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Luke's basic amplifier tests


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#241 lukeamdman

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Posted 25 January 2017 - 05:48 PM

I know this is old but did you happen to test this 4 x 4 Ohms (all four channels driven, not just two)?

 

Sorry no.  My testing rig is limited to 2 channels.  



#242 lukeamdman

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Posted 25 January 2017 - 05:50 PM

Ricci/Kyle, can this thread be pinned?  Maybe replace the "new forum for bass gear" pinned thread?



#243 lukeamdman

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Posted 26 January 2017 - 03:56 PM

stormwind13 might be bringing over a "Monster Power" brand amp for testing, and apparently the factory specs are underrated so it should be interesting.  



#244 Stormwind13

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Posted 02 February 2017 - 03:46 AM

Probably Saturday if you're around.

#245 lukeamdman

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Posted 15 February 2017 - 04:14 PM

Probably Saturday if you're around.

 

Dude did you already sell this thing?!



#246 Stormwind13

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Posted 20 February 2017 - 08:45 PM

yes



#247 lukeamdman

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Posted 24 February 2017 - 03:40 PM

yes

 

Make it up to me by bringing over a XLS-5000  :)



#248 Stormwind13

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Posted 26 February 2017 - 04:20 PM

Soon. 



#249 lukeamdman

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Posted 26 March 2017 - 01:57 AM

I was asked to test this over 2 months ago but I've been a huge slacker:

 

http://www.prosoundw...wer_delivered_/

 

The basic theory is that if an amp is driven in stereo and both channels are producing the exact same signal, both channels are also drawing current from the power supply at the exact same time/interval.  The author of the article claims that if you parallel the inputs but flip the polarity on the input of one of the channels, causing the sine waves from each channel to be exact opposites, the channels are now "taking turns" drawing current from the power supply.  

 

For these tests I used a CC4000, wired my test rig for 3.4ohm per channel, and used a 30hz sine wave for a duration of 2 seconds.  I pushed the amp as far as it could go while still producing a clean sine wave.    

 

For test #1, I used an XLR y-splitter cable to parallel the same signal to the inputs and the amp was in stereo mode.  

 

For test #2, I put the amp in bridged mode and didn't make any changes to any cabling.  According to the article, all this switch does is reverse the polarity going to the B channel of the amp.

 

 

Results:

 

Capture_zpstdxoniqp.png

 

 

Test #1:

 

DS1Z_QuickPrint3_zpsm9um0dtq.png

 

 

Test #2:

 

DS1Z_QuickPrint4_zpsvlpuz4zr.png

 

 

 

 

Really no difference at all, certainly not the 5-15% increase claimed in the article.  In fact, I think test #2 has slightly more distortion in the wave form when pushed to the same 190Vpp.



#250 Ukko Kari

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Posted 26 March 2017 - 02:45 AM

I was asked to test this over 2 months ago but I've been a huge slacker:

 

http://www.prosoundw...wer_delivered_/

 

The basic theory is that if an amp is driven in stereo and both channels are producing the exact same signal, both channels are also drawing current from the power supply at the exact same time/interval.  The author of the article claims that if you parallel the inputs but flip the polarity on the input of one of the channels, causing the sine waves from each channel to be exact opposites, the channels are now "taking turns" drawing current from the power supply.  

 

For these tests I used a CC4000, wired my test rig for 3.4ohm per channel, and used a 30hz sine wave for a duration of 2 seconds.  I pushed the amp as far as it could go while still producing a clean sine wave.    

 

For test #1, I used an XLR y-splitter cable to parallel the same signal to the inputs and the amp was in stereo mode.  

 

For test #2, I put the amp in bridged mode and didn't make any changes to any cabling.  According to the article, all this switch does is reverse the polarity going to the B channel of the amp.

 

 

Results:

 

Capture_zpstdxoniqp.png

 

 

Test #1:

 

DS1Z_QuickPrint3_zpsm9um0dtq.png

 

 

Test #2:

 

DS1Z_QuickPrint4_zpsvlpuz4zr.png

 

 

 

 

Really no difference at all, certainly not the 5-15% increase claimed in the article.  In fact, I think test #2 has slightly more distortion in the wave form when pushed to the same 190Vpp.

 

I read that article many years ago, and in some cases, it can be applicable. Keep in mind that you are also driving essentially a dummy resistor load, and the results may be different driving a reactive load, where back EMF is reflected on the power supply.


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#251 lukeamdman

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Posted 26 March 2017 - 04:05 AM

I read that article many years ago, and in some cases, it can be applicable. Keep in mind that you are also driving essentially a dummy resistor load, and the results may be different driving a reactive load, where back EMF is reflected on the power supply.

 

I'm sure someone could find an application for this, but the more I think about it the less it seems worth the hassle.  Wouldn't it be easier to series the load and use the amp in bridged mode like you normally would, and skip the parallel inputs and reversing the polarity on one of the outputs?  

 

Even in the best case scenario of a 15% gain, we're talking about a fraction of a single dB of gain.  



#252 Ukko Kari

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Posted 26 March 2017 - 06:20 PM

I'm sure someone could find an application for this, but the more I think about it the less it seems worth the hassle.  Wouldn't it be easier to series the load and use the amp in bridged mode like you normally would, and skip the parallel inputs and reversing the polarity on one of the outputs?  

 

Even in the best case scenario of a 15% gain, we're talking about a fraction of a single dB of gain.  

 

The real answer is it depends. I agree that it may only be a small fraction of a difference. It would be interesting to note the input power to the amplifier to see if the efficiency / breaker utilization changes any, which may be a bigger deal for large systems with racks and racks of amplifiers running off a generator, or in a venue where power is subject to droop. ( older wiring, smaller services )






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