Peavey SP4 speakers nackered, new baskets or magnets?

R

Richard Stringer

Sophomore
Jan 13, 2011
124
0
16
Boston, Lincolnshire, UK
Hey ya guys, erm, well, i've got two Peavey SP4 speaker cabinets and two drivers sound nackered. I power the SP4 cabs each with a bridged QSC RMX1450, I set gain structure using a 400hz sinewave and piezo tweeter before the event and used very thin red tape to mark exactly which vu meter levels on the dj mixer are at the clip point, where the dbx 223XL crossover knobs should set and amplifier attenuators should be set at the onset of clipping. Then left 2dbu of headroom on the dj mixer by putting the red tape marks 2dbu below the dj mixer clip point.

So technically the drivers shouldn't of blown seeing as not once all night did I run my system into clipping and I didn't even get to have my system on full (still leaving 2dbu headroom). So, two questions, what do you guys think about the SP4 cabs handling 1,450 watts per cab even with leaving 2dbu headroom, should I technically be able to power them with the bridged RMX1450 amps or are Peavey pretty weak speaker cabs which ideally you should never power with anything more than their continuous power rating?

Also, i'm not sure if I need new magnets or new baskets, here are two video demos, i've never once ever blown drivers before and i've been doing events for 17 years, albeit with different pa speakers and amps. One driver out of each SP4 cab failed so I put both working drivers in one cab and both failed drivers in the other cab so you can hear the difference. Anyway, if you can tell me if I need new magnets or baskets i'd really preciate it.

The SP4 with working drivers (the bass is rattling the camera microphone a little)
Test video 2 (working drivers) - YouTube

The SP4 with failed drivers (the drivers themselves are rattling and sound awful)
Test video 1 (broken drivers) - YouTube

I'm pretty sure myself that I need new baskets because of mechanical damage to the drivers but I wanted to make sure so I thought i'd ask you guys, thanks.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Which drivers were damaged in each cabinet?

The SP-4 is a Quasi-3-way design with both woofers going all the way down and different upper crossover points for the lower woofer versus the upper woofer.

Could you have possibly sent some really sub-sonic signal to the boxes that may have over driven the X-Max of the drivers and thus damaged them?

How old are these drivers? I've had a 15 in one of my Peavey DTH 2S loudspeakers tear the cone apart between the dustcap and the voicecoil. The cone literally ripped concentrically right around, though I think it had been damaged for a while previous.

Most likely you will only need to replace the baskets on those two drivers. They can be had for a relatively reasonable price from any Peavey dealer. It is an easy fix, especially if you are already well versed in pulling the drivers out of your boxes.

Full Disclosure: I do work for Peavey Electronics Corporation, but I work in Peavey Commercial Audio - MediaMatrix Technical Services, not parts, not repair, nor even customer service.

Good luck!
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Funnily enough it was both top drivers, the forward facing drivers in the speaker cabs that failed but I took one out and put it in the other SP4 so that i've got one fully functioning SP4 and the other SP4 has both the faulty drivers. The drivers age I haven't got a clue about, but I got both the SP4 cabs used and they're in well used condition so maybe the user before me spanked them hard and it was only a matter of time before they failed, which they did fail on me. I'm from the UK and here the baskets aren't cheap, they're £76 each which is $121 each in your money. I was using the SP4 cabs with JBL SRX728S subs and set the crossover point for 90hz so maybe although the bottom drivers in the SP4 cabs weren't handling barely any of the audio frequency range, the power was too much for the top two drivers which were handling more of the frequency range.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Richard Stringer said:
the power was too much for the top two drivers which were handling more of the frequency range.
Click to expand...

There you go.

You had significantly more power going to the top drivers, the bottoms were still working, but over a much smaller range than the top drivers were. It is entirely possible that whomever had them before you gave them a serious workout. A pair of replacement baskets are far more reasonably priced than complete replacement drivers. Poke around on Ebay, call a friendly dealer, get the best price you can.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

I'm gonna buy two new baskets and then get rid of my RMX1450 amps I think, and try and see if I can possibly save up and afford a used QSC PLX3402 because that only outputs 1,100 watts continuous average power per channel into 4 ohms so surely the Peavey 1508-8 SPS drivers can handle that, if they can't then it tells me that Peavey drivers are f**king useless.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

My experience with Peavey drivers is that they typically will sound like absolute hell way before they burn up from overpowering them. However, you can cause over excursion with the right frequencies and power applied.

The Peavey SP4 has a power rating of 1000 watts continuous, 2000 watts program, and 4000 watts peak. However, that's the full cabinet, operating in full range. If you're filtering out the low end and still driving it with that much power, you're asking the top driver to work harder than the other which means the power rating available is going to be lower. Roughly speaking, if the 2 drivers together can handle 1000 watts, but you're sending frequencies to only one of those drivers, it's only going to be capable of 500 watts.

Under normal conditions, an RMX1450 should be just fine on that speaker. However, if you're running heavily compressed music, you're asking for trouble. My general rule of thumb is when matching amps to speakers, if the term DJ ever comes up, the amps are never sized more than the continuous rating of the speakers they are going to be attached to.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

The built in passive crossover should of taken care of power and frequencies so that regardless of the fact I was using subs or not with the SP4 cabs, each 15" driver should of got equal power as they would if I was running them full range, the top drivers shouldn't of got more power seeing as I was running subs with them, they should of still got the same power but just been handling less of the frequency range.
 
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Re: Peavey SP4 speakers nackered, new baskets or magnets?

That's absolutely NOT how a crossover works. A crossover divides the frequencies to the different components, but doesn't do anything to limit the power. If you sent all of the power of your amp as a high frequency tone, you'd blow out the horn in very short order. Of course, there is a protection lamp inside the speaker that would likely blow first, but the point is, the crossover only filters out frequencies from a driver. If you tell the amp to send all the power to one speaker, you're going to run into problems.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Brian jojade said:
if the term DJ ever comes up, the amps are never sized more than the continuous rating of the speakers they are going to be attached to.
Click to expand...

EXACTLY!!!!! +1

The term "headroom" is often thrown around-mostly by people who don't understand what it means.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Brian jojade said:
That's absolutely NOT how a crossover works. A crossover divides the frequencies to the different components, but doesn't do anything to limit the power. If you sent all of the power of your amp as a high frequency tone, you'd blow out the horn in very short order. Of course, there is a protection lamp inside the speaker that would likely blow first, but the point is, the crossover only filters out frequencies from a driver. If you tell the amp to send all the power to one speaker, you're going to run into problems.
Click to expand...

Did you not read what I wrote above? I've already said that I didn't send power to one driver, the bottom driver operates frequencies upto 250hz, so it was being sent frequencies from 90hz (the crossover point) to 250hz.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

If you've got mechanical damage you should be able to remove the magnet from the basket on a Peavey BW and give it a visual examination.

I'm not sure from your explanation what your gain structure is. What is important is how hard you are driving the power amp and how low the frequency can go. Do you have the limiters engaged on the power amps? HPF?

As far as power handling there are a number of things called SP4s all with different power handling so you need to make certain which you are looking at. Also power handling is probably a bit lower when you connect to the drivers without going through the internal passive crossover as there is likely a dB of loss in it. I know of one Peavey SP speaker system that although rated at 500W the LF driver never sees 300W delivered to it.

In any event I don't think simple overpowering is your problem. You probably have drivers that were already damaged by over excursion. If they were thermally damaged chances are they would simply be dead.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

The 15" drivers in the current SP4s are rated at 500 watts continuous power. The listed crossover spec between LF and HF is 1800hz. The spec sheet doesn't list where the crossover point to the lower speaker is, but you stated its at 250hz. So, if you're sending an audio signal that is heavy in the 250-1800hz range, all of that power is being dissipated by the mid speaker. It's not magically controlled by the crossover. If you sent 1000 watts of 1K tone, 1000 watts (roughly) will pass through the crossover to that speaker. Little to no power will be sent to the low or high speaker.

On Peavey's spec sheet, they say that their power ratings are determined by sending a 20hz-20Khz pink noise to the fully functional speaker. This evenly is distributing the power to the components of the speaker. If you reduce the frequency range that eliminates one of the speaker components, the power dissipated by that component no longer happens. If the same amount of power is still applied, the other components have to take over.

Essentially, with this speaker, it's possible to blow up the drivers with any amp that produces more than 500 watts. Difficult with normal music programming, but possible.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Thanks for the reply Don. How I set gain structure is by running a 400hz sinewave through my system and connect the piezo to the output of each piece of equipment, then I turn up the channel gain controls on the dj mixer and then the master output gain control until I hear the harmonics out of the piezo. Then I turn the channel gain down just a tad so I can't hear the harmonics so the gain controls are just below the threshold of clipping and go to the next piece of equipment (my dbx 223XL crossover) and connect the piezo to the outputs and adjust the input gain knobs and both frequency output gain knobs until I can hear the harmonics sound again, and then back off on the inputs of the crossover. Then lastly I adjust the input attenuators on the amps until the clip lights only just start to flicker and then turn them down just a bit until the clip lights don't even flicker. Then I used red take cut in thin strips to mark about 2mm before where all the gain controls are set so that I know never to exceed those levels. Would it of been more accurate to use an oscilloscope?

I had the 30hz high pass filters switched on, on the amps, but my SRX728 subs were handling the frequencies from 30hz to the crossover point of 90hz, then the Peavey cabs handled frequencies from 90hz upwards. My SP4 cabs are rated at 1,000 watts continuous power handling, 2,000 watts program. I was going through the internal crossover in the SP4 cabs, I was running them in passive mode, and like I say, crossed of at 90hz on the dbx 223XL.

And yeah, the Peavey tech guys I spoke to earlier today suggest after explaining everything to him, that the most likely reason for the failure is probably that the person who owned the SP4 cabs before me most likely drove them extremely hard and for quite a few years and the tech guys think it was just unlucky for me that they couldn't take anymore so when I tried to run them sensibly, it pushed them over the edge into failure. He said he especially thought this was the cause because two of the drivers in the cabs had wires which lead from the cones to the terminals on the basket which had snapped and the wires on one driver had been soldered very poorly and the other wires on the other driver had been simply taped with electrical tape to hold them back together. It's looking like the previous owner raped the speakers for ages and then decided to sell them to me and scam me by telling me they were in perfect working order and had original drivers, when in fact one of the drivers was even an old 1505-8DT driver which Peavey stopped making years ago.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Hi Richard,
From listening to the videos you posted the "bad" drivers sounds like something is rubbing. Try taking them out of the cabinet and slowly moving the cone on each one to see if you hear or feel something rubbing. You may have to put your fingers in different positions on the cone and move it. Some positions may elicit a rubbing feeling, some may not, or it may not feel like there is a rub at all. If you do feel a rub, remove the magnet structure from the basket & clean the voice coil gap in the magnet structure. Use masking tape folded over itself several times to make a triangle with the adhesive on the outside. Run this "football" of masking tape around the gap to clean it out. Put the magnet back on the basket & try the driver out again. Also look at the voice coils on the drivers to make sure nothing looks wrong with them, like a burr or something that might cause the buzzing sound.

The other thing that may be happening is that the lead wires (tinsel leads) from the driver terminals that go into the back side of the cone may be slapping against the cone & causing the buzzing sound. Gently pull these away from the cone, but not out of the cone. The tinsel leads should kind of loop out & away from the cone and go on their way to the input terminals. You can test for this slapping by playing full-range music or low frequency sine waves directly into the driver while it is out of the cabinet (no crossover needed). If using a sine wave you may have to change the frequency to get the tinsel leads to buzz. You shouldn't have to turn the driver up too loud for this. If this is the problem you'll know it when you hear it. You'll also be able to see the tinsel leads slapping the cone.

FWIW, I redesigned at least 2 different iterations of the SP4 when I worked at Peavey many years ago. Good luck trouble shooting the problem & getting it fixed.
 
Re: Peavey SP4 speakers nackered, new baskets or magnets?

Thanks ever so much for replying Charlie, I did actually take both drivers out, placed them on the floor and gently pressed on the cones where the dustcaps are and felt around the cone and pressed down a few times in different places and both drivers drivers sounded like something was scraping. When I told Peavey about this they seemed to think it might either be due to over excursion and the voice coils have been damaged or that due to the voice coils heating up the the coils might have warped a little bit causing the voice coil to rub against the voice coil gap in the magnet.
 
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