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Author Topic: Speaker Question  (Read 1043 times)

Bob Burke

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Speaker Question
« on: July 08, 2014, 07:14:40 am »

  Another stupid question:

  I'm using a QSC PLX1804 (550 @ 8 ohms/ 800 @ 4 ohms) with two Yamaha S115v's on channel 1, and two Peavey PR-12's on channel 2. The Yamahas are rated at Power handling 500 watts program, 1,000 watts peak, and the PR-12 are rated at 400 watts program/ 800 watts peak.

  Since they are daisy-chained, two per channel, the amp is seeing a 4 ohm draw, correct?  Mike Pyle, who sold me the QSC, said it was a great match for the Yamahas, which it is. My concern is for the Peaveys I don't want to blow the tweeters (again*). I usually run the gain on channel 1 at about 1 O'clock, and the monitors at about noon. The LED cluster in the amp never shows clipping, it occasionally shows at the -10 dB meter mark. Are these levels safe for my speakers? We're never sick loud or anything, and only vocals and backing tracks through the system.

  Is there a better way to do this, or should I get a separate amp to run the monitors?

* p.s. - Could I have blown the Peavey tweeters at that power level? I didn't think they were getting too much signal, but they were blown when the talking monkey at Guitar Satan "tested" them (with a 9-Volt battery across a 1/4" phone plug, which I understand will blow tweeters)


Thanks,

Bob

David Parker

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Re: Speaker Question
« Reply #1 on: July 08, 2014, 08:35:25 am »

  Another stupid question:

  I'm using a QSC PLX1804 (550 @ 8 ohms/ 800 @ 4 ohms) with two Yamaha S115v's on channel 1, and two Peavey PR-12's on channel 2. The Yamahas are rated at Power handling 500 watts program, 1,000 watts peak, and the PR-12 are rated at 400 watts program/ 800 watts peak.

  Since they are daisy-chained, two per channel, the amp is seeing a 4 ohm draw, correct?  Mike Pyle, who sold me the QSC, said it was a great match for the Yamahas, which it is. My concern is for the Peaveys I don't want to blow the tweeters (again*). I usually run the gain on channel 1 at about 1 O'clock, and the monitors at about noon. The LED cluster in the amp never shows clipping, it occasionally shows at the -10 dB meter mark. Are these levels safe for my speakers? We're never sick loud or anything, and only vocals and backing tracks through the system.

  Is there a better way to do this, or should I get a separate amp to run the monitors?

* p.s. - Could I have blown the Peavey tweeters at that power level? I didn't think they were getting too much signal, but they were blown when the talking monkey at Guitar Satan "tested" them (with a 9-Volt battery across a 1/4" phone plug, which I understand will blow tweeters)


Thanks,

Bob
The PR12 peaveys have a light bulb inside that is supposed to protect the tweeters. Are you sure the tweeter is blown and not just the bulb?
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David Parker

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Re: Speaker Question
« Reply #2 on: July 08, 2014, 08:38:19 am »

  Another stupid question:

  I'm using a QSC PLX1804 (550 @ 8 ohms/ 800 @ 4 ohms) with two Yamaha S115v's on channel 1, and two Peavey PR-12's on channel 2. The Yamahas are rated at Power handling 500 watts program, 1,000 watts peak, and the PR-12 are rated at 400 watts program/ 800 watts peak.

  Since they are daisy-chained, two per channel, the amp is seeing a 4 ohm draw, correct?  Mike Pyle, who sold me the QSC, said it was a great match for the Yamahas, which it is. My concern is for the Peaveys I don't want to blow the tweeters (again*). I usually run the gain on channel 1 at about 1 O'clock, and the monitors at about noon. The LED cluster in the amp never shows clipping, it occasionally shows at the -10 dB meter mark. Are these levels safe for my speakers? We're never sick loud or anything, and only vocals and backing tracks through the system.

  Is there a better way to do this, or should I get a separate amp to run the monitors?

* p.s. - Could I have blown the Peavey tweeters at that power level? I didn't think they were getting too much signal, but they were blown when the talking monkey at Guitar Satan "tested" them (with a 9-Volt battery across a 1/4" phone plug, which I understand will blow tweeters)


Thanks,

Bob
the panel on the back that has the connectors has the crossover underneath it. Take that panel off and the light bulb is on the underside. The guy at guitar satan should have known that.
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David Sturzenbecher

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Re: Speaker Question
« Reply #3 on: July 08, 2014, 08:44:47 am »

Why would you expect them to know anything? Your only setting yourself up for disappointment.


Sent from my iPhone using Tapatalk
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Bob Burke

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Re: Speaker Question
« Reply #4 on: July 08, 2014, 08:58:09 am »

The PR12 peaveys have a light bulb inside that is supposed to protect the tweeters. Are you sure the tweeter is blown and not just the bulb?



  I probably should have checked that, but was afraid of voiding the warranty. The tech I took them to yesterday said it might just be the light bulb. Fingers crossed.

  Any advice on the power vs. wattage?


Thanks.

Bob Leonard

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Re: Speaker Question
« Reply #5 on: July 08, 2014, 09:06:55 am »

I would go a step further and ask what 1/4" jack attached to what. That type of test isn't reliable, and at the very least needs to be run with a tap of the leads attached directly to the compression driver.

Remove the back plate and check for a "bulb" safety device. If you find one take your meter and check for continuity. Open = bad, closed = good. If that's not enough then take the cabinets to a speaker shop that has a signal generator. Have them test through the crossover, and then through each driver.

400 watts isn't enough to kill those cabinets if you can keep them from clipping and the system is powered off and on properly. Keep in mind though that not enough power can be a worse condition than too much power. 2x times the long term rating is a good rule to follow.
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David Parker

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Re: Speaker Question
« Reply #6 on: July 08, 2014, 09:07:21 am »



  I probably should have checked that, but was afraid of voiding the warranty. The tech I took them to yesterday said it might just be the light bulb. Fingers crossed.

  Any advice on the power vs. wattage?


Thanks.
those speakers are not as durable as the better peavey lines. When you take that back panel off you'll see that the components are tiny. I had one of mine blow a bulb. I would think that you would be hard pressed to hurt them on monitor duty, since feedback would be a problem before you overpowered them.
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Bob Burke

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Re: Speaker Question
« Reply #7 on: July 08, 2014, 09:29:15 am »

I would go a step further and ask what 1/4" jack attached to what. That type of test isn't reliable, and at the very least needs to be run with a tap of the leads attached directly to the compression driver.

Remove the back plate and check for a "bulb" safety device. If you find one take your meter and check for continuity. Open = bad, closed = good. If that's not enough then take the cabinets to a speaker shop that has a signal generator. Have them test through the crossover, and then through each driver.

400 watts isn't enough to kill those cabinets if you can keep them from clipping and the system is powered off and on properly. Keep in mind though that not enough power can be a worse condition than too much power. 2x times the long term rating is a good rule to follow.



Bob,

  The guy plugged a 1/4" cable right into the speaker input on the back of the speaker, then contacted the tip of the other end to the sleeve with the 9V poles. I later learned that you can test woofers that way, but never tweeters. I don't think they were blown at all when I brought them in (to return them) - I think this idiot did that.

  I have them at the shop now.

  The power thing - those PR-12 are getting 800 watts at 4 ohms, daisy-chained. I'm asking if it's safe to run them at 1/2 the amp level (400 watts?).


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Chuck Simon

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Re: Speaker Question
« Reply #8 on: July 08, 2014, 09:57:11 am »


The power thing - those PR-12 are getting 800 watts at 4 ohms, daisy-chained. I'm asking if it's safe to run them at 1/2 the amp level (400 watts?).
Thanks.

No, Bob L. is correct.  You are sending enough power to generate 800 watts between TWO speakers, so they are getting 400 apiece.  The "amp level" you are talking about actually just attenuates the input and does not limit the power output of the amp. No matter what you set the "amp level" at, you can still drive the amp to it's rated output and beyond if not careful.
« Last Edit: July 08, 2014, 10:09:28 am by Chuck Simon »
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Paul G. OBrien

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Re: Speaker Question
« Reply #9 on: July 08, 2014, 10:14:43 am »


  The power thing - those PR-12 are getting 800 watts at 4 ohms, daisy-chained.

No.. they aren't. The amp they're connected to is capable of delivering 800w but at -10db on the meters the speaker are only seeing 80w.
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