matching speakers to amps

[Themetallikid]

K, i hope this will be the final question before we decide to buy our PA system.

 

How do I go about comparing speakers and being able to match them with the amps. I have read some general guidelines for choosing the amps and speaker combinations but dont really remember them. Can someone explain this??

[flanc]

Since this is a relatively new area for you, you'd be well advised to pick your speakers and then check back here for advice on how much juice and which specific amp to use.

 

To answer your question, a good rule of thumb would be to apply 1 X to 1.5X the rms rating of the speaker. The novice user should use 1x....the more advanced user (with limiters in place) can apply 1.5x (and beyond) rms speaker ratings.

[Themetallikid]

the speakers I am looking at are

JBL MP225 - they have a continuous power rating of 500w, and a peak of 2000

 

the subs are JBL MP255S, I cannot find the ratings for the subs on MF.com

 

The amp for the mains we are looking at is a Mackie M2600...

[tlbonehead]

Originally posted by Themetallikid the speakers I am looking at are JBL MP225 - they have a continuous power rating of 500w, and a peak of 2000 the subs are JBL MP255S, I cannot find the ratings for the subs on MF.com The amp for the mains we are looking at is a Mackie M2600...

Read the last couple replies in the TRX thread. I wouldn't run over 500-600 watts through them.

[GCDEF]

I'm not as knowledgable as some here, but the amp looks okay for those speakers to me. Seems to me 4x15 with one horn per side, isn't going to give the best sound you could get for the money though.

[Themetallikid]

how do you figure 4 x 15. What speakers would you recommend for around $600 each? using the amp I mentioned the Mackie M2600

[GCDEF]

 

Originally posted by Themetallikid how do you figure 4 x 15. What speakers would you recommend for around $600 each? using the amp I mentioned the Mackie M2600

 

 

2 x 15 in each main, and 2 x 15 in each sub. I'm going to leave specific recommendations to those with more knowledge. Personally, I prefer 3 ways to 2 x 15.

[tlbonehead]

Originally posted by GCDEF I'm not as knowledgable as some here, but the amp looks okay for those speakers to me. Seems to me 4x15 with one horn per side, isn't going to give the best sound you could get for the money though.

415 is just the model. They are the high end MP single 15" 2-way cab. I believe they also have a 215 or something with lighter drivers.

[GCDEF]

Originally posted by tlbonehead 415 is just the model. They are the high end MP single 15" 2-way cab. I believe they also have a 215 or something with lighter drivers.

 

The model numbers he posted are for 2 x 15 mains and 2 x 15 subs.

 

http://www.zzounds.com/item--JBLMP225

 

http://www.americanmusical.com/item--i-JBL-MP255S--brand-133.html

 

Look at the frequency response on the mains.

 

Frequency Response: 42 Hz - 11 kHz (+/-3 dB)

[tlbonehead]

Originally posted by GCDEF The model numbers he posted are for 2 x 15 mains and 2 x 15 subs. http://www.zzounds.com/item--JBLMP225 http://www.americanmusical.com/item--i-JBL-MP255S--brand-133.html Look at the frequency response on the mains. Frequency Response: 42 Hz - 11 kHz (+/-3 dB)

Oops,don't know where I got that he was referring to the MP415. Yes,I'm sure everyone here will agree that it would be a very poor choice for a setup. I'd get the subs with their higher end single woofer cab instead. The MP415 that I actually was eluding to.

[dboomer]

 

Originally posted by Themetallikid t The amp for the mains we are looking at is a Mackie M2600...

 

 

Nothing wrong with the amp but DO be aware that it needs to plug into a 20 AMP SERVICE all by itself. Now you need a distro if you are running ANYTHING else.

 

You'd have a much better sounding system if you bought two smaller amps eg QSC RMX 1850s and bi-ampped your system

[Themetallikid]

 

Nothing wrong with the amp but DO be aware that it needs to plug into a 20 AMP SERVICE all by itself. Now you need a distro if you are running ANYTHING else.

 

 

 

You'd have a much better sounding system if you bought two smaller amps eg QSC RMX 1850s and bi-ampped your system

 

 

My last band used this setup. We used the Mackie M2600 to power the Foh speakers and subs, and then an OSC 1450 to pwoer the monitors. we would plug that into its own circuit and run the guitar/bass amps off a different circuit along with the smaller light setup we had. we never really blew any fuses.

 

How would running the two 1850's be better than the single 2600? Is it because the power is being used solely for the tops/bottoms? are the 1850's a single channel amp? We have a budget of $5000 and its a good deal to get the M2600 for 500, and the OSC1450 for 260.

 

 

I'd get the subs with their higher end single woofer cab instead. The MP415 that I actually was eluding to.

 

 

what makes it such a bad match? as opposed to the single woofer cabs your talking about?

[dboomer]

1> 2600 is too much power for the speakers you plan to use.

 

2> Bi-amping the system will sound way better ... excuse me

WAY BETTER ond offer additional speaker protection. That way if (when) you clip something (usually the subs) the top boxes will remain clean.

 

3> I'd rethink the speaker combo you picked out. 2x15/horn top isn't the best match for a 2x15 sub. How about a better quality 12' and horn or 12/6/horn something?

 

4> someday you will have current issues trying to drive the Mackie ... count on it. You probably aren't getting the hearoom you've paid for in the amp if you can't feed it enough current. Not to mention safty and noise/hum problems.

 

5> having redunduncy with the amps may come in handy some day if something blows up.

 

If you're getting the 2600 for $500 I'm assuming it's used (or hot). I bought 4 QSC 1850s on Ebay for $350 each ... new (that was a deal!). I guess there's not a bunch of used ones out there as they are a pretty new model. They will drive a 2 ohm load and have extra cooling capacity. They're the real bargin in that whole rMX line ... which are all a bargin in my book.

[Themetallikid]

I'm not set on getting the Mackie, just trying to understand why other options are better. I understand the bi-amp route. Seems to make more sense as well.

 

so your suggesting a pair of single 15" with a horn? or single 12" with a horn? Are the subs good enough? or something better? Our budget for speakers is probably $700 max per speaker.

[Kennykeys]

Hello MetalKid,

Read carefully: everybody is recomending that you do NOT buy the 2x15/horn mid-high cabinets. If you're getting subs, ( and that 2x15" sub is fine), then a QUALITY 12"/1" horn (or a quality 15"/horn) mid-high cab would be good.

[Craig Vecchione]

I'll second the MP412/MP415 recommendation. I'd go with the 412 unless you envision using the tops alone for some gigs. Put the money saved into a crossover.

 

For subs you might also consider the MP418. It uses the same 2241G 4-ohm driver as used in JBL's SR4718X cabinet, and you might find the size and shape of it's cabinet is more manageable. Price is about $650.

 

For power, I'd seriously consider the smaller, lighter, less power-hungry QSC PLX2402 ($900) over the Mackie. I've got a 1-year-old rehearsal-only RMX-2450 I'll sell for $450, simply because I'd like to replace it with the lighter PLX.

 

You should also consider using a component crossover rather than the built-in x-over as in the Mackie. A lot more flexible. A dbx223 is $150.

[Themetallikid]

I think my original question was answered in an earlier post but am still kinda confused. For choosing amps and speakers.

 

Lets say I am using the Peavey RQ2318 mixing board.

 

How do I go about choosing speakers and amps to match the power rating. I do not want you to suggest speakers for me, nor amps, but tell me what to look for when comparing and trying to match them for the most efficient use of power and such. Internal x-overs as opposed to external. that kinda stuff. What does RMS vs Peak mean, which is more important.

[lucho_84]

well you should match the amp to a speaker's rms rating which in general is 1/2 of the continous rating. if you read my trx thread the answer of matching amps to speakers was mentioned. what kinda music are you playing? i didn't read thw whole thread but I thought I saw a few speaker models mentioned here and there. Also, the reason people here don't recomend the 2x15 mains is that for one, they're usually not very well bilt, 2, they're muddy and without proper knowledge which is only gained by experience you won't be able to tell how to get rid of it. Usually for me i cut " a little" around 200 for 2x15's but it depends on the cabs and the room. Yes an external crossover is way way better than an internal one built into your subs. Before these guys recomend some speakers, I suggest letting them know what they'll be used for. Venue size, genre, installed/portable?, etc. By the way...$700 a cab is bette trthan what I usually see here. i see alot f peple wanting the best monitor for $100. When they hear it they're disapointed. So $2,800 isn't bad for a FOH compared to thers. Hope this helps man:)

[Themetallikid]

well we are playing modern/hard rock covers, mostly in bars that range in capacity to 50-200 people. Like I said our budget is about $700 max per speaker. we have $5000 to spend total. Would like to be able to get some lights as well with that, just some par cans for now is all.

 

I guess we would like the system to be expandable in the sense that there are some festivals and out door opportunities, that if needed we could handle it. the outdoor festivals around here, if they are any decent size like an Octoberfest, they provide the sound, but for the smaller ones, we provide our own, which it would be able to handle. If need be we can purchase additional stuff later.

[Craig Vecchione]

For basic general comparisons:

 

RMS is also called 'continuous' power.

 

"program" is also called "music" power, and is usually approximately double the RMS rating.

 

"peak" is usually double "program" (ergo 4x RMS).

 

In general, RMS is the rating a device can produce or handle continuously, program is the amount it can handle for short-term (a few minutes or hours) and peak is what it can take in sub-second bursts. It's all pretty general and somewhat random as there's no one comprehensive standard to which manufacturers comply or test. When one adds the bull{censored} factor (as agedhorse points out in another thread, some drivers are rated double what they were 5 years ago, though construction hasn't changed at all), and the fact that most specs are incompete (RMS at what distortion level, in what frequency range? etc...) it can all be pretty meaningless.

 

A decent rule of thumb is that if you don't have experience, either in general or with a particular peice of equipment, then match power output to speaker handling by using RMS x1. If additional 'headroom' is desired and experience has shown the equipment can handle it and you're willing to start taking chances, then amp power of 1.5 to 2x speaker RMS rating can be possible. Be warned that ANY minor problem in the system can spell expensive failures when running at these high power levels.

[Themetallikid]

so when picking out a system. I should:

 

Choose the board first (Peavey RQ2318)

 

the Speakers next (JBL 412's) which they say on MF.com 350 watt handling, (JBL 418's) same 350 watt handling

 

the amps according to RMS rating. = as a good starting point, 1.5x if we feel we need more headroom. and want to push them a bit harder. Correct?

 

How do you compare crossovers? whats important.

 

 

BTW, thanks for all your help, I have learned a lot the past couple weeks. Although just in my head the knowledge really doesnt take effect. But it definately is helping.

[Guest Anonymous]

 

Originally posted by Themetallikid How do you compare crossovers? whats important.

 

1) I prefer analog crossovers for basic applications.

2) Make sure it has the correct number of splits for your application. I prefer to use a 4 way crossover for a 3 way system, but make sure you at-least get a 3 way crossover for a 3 way system if that is what you need.

3) Balanced in's and out's, be it 1/4" TRS or XLR. I prefer XLR.

4) Make sure the crossover points are somewhere in the "middle" of what you intend: i.e.: 100Hz and 1500Hz

5) On-board High Pass (HP) and Low Pass (LP) filters are nice.

6) On-board output mutes are nice.

7) Signal status and clip lights are nice.

8) Variable input and variable output (labeled in dB units) on each frequency is nice.

9) 10X frequency selectors are nice, but make sure if the unit is so equipped that the 10X buttons are not easy to mistakenly change. Status lights for the 10X buttons are nice.

10) No wall wart is nice.

11) CD comp is nice.

12) On-board phase selection is nice.

13) Selectable slope is nice.

14) Easy to read and understand units on the attenuators is very nice.

15) An on/off switch with a "power light" next to the switch is nice.

16) Rack mount and durable construction is a must.

17) The electronics should be fairly "clean".

18) A GOOD operators manual is nice.

19) A security cover for the control knobs is nice.

20) On board limiters (if they function well) is nice.

21) Good detents on the control pots can be nice if the detents are sensibly placed.

22) Faceplate mounted control pots is a plus over strictly PC board mounted control pots.

[Craig Vecchione]

 

Originally posted by Themetallikid so when picking out a system. I should: Choose the board first (Peavey RQ2318) the Speakers next (JBL 412's) which they say on MF.com 350 watt handling, (JBL 418's) same 350 watt handling the amps according to RMS rating. = as a good starting point, 1.5x if we feel we need more headroom. and want to push them a bit harder. Correct? How do you compare crossovers? whats important. BTW, thanks for all your help, I have learned a lot the past couple weeks. Although just in my head the knowledge really doesnt take effect. But it definately is helping.

 

 

Yes to all. And a big +1 to Mark's (Audiopile) crossover checklist. I recommend the dbx because it'll meet your needs and last forever, and is readily available at reasonable cost. They also have good EQ's which you will also want.

[Themetallikid]

AudioPhile - Thanks for the tips, Xovers are the one piece I havent spent much time reading about, nor investigating. I printed your tips. Thanks again

 

So when they say the 350 watt handling? is that the RMS?? I didnt see anything on there listed as RMS. The subs say, it can handle 600 watts (1200 peak) does that mean that 600 is the RMS? I'm kinda confused on where to find the RMS.

[lucho_84]

peak is roughly 4x the rms. s the rms would be 300w. i just want to say that you've been a good sport about this forum and the free info. alot of people come here and complain. hey it's free. Begger's can't be chooser's right? Thanx Man. Good luck with all this info you picked up. It should keep you onn the right track:)