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sixer

Peavey IPS 150 Static

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Hello good people:

I recently acquired a set of NOS Acoustic Research AR 102's that I hooked up to a Peavey IPS 150 amp and all was good for about a month now the Peavey is causing static in both speakers with the inputs connected or disconnected, I have never had an amp like this opened up so is this a common problem and if so can it be fixed.

The sound is intermittent and sounds like this "zzxpchkshshshkzzzchchchkk" (sorry no recording device)

Sixer

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Are you certain the impedance was matched between the output of the amp and the speakers?  I do not know the specs on the AR 102, so I don't know if they can handle the output from the Peavey, wattage wise.

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I didn't know anything about either, but I found a few things.

The AR-102 is rated at 65 watts. The Peavey is rated at 85 watts output. They seem fairly well matched, to me. As always, if turned up until either distorts, then bad things can happen, and may have.

The Peavey is a bit of an odd duck. A solid state amp with an impedance selector? Unusual, to say the least. The ARs are specced at 6 ohms, so neither 4 nor 8 will be a perfect match, but I don't think that should be an issue if set on 4. If the selector was set on 8 and the volume was up high, that 'might' cause an issue. 16 would be worse.

Here's what I'd do. First, I'd make sure all of the connections were tight. Static still there? Then, I'd connect a different amp to the ARs and see if the problem persisted. I'd connect the Peavey to a different set of speakers. At this point, my guess (and it's only a guess) is that the problem is in the amp. Narrow down the possibilities, then proceed accordingly.

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Posted (edited)

Sorry guys, I  was fishing and fishing comes first , as your suggestions (Isaac42)  I am trying to source a second amp/speaker combo as  all of my other speakers are powered monitors, I will have time this week to open the amp up to clean and reseat any plugs. These AR 102's (redbox improved) have a 4 ohm tweeter and a 8 ohm woofer so, impedance of 2.6666666 ohms, below the 4 ohm setting of the amp, is this a serious problem? ( where did you find a 6 ohm spec?? I cannot find any info) This setup sounds great except at an idle when I hear the static noise,

Thanks for the help...

Lonny

Edited by sixer
spellin

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2 hours ago, sixer said:

These AR 102's (redbox improved) have a 4 ohm tweeter and a 8 ohm woofer so, impedance of 2.6666666 ohms, below the 4 ohm setting of the amp, is this a serious problem? ( where did you find a 6 ohm spec?? I cannot find any info)

isaac42 will undoubtedly be along shortly but in the meantime here's a link to the AR-102 specs: http://www.aphenos.net/electronics/speakers/klh/all_ar.htm (scroll down a bit more than halfway, you'll see the AR-102). Neither driver shows its rated impedance to an amp all the way across its working range, those are averages. The folks who designed and built the speakers knew what they were doing rating them for 6 Ohms. Take the 6 Ohm figure and work with it.

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Hello DeepEnd:

Thanks for the link, I've been looking for info on these for about a month now.  6 ohms does sound way  better than 2.666 ohms. I know  of the AR brand so when I saw these new in the box

I had to have them and the Peavey IPS 150 was a good match but is now giving me undesirable results with the static problem . I will know more when I start testing as isaac42 suggested

also if you or any of the others here know about the red box improved designation  I would be interested..

sixer

IMG_4760.JPG

IMG_4761.JPG

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Deepend is correct about the impedance. It's a bit more complicated than simply combining the impedances (but at least you know how to do that correctly!). I'd go with AR's impedance.

I tend to forget that not everyone has scads of drivers and speakers laying around the house, as I do. And a few amps. And...

No idea about the Red Box thing. I might have a chance to look later, but it's time to head out for band practice.

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Thanks guys, I am a diesel mechanic by trade and just started gathering a little knowledge about all things sound related  so these forums are a big help. 

I have a line on some equipment I can borrow to test with then we will see how to proceed from there. As to the impedance, does the crossover change the

impedance of a driver? why such a difference from there specs to mine?

sixer

 

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5 hours ago, sixer said:

Thanks guys, I am a diesel mechanic by trade and just started gathering a little knowledge about all things sound related  so these forums are a big help. 

I have a line on some equipment I can borrow to test with then we will see how to proceed from there. As to the impedance, does the crossover change the

impedance of a driver? why such a difference from there specs to mine?

sixer

I don't know how complex the crossover in the AR is, but the short answer is no, it doesn't change the drivers' impedances. What it does is change the impedance the amplifier sees. A very simple crossover puts an inductor in series with the woofer and a capacitor in series with the tweeter. The impedance of the inductor goes up with frequency, and the impedance of the capacitor goes down with frequency. At low frequencies, the high impedance of the cap means that the amp doesn;'t see the tweeter, just the woofer. At high frequencies, the opposite occurs. Somewhere in the middle, it sees both, but it also sees the impedances of the crossover elements. Add to that the fact that driver impedances are themselves complex (an 8 ohm driver will be exactly 8 ohms at maybe 3 frequencies), and the result is that the rated impedance of a speaker is pretty much a ballpark figure.

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Isaac42  

Thanks for the info, looks like I'm going back to school because I want to understand a little more about this...

sixer

15 hours ago, isaac42 said:

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55 minutes ago, sixer said:

Isaac42  

Thanks for the info, looks like I'm going back to school because I want to understand a little more about this...

sixer

There's a lot to understand. Good luck, and don't hesitate to ask questions. I'll help all I can.

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Here's a fairly typical impedance vs. frequency plot of a two way woofer+tweeter loudspeaker. It's probably a nominal "8 Ohm" speaker but you'll notice it varies quite a bit. This is what the amp "sees."

Impedance.gif.f97e23dfde0d50017d34e94723408853.gif

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Posted (edited)

Hey guys (girls)

Thanks for the help I think i got a handle on it now, I have a technical background but speaker impedance was  not part of the curriculum.

As with troubleshooting anything, as soon  as I was ready to test the amp/speakers it/they  stopped making noise??? so I will sign off for now but will be back.

Sixer

Edited by sixer
spellin

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