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Vocals causing clipping & amp cuts out


Toshy27

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hi, I've just bought a new amp and speakers. Thomann TSA 4000, 1500w @ 4ohm. Peavey RX5 500w tops and peavey rx118 500w subs.Behringer mixing desk (had for 1 year). I'm running two guitars which DI no problem. 6 drum mics, again, no problem. 3 vocals.....big problem, especially lead vox

Slightest increase in voice....big notes etc, causes the amp to cutout for a second.

The master volume on desk is only on about half. Pushing it any higher causes clipping.

Gigged last night after a 2 hr sound check trying to fix it. Lowering vox gain, turning up channel. Turning up gain and lowering channel. Trial n error on eq. Monitors unplugged. Etc etc. spent the gig with my eyes fixed on the amp's LED as can't hear it cutting out on stage as monitors (powered) are unaffected. Only way we could avoid cut outs was keeping master below halfway. No cutouts but we were way too quiet for the venue.

Any ideas? The band are blame the new gear but I think it's just poor set up. Probably has always been the case but old amp didn't have limiter so never knew.

Should I compress vox? Stay low on master on desk but set up speakers/amp in bridge mode?

I can't override limiter on amp. Amp vol settings are on full. Lowering them had no effect at all and I believe they should be on full anyway (??)

Please, any ideas or suggestions would be great

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How are you wiring your speaker outputs? I don't know much about Peavey gear but if you are talking about the HiSys range of 5RX and 118RX it looks like the 5RX's are 4ohm and the 118RX are 8ohm which a quick calculation means 2.6ohms at the amp which is an unsupported config according to the Thomann website. This is assuming you are wiring them in parallel from Sub to top.

 

P

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The sub only appears to have a low pass filter, no HPF for the tops so that may well be the problem. Can you try the rig without the subs? That would bring the speaker impedance back into spec for the TSA4000. If that works then consider a second amp for the subs (which will give you some redundancy too, with a spare/second power amp a failure doesn't stop the show).

 

Bridge mode is a non starter as the amps minimum load impedance is 8 ohms.

 

The amp's 'volume controls' are attenuators and should reduce the signal getting to the input stage of the amp when turned down. It's fine to run them at max. The clipping you hear when you raise the desk master fader above half, is it audible in the headphones output? We had an issue with a Berry Eurodesk clipping when we drove the groups too hard.

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Probably as said above: impedance mismatch. B-)

 

What do the LEDs on the amp "say" when you hear clipping and/or cutout, respectively?

 

That you can't override the limiter on the amp is good. It protects both speakers and amp, so that is a good thing.

 

Re compression on vocals: yeah, good idea in most cases, but I don't think it causes your problem.

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If the amp is in good condition and still goes into power down self protect you are over driving it or you've got the speaker impedance wrong.

 

Can you change the set-up to one speaker per amp output and make sure that the amps are capable of driving the load you want to apply.

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How are you wiring your speaker outputs? I don't know much about Peavey gear but if you are talking about the HiSys range of 5RX and 118RX it looks like the 5RX's are 4ohm and the 118RX are 8ohm which a quick calculation means 2.6ohms at the amp which is an unsupported config according to the Thomann website. This is assuming you are wiring them in parallel from Sub to top.

 

P

 

 

Hi, all speakers are 4 ohm. I sent the speaker specs to Thomann before I bought the amp to make sure.

 

Probably as said above: impedance mismatch. B-)

 

What do the LEDs on the amp "say" when you hear clipping and/or cutout, respectively?

 

That you can't override the limiter on the amp is good. It protects both speakers and amp, so that is a good thing.

 

Re compression on vocals: yeah, good idea in most cases, but I don't think it causes your problem.

 

Not sure about the impedance mismatch. All speakers are 500w at 4 ohm (confirmed)

 

Clipping isn't audible. Sympton is the amp cuts out for a second. so the LEDs on from of amp jump to red and the amp cuts out momentarily. No clips or bangs etc,

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Can you confirm the model numbers as per the label on the back of the cabs? Also how you are wiring them as per my message above.

 

Also try as per suggestion above to only have 1 top per channel and see if that fixes things?

 

Have the cabs ever had replacement drivers? Could you measure the impedance with a meter?

 

To me it seems the only logical conclusion is the impedance is wrong? Unless the amp is simply faulty!

 

P

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Pic of panel on back of sub. 500w @ 4ohm and has hi-pass output.

 

 

http://www.4shared.com/download/ZmfaEfTgce/3_online.jpg?lgfp=3000

 

Model numbers 5RX mains and 118RX subs - all 500w continuous, 1000w program, 2000w peak, Black Widow Equipped

 

Connecting with speakons. out from channels A & B on amp into mains left input. then running second speakon from main right connector to left connector on subs. so running mains to subs - not subs to mains (as per my previous rig)

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Okay the pic for the sub is great but my other questions still stand...

 

Can you confirm how you are connecting your sub/tops to the amp?

 

I am going to assume it is 2 core 1+/1- to sub and then a custom cable of 2+/2- to 1+/1- on the top from the sub hi-pass output.

 

Also what about replacement drivers?

 

Checking the impedance with a meter?

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so running mains to subs - not subs to mains (as per my previous rig)

 

There's your problem I think. The main speakers will not have a low pass output so you're effectively connecting your 4ohm speakers in parallel, giving 2 ohms, which the amp does not like one bit.

 

Try running into subs firts, then hi pass out to the main speakers. That way, the crossover in the sub should let the amp "see" 4 ohms which will make it happy!

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Maybe I'm wrong about the 1+/1- wiring on the subs then, the subs clearly state that the Hi Pass output to the tops is on 2+/2- so you need to find out how the tops Speakons are wired make some cables up that connect 2+/2- at the sub end to whatever the tops need 9 colour code them so you don't mix them up or connect them wrong way round). Alternatively contact Peavey and ask for their advice on exactly which cables you need to connect your tops to your subs.

 

Edit :-to acknowledge PDH ref to subs wiring

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