PQM 13 is louder at 1300w than UKP2100x at 2100w?! |
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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Posted: 26 August 2016 at 5:40pm |
I thought I'd try bridging my two UKP2100X amps into my 8r 18Sound 18NLW9000 cubo subs.
Infact, I ran one of them off my PQM13 and one off a Matrix to do an AB test to see which one would ruffle my hair more. Both amps were ofcourse seeing 8r I was surprised that the PQM13 was making the driver move noticeably more air at 1300w than the Matrix could at 2100w! What is going on here? Also the lowest notes didn't really come across well from the Matrix. I run all my amps at 0.775v so I had to boost the band on the ultradrive quite a bit for the Matrix. I first tried boosting by 8.8DB then by 10DB, then by 13DB just to get the amp just below clip. Even then, it didn't seem as loud as the PQM13. Here are the voltage gains for the matrix: Stereo mode: no load: 1.35V 8R: 1.25V 4R: 1.15V Mono and "bridge" mode. no load: 2.6V 8R: 2.40V 4R: 2.15VSo was I boosting the band enough for the Matrix at 10DB extra? The output meters on the amp seemed to think so... I've never been good at working out DB vs Voltage so if someone could check what the DB difference is between 0.775v and 2.40v that would be great. I also wasn't sure of the limiter setting on the ultradrive for this band either... I guessed it'd be somewhere around -12? I run a cloud CX335 (set to limit at 0.775v) before the ultradrive anyway but I strill run the ultradrive limiters as I'm a cautious sort of guy. I had the switch on the back of the matrix amps in Bridge, and was only using channel A. I then swapped the cables into the other Matrix and got the same results, so it's not that the amp is faulty. So yeah, bit confused... Any help much appreciated. |
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Timebomb
Old Croc Joined: 11 October 2004 Location: Lancaster Status: Offline Points: 2716 |
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Input sensitivity on the matrix may not be set right, possibly on both amps, try measuring output voltage?
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James Secker facebook.com/soundgearuk
James@soundgear.co.uk www.soundgear.co.uk |
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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I sent one of them off to Matrix to specifically determine how much juice the input stage needs to make full power in the different modes because the information is not available anywhere on the Internet. . And i don't trust amp meters that much!
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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How would I measure the output voltage safely and how much should I be looking for? With pink noise?
Thanks for the reply |
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Timebomb
Old Croc Joined: 11 October 2004 Location: Lancaster Status: Offline Points: 2716 |
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If you use pink noise you will need a true rms volt meter, if you use a sine wave a normal volt meter should be fairly accurate, if you keep increasing the input signal you will find a point where your output voltage stops going up at the same rate as your input voltage (in dB not volts), that will roughly be your clip point, and (should) correspond to your clip led. To do it more accurately you will need a scope, or a distortion analyzer. you can do it with the amp un loaded, but the clip point will change a bit depending on load.
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James Secker facebook.com/soundgearuk
James@soundgear.co.uk www.soundgear.co.uk |
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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I'll download some sine waves... 1khz, 80hz etc? I just tried bridging my PQM 13 as well, and failed! Again it sounded kind of thin and definitely not as loud as it is in stereo. Like something is out of phase somewhere. In bridge the PQM13 is 4.2kw X 2. Not wanting to fry the 18nlw9000 I put the volume pots at just over half way which should be a solid 2.2kw ish... and it was noticeably quiter than it was in stereo which is 1.3kw. I don't understand what's going on! |
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cravings
Old Croc Joined: 30 January 2007 Location: Ireland Status: Offline Points: 7441 |
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sorry if this is oversimplistic... but are you sure you're wiring them correctly for bridged mode? i have some 2100x and i'll look at them later cos i'm curious, but normally as well as switching the amp to bridge mode, you need to connect to pins +1 and +2 on the channel A speakon (same as +1 on channel A speakon and +1 on channel b speakon).
i don't know the SAE ones at all though. |
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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No its not oversimplistic, I think this is the problem 😂
I had no idea. Amps seem fine though, they just weren't very loud. Im looking that up now. |
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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So all my cables are nl2..
So I need to buy two nl4 male speakons, fit them to a couple of my cables and designate these for use in bridge mode only and wire them as you said. Damn. I always wondered why Amps either use nl4 outputs or have a separate bridge output like the peavey pv2600. So what did I do by connecting a normally wired nl2 to an nl4 amp socket that was configured for bridge mode?! Neither amp or speaker appears to have taken any harm |
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Timebomb
Old Croc Joined: 11 October 2004 Location: Lancaster Status: Offline Points: 2716 |
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Most likely connected 1 channel and ground.
turning gain pots to half way is not half power... its dosent work like that as it all depends on the input voltage , you could be close to clip, or you could be delivering 1 volt on the output depending on your input voltage... Assuming the clip led is correct then thats full power, 3db less than that is half power. TBH im not really sure i should be encouraging you to measure output voltage if you dont understand the basics, dont mean to be rude mate, id suggest reading a bit on voltage gain though and amp and how volts translates to "speaker watts" (V^2/R)
Edited by Timebomb - 27 August 2016 at 5:57pm |
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James Secker facebook.com/soundgearuk
James@soundgear.co.uk www.soundgear.co.uk |
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cravings
Old Croc Joined: 30 January 2007 Location: Ireland Status: Offline Points: 7441 |
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and you'll need to turn up both amp channels too (i think). pm or mail robin at matrix to make sure.. haven't noticed him on here in a while but he's normally pretty responsive to queries like this.
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charlysays
Registered User Joined: 16 June 2015 Location: Wales Status: Offline Points: 413 |
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No worries, I've got a lot more to learn there...totally crap at maths in particular.
I've got brick wall limiters in place to limit signal to 0.775v... Turning the gain pots to half makes the amp half as sensitive. So provided the limiters maintain a brick wall, the amp should be half as powerful with the pots at half way surely. Because in that setup it'd need 1.5v to clip. |
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