What does it sound like when incoming voltage clips the amp? - AVS Forum
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post #1 of 17 Old 03-25-2014, 06:10 PM - Thread Starter
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Can it sound like a clanking sound? My UXL's weren't really moving that much P-P, so I don't see how it could have been them bottoming out.

Amp is a CV5000. It's being fed by a UMC-1.

Amp gain knobs are at the max. MiniDSP is boosting by ~4-6dB, and the sub trim level on the UMC is at "+10" (whatever that means).
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post #2 of 17 Old 03-25-2014, 06:19 PM
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I think it can sound like clanking. I've had my system make very scary sounds and I've pegged it as clipping because there's no way my subs should bottom. They're in undersized boxes and severely underpowered too. The first time it happened I was very concerned. Its a rather frightening sound. As in frightened that your subs are bottoming. Not actually frightened.
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post #3 of 17 Old 03-25-2014, 06:37 PM - Thread Starter
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Quote:
Originally Posted by tuxedocivic View Post

The first time it happened I was very concerned. Its a rather frightening sound. As in frightened that your subs are bottoming. Not actually frightened.


This. I don't see how they could possibly have been bottoming, but it was still a scary sound.
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post #4 of 17 Old 03-25-2014, 06:50 PM
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Quote:
"What does it sound like when incoming voltage clips the amp?"
To me it sounds like a square wave - dirty, full of distortion
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post #5 of 17 Old 03-25-2014, 06:58 PM
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It has also been mention that an air leak can have similar sound.

Are you having issues? Trying to have your subs keep up with your mains?
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post #6 of 17 Old 03-25-2014, 07:30 PM
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Quote:
Originally Posted by Rebel975 View Post

Can it sound like a clanking sound?
Yes, it can, especially if it's a hard clip. It can sound similar to coil smack.
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post #7 of 17 Old 03-25-2014, 08:01 PM
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Quote:
Originally Posted by Rebel975 View Post

Can it sound like a clanking sound? My UXL's weren't really moving that much P-P, so I don't see how it could have been them bottoming out.

Amp is a CV5000. It's being fed by a UMC-1.

Amp gain knobs are at the max. MiniDSP is boosting by ~4-6dB, and the sub trim level on the UMC is at "+10" (whatever that means).

*poink"
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post #8 of 17 Old 03-25-2014, 08:03 PM
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The driver flutters as if its moving in free air and comes to a grinding halt.
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post #9 of 17 Old 03-25-2014, 08:37 PM
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You are probably clipping at 2 places and neither has to do with the input voltage. All movies I've seen have peaks near 0 dBfs. First, if you are doing a gain in the MiniDSP without reducing the entire level in the MiniDSP first, then you can clip the signal.

Second, any pro amp can handle 24 dBu on the inputs which is 12.28 volts. Some can even handle 28 dBu which is 19.5 volts. You aren't outputting that much voltage with your MiniDSP and UMC-1 combined. The issue is that the input sensitivity of the amp is 1.42 volts. If your gain levels are at max on the amp, then you are trying to output too much voltage. Turn down the gain knob to compensate for the input voltage.
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post #10 of 17 Old 03-25-2014, 09:26 PM - Thread Starter
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Quote:
Originally Posted by doublewing11 View Post

It has also been mention that an air leak can have similar sound.

Are you having issues? Trying to have your subs keep up with your mains?


I don't think so. Both subs have a layer of closed cell foam between the lip of the basket and the baffle. Also the speaker terminals and feet were very well sealed from the inside. I went kind of nuts with it TBH.


Quote:
Originally Posted by desertdome View Post

You are probably clipping at 2 places and neither has to do with the input voltage. All movies I've seen have peaks near 0 dBfs. First, if you are doing a gain in the MiniDSP without reducing the entire level in the MiniDSP first, then you can clip the signal.

Second, any pro amp can handle 24 dBu on the inputs which is 12.28 volts. Some can even handle 28 dBu which is 19.5 volts. You aren't outputting that much voltage with your MiniDSP and UMC-1 combined. The issue is that the input sensitivity of the amp is 1.42 volts. If your gain levels are at max on the amp, then you are trying to output too much voltage. Turn down the gain knob to compensate for the input voltage.



If I turn down the gain knobs on the amp- how do I compensate for the loss of bass? It seems that I have plenty of sub to spare, and should have plenty of amp, but yet I have trouble actually realizing it.
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post #11 of 17 Old 03-26-2014, 04:57 AM
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Quote:
Originally Posted by Rebel975 View Post

I don't think so. Both subs have a layer of closed cell foam between the lip of the basket and the baffle. Also the speaker terminals and feet were very well sealed from the inside. I went kind of nuts with it TBH.
If I turn down the gain knobs on the amp- how do I compensate for the loss of bass? It seems that I have plenty of sub to spare, and should have plenty of amp, but yet I have trouble actually realizing it.

If you turn down the gain knobs on the amp, then you can boost the subwoofer trim level in your pre/pro. I am not sure how a MiniDsp effects this, though. I would recommend reading that thread over at HTshack with regards to optimizing gain structure.
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post #12 of 17 Old 03-26-2014, 07:29 AM
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Quote:
Originally Posted by Rebel975 View Post

I don't think so. Both subs have a layer of closed cell foam between the lip of the basket and the baffle. Also the speaker terminals and feet were very well sealed from the inside. I went kind of nuts with it TBH.
If I turn down the gain knobs on the amp- how do I compensate for the loss of bass? It seems that I have plenty of sub to spare, and should have plenty of amp, but yet I have trouble actually realizing it.

First gain match your pro amp with the pre and then bring your subs close to your MLP, preferably near-field placement, to avoid boosting extra trim levels in the pre and still achieve required SPL.
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post #13 of 17 Old 03-26-2014, 09:42 AM - Thread Starter
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Quote:
Originally Posted by Martycool007 View Post

If you turn down the gain knobs on the amp, then you can boost the subwoofer trim level in your pre/pro. I am not sure how a MiniDsp effects this, though. I would recommend reading that thread over at HTshack with regards to optimizing gain structure.

Thanks. Will do. Here


Quote:
Originally Posted by braveheart123 View Post

First gain match your pro amp with the pre and then bring your subs close to your MLP, preferably near-field placement, to avoid boosting extra trim levels in the pre and still achieve required SPL.


They're already pretty close. It's a fairly small room. But I did the subwoofer crawl to see where the best placement would be.
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post #14 of 17 Old 03-26-2014, 09:53 AM
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Quote:
Originally Posted by Rebel975 View Post

I don't think so. Both subs have a layer of closed cell foam between the lip of the basket and the baffle. Also the speaker terminals and feet were very well sealed from the inside. I went kind of nuts with it TBH.
If I turn down the gain knobs on the amp- how do I compensate for the loss of bass? It seems that I have plenty of sub to spare, and should have plenty of amp, but yet I have trouble actually realizing it.
Your gain knobs should be as high as they can without causing a maximum signal to clip. You can set your gain using the Setting Power Amplifiers section in the Rane guide.

You still need to make sure you aren't clipping the signal in the MiniDSP. Since the LFE channel is always mastered with peak levels near 0 dBfs, then you should reduce the input channel level by the amount of gain you are going to add in the Parametric EQ section. If adding 4 dB of boost, then pull down the input channel slider by 4 dB.
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post #15 of 17 Old 03-26-2014, 01:44 PM - Thread Starter
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post #16 of 17 Old 03-26-2014, 01:52 PM
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The link for Setting Sound System Level Controls ( post 14 ) is mandatory for those starting out in Live sound where "blowing out" the Gain Structure is easy to do.
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post #17 of 17 Old 03-26-2014, 07:43 PM
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I found this example of clipping sounds:

Something like this (play this through your subwoofer, but not too loudly).
Clipping.zip 579k .zip file
Attached Files
File Type: zip Clipping.zip (579.2 KB, 1 views)
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