Difference between these two subs

[agedhorse]

 

Your PLX3402s may be fine, but I find that the 528s don't really 'wake up' until they start to see at least 2000 watts each.

 

 

IMO, the cabinets will not handle 2000 watts RMS for very long, not reliably anyway and they are expensive drivers to recone.

 

The knee of the power compression curve begins to get steep around 1000-1200 watts RMS, that's the point of diminishing returns.

 

Now if you are talking about "peak power", 1000 watts RMS = 2000 watts peak, they are the same waveform, just different measurement methods and different numbers for the same thing. So it depends which marketing crap you are reading.

[minn12]

 

IMO, the cabinets will not handle 2000 watts RMS for very long, not reliably anyway and they are expensive drivers to recone. The knee of the power compression curve begins to get steep around 1000-1200 watts RMS, that's the point of diminishing returns. Now if you are talking about "peak power", 1000 watts RMS = 2000 watts peak, they are the same waveform, just different measurement methods and different numbers for the same thing. So it depends which marketing crap you are reading.

 

 

The band has been running the MRX528s for the last few years with 2000 watts a cab with zero problems including outdoor festivals. They are using the proper Driverack settings for them. We tried them first with lower power amps and they didn't sound as good. YMMV.

[tedmich]

mmmmmm two subs....

 

[twostone]

mmmmmm two subs....

 

LOL

[Bugzie]

I've tried a pair of 528's on both a PL236 run in stereo and also a pair of crown xls1500's bridged. You can't even notice a difference. That's 1550 WPC vs 1100. The only real disserence is the weight of the amp rack.

[agedhorse]

 

The band has been running the MRX528s for the last few years with 2000 watts a cab with zero problems including outdoor festivals. They are using the proper Driverack settings for them. We tried them first with lower power amps and they didn't sound as good. YMMV.

 

 

If you really have the proper drive rack settings, you are limiting them back to what I recommend anyway.

 

With that much power (assuming your amps REALLY can produce 2000 watts RMS and you aren't reading marketing numbers) and you have an accident, you will then understand and appreciate my comments better.

[minn12]

 

If you really have the proper drive rack settings, you are limiting them back to what I recommend anyway. With that much power (assuming your amps REALLY can produce 2000 watts RMS and you aren't reading marketing numbers) and you have an accident, you will then understand and appreciate my comments better.

 

 

All I can tell you is the band started off running the cabs at 900 watts RMS each, then went to powering them with 2000 watts RMS each, and the sound difference was night and day. According to JBL's User Guide for the MRX528s, the recommended amplifier power at 4 ohms is 2000-4000 watts. We're running at the LOW end of JBL's recommendation. I have to assume JBL knows what they are doing when recommending how to power their own subs.

[flanc]

 

All I can tell you is the band started off running the cabs at 900 watts RMS each, then went to powering them with 2000 watts RMS each, and the sound difference was night and day. According to JBL's User Guide for the MRX528s, the recommended amplifier power at 4 ohms is 2000-4000 watts. We're running at the LOW end of JBL's recommendation. I have to assume JBL knows what they are doing when recommending how to power their own subs.

 

 

Here is the spec sheet.

 

1000/2000/4000 Continuous(rms)/program/Peak for 2 hours.

800/1600/3200 Continuous(rms)/program/Peak for 100 hours.

 

http://www.jblpro.com/catalog/support/getfile.aspx?docid=600&doctype=3

[minn12]

 

Here is the spec sheet. 1000/2000/4000 Continuous(rms)/program/Peak for 2 hours. 800/1600/3200 Continuous(rms)/program/Peak for 100 hours. http://www.jblpro.com/catalog/support/getfile.aspx?docid=600&doctype=3

 

 

That's pink noise testing in a lab, not normal 'real world' use. Two different things. Here is the User Guide with the recommended amplifier power of 2000-4000 watts at 4 ohms for the 528s:

 

http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=831

[agedhorse]

 

That's pink noise testing in a lab, not normal 'real world' use. Two different things. Here is the User Guide with the recommended amplifier power of 2000-4000 watts at 4 ohms for the 528s: http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=831

 

 

No sir, it's not 2 different things when you factor compression and energy density into this. If you are careful, and you don't have any accidents, and you have enough rig for the gig, you will be ok BUT this is not real world either.

 

I have reconed enough JBL product (and all other manufacturers), as well as designed enough commercial speaker products to be absolutely confident in my comments and opinion. It's clear from your comments that you just don't understand how these ratings are developed, and for what purposes. If you studied JBL's powered speaker products that use the same drivers, you will see that they power them at around 1.25-1.5x the RMS rating and if you were able to study the limiting and protection algorithems you would also see that there is a hell of a lot of thought that goes into the limiting protection schemes. The 4000 watt rating is meaningless because it's EXACTLY the same as the 2000 watt rating but using a different measurement scale (peak voltage is 1.414x the RMS voltage and when squared in the power equation = 2. This is why the peak power is 2x the Program power (which is accepted by the industry to be 2X the continuous "RMS" or thermal rating. The drivers in your subs are 400 watt RMS rated drivers, best powered by no more than 600 watts RMS unless you have the factory protection algorithems programmed (correctly and verified) into your speaker processor. What do you have for a speaker processor?

 

At 2000 watts, you are exceeding the mechanical power handling and this is why there is a time factor on the power rating. If you are cool with your speaker lasting a shorter time before failure, then use more power. Be aware that most manufacturers do not honor warranty claims when there is evidence of speaker overpowering regardless of what their numerical rating is. This is why powered speakers are powered and limited the way they are and I think it's good for the vast majority of users.

 

You are the reason why the company marketing folks have a job... you are proof that a bigger number sells better regardless of how the bigger number is arrived at.

 

(This is what I do for a living, and was certified by JBL in 1978)

[minn12]

 

No sir, it's not 2 different things when you factor compression and energy density into this. If you are careful, and you don't have any accidents, and you have enough rig for the gig, you will be ok BUT this is not real world either. I have reconed enough JBL product (and all other manufacturers), as well as designed enough commercial speaker products to be absolutely confident in my comments and opinion. It's clear from your comments that you just don't understand how these ratings are developed, and for what purposes. If you studied JBL's powered speaker products that use the same drivers, you will see that they power them at around 1.25-1.5x the RMS rating and if you were able to study the limiting and protection algorithems you would also see that there is a hell of a lot of thought that goes into the limiting protection schemes. The 4000 watt rating is meaningless because it's EXACTLY the same as the 2000 watt rating but using a different measurement scale (peak voltage is 1.414x the RMS voltage and when squared in the power equation = 2. This is why the peak power is 2x the Program power (which is accepted by the industry to be 2X the continuous "RMS" or thermal rating. The drivers in your subs are 400 watt RMS rated drivers, best powered by no more than 600 watts RMS unless you have the factory protection algorithems programmed (correctly and verified) into your speaker processor. What do you have for a speaker processor? At 2000 watts, you are exceeding the mechanical power handling and this is why there is a time factor on the power rating. If you are cool with your speaker lasting a shorter time before failure, then use more power. Be aware that most manufacturers do not honor warranty claims when there is evidence of speaker overpowering regardless of what their numerical rating is. This is why powered speakers are powered and limited the way they are and I think it's good for the vast majority of users. You are the reason why the company marketing folks have a job... you are proof that a bigger number sells better regardless of how the bigger number is arrived at. (This is what I do for a living, and was certified by JBL in 1978)

 

 

Seems to be getting way overcomplicated. Sorry, but my understanding is that a bench test with continuous pink noise is far different than using the subs in the real world. Under normal useage conditions, the subs can tolerate more power than the 'pink noise' ratings, because they are not getting the full power on a continuous basis. That is why there are two ratings, one for pink noise, and then the power recommendation, which is higher. I don't think I would want to put 4000 watts thru these, but 2000 watts seems fine when used properly, which was my point. But based on your info, JBL is being foolish, reckless, and putting their own products at risk by recommending at least 2000 watts at 4 ohms. If your info was correct, the MRX528s should be blowing up left and right when powered at even the low end of JBL's power recommendation. But it seems they are not, and they have sold tons of them. My own real-world experience also confirms no problems after over two years of use. Perhaps you should bring your concerns to JBL, warn them that they are putting their own subs at risk, and ask them to significantly lower their power recommendations. Let me know what they say. You're certainly entitled to your opinion, but I have to go with JBL's recommendations and my own experience using their products over the years. They haven't steered me wrong yet.

[jlb]

I power my SRX 728 with 1000w RMS. This is with an amp that is capable of 3000w RMS at 4 ohms. If I did not have the ability to RMS limit I would be using something along the lines of a QSC PLX 3600 in stereo.

[Craig Vecchione]

 

Seems to be getting way overcomplicated. Sorry, but my understanding is that a bench test with continuous pink noise is far different than using the subs in the real world. Under normal useage conditions, the subs can tolerate more power than the 'pink noise' ratings, because they are not getting the full power on a continuous basis. That is why there are two ratings, one for pink noise, and then the power recommendation, which is higher. I don't think I would want to put 4000 watts thru these, but 2000 watts seems fine when used properly, which was my point. But based on your info, JBL is being foolish, reckless, and putting their own products at risk by recommending at least 2000 watts at 4 ohms. If your info was correct, the MRX528s should be blowing up left and right when powered at even the low end of JBL's power recommendation. But it seems they are not, and they have sold tons of them. My own real-world experience also confirms no problems after over two years of use. Perhaps you should bring your concerns to JBL, warn them that they are putting their own subs at risk, and ask them to significantly lower their power recommendations. Let me know what they say. You're certainly entitled to your opinion, but I have to go with JBL's recommendations and my own experience using their products over the years. They haven't steered me wrong yet.

 

 

You stated earlier that you are using the recommended driverack settings. This means that you are setting the limiters to engage and limit power to well below 2000w rms. More like 800-1000w rms, which is right above the 100 hour spec.

 

JBL is not being reckless. They publish specifications and recommendations that if followed *completely* and with an understanding of what each factor means, will give good performance and good long-term life. Again, always remember that a failure that shows indications of thermal or mechanical exceeding of specs will result in a warranty denial. Period.

 

Look at your statement above: "If your info was correct, the MRX528s should be blowing up left and right when powered at even the low end of JBL's power recommendation. But it seems they are not, and they have sold tons of them."

 

Do you have warranty return numbers? Sales numbers? Do you perform repairs on JBL speakers and submit for warranty? If not, then you're simply making assumptions and basing your opinions on this and false interpretation of specs. You aren't alone, and I'm not intending this to be taken as an insult. The bottom line is that you aren't powering your speakers with anywhere near the power you're assuming.

[agedhorse]

It comes down to how long you wish your speakers to perform properly. I see enough product in for recone to know that gear is indeed being damaged. If you are good with a speaker lasting 4 or 5 years than power away, if you want to get 10 years out of them, be a little more conservative.

[agedhorse]

 

Seems to be getting way overcomplicated. Sorry, but my understanding is that a bench test with continuous pink noise is far different than using the subs in the real world. Under normal useage conditions, the subs can tolerate more power than the 'pink noise' ratings, because they are not getting the full power on a continuous basis. That is why there are two ratings, one for pink noise, and then the power recommendation, which is higher. I don't think I would want to put 4000 watts thru these, but 2000 watts seems fine when used properly, which was my point. But based on your info, JBL is being foolish, reckless, and putting their own products at risk by recommending at least 2000 watts at 4 ohms. If your info was correct, the MRX528s should be blowing up left and right when powered at even the low end of JBL's power recommendation. But it seems they are not, and they have sold tons of them. My own real-world experience also confirms no problems after over two years of use. Perhaps you should bring your concerns to JBL, warn them that they are putting their own subs at risk, and ask them to significantly lower their power recommendations. Let me know what they say. You're certainly entitled to your opinion, but I have to go with JBL's recommendations and my own experience using their products over the years. They haven't steered me wrong yet.

 

 

It's the mechanical power handling limitations that causes the problems. The power handling is not a single number like the marketing folks would like you to believe. It's a curve that varies with frequency and temperature. A speaker that has a thermal rating of say 1000 watts may only have a mechanical rating of 250 watts at 30Hz, but the proper speaker processor settings will account for this by insuring that the electrical response is down by 6dB at 30Hz (reducing the power to the driver by that amount) as part of the overall protection of the driver. This is exactly what engineers (like me) who develop powered speakers consider.

 

Also, you mention not wanting to put 4000 watts into your subs. If you understood what the numbers mean in their ratings, you would quickly realize that if you put 2000 watts "RMS" into your speaker you are also putting 4000 watts peak into your speaker. This single misunderstanding brings a lot of profit into my recone shop.

 

Have you ever investigated the effects of power compression on LF drivers? I have some of the JBL power compression curves (and these are good drivers) and those curves alone would make it clear why much past the RMS rating is the point of diminishing returns and is why that's what most powered speaker designs end up around that point. At "program power", you lose almost 75% of the incremental SPL gains... meaning that for the additional doubling of power, you gain about 3/4 additional dB but quadruple the risk of damage. YOu have a log and antilog curve overlapping at this point which is the worst of all worlds.

[Miko Man]

 

Also, you mention not wanting to put 4000 watts into your subs. If you understood what the numbers mean in their ratings, you would quickly realize that if you put 2000 watts "RMS" into your speaker you are also putting 4000 watts peak into your speaker. This singloe misunderstanding brings a lot of profit into my recone shop.

 

 

Aged, is there a typo here, or did I misunderstand the earlier posts? 1000 watts RMS = 2000 watts "program" = 4000 watts "peak"? Thanks for the clarification. Mark C.

[agedhorse]

 

Aged, is there a typo here, or did I misunderstand the earlier posts? 1000 watts RMS = 2000 watts "program" = 4000 watts "peak"? Thanks for the clarification. Mark C.

 

 

I see the need to clarify... program power is twice the RMS power and represents 6dB crest factor of continuous... 3 dB comes from doubling from 1000 to 2000 (and the units remain based on RMS voltage) and the other 3dB is the units change from RMS voltage to peak voltage. so with that unit change, the 2000 watts "RMS" is identical to 4000 watts "peak". The point I was trying to make is that if you were to power it with a 4000 watt RMS rated amp, you would be exceeding the 4000 watt peak power by 3dB or in other words, the peak power of a 4000 watt RMS rated signal is 8000 peak.

 

This is one of the common causes of speakers coming into the shop... folks who think they know more than they do, and it can be a costly mistake on some speakers with expensive components. Then the waters are muddied with amps that only show the peak rating because bigger numbers vreate bigger wood in those customers who that marketing generally applies. Mmmm, big = good... [insert neandrathal grunt here]

[minn12]

 

You stated earlier that you are using the recommended driverack settings. This means that you are setting the limiters to engage and limit power to well below 2000w rms. More like 800-1000w rms, which is right above the 100 hour spec. JBL is not being reckless. They publish specifications and recommendations that if followed *completely* and with an understanding of what each factor means, will give good performance and good long-term life. Again, always remember that a failure that shows indications of thermal or mechanical exceeding of specs will result in a warranty denial. Period. Look at your statement above: " If your info was correct, the MRX528s should be blowing up left and right when powered at even the low end of JBL's power recommendation. But it seems they are not, and they have sold tons of them ." Do you have warranty return numbers? Sales numbers? Do you perform repairs on JBL speakers and submit for warranty? If not, then you're simply making assumptions and basing your opinions on this and false interpretation of specs. You aren't alone, and I'm not intending this to be taken as an insult. The bottom line is that you aren't powering your speakers with anywhere near the power you're assuming.

 

 

So you agree that JBL's power recommendations for the MRX528s are proper. Thank you. That was my point. It's always interesting when people post that they are using the manufacturers' recommendations for whatever product, then get told those recommendations are wrong, dangerous, marketing hype or whatever, with the general assumption that most users aren't properly using their gear. I guess that comes with the territory when using internet boards. Don't get me wrong, I learn something new every day, and many posters provide good information. What I meant by 'recommended settings' is the Driverack was set up with proper high pass/low pass/crossover settings for the system. They were 'custom' settings we did over two years ago. They are NOT being limited to '800-1000 watts'. So your 'assumption' is incorrect, sorry. Thanks for weighing in, but I think it's time to move on.

[agedhorse]

So you have "custom" settings that do not limit the power matched to the limits of the drivers?

 

That would then fall outside of the manufacturer's optimum settings and thus require derating from the MAXIMUM power handling under optimum conditions.

 

You need to better understand what optimum conditions are from the manufacturer's engineering perspective and seperate those from the marketing department's perspective. Since I develop and analyze transducers as part of my day job, I am intimately familiar with the failure mechanisms associated with real world applications and also how to minimize the liklihood for warranty claims when such real world "tragedies" do occur.

 

Or you can just go with what you are doing now, and it may work out just fine assuming you don't have any unfortunate accidents or lapses of good judgement that are often at the root of the damage done.

 

Incidently, there are a lot of other folks who read these threads and the information I provide are more for them than you, so if you don't like what I present, that's just fine with me.

[6Imzadi]

 

Incidently, there are a lot of other folks who read these threads and the information I provide are more for them than you, so if you don't like what I present, that's just fine with me.

 

 

Thanks, BTW.

 

I really would like to understand more about how to power and limit the MRX528s using two PLX3402. In my mind, this is the sub I feel I want next. I am looking at 2 per side. Any help with the processor settings would be more than appreciated.

[agedhorse]

With regards to the processor settings, there are some things I can easily explain and some that I can explain but can't disclose the back-up data because it's not available to the general public and I must respect the IP of the company and those who have allowed access, plus my own internal testing data.

 

1. HPF: This is always in part a judgement call as there is a tradeoff between LF extension and HPF choices. These are also affected by the choice of LF extension boost. The following is what I find to be a reasonable, real world tradeoff between performance and (mechanical) reliability: 35Hz, 24dB/octave, BW

 

2. LP xover: This is affected by your choice of tops and the relative balance between power and bandwidth of your speakers, but generally something between 90 and 100Hz, 24dB/octave LR will give good, predictable results

 

3. LF extension eq: Generally, this is done using an under-damped filter but for practicality the best way (and maybe the only way depending on what you have available) is to add parametric eq that will exist on top of the HPF forming a compound asymetrical filter. Add a peaking filter, approx +5dB at between 40-45Hz, with a Q of about 3.5-4.5. Do not do this without the HPF, or you will exceed the mechanical power handling of the cabinet.

 

4. If you power this at the continuous rating and limit at that point (amp's clip limiter" you are quite save. You can also limit with a long term (RMS) limiter at the continuous rating and then set the short term limiter to 1.5x the RMS value. Note that I can't be specific because each amp and DSp designer has different ways of doing so. With Crown, the peak voltage corresponds to peak power so you would have to calculate the RMS voltage at 1.5x the continuous rating and then multiply by 1.414 to get the peak voltage and enter it in Band Manager or front panel. Also note that RMS power on Crown amp products uses watts at rated impedance so remember to use 4 ohms.

 

As far as additional eq, and sub xover out gain, this will depend on amp sensitivity but generally for flat response between subs and tops, somewhere around +3dB on the sub band to top band will get you in the ballpark on what you have.

 

I have a customer that I worked up this DSP algorithm for a while back and it works very well. He uses XTI-4000's and it's a really good match all around.

 

If you use the 3402, one box per channel is just about right as well. That is exactly what I used when testing his subs here at the shop developing some power compression data. The knee on the power cpompression curve steepens around 1200 watts into 4 ohms. This is one of the best uses for the Iasys analysis system, as it allows automatic generation of power compression data and seems to be a good real world indicator.

[jlb]

Thanks for another great post Aged!

[6Imzadi]

Thread subscribed and saved. Thank you for that super information.