Speaker Cut Out

[safehands 0]

hi all,have got a residency in a town centre boozer,nice sounding system except the yamaha 18 inch subs tend to cut out,around an hour and a half into playing,i have wired them up together to get 4 ohms,and they are run bridged on a peavey cs800 x,which gives 1200w out in bridged mode,the yamaha are 600w rms each.

 

amp isnt clipping at all,it just goes off then comes on around 1 minute later,this gets worse towards the end of the night,is this a speaker protect or amp going thermal on me,.i play dance music all night,so its thumping non stop.if i turn the bass down a touch would this cure the problem or wil it just do the same thing,?cheers

[chris_gilly 0]

hi all,have got a residency in a town centre boozer,nice sounding system except the yamaha 18 inch subs tend to cut out,around an hour and a half into playing,i have wired them up together to get 4 ohms,and they are run bridged on a peavey cs800 x,which gives 1200w out in bridged mode,the yamaha are 600w rms each.

 

amp isnt clipping at all,it just goes off then comes on around 1 minute later,this gets worse towards the end of the night,is this a speaker protect or amp going thermal on me,.i play dance music all night,so its thumping non stop.if i turn the bass down a touch would this cure the problem or wil it just do the same thing,?cheers

 

check the amps fans. are they working?

it does sound like the amp thermal cut out my studiomaster 3500ax does this . some amps do have a limiter button on the back to stop it cutting out. you could put this off but i wouldnt recommend it as you can do more damage!!!!!

[safehands 0]

check the amps fans. are they working?

it does sound like the amp thermal cut out my studiomaster 3500ax does this . some amps do have a limiter button on the back to stop it cutting out. you could put this off but i wouldnt recommend it as you can do more damage!!!!!

 

hi dj cee,yeah fans working,had the amp serviced a few eeks bk,its like a mirror inside,no dust at all,think i will cut back on the bass tonight,then use another more powerful amp tommorow night.

[superstardeejay 0]

Check the DDT switch is on. This causes the amplifier to automatically reduce its output if it gets too hot to reliably work and shouldn't allow it to trip out.

 

Has it been serviced properly? Just because it's clean doesnt mean it's ok. Has it ever been repaired? Has it got its original Peavey transistors?

 

Are the speakers actually ok? You might have a voice coil gone, on bass duty you might not hear any difference. One speaker could be short in which case the amp will see a 2ohm load which may trip it. I once had a customer bring a mackie powered bass bin in for a 'service' because he said it would trip out half-way through the night. When I looked at it, the woofer was a direct short..it had continued to produce credible bass like this for months of discos until he'd 'decided' to have it 'serviced'. The burned-out woofer was a surprise to him.

 

A fellow engineer once showed me a Pioneer bass bin whose only fault symptom had been a resonance on The Prodigy-Breathe during the sustained low note. The driver was seized..so fried that the cone was jammed solid...yet it still produced bass nicely on anything except the Prodigy record and had done so in the nightclub for months!

 

Dont forget that running it bridged into 4 ohms means you're running it at maximum load, this is not a good idea even given the tank-like build quality of this old timer. Check the signal leads dont run too close to the speaker leads in case you have supersonic oscillation, unlikely but worth a mention.

Edited September 11, 2009 by superstardeejay

[safehands 0]

Check the DDT switch is on. This causes the amplifier to automatically reduce its output if it gets too hot to reliably work and shouldn't allow it to trip out.

 

Has it been serviced properly? Just because it's clean doesnt mean it's ok. Has it ever been repaired? Has it got its original Peavey transistors?

 

Are the speakers actually ok? You might have a voice coil gone, on bass duty you might not hear any difference. One speaker could be short in which case the amp will see a 2ohm load which may trip it. I once had a customer bring a mackie powered bass bin in for a 'service' because he said it would trip out half-way through the night. When I looked at it, the woofer was a direct short..it had continued to produce credible bass like this for months of discos until he'd 'decided' to have it 'serviced'. The burned-out woofer was a surprise to him.

 

A fellow engineer once showed me a Pioneer bass bin whose only fault symptom had been a resonance on The Prodigy-Breathe during the sustained low note. The driver was seized..so fried that the cone was jammed solid...yet it still produced bass nicely on anything except the Prodigy record and had done so in the nightclub for months!

 

Dont forget that running it bridged into 4 ohms means you're running it at maximum load, this is not a good idea even given the tank-like build quality of this old timer. Check the signal leads dont run too close to the speaker leads in case you have supersonic oscillation, unlikely but worth a mention.

 

SUPERSONIC OSCILATION,WHAT IS THAT LOL,anyway superstar,i used it last night,didnt cane the bass line and it never cut out once,i had it serviced by sound and light in leamington,bloke said its as good as new,yes i have the ddt switch set to on,yeah i no running in bridge mode isnt the best but havent got any choice at the minute as cant afford a behringer 2500,but i am getting there.on a brighter note,i said before bout my pro 15 compression drivers blowing,well i bought some soundlab 60w compression drivers,they are far superior to the peaveys,they are louder,clearer,and havent blown once,all for £20 the pair.

[superstardeejay 0]

SUPERSONIC OSCILATION,WHAT IS THAT LOL

 

Supersonic oscillation is where you run signal leads too close to your speaker leads. The high current in the speaker leads induces a similar smaller signal back into the signal leads which is amplified and forms a feedback loop similar to a microphone screech. Because of the small inductance and capacitance of this coupling, the feedback is at a frequency too high to hear (supersonic) especially if the amp is connected to bass bins without an active crossover, as the speakers wont reproduce a high frequency. It's rare, because most amps these days have supersonic protection, and the input stage of an amp is relatively low-gain, and most modern bass bins have low-pass crossovers that present a high impedance to high frequencies. However, it has been a known problem and can lead to unexplained amplifier overheating when using long cable runs; some amplifier handbooks explain this.

 

Like I say, its unlikely but in a forum like this our job is to enlighten, educate, entertain and inform...(like the BBC???)

 

 

 

 

Edited September 12, 2009 by superstardeejay