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[Mike Karseboom]

One of my SRX815P speakers started making some very noticeable distorted sounds at moderate volume. This is a speaker I have using for about 3 years without problem.


This is not the "buzzing" from the back of the speaker some people have experienced.  This is distortion coming out the front that sounds like the LF driver is completely shot.  But I think the driver is OK. 


I am wondering if the amp module needs replacing?  Here are some aspects of the problem:



- Turning the volume down and rolling off the bass around 100Hz helps reduce distortion
- the problem is sporadic and may be heat related.  Later in the evening it seem to  be "fixed"
- I did notice some "electronic" noise coming from the speaker with no signal input.  That seemed to be fixed with a different siamese power/signal cable but later testing of the original siamese cable showed it was probably OK.


I was going to buy a used SRX815P from guitar center a couple of years ago at an excellent price ($600) until I played some music through it and it sounded similar to what I am experiencing with mine (only it was much worse).  But I don't know if and how they fixed it.


Has anyone had this type of problem with SRX815P and if so is an amp replacement the cure?
 

[Riley Casey]

It's very unlikely that an amplifier would distort only under 100hz and very likely that a bass driver would so I'd start by pulling the low frequency driver and testing that by itself. Get a phone app like Audio Tools or something similar that allows you to sweep sine wave tones around 50 to 150 hz and I suspect you'll discover a driver that requires reconing. If you're lucky you may just discover that something has come loose in the enclosure and can be glued back down. Either way it's time to open it up and look inside.

[Mike Karseboom]

It's very unlikely that an amplifier would distort only under 100hz and very likely that a bass driver would so I'd start by pulling the low frequency driver and testing that by itself. Get a phone app like Audio Tools or something similar that allows you to sweep sine wave tones around 50 to 150 hz and I suspect you'll discover a driver that requires reconing. If you're lucky you may just discover that something has come loose in the enclosure and can be glued back down. Either way it's time to open it up and look inside.

Thanks for the reply.  I probably wasn't clear but the distortion was not just 100Hz and below.  I would say the distortion was more widespread through the whole frequency range.  But lowering the volume and taking out some low frequencies made it less noticeable.


I haven't had time for a sweep test but today I tightened all the screws everywhere.  I also gently pushed in on the LF driver and could not feel any problems.  Finally I cranked it up for 30 minutes in my basement with full range sound and it seemed fine.  That was in a cool basement.


I am going to put it out in the sun today (101 degrees predicted) and run it loud while I do some setup and see if getting it hot causes it to distort.

[Mike Caldwell]

Does it distort when it is cool and first turned on?

Pull the speaker, connect it to a known good power amp and do the sine wave test that Riley mentioned and listen for buzzing and or distortion.

Like wise you could connect a know good woofer to the woofer leads from the internal and listen to that.

Actually if the speaker is really cooked just pushing some on the cone you may feel and hear some grinding sounds.

Keep in mind that the JBL woofer in those is a 2 ohm woofer.

For testing any woofer will work just to hear what is coming from the amp.

[Brian Jojade]

Well, if you've got a pair of the speakers, it's easy enough to swap parts between them to narrow down troubleshooting.  Either swap amp modules or swap drivers between the two.

Of course, there's a very tiny risk that you have a blown amp that in turn blows the driver, but that's pretty rare.

[Mike Karseboom]

Ran the speaker fairly loud with some playback music in the hot sun for a few hours with the backplate facing  the sun.  It got pretty hot but I could not hear any distortion on that test.


Did the frequency sweeps slowly at fairly high volume and could not hear any problems.


Basically I have not been able to reproduce the distortion I was hearing.  Possibly it is because nothing seems to stress a speaker as much as an actual gig.  I will run it at the same gig next Saturday and see if I have a problem


I am starting to wonder if maybe my tired old X32 rack mixer might have some problems.  It has had a few strange sporadic anomalies in the last couple of years.  I have recently reset it to factory, gotten rid of all my presets, shows, scenes, etc. and updated to 4.09 firmware hoping to clear out any cobwebs. 


There are always some logical tests you wish you would have done in the moment but did not think to do.  If the problem happens again I will remember to do those tests.

[Matt Modica]

I am starting to wonder if maybe my tired old X32 rack mixer might have some problems.  It has had a few strange sporadic anomalies in the last couple of years.  I have recently reset it to factory, gotten rid of all my presets, shows, scenes, etc. and updated to 4.09 firmware hoping to clear out any cobwebs.  .

I had been thinking it might be your source rather than the speaker while reading thru this thread.

Either that or maybe a bad cable? Have you tried swapping the speakers (assuming there 2+)?

I've been running a rig w/ VRX tops/subs and SRX815P monitors for a couple years now and gone thru a handful of amp failures on the VRX, but none which produced the symptoms you're describing, The VRX live in rain bags and bake in the sun all day, yet I've never had an issue with them overheating. The only time I ever had to dignose an 'issue' with the SRX, it actually turned out to be a bad 1/4" cable jack as the culprit.

Hope this helps.

[Mike Karseboom]

Well I think I eliminated the X32 rack and Cable as the problem as well as any weird X32 setup I might have created.  Same gig with 2x speakers on sticks yesterday but with new X32 rack, different cable, different band. 


It seemed to start off fine but then after only 15 minutes or so I was hearing the same distortion from the "bad"  srx815p.  I unlinked the stereo mains and high passed the problem speaker around 150Hz and lowered the volume on that one.  That helped but I could still distinctly hear some audio issues.


It sort of sounds like what I would imagine severe IM distortion to  sound like.  Kind of a very fast warble in the low mids on top of the regular program material.  Hard to really quantify both the character and the affected frequencies in the live setting but definitely something that does not sound right.


Replaced the "bad" SRX815P with a PRX615p during the first set break and everything sounds good again.  Got rid of the high pass and volume compensation and returned the mismatched mains to stereo link and carried on with no problems.


So back to more home testing to figure out if it is a bad driver, a bad amp, or maybe some rodent has made a nest inside the box.  I guess I will get out Systune and do some FFT tests.  It is hard in my shop (basement) as there is a ton of stuff down there that vibrates loudly at all different frequencies.  Tough to do it outside without annoying the neighbors.  But if I can just reproduce the issue I will start swapping components with the "good" SRX815p to isolate the problem.

[Matt Modica]

Hmm maybe I stand corrected and it is the amp. If I were in your shoes, my next step would be to dive into both the enclosure and amp module itself for a visual inspection.

Tbh, I've never taken apart the amps on our SRX, but I've opened up our VRX amps a bunch. Here's a pic of a recent VRX932LAP amp failure, which was characterized by static coming from the tweeters even with no input connected. That white stuff is salt, which was all over the interior of the amp. We're not entirely sure how it happened; the rig lives on a seabourne vessel 5 months of the year, but none of the other 11 VRX amps had salt inside. Regardless, looking inside made it imediately obvious what the culprit is.

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