all. Yes it's loud but no it doesn't sound good. If it were me I'd run just the SP2x and get a second pair on a tight budget.

 

Amps can still be the USA's even bridged @4 ohms. The USA's aren't very efficient and your chance of blowing something up go skyhigh when bridging this amp @ 4 and you may be shortening the life of said amps but it can be done. The best option:

 

Amps that put out in the 900-1200w (4ohm) PER Channel for mains and subs. USA's can be used in stereo mode for monitor mixes and are a great size for that. For subs, get the yamaha dual 18 or any dual 18 and sell the dual 15's.

 

Mixer: I will get some flack for this but pick up a used mackie 244, they are a real workhorse and despite what many say they are quite reliable. Kinda falls in the PV catagory where people do stupid things to the mackies and wonder why they break. Anyway they can be had cheap and offer 4 monitor mixes if needed.

 

Also I didn't see any EQ's listed, 31 band EQ before EVERY monitor and main amp channel (one 31 for L/R each, 1 31 for each monitor mix).

 

good luck

[Square]

 

So parallel mode is for linking amps together? Would this be of any benefit to get maximum wattage from my arrangement of speakers I have listed above?

 

 

Parallel mode will not let you increse wattage in your situation.

 

The purpose of parallel mode is to give both channels of the amp the same signal without having to use a "Y" cable to feed both inputs.

 

A scenario where this is handy would be something like this:

 

- you have 4 double driver subs per side

- you have 1 amp to drive all 4 boxes, something larger, say a QSC 6.0

- The 6.0 is 2 ohm stable and produces 3,000 watts at 2ohms per channel

- You can chain 2 subs together and hook them to one channel of the 6.0 giving you 3,000 watts total or 1,500 watts per box.

- since you have 4 subs per side you need both channels of the amp to amplify the exact same signal (both channels are amplifing "left side subs").

- This is where parallel mode comes in handy

 

It is also useful if you need to hook a bunch of monitors together on one monitor mix (say for 4 backup singers).

[agedhorse]

Be VERY careful with Crown and parallel mono mode. This mode is different and uses different output connections than stereo OR bridge mono mode. ALWAYS, read the manufal and be sure you understand exactly what it means before using in these modes. Crown is the exception to the rule concerning parallel mono on many (but not all) models.

[AJ Ta Misery]

Yeah, I'm definitely a manual stifler. I read the section on parallel mono for the Crown amps. But thanks for the example on Parallel Mono ... I understand it now except for this ... is it possible to link the power amps together in parallel mono mode? Is that what the free'd up extra input is for?

 

And yes, I'd like to just get another set of Peavey SP2XTs ... but they don't pop up too often locally ... even on EBay. I've never had a problem with Mackie ... my first PA set up was a Mackie 406M powered mixer with a set of Yamaha 15s ... worked great for what I needed for 4 years with no problems ever.

[tlbonehead]

Sure is a lot of power to try and put through those subs. No wonder you have more than one "I blew 'em up" posting.

[Square]

 

Be VERY careful with Crown and parallel mono mode. This mode is different and uses different output connections than stereo OR bridge mono mode. ALWAYS, read the manufal and be sure you understand exactly what it means before using in these modes. Crown is the exception to the rule concerning parallel mono on many (but not all) models.

 

 

Thanks for posting this Agedhorse!

 

You are absolutely correct. I forgot about Crown's version of parallel mode and the OP's Macro Tech's definitely do not operate in parallel mode as I had illistruated above.

 

Thanks again!