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Author Topic: STX825 blown HF drivers  (Read 4179 times)

Nitin Sidhu

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STX825 blown HF drivers
« on: March 30, 2013, 01:41:18 pm »

Hello!

I have been hearing a lot of local reports of the HF driver with the 825 blowing themselves out even on moderate level operation. I always tend not to pay much heed to such reports.

We were contracted to provide SR and engineering services for a small festival in the hills, and I really liked how the 825 sounded when i demoed them, so decided to spec the same for the festival. We don't have any 835's around, and I have an eye on them. The venue does not really more a pair in all, we sent in a pair a side, to be safe.

I made presets for the ITech amplifiers, copied eq setting off the XTI, tansfer compared them with the HD presets, and it sounded great!

To be cautious, I setup a system architect custom panel to monitor all inputs and outputs, and GR meters. the RMS and Peak limiters are set to 1/3 of continuous power, and 3/4th of program power respectively.

My partner is now in the hills engineering, last night, midway, he was very impressed with te rig. Loud and hi-fi, without him hitting a single clip or getting the GR into action. However,
During the last act, he reports one HF driver has gone down.

As of midway today, 2nd and last day, he has lost two more HF drivers, and is now happily running the show of just 1 HF, loud enough to cover the small area. He hopefully will manage though the last act. We have taken some 712's off monitor duty as an SOS.

System :

4 x STX825
2 x ITech 4000
4 x SRX728
2 x ITech 6000

Any ideas ?

Thank you for the time.

Regards,
Sidhu
« Last Edit: March 30, 2013, 01:43:29 pm by Nitin Sidhu »
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Art Welter

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Re: STX825 blown HF drivers
« Reply #1 on: March 30, 2013, 02:01:55 pm »

Hello!

I have been hearing a lot of local reports of the HF driver with the 825 blowing themselves out even on moderate level operation. I always tend not to pay much heed to such reports.

To be cautious, I setup a system architect custom panel to monitor all inputs and outputs, and GR meters. the RMS and Peak limiters are set to 1/3 of continuous power, and 3/4th of program power respectively.

My partner is now in the hills engineering, last night, midway, he was very impressed with te rig. Loud and hi-fi, without him hitting a single clip or getting the GR into action. However,
During the last act, he reports one HF driver has gone down.

As of midway today, 2nd and last day, he has lost two more HF drivers, and is now happily running the show of just 1 HF, loud enough to cover the small area. He hopefully will manage though the last act. We have taken some 712's off monitor duty as an SOS.

System :

4 x STX825
2 x ITech 4000
4 x SRX728
2 x ITech 6000

Any ideas ?

Thank you for the time.

Regards,
Sidhu
Could be a batch of defective  diaphragms in your local pool of cabinets.
Need to inspect them to tell the exact cause of death.

The 2453H driver used in the STX825 is pretty tough, but with highly compressed music with concentrated HF level above the crossover point it still would be possible to burn them in passive mode with the RMS and Peak limiters set to 1/3 of continuous power, and 3/4th of program.

They should be quite loud before they burn, any idea of what levels were being run "A" scale, at what distance?
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Tim McCulloch

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Re: STX825 blown HF drivers
« Reply #2 on: March 30, 2013, 02:16:41 pm »

Sidhu, I take it you are bi-amping the 825s?  If so I suspect an error in the entry of the settings into the ITech, barring any product defect.
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Nitin Sidhu

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Re: STX825 blown HF drivers
« Reply #3 on: March 30, 2013, 02:22:05 pm »

Could be a batch of defective  diaphragms in your local pool of cabinets.
Need to inspect them to tell the exact cause of death.

The 2453H driver used in the STX825 is pretty tough, but with highly compressed music with concentrated HF level above the crossover point it still would be possible to burn them in passive mode with the RMS and Peak limiters set to 1/3 of continuous power, and 3/4th of program.

They should be quite loud before they burn, any idea of what levels were being run "A" scale, at what distance?

Not loud. No compressed music, a mix of folk, blues and fusion.

Cant say bout level, will ask, but I can tell from last year, it was a very melow event.

Regarding the limiters, conservative as they might be, they were not being put into action, so full dynamics.

I would not know what to inspect, and have come to not trust local service centers. Possible for me to send a picture across, any help ?

Thank,
Sidhu
« Last Edit: March 30, 2013, 02:27:38 pm by Nitin Sidhu »
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Nitin Sidhu

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Re: STX825 blown HF drivers
« Reply #4 on: March 30, 2013, 02:23:03 pm »

Sidhu, I take it you are bi-amping the 825s?  If so I suspect an error in the entry of the settings into the ITech, barring any product defect.

Passive.

4 channels of IT4K running 4 cabinets @ a 4ohms load each.

Sidhu
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Nitin Sidhu

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Re: STX825 blown HF drivers
« Reply #5 on: March 30, 2013, 02:25:52 pm »

Also, to makeself clear, we dont own this inventory, and it is a cross rent.

Even more embarrassing.

To state that we treat cross rented gear better than our own would be an understatement.


Sidhu
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Nitin Sidhu

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Re: STX825 blown HF drivers
« Reply #6 on: March 30, 2013, 02:35:20 pm »

Sidhu, I take it you are bi-amping the 825s?  If so I suspect an error in the entry of the settings into the ITech, barring any product defect.

Here the Device file for the ITech if anyone cares to review.

Thanks again!

https://docs.google.com/file/d/0B7sbO0TYr9ryU25OdHVjZzdFd1E/edit?usp=sharing

Preset number 9 was being used.

Sidhu
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David Sturzenbecher

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Re: STX825 blown HF drivers
« Reply #7 on: March 30, 2013, 03:29:17 pm »


Preset number 9 was being used.

Sidhu

The limiters appear to be set really conservative...but if you weren't touching them...
You did forget to rename your preset...but I am guessing you would be able to tell if you were sending the 4880 SUB signal.

I don't see anything glaringly wrong.
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Bob Leonard

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Re: STX825 blown HF drivers
« Reply #8 on: March 30, 2013, 07:09:09 pm »

A quick look at file #9 w/ SA shows all devices bypassed or off and a crossover center frequency of 1.2khz. My take on this preset is that it's for a bi-amped cabinet. Also, if you've not done anything with SA and the parameters for this preset then none of the modules are active by default.

Again, this is my take on the subject based on what I see in SA and not seeing any details in your post as to what you have done with these settings.
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David Sturzenbecher

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Re: STX825 blown HF drivers
« Reply #9 on: March 30, 2013, 08:08:00 pm »

A quick look at file #9 w/ SA shows all devices bypassed or off and a crossover center frequency of 1.2khz.

Bob, I attached a screenshot of what I am seeing. Both channel 1 and 2 appear to be the same.
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