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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Audio Measurement and Testing => Topic started by: jamie ashton on January 22, 2019, 05:52:28 pm

Title: RE: smaart advice/opinion please
Post by: jamie ashton on January 22, 2019, 05:52:28 pm
Hoping someone with more knowledge than myself could take a look at a measurement I have recently made with my mid tops please.
They are tannoy vnet 100s, powered with the linea research amps and dsp. Crossover points are 450hz dsp generated from dual 12s to 2" and 6.3k passive between 2" and 1". All wiring from amp to drivers is positive polarity and this has been confirmed to be correct by tannoy.
I noticed something lacking in the top end so decided to have a look. I'm not very experienced with smaart but competent enough to understand to an extent.
Attached is my response taken with program material with dual fft.
Measured in my local small to medium sized club, measurement mic approximately 1 metre from the cab between the horn and dual 12 section. Any help would be greatly appreciated.
Title: Re: RE: smaart advice/opinion please
Post by: Alex Pregel on January 22, 2019, 06:03:09 pm
It looks like a polarity or timing issue (very unlucky mic placement). On the data sheet for your speakers, there is a passive crossover at 7kHz, right around where the dip is. It could also just be an unlucky microphone position where those two drivers have phase issues at 7kHz. When you move the mic a little bit does the dip move? If it does, it's the timing/phase cancelation. If not, it's probably a polarity issue with the HF driver. (My bet is a polarity issue)

Hoping someone with more knowledge than myself could take a look at a measurement I have recently made with my mid tops please.
They are tannoy vnet 100s, powered with the linea research amps and dsp. Crossover points are 450hz dsp generated from dual 12s to 2" and 6.3k passive between 2" and 1". All wiring from amp to drivers is positive polarity and this has been confirmed to be correct by tannoy.
I noticed something lacking in the top end so decided to have a look. I'm not very experienced with smaart but competent enough to understand to an extent.
Attached is my response taken with program material with dual fft.
Measured in my local small to medium sized club, measurement mic approximately 1 metre from the cab between the horn and dual 12 section. Any help would be greatly appreciated.
Title: Re: RE: smaart advice/opinion please
Post by: jamie ashton on January 22, 2019, 06:27:52 pm
It looks like a polarity or timing issue (very unlucky mic placement). On the data sheet for your speakers, there is a passive crossover at 7kHz, right around where the dip is. It could also just be an unlucky microphone position where those two drivers have phase issues at 7kHz. When you move the mic a little bit does the dip move? If it does, it's the timing/phase cancelation. If not, it's probably a polarity issue with the HF driver. (My bet is a polarity issue)
  yes I thought polarity too so I inverted the 1" and got this.  But has it now made the phase wrong?
Title: Re: RE: smaart advice/opinion please
Post by: Jeremy Young on January 22, 2019, 07:21:18 pm
Looks like an improvement in the phase to me. 
Title: Re: RE: smaart advice/opinion please
Post by: David Sturzenbecher on January 22, 2019, 09:14:29 pm
  yes I thought polarity too so I inverted the 1" and got this.  But has it now made the phase wrong?
What is wrong about it?


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Title: Re: RE: smaart advice/opinion please
Post by: jamie ashton on January 23, 2019, 04:28:42 am
What is wrong about it?




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I thought with the extra phase wrap and there being no line at the crossover point that it is now out of phase even though the dip is fixed. Whereas on the first screenshot it's one continuous line that's at 0 at 7k. As I say I'm not that knowledgeable but I have an idea.
Title: Re: RE: smaart advice/opinion please
Post by: Sam Feine on January 23, 2019, 08:15:32 am
Did you have Smaart re-time align once the HF polarity was flipped?
That might be the cause of your extra wrap.