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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Raj Sookraj on April 17, 2005, 12:15:02 AM

Title: 4 Labhorns on a Crown MA-5000?
Post by: Raj Sookraj on April 17, 2005, 12:15:02 AM
I have 4 Labhorns under construction and I was wondering if my MA-5000 could handle 2 labhonrs per channel.  I was concerned that each sub is 6 ohms/4.29 RE divided by 4 subwoofers would be 1.5 ohms/1.0725 RE per channel!  Do you think this is safe for the MA-5000?  Does any one have experience using the MA-5000 to power labhorns or using the MA series down to 1 ohm per channel?  Thanks for your input.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Ivan Beaver on April 17, 2005, 07:42:19 AM
If you are building 4 labs, then would you not put 2 on a channel for a total of 3 ohms/channel?  The 5K should be fine with that.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Alan Searchwell on April 17, 2005, 09:19:03 AM
Ivan,

looks to me like you've misinterpreted Bubblersound's strange use of terms. He is building 4 "labhorns" (seems pretty straightforward, he's building 4 cabinets) but, he then goes on to say that "each sub is 6 ohm". I think he means each lab12 (transducer) is 6 ohm and not each cabinet. He continues, "divided by 4 subwoofers would be 1.5 ohms/1.0725 RE per channel!". Here again I think he means 4 lab12s (transducers), in which case his calculations are correct.

As a newbie, I guess bubblersound does not know that we often use terms like labhorn, labsub, sub and subwoofer interchangeably to describe the lab sub or any cabinet designed to reproduce sub bass frequencies. Rarely, if ever, are the component drivers refered to as subs or subwoofer since you won't get much sub bass out of driver that is put in a box that's not designed properly even if the driver itself was designed for that application.

This is a technical forum with several very knowledgeable people participating so I guess we should be a little more careful with the terms we use Confused .
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Timmahh on April 17, 2005, 09:30:05 AM
   each Lab Cab uses 2 drivers each @ 6ohm each, when you wire the cab in parrallel it will then of course give you a 3 ohm load per cab. if you were to then parrallel two cabs together you would then have a 1.5 ohm load for the amp to see.
   assuming you wired it all together correctly,  i am unsure of the MA series, but i was under the impression they could handle a 2 ohm load per side, i would think the op would be fine.  Others would be more qualified to answer this in more detail as when using the Labs the actual ohm draw the amps see will vary depending on the frequencies in play.  As i understand it from reading previous posts about this,  in most cases the drivers would most likely would of been labled an 8 ohm driver via most manufacturers, but because of certian criteria of which i an unaware, eminace labeled the Lab Driver a 6 ohm load.  in real world use, i hear of quite a few people driving one lab sub on an amp that is rated down to 4 ohm, like the people that are useing one QSC 1850HD bridged for one cab. the 1850 i think is only rated to handle a 4 ohm load in bridge mode, but it seems to be doing fine considering the load from the Lab Sub is ideally LABLED a 3 ohm load.
i run one cab off off one side of my amp which is rated down to 2ohms at 1800w per side. so i figure i m giving each lab approximatly 1500w per cab with a 3 ohm draw.  but for a couple weeks, i ran it off an amp that was rated to 4 ohm per side. and i did not see any problems other than the Lab was only getting 1000w per cab. so cliping was a lil more frequent than desired. thus the move to the bigger amps.
personally, i think as long as you set it up correctly, use the xover points correctly, hpf around 40 or so, and xover near 80 or 90 area, the op should be fine with it.  a search of the Lab Archives should reveal many great posts about this very subject, one i recall was labled, Final Amp choice for the LabSub. or something to that effect.  and anyone that read that post also would probably agree the choices are as varible as current gas prices......

if your MA5000 is speced at 2 ohm per side in stereo mode, im confident you ll be fine, and im sure that there are other Lab users using the Crown MA5000 with success.
HTH
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Elliot Thompson on April 17, 2005, 03:25:24 PM
When I got my first MA 5000 (9 years ago), I drove
it into 1 ohm per channel stereo, with no issues.

Just keep an eye out for the Limit/Load indicators,
and, it would be wise to refresh your memory on what
the lights mean, using the Crown Manual as reference.
(Thats page 8, BTW)

Also, Keep those filters clean! It takes less than
3 minutes to wash the filters, oppose watching your
ODEAP lights dimming due to insufficent cooling in
the middle of the show.

For the record, what I was doing 9 years ago, is
not enforced today. And, I would recomend getting
a second one, when you have the available funds.

Best Regards,
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Ivan Beaver on April 17, 2005, 04:32:35 PM
DUH my bad-BIG brain fart!

Thanks for the correction-I don't know what I was thinking-my mind was elsewhere!
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: David Trotter on April 18, 2005, 11:01:22 AM
bubblersound:
I ran 4 labs off a single 5k for a few months.

Worked absolutely fine the first couple of times- 7 hours straight at a time running very hard. i did however pick up some problems after a while - mainly due to the bass vibrating internal screws loose!

I ended up selling it and buying 2 PLX3402's. I can hear the difference -the sound is now much tighter and cleaner than with the single crown. Bass is louder, never got anywhere near clipping the amps and they are much easier to power.

Basically it'l work fine as long as you don't ilimit and it gets enough power. You'l get plenty of bass. BUT because your running 4 speakers in parallel at low impedance, you have problems with back EMF and damping.

Watch out when you take just 2 labs out.

hope that helps.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Gareth James on April 18, 2005, 12:21:57 PM
I think someone on this forum already went through this before, but i believe the labs are to be considered as 4ohm nominal loads.

Yes the impedance min is 3ohm per box but there are only a few points across the frequency range of the labsub where the electrical impedance gets this low (mainly because of it being a horn-loaded box).

So unless your running a whatever hertz sine wave at this min point all night i can't see there being a problem!
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Marty Bilecki on April 25, 2005, 09:18:02 AM
 I have 8 labs and for the past year have used 4 labs on 1 5002vlz with great results....     So far no trouble and and no speaker failures..........  I just recently converted the amps to a Crown usb pip 3 card which can monitor amp functions from my laptop....   The nominal ohm load shows up in real time... Ill report back with some real world show numbers but in recent gigs I have only used 2 labs per side  ( Doo wop Oldies shows and church concerts)  so no 8 box r and r shows until this weekend coning up........     I am looking forward to tweaking the delay shading with the Crown I quik software  on the outer boxes to help with power alley buildup....
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Scott Smith on May 04, 2005, 10:42:46 PM
A speaker with 3 ohms dc resistance, can actually have anywhere from 3-10ohms ac impeadance, depending on resonance.  Either way, it won't be constant across the entire sub frequencies.

That much load will certainly decrease damping in any amp.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: sheldon harris on July 01, 2005, 01:43:55 PM
this is a really nice forum, i am new here but not new to crown ma 5000.
the ma5000 will drive the lab subs if each driver is 6 ohm. when hornloaded the impedance will vary according to the frequency range.in the case of a horn loaded enclosure its usually higher as opposed to the same driver in a vented box.

with the ma5000 you can set the switch at the front of the amplifier to "lock low" that would get the power supply ready for high current low impedance mode. put the gain switch back to the center position i think its 26 db(.707 will bring on the gain too quickly for that low of an impedance) look out for the current limit light. if it lights red and the signal light is normal,it means your load is too low.
ideally, when driving low impedance loads with the ma5000, the current limit light will be flashing along with the signal light (i/o comparator)showing momentary bright/normal operation.
if the red (i load light is on and the i/o signal light is bright abd stays bright, you will toast those drivers, easily.

Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: jeffhtg (Jeff Kenney) on July 16, 2005, 01:34:01 PM
umm on a Crown Macrotech 5000VZ ("00 series") the red lights are on to show power and ODEP.

to clarify on this older macrotech.. the red lights should be on - signifying power and that there is some 'juice in the unit'.. they will dim a little if you really drive them hard - however I drive the hell out of 4 labs with a 5000vz and the lights NEVER dim.

Now on every crown "00" series I have used I have never seen a red clip light.. The load light signifies current flowing at like -60 or something silly.. the next light up shows -10.. then the bottom light glows brightly to show .1% THD or "Pre clip"

The "02" series Has the red clip lights.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: sheldon harris on July 17, 2005, 12:23:04 AM
jeffhtg wrote on Sat, 16 July 2005 18:34

umm on a Crown Macrotech 5000VZ ("00 series") the red lights are on to show power and ODEP.

to clarify on this older macrotech.. the red lights should be on - signifying power and that there is some 'juice in the unit'.. they will dim a little if you really drive them hard - however I drive the hell out of 4 labs with a 5000vz and the lights NEVER dim.

Now on every crown "00" series I have used I have never seen a red clip light.. The load light signifies current flowing at like -60 or something silly.. the next light up shows -10.. then the bottom light glows brightly to show .1% THD or "Pre clip"

The "02" series Has the red clip lights.


"RED CLIP LIGHTS ?" MACRO TECH 5000? who told you that?

"ALL" crown macro tech 5000 have 3 pairs of lights,IT BE MA5000 OR MA5002 FROM FIRST MODEL TO LATEST.

first set from top are 1) odep, glows bright red when amp is fully energized,they show power reservs, they dim as the amp gets driven hard, they go out, when severe limiting is taking place or a channel overheats........

second set from top are 2) ioc or input output comparators, they show signal, and within that signal they show,distortion in two stages, the first stage they glow bright for a split second then back to normal, if the distortion,gets even more severe, they glow bright, but takes a little while longer to get back normal.(they stay bright longer or even stay on bright)

third set from top 3)i load/i limit or current load /current limit. if no speaker or load is connected, they would not light,when a load or speaker is connected, they light,with an intensity almost like the signal level in the second set of lights,however when the amplifier is really driven,those same two set of lights,the third set, TURN RED. they blink red to show current limiting, under sever conditions,they stay red, and the odep lights begins to dim.

i have been using crown macro tech 5000 within the first few months of them hitting the market and still do, as a matter of fact, i sent a picture to crown international showing what I called a stack of ma 5000 doing the " UPSIDE DOWN CHRISTMAS TREE EFFECT"  if you look at a stack of ma 5000 being driven hard in darkness, the lights form what would be a perfect christmas tree or pine tree (triangles stacked on each other)
but the lights were all mixed up because the amps were being driven so hard! odep lights off, ioc lights bright green and on, and the i limit light(bright red,cant miss it, if you do you never seen a crown ma 5000 in real action) on bright red, so the one technician asked me if the amps were upside down. if you are not a regular ma 5000 user you wont get it Smile

as i stated earlier, knowing what to look for on the display, and knowing how to set the switches under the front panel of the amplifier would allow the user to effectively use the amplifier.
if you have not seen that bright red i limit light lit on that 5000 when driving those labs, it simply means that you havent begin to tap into the real power of that amplifier,
for 4 labs,with that resistance,  lock low,set the level switch, that with max gain, the ioc lights hit the first stage, thats .05% distortion, and the limit BIG RED BRIGHT LIGHTS AT THE BOTTOM (THEY ARE GREEN BUT TURN RED) comes on simultaneously with the ioc first stage.

Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: jeffhtg (Jeff Kenney) on July 17, 2005, 06:19:17 PM
I have 4 crown 5000 that do not have red clip lights.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: sheldon harris on July 18, 2005, 12:23:02 AM
the 4 ma 5000 that you have,do they have a third row of lights, that says    I LOAD/I LIMIT? the reason you probably did not notice them is because you never drove the amps that hard to light them.
they are yellowish green, but when the amp is being driven hard esp. into 2 ohm loads, they flash bright red, you cant miss it its very bright red. i have never seen them lit when driving an 8 ohm load,and only occasinally when driving driving 4 ohm loads
hard.
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: jeffhtg (Jeff Kenney) on July 18, 2005, 05:48:57 AM
nope they have definatley never turned red.. In the past I have run 2 ohm loads on them for many moons.. perhaps its because clip limiter is engaged - but i doubt it.. I seem to recall talking to crown about this and learning that only the "02" amps had red clip lights...
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: David Trotter on July 18, 2005, 07:44:29 AM
Our old crown had a red ilimit light. 5000 version. I presonally think the lights on the crowns are stupid because in a dark, noisey place where your probably pissed, its really difficult to catch and understand the distortion flashes. My friends crowns have eaten 4 lab12's, 2 Fane xbs and 4 PD1850's drivers now because it's so hard to tell when they are clipping!

PLX amps -
1 green light  > 0.1%
2 green lights > 1%
3 green lights > 10%
Red light      > clip/limiting

All amps should be like this!
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: Elliot Thompson on July 18, 2005, 08:35:12 AM
The Crown Macrotech was designed for people that have a
clue what they are doing.

I don't know how anyone can call the two color limit light
a clip light, when the limit light only triggers red if
your driving a very low impedance.

I've had my limit lights trigger only twice, in a 9 year
period.

Back in 1996, when I was driving 1 ohm stereo,(I wanted to
see if it could do it  Twisted Evil )and, the Subwoofer Shootout
in NY, in 2003 when we overdrove the PL 9.0, Crest 10,001,
and, MA 5000, to hear how each amp sounded in 2 ohms once
overdriven on Bassmaxx, and, BDeap 32. And we backed off
so it wouldn't blink during the test.

Surely something the average soundman would do if they
have enough amps, and, subs to begin with.  

The limit light flashes red when the amp reaches its current
limit. Voltage wise, if its triggering, you've gone far beyond
clipping...  Rolling Eyes

Anyone who doesn't understand what the Load/Limit lights
mean, need to turn to page 22 on their manual.

The Macrotech is the most detailed manual in the market.
So, if anyone is losing drivers on the MA 5000, don't
blame the amp, blame yourself for not reading the manual.

Sheldon D

I agree. A rack of Macrotechs do look like a lited Christmas
Tree. Laughing

Best Regards,
Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: sheldon harris on July 18, 2005, 11:07:20 AM
jeffhtg wrote on Mon, 18 July 2005 10:48

nope they have definatley never turned red.. In the past I have run 2 ohm loads on them for many moons.. perhaps its because clip limiter is engaged - but i doubt it.. I seem to recall talking to crown about this and learning that only the "02" amps had red clip lights...



very strange!
i have all three(its really three and not two versions)if you include the amcron 5000 0r 5001)
and the I LOAD/I LIMIT LIGHTS ON ALL OF THEM. THEY ARE GREEN AT FIRST, BUT LIGHT RED WITH SEVERE DRIVING.

ahh, dont worry about it, as long as the amps are working properly and not toasting drivers, they are ok.

take care dude.


Title: Re: 4 Labhorns on a Crown MA-5000?
Post by: sheldon harris on July 18, 2005, 11:52:59 AM
Elliot Thompson wrote on Mon, 18 July 2005 13:35

clipping...  Rolling Eyes

Anyone who doesn't understand what the Load/Limit lights
mean, need to turn to page 22 on their manual.

The Macrotech is the most detailed manual in the market.
So, if anyone is losing drivers on the MA 5000, don't
blame the amp, blame yourself for not reading the manual.

Sheldon D

I agree. A rack of Macrotechs do look like a lited Christmas
Tree. Laughing

Best Regards,



hey E.T that is so true,from the display(if you know what you are looking for) you can tell exactly what state the amplifier is in.you can even almost guess the load of the speakers its driving!
the cristmas tree stacks i had were severly overdriven, because power went out during the middle of the performance, they brought in a generator,but because it was not planned for, the power cables could not effectively adapt. 1 of the sub racks could not be powered unless we did some cutting, decided it was costly and time consuming and powered half the subs on each side with 1 rack, it was , well half the amps, so we decided to run all of the cabinets,at 1 ohm using the 1 rack. at that time we had custom made double 18" evx 180b cabs (we nicknamed "sledge hammers" i stood there looking at that stack of amps almost all night! it was indredible! the picture that i sent to crown,doesnt do it justice, with each pause in the music,the odep lights would begin to glow slightly red(they were off) and as the music comes back, they would go on and off to the signal, while the 2 I limit lights would stay on bright red.all the amps were doing the same exact thing in perfect unison!(well, same signal, same load)

the technician was asking me a whole bunch of questions(to him it was unbelievable! they make the amp they should know Laughing
all i rembered really is i switched them to lock low, took the filters out,i took down a 10" ac vent (ice cold) and had it blasting on the front of the rack, i also had one of those industrial fans at the back sucking out the hot air!

you could not touch the back panels of the amps!

not one single failure, not one.(they were still under warranty anyway)

i'm thinking on moving on to crest though,
btw. i need a single crest audio 10001 amplifier do you know where i can get one?

regards
sheldon.